BN1 Gearbox. A Plethora of Threads

Back in the days when I was a really poor British sports car mechanic I managed to pick up a Suzuki LJ80V all-wheel drive van with a badly slipping clutch to use for winter transportation.

Suzuki LJ80V

Suzuki LJ80V

It was a horrible little thing but great in the snow and all I could afford at the time. Before I could use it I had to replace that clutch and in doing that job my opinion of Japanese design improved immeasurably. The only tool required to change the clutch, which required that a gearbox with a 4WD transfer case be removed, was one 13 millimeter wrench. ONE!!!

 

 

For a guy who was accustomed to using almost every tool in his 15 drawer tool cabinet and a few borrowed ones just to change a fan belt in an MGB this was a revelation and made me realize just how far the British motor industry had to go in 1953 when they started producing the Austin Healey 100.

From the manufacturers perspective such simplicity can produce extensive benefits because not only is the vehicle easier to construct and service but the parts inventory required both for construction and after sales service is dramatically reduced.

 

The Austin Healey 100

The Austin Healey 100

1952/3 must have been interesting and challenging times for the Austin engineers as the Longbridge factory was geared up to produce the new Austin Healey 100. Britain was desperate for overseas sales but their factories were old and funds for new machinery and imported materials were just not available.

Unfortunately as a result of the shortages the new car had to use an old power train. The engine, with two cylinders lopped off, was a copy of a pre-war six cylinder Bedford lorry power unit which had been adapted from a 1929 Chevrolet design. There was no time or money to “modernize” the engineering so it was still being produced with outdated British Standard threads, British Standard Fine (B.S.F) and British Standard Whitworth (B.S.W) at a time when all new designs were being produced using the modern SAE thread system of Unified National Fine (U.N.F) and Unified National Course (U.N.C.). This was not ideal situation but there really weren’t any viable alternatives.

However, if the engine was not exactly “start of the art”, the gearbox was even less suitable for the latest in sporty motoring vehicles. Adapted from a column change saloon car “cog box” it was never designed to handle even the modest 144 lbs. ft. of torque delivered by the lump ahead of it but, again, it was all that was available within the budget so it had to be used. I suspect another factor was that Len Lord the president of the newly formed British Motor Corporation had hundreds of them lying around as a result of the Austin Atlantic disaster.

The BN1 Gearbox

The BN1 Gearbox and Overdrive Unit

Studying the threads used in this gearbox gives us an idea of the lengths the engineers at Austin needed to go to in their efforts to get those Healeys out the door.

The starting point was a 4 speed box designed to be used in vehicles like the Austin 16, a staid family car with barely enough power to “pull the skin off a rice pudding” as my Dad used to put it. The first job was to come up with an inexpensive way to produce a floor shift as no self-respecting “sports car” could have anything resembling the “three on the tree” gear change that the gearbox was designed around. This was achieved with a nifty adaptation of the original gearbox side cover and the addition of an Austin Taxi “change speed control box body” upon which a gear lever could be pivoted.

The Change Speed Control Box Body

The Change Speed Control Box Body

Everything worked out just fine but the threads… oh my, the threads.

Change Speed Box Cover Stud

The interesting thing about this “change speed control box body” is that within the design of this small cast part 3 different threads were used and that is just the beginning!

Two Different Threads in Very Close Proximity

Two Different Threads in Very Close Proximity

It was found that because of the 4.125/1 Austin Healey differential ratio (another saloon car legacy) 1st gear in the four speed box was useless and reputedly produced “nothing but wheel spin with anything like a spirited take off.” (See note below). The solution was that the 1st gear in the box would need to be blanked off producing a three speed gearbox.

One can only imagine the wails of anguish from the marketing department as no sports car of the day could be sold with a three speed gearbox even if it was all synchromesh … an overdrive unit was required. Fortunately the Laycock-de Normanville unit selected was a modern design which used U.N.F. and U.N.C. threads.

Speedometer Pinion Bearing Locking Screw

Speedometer Pinion Bearing Locking Screw

This clever addition appeased the marketing department but really complicated the thread issue as it required an adaptor plate with BS threads on one side and SAE threads on the other; not a design achievement that any engineer could be very proud of.

Joseph Lucas’s Switch

As a further complication the overdrive unit required a plunger switch on the side of the gearbox to prevent the overdrive being engaged when the gearbox was in reverse as doing so would destroy the overdrive unit. Enter Joseph Lucas. Now Joe was a very traditional guy and, apparently, a big fan of BS threads which the Lucas Company stuck with right through into the 1970’s so the switch he supplied used yet another thread form namely British Association (B.A.).

 

 

So now we have five different threads in this unit; B.S.F., B.S.W., U.N.F., U.N.C., and B.A….but wait… there’s more! We have to consider the drain plug for the gearbox.

The Tapered B.S.P. Threaded Drain Plug

The Tapered B.S.P. Threaded Drain Plug

Rather than use a standard parallel thread screw with a soft washer under its head the gearbox incorporated yet another thread system British Standard Pipe (B.S.P), which is tapered, in order to stop the oil from leaking out and to save the cost of a sealing washer.

Surely at this stage the engineers must have been tearing their hair out; six different thread standards in one gearbox unit but we aren’t finished yet.

 

As a grand finale the box incorporated this 1 7/16” LEFT HAND THREADED nut with fourteen threads per inch to lock the front bearing of the gearbox onto its shaft. As far as I can figure there is no “standard” for this gem.

The Front Bearing Nut

The Front Bearing Nut

Seven different thread forms in one gearbox unit that’s quite an achievement. You can see why I was so impressed by the Suzuki.

Note.

I have a theory about why the 4.125/1 rear axle ratio was used in the 100.

Geoffrey Healey states in “The Healey Story” that ”Austin did not have a high* enough gear ratio for the A90 rear axle” but that is not strictly correct. The Austin Atlantic convertible used a much better 3.66/1 ratio which, incidentally, was even offered as an option on the 100 and a 2.92/1 and even a 2.69/1 ratio became available in the 100S and those cars used the same rear axle housing .

Conventional wisdom has it that the 1st gear in the BN1 gearbox was too low and produced excessive wheel spin but I think that is a marketing myth. Donald Healey in “My World of Cars” states “The only disappointing part of the A90 was its gearbox, which was not man enough for the job in a sports car”.

My bet is that it was discovered early on that the torque of the engine was just too much for the gearbox and “The New Austin Healey 100 with enough torque to rip the teeth right off its 1st gear” didn’t sound like a winning slogan. The decision was made to stick with the lower diff ratio, which meant that 2nd gear starts were satisfactory, and “block off” 1st gear in the interests of reliability. Unfortunately that limited the top speed to 90MPH at maximum RPM, a problem solved by fitting an overdrive unit.

* A “high ratio” differential has a low ratio number whereas a “low ratio” has a high rati0 number.

Posted in Classic Rallying, Healey Stuff | 1 Comment

Laycock-de Normanville Overdrive Installation Tool

Many years ago I made up a little tool which has proved invaluable when attaching an “A” type Laycock-De Normanville overdrive unit to a gearbox.

For those not familiar with this operation a little explanation will help. If you have “been there, done that” skip this part down to the picture with the tape measure in it.

The rear shaft of the gearbox mated to these overdrive units has to be aligned with three individual splines while compressing an oil pump spring and 8 clutch springs as the two units are joined together.

One of the splines is located on the inside of the oil pump cam.

Oil Pump Cam With internal Spline

Oil Pump Cam With internal Spline

The other 2 sets of splines are away down in the middle of the overdrive unit, one in the clutch sliding member and the other in the unidirectional clutch.

8 Springs, 3 Splines, Big Problem

8 Springs, 3 Splines, Big Problem

As can be seen in the above picture when the pump cam is positioned on the pump plunger roller the plunger spring holds the cam out of alignment with the rest of the bore of the unit.

Conversely when the cam is fitted on the partially installed gearbox shaft the pump plunger roller protrudes below the cam and will not allow the cam to slip by into its correct position against the overdrive centre bushing.

The Pump Roller Blocks the Pump Cam

The Pump Roller Blocks the Pump Cam

The factory workshop manual for the Austin Healey 100 illustrates the “recommended” method of installing the overdrive. They suggest “placing the oil pump cam in position on top of the center bushing (as in the photo above) then carefully threading the mainshaft through the oil pump cam and into the center bushing.”

Try Holding a Gearbox at Arms Length Like This for a Few Minutes

Try Holding a Gearbox at Arms Length Like This for a Few Minutes

What they don’t mention is that the gearbox weighs in at some 25 kg so holding it with one hand as illustrated while attempting to align the various components with the other is just a little difficult.

They also add as a NOTE: ”the gearbox mainshaft should enter the overdrive easily provided that the lining up procedure previously described is carried out and the unit is not disturbed.”

Well, if I know of one sure way to become “disturbed”, it is to try to mate the gearbox to the overdrive the way that they describe!

This is where the little tool mentioned above can help you maintain your sanity.

The Tape Measure is For Scale. (In Case You Didn't Guess)

The Tape Measure is For Scale. (In Case You Didn’t Guess)

This very inexpensive “Special Tool” is made from a piece of coat hanger wire. After you find out how well it works you may want to get it chrome of even gold plated!

So…How does it work?

In the filter cavity of the overdrive unit there is a conveniently located hole.

Tool in Place Viewed From Below

Tool in Place Viewed From Below

The “Special Tool” is inserted through this hole and up the side of the pump plunger.

Tool in Place Before Installing Springs

When the pump plunger is pushed down against its spring the hooked end of the “Special Tool” engages into the plunger just below the roller and holds the plunger in the down position. It is easiest to install the “Special Tool” before placing the clutch springs in position.

The shape of the little hook on the top of the “Special Tool” is very important but not difficult to form.

Again..Pencil Tip is for Scale

Again..Pencil Tip is for Scale

Now when the cam is placed in its correct position there is plenty of clearance between the lower section of the cam and the plunger roller allowing the cam, while installed on the gearbox shaft, to pass into position against the overdrive centre bushing without contacting the pump roller.

No More Interference Problems

No More Interference Problems

Now the installation procedure is much easier.

Use a little heavy grease to hold the pump cam in place on the gearbox shaft with the high part of the cam uppermost.

Position the overdrive unit with the drive shaft flange on the ground.

If You Can't Find Anyone to old the Overdrive Bolting The Flange to a Piece of Wood Works.

If You Can’t Find Anyone to old the Overdrive Bolting The Flange to a Piece of Wood Works.

Use a dummy shaft to check the alignment of the internal splines and then ensure that all the clutch springs are correctly installed (short ones innermost).

Put the gearbox into 1st gear then carefully lower the gearbox down onto the overdrive unit. You may have to turn the gearbox input shaft align the splines inside the overdrive. When the gap is down to about 1/2″ peer in using a flashlight to ensure that the clutch springs are all correctly positioned at the top.

The gearbox and overdrive should pull together easily.

Don’t forget to extract and save your “Special Tool”.

Posted in Classic Rallying, Healey Stuff, New Parts | 1 Comment

LUCAS HF1748 Horn Rims

At last after months of back and forth with various die makers and die casters I have received a shipment of horn rims for the Lucas HF1748 horns.

These 12 volt horns were used on Austin Healey 100-4 (BN1 and BN2), 100M, 100-6 (BN4, BN6), and 3000 Mark I (BT7, BN7), Jaguar XK 140, XK150, Mark VII VIII & IX, Mark II, and Aston Martin DB3/S vehicles. The same design of horn was also available in 6 and 24 volt versions.

This whole process was initiated by my being unable to find a pair of the original, zinc die cast, rims for the horns on my 1953 Austin Healey 100.

THE DESTINATION OF THE HORN RIMS 1953 AUSTIN HEALEY BODY #174

THE DESTINATION OF THE HORN RIMS 1953 AUSTIN HEALEY BODY #174

Because the horns are mounted low down under the radiator they are very vulnerable to damage and corrosion. The first and often only part to break is the rim which is secured by six steel ¼” B.S.F. cheese head screws. Galvanic corrosion of the rim produces zinc oxide which swells and causes the rim to crack. The ones on #174 each came off in completely unusable condition.

THE HORN RIMS REMOVED FROM #174 WERE IN VERY POOR BUT TYPICAL CONDITION

THE HORN RIMS REMOVED FROM #174 WERE IN VERY POOR BUT TYPICAL CONDITION

As the last of these horns were fitted to cars over 50 years ago spare parts are very hard to find. After trolling the internet for over 2 years I was only able to find one already cracked rim so I started investigating methods by which the rim could be reproduced

The work required to produce these accurate reproductions has given me a new respect for anyone who undertakes small batch production of any cast component, that said however I still don’t have much time for companies who make “close approximations” when, with a little more effort and time, they could produce parts which are indistinguishable from the originals.

The first idea that I investigated was 3D printing. Because I don’t have access to a 3D scanner the first step in that process was to produce a CAD drawing of the rim. Fortunately I have a very good friend with vast CAD drawing experience who was kind enough to work on this for me. Everything went swimmingly until the time came to find the correct font for the “LUCAS” lettering as was on the original rims.

I had no idea that there were so many fonts in the world and we were unable to find one which had the straight side on the “U” and an “S” that looks like a mirror image “Z” as the lettering was on the original. The only solution was to painstakingly draw each letter and individually position them on the curve of the rim, a very time consuming process.

PART OF THE CAD DRAWING REQUIRED TO PRODUCE THE RIMS

PART OF THE CAD DRAWING REQUIRED TO PRODUCE THE RIMS

Finally the drawings were done and sent off for 3D printing in nylon.

Although the plastic rims produced by 3D printing were pretty good they required quite a bit of post-production work which included filling the surface indentations with spot putty followed by careful sanding and painting to produce a reasonably acceptable part. The biggest problem however was the cost of the 3D printing process which is, after all, intended for making prototype parts.

I was not satisfied that this process would ever be practical for making even a small batch of accurate rims at a reasonable price so started looking for a more viable alternative.

Given the difficulty that I had encountered in finding replacement rims I decided that it may be possible to have a set of steel cavity molds made and produce the parts using the “Cold Chamber Die Casting” method.

Die casting of high volume parts is very economical but the initial outlay to produce the die is substantial. I figured that if I could sell 100 rims that could cover the cost of the die and the manufacturing of the rims. The die maker was very helpful and by modifying a die used previously and fitting my work in between other jobs he managed to produce a very accurate die within my budget and the casting process started.

AFTER A LOT OF WORK THE REPRODUCTION HORN RIMS ARRIVED

AFTER A LOT OF WORK THE REPRODUCTION HORN RIMS ARRIVED

The quality of the finished parts was absolutely astounding and the rims can be installed without any hand finishing at all.

I decided to send one to Roger Moment, the world renowned Austin Healey expert, and his comments were as follows:

“I have been able to inspect one and it is truly accurate.  The only variation I can find is that on the back side of the ring there are 5 marks where the vents and fill sprue on the mold were located.  These marks are all flush or slightly recessed so they won’t affect the mounting and are totally hidden.  …The cast metal surface is totally smooth, as-original.”

THE FINISHED RIMS REQUIRE NO POST PRODUCTION WORK AND FIT PERFECTLY

THE FINISHED RIMS REQUIRE NO POST PRODUCTION WORK AND FIT PERFECTLY

THE "LUCAS" WORDING IS A PERFECT REPRODUCTION OF THE WAY IT WAS ON THE ORIGINAL RIMS

THE “LUCAS” WORDING IS A PERFECT REPRODUCTION OF THE WAY IT WAS ON THE ORIGINAL RIMS

My efforts and investment were all worth it but it is a very complicated and expensive way to get a pair of horn rims. I certainly won’t be casting any more in the foreseeable future.

If you require accurate replacement rims for your Lucas horns please don’t hesitate to contact me. michaelsalter@gmail.com

Posted in Healey Stuff, New Parts, The Restoration of Healey #174 | Leave a comment

Early Austin Healey 100 Steering Wheel Detail.

When I was a little nipper back in Dunedin, New Zealand our family car, the first I remember anyway, was a 1948 Austin 16.

An Austin 16 BF1 Our Family Car 1954 -63

An Austin 16 BF1 Our Family Car 1954 -63

I have 4 siblings so journeys in the Austin with 3 in the front and 4 in the back were cozy affairs.

The Austin's Dashboard

The Austin’s Dashboard

There was always a race for which of the kids got to ride up front between Mum and Dad, whom of course always drove. As a result I spent many hours at pretty close quarters with the dash and controls of that Austin and many of the details are etched indelibly in my memory. I remember the combined ignition and lighting switch with the little window within which the words “OFF”, “SIDE” and “HEAD” showed and I remember the cream coloured instruments with the brown centers.

The Lucas Combined Headlight and Ignition Switch

The Lucas Combined Headlight and Ignition Switch

I recall the turn signal switch in the center of the steering wheel, with its chrome handle and the brown Bakelite steering wheel center.

Among my recollections, for some reason is the finish on the hub of the “banjo” style steering wheel. It was “wrinkle” paint with the same texture as my Dad’s Philco radio which was “wrinkle” brown. It is amazing the details that one remembers so clearly from one’s childhood.

The memory of the hub of that steering wheel immediately sprang to mind when I studied the original steering wheel for the 1953 Austin Healey body #174 that I have just finished restoring but first a little background.

The first 1000 Austin Healeys did not have the luxury of seat slides. If you needed to adjust the distance between the seat and the pedals a half inch wrench was used to unbolt the seat and move it to another of the 5 pairs of holes provided in the seat base.

The "High Tech" Seat Adjustment System on #174's Driver's Seat

The “High Tech” Seat Adjustment System on #174’s Driver’s Seat

Not really convenient but I presume that the tooling required to produce compact seat slides had not been produced at that time, so compromises were required.

Additionally those first 1000 cars had a steering wheel which, after loosening a locking nut, could be moved forward or backward on the steering column. This feature was dropped for the later 100s when seat slides were eventually fitted but reintroduced, as an option, on the six cylinder cars.

The adjustable wheel on the early 100s used a hub with locking nut which had the manufacturer’s name “BLUEMEL’S” stamped on it. Interestingly the profile of the early hub was considerably different from that used on the 6 cylinder adjustable steering wheels.

Early 100 Steering Wheel Hub Profile. (Mike Lempert Photo)

Early 100 Steering Wheel Hub Profile.
(Mike Lempert Photo)

But the really interesting thing is the finish on this early hub which was, I believe, black wrinkle paint just like the wheel on my Dad’s Austin 16.

The Steering Wheel  Hub Profile of a  6 Cylinder Austin Healey

The Steering Wheel Hub Profile of a 6 Cylinder Austin Healey

As can be seen in the picture below the finishing material on the early 100 hub is is only microns thick and crumbles into dust when peeled off. It is like normal paint in this respect.

Detail of The Finishing Material Used on The early 100 Steering Wheel Hub  (Mike Lempert Photo)

Detail of The Finishing Material Used on The early 100 Steering Wheel Hub
(Mike Lempert Photo)

The material used on the later six cylinder adjustable steering wheels is not paint, is very similar to powder coat being about 0.025” thick and it can only be peeled off in larger pieces.

The Thicker Finishing Material Used on the Later 6 Cyl Adjustable Wheel Hub

The Thicker Finishing Material Used on the Later 6 Cyl Adjustable Wheel Hub

The other interesting difference between these finishes is what happens to them when they are polished. The later hub coating easily polishes up to a deep gloss black surface.

The Later Hub Finish After a Little Polishing

The Later Hub Finish After a Little Polishing

The material on the early wheel appears to be pock marked and rough with pitting on the surface and will not polish to a glossy surface.

Detail of The Original Finish on #174's Wheel

Detail of The Original Finish on #174’s Wheel

Unfortunately most of these early 100s have be restored over the last 60 years and it is very difficult to confirm for sure that they had this unique “wrinkle” finish on the steering wheel hub but there is no question that the material used to finish the hub was very different from that used on the later cars and it was also different from plain gloss black paint.

I have decided therefore that, in light of a lack of evidence to the contrary, it is most likely that in addition to being used on the heater housing and air filters black wrinkle paint was the finish applied to these steering wheel hubs and that is what I have used in the restoration of #174.

The Refinished Wrinkle Black Steering Wheel Hub on #174

The Refinished Wrinkle Black Steering Wheel Hub on #174

I think it looks great and very much “period correct”.

Posted in Healey Stuff, The Restoration of Healey #174, Used Parts | Leave a comment

What is an Oakenstrong Washer?

I received a copy of an SU information bulletin from Earl Kagna during my research into whether or not identification tags were fitted to Austin Healey 100 carburettors. Our local SU guru Blain Hughes was good enough to send me pictures of what he had in the way of ID tags from SUs with the type of float chamber lid held on by one center cap nut.

ID Tags..other models

These tags are a different shape from the type used on SU carburettors having float chamber lids held on by 3 screws which look like this.

MGB TagNone of the 4 tags that Blair’s photo show are from a 100 as the number for those carburettors is AUC718 (1953) or AUC739 (1954 M).

Anyway, back to Earl’s SU bulletin.

Healey Hundred Carb Sheet

On the third page of the bulletin one item description caught my eye…#48. This is the large washer or gasket fitted between the float chamber lid and the float chamber itself.

Oakenstrong washer

It’s called an “Oakenstrong washer-lid”. What is an Oakenstrong washer?? I’ve been around old British cars and machinery all my life and I have never heard of an Oakenstrong anything.

Does anyone know where that name comes from?

BTW the jury is still out on whether or not Austin Healey 100s had carburettor tags but, as no one has been able to come up with one or even a photo of one, it seems fairly likely that they were not fitted.

It is possible that they were not used because of the extra space required under the float chamber cap nut for the support strut that is used between the carburettors and the inlet manifold as can be seen in this photo of #174’s carburettors.InstalledInterestingly the cap nut used on the H6 (100M) Item No. N1 is noted as being “long”. Perhaps it was lengthened to accommodate the tags on the 100M, if they had them.

 

Posted in Healey Stuff, The Restoration of Healey #174, Used Parts | Leave a comment

Wear Resistant Suspension Materials

Wear of suspension bushes has been a problem that has plagued vehicle manufacturers since the days of horse drawn coaches. To combat this wear modern automobiles use complex and expensive ‘ball joints” which, as long as the protective rubber boot covering them remains intact, last almost for ever.

However, as anyone who owns a utility trailer will know, wear in the pivot points of leaf springs is a constant problem.

A load of of Wine Barrels Wedding Decorations

The “Carcamel”

One of the most interesting things that I have discovered in using my Carcamel for 10 years and 200K kilometers is the longevity of the suspension arm bush design that I came up with. I believe that with a little ingenuity this could be adapted to improve the reliability of almost any leaf spring or trailing arm suspension.

Susp armTaken during construction this photo shows the general layout of the suspension arms. This is the left side forward “trailing” arm.

Visible above, where the arrow indicates, is the 1 1/4″ schedule 80 pipe (pivot shaft) upon which the suspension arm pivots and the 2″ pipe on the end of the suspension trailing arm into which the 2 “top-hat” type Nylatron GSM suspension bushes are pressed; one in each end of the 2″ pipe.

Trailing Arm PivotThe outer rim of one of the outer Nylatron GSM suspension bushes can be seen in this photo. The arm itself  is prevented from sliding off the pivot shaft by the keyhole shaped plate. This is the left side rear “leading” arm.

The bushes themselves are about 2 1/2″ long and are a “press” fit into the arm. Once installed in the arm the bushes become a “push” fit onto the pivot shaft. An “O” ring groove is machined into the outer end of the inside diameter of each bush to accommodate a standard rubber “O” ring. This “O” ring prevents the entry of moisture and dirt.

The big secret to this whole system is, I believe, the fact that the pivot shaft is galvanized. In fact the entire rear deck assembly including the suspension arms is galvanized.

RR Susp The completed and installed left front (trailing) arm assembly can be seen in this photo.

During assembly the pivot shafts and ID of the bushes were coated with wheel bearing grease and care was taken to ensure that the “O” rings remained in place. Provision was made to allow these pivot points to be lubricated during servicing but I have never actually done that.

In normal road use the arms only move through about 5 degrees of arc although the total available range of movement, limited by the extension of the shock absorbers, is about 26 degrees of arc.

Here is the amazing thing. When I initially installed the arms the bushes were tight enough to just prevent the arm from pivoting to allow the wheel and brake assembly to drop under its own weight when the chassis was raised. Now, after 200K kilometers and 10 years, the arm will still not quite drop under the influence of the weight of the wheel and brake assembly indicating that there has been absolutely no wear in the pivot.

I’m  huge fan of “maintenance free” anything!!!

Posted in Global Warming | Leave a comment

AN INTERESTING THING ABOUT CLUTCHES

One of the cars that I own is a 1992 Mitsubishi 3000 GT VR4.

photo rearI purchased this car many years back and use it quite a bit in the summer months. It is absolutely stock and a real pleasure to drive however, a couple of years back, the clutch started to give some trouble.

If you know all about clutches you can skip the next bit because it is just a primer for those not familiar with how they work.

Modern clutches, that is clutches designed after the mid sixties, are called “diaphragm “clutches.

Exploded clutch small

This type of clutch replaced the “spring” clutches in use at the time because they were less complex, lighter, stronger and cheaper to make.

There are various styles of diaphragm clutch but they all operate in the same way and are based upon the principle of a diaphragm spring (know also as a Belleville spring and named after its inventor Julian F Belleville) and use the pressure exerted by the diaphragm spring to clamp the clutch disc between the pressure plate and the flywheel.

Clutch operation smallBecause they are friction devices all clutches are subject to wear and, when they wear, they fail to transmit the torque to which they are subjected and start to slip.  Because the diaphragm spring, which provides the clamping force in the clutch has a very limited range of movement these clutches tend to slip when they get worn.

Because the VR4 is all wheel drive and produces over 300 BHP the clutch is a pretty substantial unit that it uses a vacuum assist unit to decrease the required pedal pressure.

The problem I encountered was that the clutch pedal was getting harder and harder to depress but the clutch was starting to slip under high loads. My initial suspicion was that the servo assist unit was starting to fail but, when I expelled the entire vacuum and tried to operate the clutch without its assistance I could hardly press the pedal to the floor with one foot. When I tried this with the clutch in a friend’s Stealth Twin Turbo, essentially the same car, the pedal was noticeably heavier without the servo assistance but could still be operated, with difficulty, with one leg.

These symptoms just did not add up. All my experience prior to this had been with British cars. In those cars clutch slip was always associated with a decrease of required pedal pressure because as the clutch slipped it overheated and weakened the diaphragm spring.  In fact I’ve seen MGB clutches which have been overheated to such an extent that the diaphragm spring had become a flat limp piece of blue steel which had absolutely no resilience at all!!

The symptoms exhibited by the VR4 clutch bore no resemblance at all to what I was used to.  Finally, despite my policy of diagnosing a problem before trying to fix it, the clutch became unbearably heavy so I decided that I had no option but to replace it to see if the problem went away.

I changed the clutch, not my favorite job on any car and particularly difficult in the AWD VR4 and voila, everything was perfect…

So…what was wrong with the clutch I removed? It appeared to be the original and although the friction disc was well worn it was still in very good condition with no sign of having been overheated.

After a bit of study I did finally figure out what was wrong…

Can you explain the cause of the symptoms that I was experiencing?

Posted in Global Warming | 3 Comments

Carcamel 8 Years and 200,000 km Down the Track

Well it is now 8 years since I built the CARCAMEL and it has proved to be a very versatile and reliable machine far exceeding my expectations of a “homebuilt” vehicle.

It has been used for carrying all manner of things.

SOME VERY HEAVY

The Remnants of a 26 meter Pine Tree

The Remnants of a 26 meter Pine Tree

 

A pair of 12" x 12" Steel Beams and a Cable

A pair of 12″ x 12″ Steel Beams and a Cable for a Winch Job

 

A Load of Oak Logs

A Load of Oak Logs

 SOME VERY LONG

4 Trips to St John NF 6000 Km Round Trip
Hauling a Mini Racer on its Trailer

 

 SOME VERY BULKY

32 Packs of Insulation Try getting that in an F150

32 Packs of Insulation
Try getting that in an F150

A load of of Wine Barrels Wedding Decorations

A load of of Wine Barrels
Wedding Decorations

 

SOME VERY BIG

A New Hoist for the Garage at the Cottage

A New Hoist for the Garage at the Cottage

 

A Pickup Trick Cab for Techno Strip

A Pickup Truck Cab for Techno Strip

 

SOME DIFFICULT TO LOAD AND UNLOAD BY MYSELF

My BusyBee Lathe to The Cottage Garage

My BusyBee Lathe to The Cottage Garage

 

SOME THAT WOULD OTHERWISE REQUIRE A LARGE TRUCK

A load of Beams For the Cottage Porch

A load of Beams For the Cottage Porch

Since the conversion I have driven the CARCAMEL over 200,000 km .

That old Dodge 3.3 liter V6 still runs strong and doesn’t burn any oil, it hasn’t been touched since it was built in 1994.

As expected some things have caused problems but all have been satisfactorily resolved. The following are the ones I remember
CV SHAFTS

The CV shafts of the van both failed within the first 100,000 km. I originally thought that the modifications to the vehicle may have been a contributing factor but the real problem proved to be poor quality replacement parts. It wasn’t until I took the failed shafts to a rebuilder in person that I found out aftermarket replacement shafts had been installed before I got the van and their poor quality was the cause of the problems.
The rebuilder pointed out that the heat treating of the aftermarket shafts was totally inadequate and sold me a pair of remanufactured originals which have been in ever since with no problems what so ever.

PNEUMATIC VALVES

Originally I installed some valves that I found on eBay which were intended for industrial machines. Unfortunately they didn’t much like this application and became a bit unreliable.

The Suspension Control System Uses 4 of These Solenoid Valves

The Suspension Control System
Uses 4 of These Solenoid Valves

I purchased the above as replacements from Princess Auto and moved them into boxes mounted between the rear wheels which completely resolved the problems.

FUEL TANK AND PUMP

The original EFI fuel pump failed at about 225,000km. When I pulled the tank to replace it I found that the top of the tank was badly rusted so I installed a new replacement and a new pump. Unfortunately the fuel tank is the lowest part of the vehicle so it is inclined to take a bit of a beating if I forget to raise the rear suspension when passing over high crests. So far that hasn’t created any serious problems but in a MK II version I would try to prevent the tank hanging so low.

AIR COMPRESSOR

Originally I used the suspension compressor from an Oldsmobile 88 to provide the pressure for the rear air spring suspension. This proved to be of too small a capacity so I have now installed one used to level motor homes which, although just adequate has proved to be reliable.

 

Although it is a Llttle noisy this Viair 450 C seems to be holding up well

Although it is a little noisy this Viair 450 C seems to be holding up well

REAR WHEEL BEARINGS

This one took a while to solve. Every time I drove for a prolonged period in rain the rear wheel bearings would get noisy a few weeks afterward. When I pulled them apart the bearings were rusty and damaged as a result of having water get into them. The rear stub axles were from 94 era Dodge Caravans but the 4 bolt hubs (required to allow me to use 13″ wheels with the correct offset) were from the very first model 1983. After some judicious measuring I determined that the later stub axles were 1/4″ longer and the hub seal was not running on its seal face. Some little spacers, machined up on my lathe, solved that one.

CRUISE CONTROL FAILURE

Another one that I struggled with for a while. Eventually solved by changing the cruise module.

IN CONCLUSION

Most or these problems are to be expected in a 19 year old 380,000 km vehicle and none have been close to being show stoppers.

 

Overall the fuel consumption, combination of loaded and unloaded highway and city has averaged 10.8 litres / 100km (26.1 Miles / Imperial Gallon) (21.8 Miles / US gallon).

I don’t drive the CARCAMEL in winter because salt damage would finish it off very quickly.

This vehicle has saved my friends, my relatives and myself thousands of dollars in transportation costs and allowed us to easily and conveniently transport goods and vehicles for large distances very safely.

 THE FUTURE

My buddy bought a new Dodge Caravan in 2011, when it is time for him to replace it we are going to “abbreviate” it the same way we did the ’94 and the rear deck will have a new life and the CARCAMEL will live on.

Posted in My Transporter | Leave a comment

Austin Healey 3000 bores in a 100/6 block.

Over the years I have been asked many times if there is any good reason why a 100/6 (3.125” bore) should not be overbored to 3000 specifications (3.281”). Back, before I knew better, I believed that there was no good reason not to do so and in fact we successfully rebuilt more than one 100/6 engine to standard 3000 specs.

We never realized how lucky we were.

In the late ‘90s we had a customer bring in a 100/6 that was having problems as a result of coolant leaking into the oil. The leakage only seemed to occur when the engine was warm and the cooling system was at operating pressure. After a long and involved period of analysis we discovered that the water was leaking through a tiny crack in the block about half way down one of the bores.

Our local race engine shop had recently acquired a sonic cylinder wall thick tester and using that piece of new technology we determined that the walls of that block were perilously thin in many areas as a result of being bored to 3000 specifications and the only solution was to rebuild the engine with a 3000 block.

After I read in Geoff Healey’s book “The Story of the Big Healeys” that the engine block had to be redesigned to produce the 3000 I put two and two together and decided not to “overbore” any more 100/6 blocks.

Unfortunately this problem was not common knowledge and just before I sold my business we purchased a “race ready” 3000 for a long time customer never imagining that the engine had been produced from a 100/6 block.

The engine ran for about 20 minutes before it “grenaded”.

The following photos illustrate the result and should serve as testimony as to the folly of “overboring” a 100/6 block.

An Indication That All Was Not Well

Look Closely…Something Is Missing

It Takes A Lot of Force To Do This

You Can See How Thin The Cylinder Walls Were

The Remnants of a “Race Ready” Engine.

BOTTOM LINE……3000 INTO 100/6 DOESN’T GO!!!

Posted in Classic Rallying, Healey Stuff, Used Parts | Leave a comment

Austin Healey 100 #174 Heatshields

The drivers footwell heatshields on  #174 were original and somewhat different from those that I have seen on later cars.  These heat shields are installed on all “Big” Healeys to limit the amount of heat that is radiated onto the driver’s footwell from the exhaust manifold and down pipe.

The Original Heatshield on the Front of the Footwell

Footwell Heatshield Around Pedal Apertures

Footwell Side Heatshield

These heatshields are all made of the same asbestos material, with a pressed pattern on one side, that was used throughout later Healey production. Later 100s used a different material which is called “millboard”. Millboard is softer, a little more flexible and of layered construction. All 6 cylinder Healeys used the same material as was used on #174.

As is the case on Healeys that I have seen the material was not fitted with the pattern consistently inward, against the footwell, or outward.  In fact on #174 of the two panels fitted around the pedals one was “pattern in” and the other was “pattern out”.

The heatshields on later cars were much more carefully shaped so as to  cover the exposed areas of the footwell more completely.

Also of note, and peculiar to 100’s I believe, is the fact that no spacers were fitted between the material and the footwell to produce an air gap as was the case in the later cars.

#174, being a very early car, has some interesting differences in the types of fasteners used throughout the car. This was the period when many BSF threaded fasteners were still in use and quite a number of slot head screws.

Heatshield Fasteners

As can be seen in the photographs taken before the heatshields were removed the fasteners were all installed with the nuts outward so the slotted “pan” heads of the screws were all under the carpet in the footwell.

Also of particular interest is the way that the panel around the clutch pedal and around the dip “dimmer” switch has been broken away, probably during assembly at Longbridge,  to provide adequate clearance.

I intend to reinstall these heatshields after painting them all over with latex paint to prevent their “shedding” asbestos fibers.

Posted in Healey Stuff, The Restoration of Healey #174 | 3 Comments