Dave's Cars

Triumph Clutch Info

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from

John Cyg

70 Damson CC52927LO
This is specifically about the TR250/TR6, but has relevance to the entire TR line (not TR7/8)
"The six cylinder car's clutch is not such a happy story and is the Achilles Heel of the 6 cylinder cars."
So says Roger Williams in his book; How to Restore Triumph TR5/250 & TR6.
I am not going to reproduce that section of the book here, but I will try to de-mystify this area of the car.

    The issues center around:
  • mechanical tolerances/design deficiency
  • supersession
  • poor documentation

   

The clutch design does not have much allowance for wear & tear. Originally a 0.75" Master Cylinder was fitted and this worked well but their were complaints of "heavy clutch" with this system. During the 1970 model year, the master cylinder was changed to a 0.70" unit. This did soften up the clutch pressure, but now wear and tear deficiencies of the mechanical parts became significant issues causing drag and partial clutch disengagement. Bushing wear, clutch fork pin wear , cylinder leaks etc. will cause poor performance.

   

The car parts biz is quite dynamic, and companies get sold, go out of business, or simply manage the life cycle of their products. Part of this is that if they have a slow or small selling item, they look around to see if they have another part with greater sales that could be use for the slow selling application and they discontinue the part for the slow selling application. The original clutch & driven plate were Laycock units and worked quite well. But Laycock sold their clutch business to LUK. LUK stopped making the TR6 Clutch some time ago. Enter Borg & Beck. They offered a clutch for the TR6 that I think became a standard. It worked quite well. But in time, they saw slow sales for this model and it disappeared from the inventory. B&B used colored paint spots to mark their different pressure plates - I believe there was a "Yellow-spot" a "Green-Spot" and a "Blue-spot". I don't recall which one was used on the TR6, but it was discontinued and superceded with one of the other clutches. Should be ok right? It fits right? No problem then!

   

Wrong! Wrong because one of these clutches was designed for a much heavier vehicle (Van). You want a good tight clutch right? Yes, but excessive spring pressure is very hard on the thrust washers when the clutch is disengaged. Not a good situation. Also it increases pressure on the clutch fork pin and can break it. Anyone who has ever had a broken clutch fork pin knows what a PITA it is. Then B&B was sold to Delphi and that product line was rationalized with yet another clutch that had "cranked" spring fingers. Another generic parts vendor Quinton Hazel also has such a clutch. I have heard mixed reports on this type, with some folks reporting squealing and other reporting good operation. I can only tell you that their original Laycock design was straight fingered. Some of the squealing reports seem to be linked with larger throw-out bearings when used with the cranked fingered clutches.

   

Now some info about the throw-out bearings. The original configuration was an RHP bearing on a bronze carrier that was pinned. A while back reports came out about premature failures with the RHP bearings. Either a bad batch of bearing was made or quality had suffered. It is hard to know what happened, because once a part like this gets a "black-eye", people move away from them because they are such a pain to change, nobody wants to take a chance on it again. I am not saying that RHP bearings are good or bad, simply relating what I have heard. Anecdote - This became an issue for me because I was a "clutch rider" (head hung in shame). I would sit there at a light with my left foot on the clutch and my foot on the brake. After a while I began to hear my bearing (an RHP as it turns out) whirring away. So when I pulled the tranny for another project, I decided that I should get a new bearing and it would not be an RHP. Now was it a crappy bearing or a crappy driver that was the issue? These things are hard to tease apart. There are now a number of brands out there, but I will mention 3. The Koyo bearing was originally designed for a Landcruiser. It was larger than the other bearings. Some folks love'em and some folks have reporting squealing. It is true that being a larger bearing it is going to take more force to overcome inertia and get it spinning.

   

There is another bearing that comes highly recommended called KYK. Never used one but would because of this recommendation from a source that I trust. Gunst has become a dirty name in some quarters of the Triumph community. It was hyped as a godsend, and then a few problems were mentioned (hard to track down the variables). I will say that the Gust bearings are different in that they are meant to contact the clutch at all times. I have put one in my car. I don't know what to expect but I hope for the best. Finally carriers. Bronze carriers have been mentioned as preferred. It makes sense as they are useful in circumstances when you have surface movements in that bronze seems to resist abrasion and not gall. Mating the carrier to the bearing is a precision operation. Most of us should either buy a bearing that is mated to the carrier or have a good machine shop do it for you. "Pinned" refers to a hardened pin that prevents the bearing carrier from rotating on the clutch fork pin. This makes sense to me as we want to gearing to rotate and not the carrier. I know folks who have had squealing issue without a pin. Again drilling and installing an anti-rotation pin is best left to a shop for most of us.

   

"Magic Clutch" Kit - Hype or for real? A word about Charles Runyon. Charles Runyon, the former proprietor of the Roadster Factory has recently passed away. I won't speak ill of the dead except to acknowledge that some folks in our community may have got hurt over some of his business practices late in his life. I will say that Charles and his company have been for a very long time, real friends and proponents of our community. Charles had noticed that there seemed to be a lot of clutch issues with our cars and some of these issues no doubt blew back on him, when new parts he sold didn't fix the issues (remember these problems are hard to tease apart).

   

Being very well connected in the community he was able to pull opinions from some of the most knowledgeable folks in our hobby and come of with a serious attempt at rectifying these clutch issues. Charles realized that the reliability of the clutch mechanics was as important as the clutch components themselves and pulled together a kit of parts that would significantly improve the probability of successful clutch repair. So I think it is for real and not hype, that when you do a clutch job you should replace everything. It isn't that much more money and it worth the extra effort. He also discovered the Sachs clutch. This clutch most resembles the original Laycock clutch design. This is the clutch I have used in my car. I have gone a bit further and added a feature that allows me to lubricate my clutch shaft with a grease gun. If you are interested I can tell about this in another post.

   

Despite all of these there were still more people than there should have been that were reporting clutch issues. A few years back a couple of sleuths uncovered the "dowel" bolts. In the parts lists, there are 2 special bolts among the many bolts that mate engine the bell housing. These are referred to as "dowel bolts". Williams in his book obliquely mentions "locating bolts". If the bell housing is misaligned to the engine even a little bit, poor clutch performance results. These bolts have larger chanks and are located at 2 and 8 O'clock and align the transmission to the engine. If you lose these bolts or don't put them in first than you can have clutch issues no matter what you do. Many folks have installed hardened steel dowels in place of these bolts.

   

Hopefully, this summary will help you with your clutch replacement. Please excuse the length of it. Many folks referred to different aspects of this story, but I thought it would be good to put it all in one place.

   

Drop me a line!


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