Michael’s Blog

Targa is over for another year. It takes a while to come back to earth after the event and this year was no exception.  2008 was my 5th year of Targa competition and certainly one of the better ones. With AHX12 now in its 4th year in the event I believe we have sorted out most of the bugs and turned it into a very competitive Targa car and Michael Oritt, my neophyte co-driver in 2007, really came into his own and started feeding me accurate and timely instructions throughout the grueling 5 day event.
There is no question that Blair Harber’s vision for AHX12 seems to be coming to fruition. When he and I competed in 2003 and 2004 the car performed very well and proved to be quite reliable but after a 2 year hiatus Michael and I found last year that the intensity of the competition had risen to a new level and the 6th overall position that Blair and I achieved in 2003 was not going to be easy to repeat.

As can be read in my earlier posts I made some substantial improvements to the rear axle casing on “12” this year to overcome the weaknesses revealed in our minor off road excursion in 2007. There is no question that designing and installing the 4 link system with the Watt’s linkage was a good decision, but minor bugs in the new design proved to be the weak link in our campaign last year and, unfortunately, again this year.

In 2008 Targa reconfirmed its reputation as “The Ironman of Motorsport” with Eastern Newfoundland’s rough and twisting roads taking the usual toll of competitors. The results show that of the 48 starters in the Targa Class, 3 cars rolled,  4 scratched with mechanical problems and one went “off road”, which is never a good thing in Newfoundland because the locals store their rocks in the roadside ditches.

With Michael’s vastly improved navigating skills we managed to keep AHX12 on the black stuff throughout the entire event and only went off course once while trying to negotiate an extremely complex intersection which was very poorly illustrated in the route book.

Unfortunately after securing a solid 1st place over the first twelve stages “12” met her match in the form of a huge pothole on the extremely rough Glenwood Stage on day two.

As soon as we started this penultimate stage of the day things started to go “pear shaped”. The road was so rough that in my efforts to drive around rather than over the holes and bumps I found that we were starting to run behind our required average speed. As we rounded the last sweeping right curve of the stage we were about 0.1 KPH over the required average so I deliberately took a wide line with a late apex in order to keep up our average and hopefully “clean” the stage. Great idea, poor execution. So intent was I on looking ahead to get the best speed through the turn that I  missed seeing the huge crater on the left side of my line until the very last second and, with the car on the limit of the adhesion of the Avon tires, we just didn’t have the grip to jog right and avoid it. You can view Keith Tanner’s video of the stage taken from his Miata here to see just how rough the stage was.

“12″ hit the hole with a tremendous crash and immediately the car slewed right, almost spinning. The impact on the already fully compressed left rear suspension was just too much for the lower left suspension link and the head of its rod end parted from the thread. This resulted in all the forces being transferred to the upper right link and it too collapsed. With nothing to stop the differential from rotating under braking or acceleration we weaved down the last 200 meter straight, virtually out of control, to cross the finish 11 seconds late.

As it turned out only one car cleaned the stage and if we had made it we would have retained first position with a one second lead over the eventual winner.

When we jacked the car up on the side of the road a few yards from the finish I realized that we were very lucky to have finished the stage at all as the only thing stopping the entire differential assembly from rotating was the coilovers!
A quick radio call summoned our support crew with the Carcamel.  Being able to load the Healey onto the Camel and, against all the rules, quickly transport it to the start of the next stage saved the day. As we whistled down the Trans Canada Highway the support crew and I formulated a plan.
Upon our arrival at the start of the next stage in Gander we unloaded the car and used the tie down straps from the transporter to lash the rear axle to the frame so that we could at least try to complete the 7 kilometer stage within the trophy time.
Perhaps an explanation of “trophy time” required. The first goal of all the Targa crews competing is to complete every stage of the event in “trophy time” which is 35% longer than the target or “base time” for the stage. One makes target time for an overall win but you only have to make trophy time to get the coveted Targa Plate.
With the precarious condition of the car we were granted permission to start the stage as last car. This removed the necessity for me to watch for cars catching us as we weaved and wobbled a wounded “12” through the stage and meant that we wouldn’t hold anyone up..
As luck would have it the start of the stage was delayed which resulted in the last cars starting in the dark which in turn resulted in the stage being downgraded to condition 2 and our just making our trophy time.

We limped back to the service point at the Gander Arena to see what could be done to repair the rear suspension. This was achieved with the help of the good people from the Gander Arena and in particular Andy Gillingham who took our 2 broken rod ends, and a third which was cracked, and welded them back together to get us through the event.

Thanks again Andy and the team at the arena; that’s 2 years in succession that you have saved our bacon.
Although we were still in the running for our Targa Plate the 11 seconds in Glenwood and then the 2 minutes 45 seconds in Gander had dropped us back to 32nd place overall. This was starting to look like a repeat of 2007!!

The rest of the event was relatively uneventful for us, but some entrants had their moments!!

With dogged determination and the usual attrition we managed to work our way back up to 23rd by the end of day three,  15th by the end of day 4 and then finished in 9th place overall just ahead of Frank Sprongl 3 time North American and five time Canadian Rally Champion in an awesome 1983 factory prepared Audi Quatro Coupe.

When we got back home I pulled the rear suspension apart to see if I could determine what went wrong. It didn’t take too long to figure it out. The problem was my choice of parts because, in my efforts to economize, I opted for less expensive rod ends and careful examination of them and their specifications revealed that their ultimate tensile strength was only around 7000 lbs, plenty for normal driving but when subjected to the loads that the Glenwood pothole provided they just couldn’t take it.

I have changed them all and “12” now sports 8 new QA1 XMR rod ends good for over 16,000 lbs. definitely a case of “racing improves the breed”.

ROLL ON 2009….

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There are many definitions of “handicapping” but Wikipedia states:
Handicapping, in sport and games, is the practice of assigning advantage through scoring compensation or other advantage given to different contestants to equalize the chances of winning.

I’m sure with the best of intentions the organizers of The Targa Newfoundland have, for the last 7 years, used a system of “Targa Factors” or handicaps in an effort to give every entrant a chance of winning the coveted Christos Targa Award, which is presented to the overall winner

Obviously in the early days of the event assigning appropriate handicaps, or for that matter even establishing classes, was by necessity a very “hit and miss” exercise. I understand that the organizers based their system on that in use in Targa Tasmania and applied “local content” as required but exactly how these factors are calculated is something of a mystery.

It seems to me, that with seven events now completed sufficient data has been accumulated to assign handicaps based upon actual performances and by so doing the real aim of a handicapping system could be achieved.

There are several sports which use handicapping but the best known is golf wherein handicaps are assigned by calculating an individual competitors playing ability from his recent history of rounds with the intention of giving every competitor an equal chance of winning. I thought I would try to apply this method of handicapping to Targa.
The results are very interesting and go a long way toward explaining why there have only ever been three Modern Division cars in the top three placings at Targa Newfoundland in seven years of competition.

The method that I used to establish the “results based” handicap is explained below***.

In the five days of competition the fastest cars take around 180 minutes to traverse all the stages and the following list shows the difference between the two handicapping systems expressed in minutes in 180 minutes.

Just to be clear this list shows the disadvantage that the current system applies to each class of car.

Class 3 Standard Large Capacity 0.0 minutes

Class 4 Modified Large Capacity 3.3 minutes

Class 6 Modified Large Capacity 5.8 minutes

Class 4 Modified Small Capacity 6.7 minutes

Class 9 Standard large Capacity 7.2 minutes

Calss 3 Modified Small Capacity 8.6 minutes

Class 8 Modified Large Capacity 11.0 minutes

Class 5 Modified Large Capacity 11.0 minutes

Class 7 Standard Large Capacity 11.3 minutes

Class 9 Standard Small Capacity 11.6 minutes

Class 5 Modified small Capacity 12.1 minutes

Class 5 Standard large Capacity 12.1 minutes

Class 2 Standard large Capacity 12.1 minutes

Class 9 Modified Large Capacity 13.9 minutes

Class 4 Standard Large Capacity 14.1 minutes

Class 8 Standard large Capacity 14.8 minutes

Class 2 Modified Small Capacity 16.1 minutes

Class 1 Unlimited 16.5 minutes

Class 5 Standard Small Capacity 16.7 minutes

Class 7 Modified Small Capacity 17.3 minutes

Class 2 Modified Large Capacity 22.2 minutes

Class 7 Modified Large Capacity 28.7 minutes

Class 8 modified Small Capacity 37.4 minutes

Class 9 Modified Small Capacity 44.6 minutes

Class 6 Standard Small Capacity 47.0 minutes

As I mentioned above, the results are very interesting.

For example, under the current Targa Factor system, the minimum Modern Class disadvantage is 7 minutes and 12 seconds  when compared to a Class 3 Standard Large Capacity car. It is hardly surprising that in seven years of competition Modern Class cars have only ever placed 2nd once and 3rd twice.

*** Methodology

In my study I have used stages for 2005, 06, 07, and 08 where 10 or less competing cars “cleaned” the stage to minimize situations where a competing team “backs off” to save their car when they have plenty of time in hand.

From those stages I have taken the fastest car in each of the competing classes and compared its time to that of the fastest car through the stage. By dividing the competitor’s time by that of the fastest car I was able to establish a factor for each car for each of these stages.

Once all these factors were calculated I eliminated the fastest (smallest factor numerically) and the 3 slowest (largest factors numerically) for each car (to eradicate miracles and “screw-up’s’) and then averaged the remaining factors.

Using this method establishes a factor for each class within which there has been a competitor since 2005 and from this a true “Results Based” handicap system can be developed.

Targa Newfoundland Forum discussion on this subject can be found here:

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I hesitate to say this, but I think the time has come where I have to admit that I have more projects than I’m ever going to finish and more cars than I’m ever going to drive. I always dreamed of having a decent sized shop at home where I would be able to work away on these projects and get them restored to the condition I wanted but circumstances have changed as, to an extent, have my interests. So, after some sleepless nights thinking about it I have decided to find new homes for some of my cars.
Over the last few years I have whittled things down to more manageable proportions; there was a time when I had about 12 projects either awaiting work or on the go but now some have been finished and some have been sold so that number has dwindled to five.
Now that I have made that decision I have to wrestle with which cars have to go.
First there are the two minis which have been in indoor heated storage for years. These two are the last of the 22 minis that I imported from New Zealand in the early days of this millennium.

This picture is proof positive that 8 minis will fit into one 40′ shipping container. You have to remove the wheels and build a fairly substantial trestle to support the top layer, but it can be done.

The whole exercise was prompted by the numerous inquiries that I received from customers of Precision Sportscar who were looking for minis to restore. Because minis in their day were the cheapest cars available in Canada they were all driven in the winter and as a result rotted away to the point where they were well beyond economical or safe repair. On the other hand however, cars in New Zealand never see salt and therefore rust is virtually unknown.
The two I have left are ones for which I had plans. One is an 1971 Mini Estate. I bought this one in Christchurch and it had been a competitor in a local fun event named the “Undie 500″.

These are somewhat rare in North America and my intention was to restore it as a Mini Traveller, the model which is affectionately known as a “Woody” like the one in this picture.

I don’t own this one sorry to say. 

The problem with the original Mini Woodies is the wood. This timber, which is purely decorative, has a tendency to absorb water and rust the metal beneath it. The Estate is a Woody without the wood and the wood, which apparently is ash, is available as a kit.  A great project that I’m just not going to get to.
The other mini is a regular 1978 sedan completely solid with a few minor battle scars but again a great starting point for an easy, inexpensive and fun restoration project.

Next on my list is my 1970 MGBGT. I always loved the BGT as a model; it was a brilliant design for its day and I have owned this one since 1975. That’s 33 years!! I’m the second owner and I haven’t used the car since about 1982 which is long before digital cameras so I don’t even have a picture of it but here is a site that describes the model. The car started life as a right hand drive with wire wheels and overdrive and was imported into Canada by a chap who immigrated from the UK. He traded it in on a Jaguar XJ6 at our local British Leyland dealer and I remember him calling me not long after I had bought it, when he was suffering from a bout of sellers remorse, and asked if he could buy it back. I converted it to left hand drive using all the correct components and drove it for several summers before I bought my first Healey.. just never seemed to get back to it.
Reluctantly I think my Bugeye Sprite race car has to go as well.

The Bugeye Racer at Mosport in the mid 80s

This is a photo of Tom Haubert racing it at Mosport with a special fiberglass nose in the  ’70s.

I’m also considering selling my 1992 Mitsubishi 3000 GT VR4. This model was never imported into Canada but this one has been legally imported and licensed.

I have really enjoyed this VR4 but Winter Storage Space has become a problem.

This has been my occasional summer driver for the last few years and, unlike most VR4s, is in remarkable original condition. From the time I read the first Road and Track road test of the VR4 I decided that one day I was going to get one for myself. This 320 BHP, twin turbo, intercooled, all wheel steering, all wheel drive grand touring coupe was, at the time, the fastest road car that they had ever run through their slalom test course and even today its performance is impressive. It now has over 100K miles on it and is fast, comfortable and reliable

How much you ask. Well I’m open to reasonable offers but they would have to be close to these. The $us prices were the the equivalent at the time of writing but should be taken a a guide only.

Mini Estate : $CDN8,500 ($US8000)

Mini Sedan : $CDN 4,800   SOLD

MGBGT : $CDN7,500 ($US7100)

Bugeye Racer : $CDN11,500   SOLD

Mitsubishi 3000 GT VR4 $CDN16,500 ($US15,600)

If you are interested in any of these please contact me.mailto:magicareprotect-usedparts@yahoo.ca

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For those who aren’t members of The Austin Healey Club U.S.A. and therefore don’t get the Austin Healey Magazine I have posted this article that I wrote at the request of Gary Anderson the editor.

Targa Newfoundland is a highly addictive event. Billed as “The Ultimate Motorsports Adventure“ the event is rapidly gaining a reputation as a test of endurance for man and machine. On the 2007 running of the Targa, Michael Oritt and I learned how challenging “The Targa” can be.

In 2003 and 2004, Blair Harber and I competed in AHX12, the 12th Austin Healey ever built, which he and I had restored and modified within the classic traditions for just such an event.

We achieved a Targa Plate both times for completing every stage within the so called “Plate Time.” But the organizers, knowing that the easiest customer to attract is one who is already converted, follow the traditions of the Alpine rally and dangle a Gold Plate in front of you as the award for completing three events within plate time. So, after a two year hiatus, the quest for gold was the carrot which drew me back.

After months of preparation we loaded AHX12 onto my special transporter, and with “Betty” – the ’59 mini campaigned by my brother-in-law and long-time friend Dick Paterson – on a trailer behind headed off on the 2100 km journey to St John’s, Newfoundland.

We arrived in St Johns early on Saturday 8 September and spent the rest of the day checking the cars over, completing the necessary formalities and calibrating our odometers in time to be ready for the Prologue on Sunday, 9 September 07.

Day 1: Prologue

The Prologue is really just an opportunity for the crews to shake down their equipment, and for the organizers to get some comparative times to set the start order for the first day of competition. In the right seat of AHX12 this year was Michael Oritt from Solomon’s , Maryland, an admittedly very “green” co-pilot.

 Although Michael had competed in a prestigious European event some years previously, performance rallying was to be a new experience. With its full cage and hardtop AHX12 is not the easiest car to get in and out of, so it took a few attempts to formulate an entry /exit procedure and, once Michael was comfortably installed, he was content to stay put as long as possible.  We had run through the first prologue stage the previous day as part of our mileage check; in fact Michael and I ran it about five times before we were happy with the calibration of our Brantz Rallymeter, so the prologue stages gave us the opportunity to make a start on sorting out terminology. Prior to the event I had tried to work out with Michael the terms he could use to consistently and quickly describe the turns detailed in the instructions. I don’t think I did a very good job because we were still working on this toward the end of the last day!

We made it through the two prologue stages without problems, and although a little apprehensive, felt we were as prepared as possible for the next day.

Day Two: Leg 1, North Avalon

For those not familiar with the format of this type of event, a short primer: The Targa consists of five days of competition. with each day including between six and nine “stages.” A “stage” is a section of road which is closed to the public with all the side roads and drive-ways taped off to prevent public access. Marshals are positioned along the route to ensure that the road is clear and that any spectators are safely positioned. Once this is all set up, the competing cars, starting at 30-second intervals, drive through the stage as fast as necessary to attain what is often an impossibly fast average speed. Each car has a driver and a navigator and the navigator is provided with a book of “tulip” diagrams which describe sections of the course which depart from the normal flow of the road. 

Sounds easy, right? …Wrong. The roads in Newfoundland are often very rough which, in addition to being really hard on the machinery, makes even reading the route book very difficult.

Unlike our 2004 start we actually turned the correct way out of the parking lot at the start this year…big bonus…and for the first three stages we did pretty well. The second stage was a bit of a wake-up call for us all and a sad day for Healeys.

As we lined up to start the stage, being the first Targa car for the day after the Touring class cars had been sent off, there was a little commotion among the marshals and the stage was held while an ambulance tore off into the course.Seconds later we were asked if we were ready to start and, despite my protestations that the ambulance must surely still be on the course, we were sent off into the stage.

 I found that I had to keep the pedal down fairly hard to maintain our required 78 KPH average sped through this windy and bumpy stage and then as we hit an enormous bump in a long sweeping left hand curve, which launched AHX12 into the air and threw us sideways several feet, I was startled to hear Michael shout, “ambulance.” I had been concentrating so hard on the road surface that I hadn’t even seen the huge white and red behemoth on the side of the road and only caught a fleeting but very up-close glance of it as we passed by with all four wheels off the ground To this day I have no idea how we missed it, but in the same instant I caught sight of the unmistakable profile of a turquoise Healey well off the road and bent over some very large rocks.

This car, running in the Touring class, was the only other Healey in the event and was severely damaged and had been the reason for the ambulance call. Fortunately. neither one of the father and son team of Ivan and Ian Shelton was seriously hurt but the Healey looked like it would need some serous renovation.

After we had passedthe stage was closed while the ambulance made its way off the course and then when it reopened one of the open class cars came to grief in the same spot.

Targa Newfoundland is indeed a tough event!!!

  The fourth stage, named Northwest Brook, proved to be our undoing. The stage was originally meant to be 31 kilometers long, but when we arrived we were informed that it had been shortened to only 13 kilometers and we were to start at the 18.6 kilometer mark. This change created some problems for us and within one kilometer we went off the road when we missed a left turn at the top of a crest. One of the disadvantages of running a Healey in this type of event is that the combination of long nose and low seating position makes seeing the road ahead very difficult as the car crests a hill, and it is that which caught us out. AHX12 gracefully flew over a large ditch on to a beautifully manicured lawn and landed on top of one of the two fairly substantial pine trees we had flattened.

 

 

 

Michael and I climbed out just in time to dive for cover as a Porsche 914 almost landed on top of us. Fortunately, he managed to miss the ditch and was able to carry on, though a little more cautiously. After a bit of a struggle we succeeded in extricating a slightly less pristine Healey from the trees and, after a quick check for damage, we managed to carry on through the stage.

 

 

Unfortunately that incident, as well as causing sufficient of a delay to put us firmly out of contention for a Plate, caused hidden damage which would return to haunt us later in the day.

There were only two more stages on that day, both of which we “cleaned” easily before starting out on a 120-kilometer transit to the town of Gander. As we neared the end this I made the fatal mistake of commenting to Michael: “I am amazed at how much abuse this car can take and keep going.” At that very moment, with a bump and a grind, a rear axle shaft broke, allowing us to just limp to the end of the day courtesy of AHX12’s Dana limited slip differential.

 

 

Our crew jumped into action and despite considerable difficulty, had the broken shaft out within a couple of hours while I phoned Toronto to arrange to have the only spare in the world flown out to us, a process which would take until well into the next day.

Day 3: Leg 2 – Exploits
It was a pretty disappointed pair of Healey enthusiasts who stood aside and watched as the rest of the cars headed of on Leg Two, knowing that we were out of the running; little did we realize that there was worse to come. The axle shaft arrived late in the afternoon but, when we went to install it there was more bad news: the entire axle casing had been bent in our “tree felling” excursion requiring that we remove the entire rear axle assembly and try to straighten the case before we could continue.    

 

 

Then, to add complications to the process the crew of “Betty” showed up with Betty on a flatbed truck. They had cooked Betty’s engine as a result of a serious water pump leak…the day was not going well

Once the diff was out we took it over to a nearby gas station where the resourceful mechanics used a pair of axle stands, a sledge hammer, a five-ton truck on a hoist and a large oxyacetylene torch to straighten the case.

 

 

They finished their work around midnight after which our youngest crew member and I worked until three a.m. to reinstall the diff, only to discover that the spare axle, shipped in from Toronto was too short for the modified differential.

Day 4: Leg 3 – Kittiwake
The next morning we pulled the axle out again and took it to a local machine shop where, using an ancient and very secret Kiwi technique, they lengthened it by half an inch! Sadly for us this process and the time needed to catch up on the rally, which by this time had moved 200 kilometers south to Clarenville, took up the entire day so we missed our second day of competition.

Day 5: Leg 4 – Heritage
We were up bright and early and off down Newfoundland’s Burin Peninsular for a long seven-stage day centered on Marystown. 

 

 

 

 

 

 

After so much rebuilding and patching I made a point of taking it easy for the first stage as the goal now was to finish.Nevertheless, AHX12 seemed to be handling and performing well, so we cranked the pace up a little for the next four stages, but during the fast Garnish stage the differential started to emit some new and rather alarming noises, indicating that all was not well. We managed to complete the short Fortune town stage but decided that we had best skip the last two of the day and head back to Marystown to investigate the problem before something failed
catastrophically.When we removed the differential we found that the crownwheel bolts had come loose. These were the original Healey 100 BSF bolts. They had stretched and were looking decidedly worse for wear. As we didn’t have any spares, I decided to apply Locktite and tighten them as much as I dared. The next day had seven stages and I was far from confident that these over-strained,  45-year-old fasteners were going to make it through.

 Day 6: Leg 5 – Avalon
Our accumulated penalties of the last three days had managed to push us down to 46th position out of the 53 cars still running and I stagger to think of the trials that those crews who were trailing us must have suffered!Now it really was a case of just making it to the end, and to add to our woes was a 190-kilometer transit to the beginning of the first stage. My concern about the crown wheel bolts was that a seized differential in the middle of a stage could have some fairly serious consequences and even before we had finished the transit the diff was starting to complain.Interestingly, one of the odd phenomenon of Targa competition is that if you try to drive a little slower than normal you are inclined to make mistakes so I decided to drive as quickly and smoothly as I could hoping that we could avoid mistakes and preserve our differential.

The first stage, Osprey Trail East, was an easy one which had been shortened and we breezed through with 33 seconds to spare.The second stage of the day, Spaniards’ Bay/Bishop’s Cove, was a really tough one. In previous years of the event some cars were “clean” up until the very last stages of the last day, so the organizers had decided to insert four stages with impossibly fast times to prevent a draw. We took 57 seconds of penalty but were still running. 

 

 

Two stages later we ran Brigus, a short fast town stage, requiring us to maintain an 84 KPH average. Incredibly, while trying to drive as smoothly as I could, we still managed to be one of only 12 cars which cleaned this stage and the two following ones. Unfortunately, this was followed by a 25-second penalty in the final stage of the event, during which we missed a turn and nearly took out a 15-foot-high rock.AHX12 had survived yet another Targa Newfoundland. Despite placing a rather ignominious 44th, we had still managed to win our class and at the gala were delighted to learn that our efforts to finish had resulted in our being voted the co-winners of The Spirit of Targa Award by our fellow competitors. The other winners were the crew of Betty who, after overheating and ruining one engine, trucked their car all the way back to St. Johns and worked for three days and nights to replace their fuel-injected, dry-sumped, crossflow-head engine with one from a regular Cooper S in time to complete the final few stages.

 

Once again Targa Newfoundland had confirmed its reputation as a tough but very memorable event. My calendar says I’ve got 353 days left to rebuild AHX12 in time for next year’s event.

You can view the complete results for the 2007 Targa Newfoundland here.

 

 

 

 

 

 

 

       

 

 

 

 

 

3 Comments »

Thanks to the very welcome advice of Jim Hockert, Mike Gladwin, Bob Haskell, Richard Ewald, Dallas Congleton and Ken Freese, all of whom made very worthwhile suggestions, I think we have the problem solved. My idea of the tab washers became a non starter when I realized that I would be unable to get a socket on the bolt heads with them in place .
The solution that I have finally settled upon is a combination of recommendations and involves using Loctite, hardened (grade 8 ) washers and lock wire in grooves cut into the side of the cage.

As Richard suggested, it is very likely that the Loctite job that I did between legs in Marystown, Newfoundland, with the lack of a torque wrench, stretching bolts and insufficient time to allow the Loctite to properly set up was almost certainly far from satisfactory.
This time I have used new alloy steel bolts and Loctite 243, an oil resistant grade .  As recommended I spent lots of time properly cleaning the threads on the bolts and in the blind holes in the crownwheel before assembly.
Using a modified version of Jim’s recommendation I drilled the bolt heads and, with a cutoff wheel, cut slots between pairs of bolts to accommodate lock wire installed after torquing them to 45 lb ft.
I’m still debating whether or not to use J B Weld to “glue” the lock wire into the slots to preclude the possibility of it slipping out and getting damaged through contact with the carrier….stay tuned.
Again thanks to all who took the time to read my post and recommend solutions to this problem.

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As noted in my previous post one of the problems we had with AHX12 in the 2007 Targa Newfoundland was caused by the stretching of BSF bolts which hold the crownwheel to the differential carrier. These 50 year old bolts, made at a time when the quality of  fasteners available in Britain was not that good, were not up to the rigors of Targa.  

The rules for Targa Newfoundland read as follows:
The central differential housing must remain OES.
The carrier, ring/pinion, axles, and all bearings are free.
Mechanical limited slip differentials are free.
The diff in AHX12 is not your run of the mill BN1 unit. In my previous post I have explained how we have managed to retain the central differential housing but strengthened the outboard sections to resolve the problem of the inherent weakness of the BN1 style case.
The carrier is a standard BN1 item, however the cage is from a Studebaker Lark V8 and incorporates a Dana POWR-LOK 27 limited slip unit. In order to get this cage assembly into the BN1 housing we had to turn down the bearing mount on one end of it and install a BN1 style ball bearing there, and use one of the taper roller bearings from the Dana unit on the other end.

Next an annular ring was machined and welded on to produce a correctly sized and positioned mount for the 32 tooth crownwheel from the 3.55/1 ratio gear set. This is what the whole thing looks like with the crownwheel not installed.
With this arrangement the cage assembly ends up being very close to the housing and, as there was insufficient clearance for the heads of the crownwheel mounting bolts, we counter-bored holes to recess the heads below the surface of the cage.

As the crownwheel is on the right side, when these bolts started to back off, their heads contacted the carrier casting which in turn tended to loosen them further. The noise generated as their heads ground away at the cast aluminium carrier was quite dreadful.

In this picture you can see just how much material was worn away.

Now, as I’m rebuilding the diff unit, I am somewhat perplexed as to how to prevent a reoccurrence of this issue. Previously I had used Loctite and good lock washers to lock the crownwheel bolts but even though the real problem was initiated by the stretching of the bolts I’m not confident that this locking method is satisfactory.
In the original BN1 differential 4 two hole tab washers were used to mechanically lock the bolt heads but, because our bolt heads are recessed, that system won’t work.

After considering drilling the bolt heads and lock wiring them, or drilling the heads, tapping a small thread in the hole then installing a tiny Allan head screw into the hole to be tightened against the wall of the recess, the best that I’ve been able to come up with is to make some two eared tab washers like this.

The flat tab would project through the gap at the outer edge of the counterbore and the turned up tab would be pressed against a flat of the bolt head to prevent it from loosening off.
Unfortunately I’ve been unable to find a production tab washer of this type so it would appear that my only options are to grind and file some out of some 3/8” fender washers, very time consuming, or have them laser cut, very expensive.

Does anybody out there have a better idea…

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The Targa Newfoundland 2007 is over and it proved to be a very revealing test of my revisions to AHX12’s rear suspension. By reading my previous posts on the subject you will get an appreciation of why I decided to make this fairly radical change to the suspension and how I did it.

All in all the suspension system was a success. I managed to get quite a bit of track time with the car after the work was completed and, once I had managed to sort out anti roll bar settings and find suitable tires, there was no question that there was a dramatic improvement in the handling. Unfortunately driving around a smooth race track is not the way to test for Targa conditions. The roads in Newfoundland haven’t improved much over the last 5 years and at best they could only be described as “rough”. Frost heave is a big problem in the maritime climate and the damage that this causes to the roads is something that needs to be seen to be appreciated.It was not the rough roads however which proved to be a test of the new set up but a small “off-road excursion” on the first day of competition.This “incident” in part involved jumping over a rather substantial ditch before bowling over a couple of small pine trees and coming to rest on top of one of them.  

 The “jumping” part of course resulted in a “landing” part and it is that which, as is normally the case, caused the damage. Although we managed to get the car off the trees and continue on our way we were not aware that the rear axle casing was bent and that the axle shafts were being subjected to enormous stresses which would result in the failure of one some 200 kilometers down the road.

For those of you who have managed to stay awake this far here is an analysis of what actually happened.

You will recall that to install the coilover suspension I fabricated plates with gussets on them to pick up the lower end of the coilovers. This moved the point where the axle casing was subjected to the weight of the car inward about 2″.

This increased the moment about the wheel by about 20%. I figured that this in of itself would present no real problems. Little did I realize that the BN1 axle casing had an inherent design flaw. As depicted in the drawing there is a very sudden change in section of the casing about 3″ inboard of the spring bracket. This change of section makes the tube very weak at that point. For this weak area the additional moment resulting from the movement of the load together with the ditch jump was just too much and it bent at this point on both sides.

This bending caused the axle shafts to rub on a scroll seal which is inside the machined “snouts” which the rear hub bearings mount on. I actually had no idea that there was a scroll seal in there and cannot really figure out why it is necessary. Anyway this rubbing of the shafts on the seal must have been sufficient, after a long straight run, to heat up the axle shaft to the point where it was weakened and it broke.

In the photo below the difference between dimensions “A” and “B” is an indication of how much the casing had bent.

The BN1 differential is a spiral bevel unit and uses an Austin casing which interestingly is pressed from one piece of 0.140″ thick steel. When we had the diff out and in pieces on the ground one of the onlookers started taking photographs of the casing and studying it very closely. I got chatting to him and found out that he worked for a manufacturer of differential casings in Toronto. It just so happened that they were just “inventing” a completely new system of pressing out diff casings using one piece of steel and he was dumbfounded to hear that the same process had been used by Austin some 60 years previously!!

It was not until I got the car back home and took a look the axle casing on my 100S that I realized that the Healeys must have been aware of this weakness. The 100S differential although still a spiral bevel unit uses a casing which does not have this change of section, in fact the 100S axle casing doesn’t look like an Austin axle casing at all but appears to be a Morris pressing much like that used in the BN2 and later Healeys. These casings are made in the more traditional method using 2 halves welded together. I suspect that the 100S used a modified MGA casing. As I don’t have many spare 100S diff housings lying around I had to come up with a modification to strengthen what we were using in AHX12. I could have opted to install a BN2 type axle but the BN1 unit is considerably lighter and I have a substantial investment in special axle shafts, hubs and limited slip units which would not be of use with the BN2 diff.

This is my solution.

I have cut the original housing off just inboard of where it would normally contact the frame rails on full droop and replaced the outer sections with 2.5″ 0.187 wall welded tube.  

The original “snouts” from the old diff have been turned down and welded onto the ends of the new tubes after 4 laser cut brackets, with pick up points for the radius arms and coilovers, were installed. This is what the fnished job looks like prior to the installation of the hub and brake.

All this work should go a long way toward strengthening the rear end which of course wouldn’t be necessary if I would just stay on the road!!                   

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At last we are ready to leave for the 2007 Targa Newfoundland. With Michael Oritt as my co-driver we have been lucky enough to join a “marque” team called “Brick and Brute Racing” The other team members are cars #301, a 1963 Mini Cooper “S” crewed by Dyrk Bolger and Terry Milnes and #307 the highly modified 1959 Mini run by my buddy Dick Paterson with Tony Mattson from New Zealand as co-driver.

After consulting with various people I decided to use Avon CR6ZZ tires for this year. These have a wear rating of only 80 and are so soft that your finger almost sinks up to the first knuckle when you press into the tread. Apparently these are what the “hot shoes” in Europe and Australia are running, and although they are somewhat narrower than the tires we have run in previous years they are much stickier. These tires don’t have the radical tread pattern that you see on the tires most of the other cars are running but, by most reports, they still work well in the wet….we shall see. You will be able to track our progress throughout the event here.

After having the rear bodywork on AHX12 damaged during transportation in 2004 we decided to haul both cars down to Newfoundland with my transporter (see below) and I have built a special trailer for Dick’s mini which will tag along behind.

In desigining the mini’s trailer I chose to ignore the advice that I received on draw bar weight and my first attempt resulted in some “issues” with trailer sway on test drives. Good trailer design calls for 12 - 15% ot the total weight of the trailer to be the tongue weight. I enquired of a couple of trailer makers but no one could explain why a zero tongue weight trailer would not be satisfactory so that is what I built. Well….it turns out that there is a very good reason for that tongue weight rule and it was only after thinking about it for a while that I have concluded what it is. I will try to explain and I’m sure that Steve Byers will correct my terminology after he reads this through .This is the way I understand it.

If you have a single axle trailer hooked onto the back of a car and you push sideways on the back of the trailer you will find that the trailer tends to rotate horizontally about where its wheels contact the ground and a horizontal force is applied to the tow ball on the car which makes the back of the car jiggle sideways on its tires. This is essentially what trailer sway is all about. In other words if you apply an oscillating force sideways on the car’s tow ball the car will start to rotate about a vertical axis, and if this oscillating force happens to have a similar frequency to the rate of “jiggle” the “jiggle” will get bigger…fast.

When the car is traveling down the road the “jiggle” also results in the car changing direction slightly and this can further accentuate the “jiggle” which, by this time, has become “sway”. It turns out that the way to prevent this is to minimize any side loads which are applied to the tow ball as a result of the trailer moving from side to side on the road.

Now you would think that if half the trailer’s weight was ahead of the trailers wheels and half was behind  (i.e. no toungue weight) a side force on the trailer would have no reaction at the tow ball, but that is not how things work.

When the trailer is moving from side to side, say as it would if one wheel dropped into a bit of a hole, the trailer is actually rotating about the tow ball on the car like a pendulum. This means that the mass behind the trailer’s wheels has a greater momentum than that ahead of the wheels so that there is a net force sideways on the tow ball. I guess you could best visualize it like this.

Lay a ruler flat on a table and restrain one end so that it can spin around the restrained end. Now, place a heavy object on the table such that the ruler strikes the object as it rotates. If the ruler strikes the object at the mid point of the ruler there will be a tendency for the restrained end to kick sideways when the object is struck. If however the object is moved away from the restraining point a position will be reached where there is no resulting side force at the point of rotation when the object is struck and, if the object is moved still further away, the ruler will tend to kick in the opposite direction at the restraining point.

Now that may all be as clear as mud to many but the end result is that you require 12 - 15% of the total weight of the trailer to be on the tongue to reach the balance point where there is a minimal side reaction on the cars tow ball; so if you are building, or even just loading a trailer keep that in mind.

Anyway here is the rig all loaded and ready to go…The whole contraption is 37′ 10″ long and sure does attract a lot of attention on the highway. I suspect that we will see a lot of camera phones on the way to Newfoundland!!

WISH US LUCK!!   

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Judy and I are up in N’Zed ( Kiwis believe that south should be on the top of the globe) for our annual winter get away. While I’m here I’m managing to take in a couple of events of the Southern Festival of Speed which has been held here for the last few years.

The first of these events that I managed to get to last weekend was the one at Teretonga in the very south of the country “up” near Invercargill. Teretonga, although flat, is a fantastic track has lots of run off areas and some very challenging turns. It was first built in the late 50s and has been the scene of some great racing. It is here that I first saw Jim Clark race and I remember standing on the inside of the corner before the main straight with my Dad who pointed out to me how incredibly consistent this flying Scotsman was when lap after lap his inside front wheel passed within 2 -3 inches of a white mark on the track surface. His passing was a great loss to the racing world.

The event at Teretonga was part of the club’s 50th anniversary celebrations and one of the special attractions of the event was the gathering of many of the cars built by a local genius by the name of George Begg. Between 1964 and 1974 George, who also wrote the book upon which “The World’s Fastest Indian” was based, built 18 race cars in his Drummond “toy shop” and all but 2 of these were on display this weekend. The first car was a 650c.c. single seater powered by a BSA motorcycle engine

Begg 650

and he worked up building some fearsome Formula 5000 cars of the early 70s.

Begg FM5s

Daimler Begg

For me the most memorable was one called the “Daimler Begg”. In its day this car was very successful in New Zealand but the most amazing thing is that it was powered by a Daimler V8. Why a Daimler? Well V8 engines were not that easy to come by those days in New Zealand and George was quick to recognize the potential of the engine used by the venerable old English Daimler company to power its version of the Jaguar MkII sedan and the fibreglass SP250. The engine itself was a very interesting design by Edward Turner the designer of many British motorcycle engines including the Triumph 650 the combustion chamber of which bears a remarkable resemblance to that of the 2500c.c. Daimler V8. When I last saw the car the engine was dominated by 4 enormous Weber IDA carburettors and its performance was nothing short of awesome. The current owner Brian Grant has replaced the Webers with a Holley 4 barrel which is a bit of a shame because the originals with their ling chrome intake trumpets gave the car a very professional look.

A small collection of other examples of Kiwi Ingenuity was present and here are some pics.

105E

Stuart Special

Baldwin Mercury Special

Hillman Powered

That’s a Jaguar Engine in There!!

Restored “A” Series Grand Prix Connaught

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As the work on the conversion of AHX12’s rear suspension to coilovers proceeds I have been looking at other rear suspension systems for inspiration. One of the most interesting drawings that I have come across is that of the rear suspension used in the Lotus 33 F1 car of 1963.

This state of the art car used fully independent double wishbone suspension with the springs on an angle, similar to what I’m trying to do with AHX12. (I can assure you that the similarity ends right there).

The thing about this suspension type, which is used in many cars, and which has me most perplexed, is the angle of the springs. In the normal ride position the springs are inclined to the vertical and, as the suspension compresses this angle increases considerably.

At first glance this may seem a little unusual, but nothing to be particularly alarmed about. However, inclining the springs in this way, has a profound impact upon their effectiveness.

Let me explain. If the spring had a rate of 100 lbs/inch and was installed vertically such that its lower attachment point was the top of the wheel (ignoring for the moment of course the difficulty of actually achieving this) the spring rate would be equal to the wheel rate. i.e. if you pushed up on the wheel (the equivalent of adding weight to the car or going over a bump) with a force of 100 lbs the spring would compress one inch. Now lay that spring over at 45 degrees. In this case when you pushed up on the wheel with the same 100 lb force the wheel would move up 1.414 inches because the vertical force applied to the wheel by the spring is effectively decreased by the angle of the spring. Taken to the extreme if the spring was installed at right angles to the load it would have no effect at all.

Now let’s consider the Lotus 33. As far as I can determine the spring has an installed angle of something very close to 40 degrees in the normal ride position. This is in itself perhaps not to much of a problem however, when the suspension is fully compressed, the spring adopts an angle of something like 51 degrees. The results of this change of inclination, insofar as the effective spring force, is concerned is a decrease from .76 to .63.

The motion ratio of this suspension is about .66 , i.e. the spring is mounted to the lower wishbone 2/3rds of the way out. Presuming that the spring is a 100lb/in spring this means that the wheel rate is about .32 (.43 [motion ratio squared] times .76) at normal ride height and .27 at full bump. I trust you are keeping up here!!

The important point I’m trying to make here is that the wheel rate decreases by 15.5% from normal ride to full bump.

What I don’t understand is why they did this. It seems to me that a much more desirable condition would be an increasing spring rate as is provided by those wonky looking coil springs that you can buy with changing pitch, or arranging for the spring angle to decrease in bump!!

I can only presume that the decreasing rate was considered to be a reasonable trade off for simplicity and space savings.

All comments welcome (below).

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