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Triumph TR6 - Clutch Replacement
|Further to my "Gearbox Removal" thread and earlier enquiry re the Sachs clutch which I subsequently sourced from BPNW together with the KOYO release bearing.|
I have a problem which is hard to describe. A new cross shaft, release fork and the KOYO bearing have been installed. On its own, the bearing sleeve moves very smoothly on the inner support, both axially and rotationally. However, once the release fork pins are engaged into the sleeve groove, the sleeve jams when actuated, but only in some angular postions. At first I thought that the release fork pins were not parallel to the cross shaft mounting, however, this would not explain why jamming only occurs in some angular positions of the sleeve. My next thought was that the sleeve groove may not be true to the axis but this is hard to beleive as likely.
A little further explanation of the following might help.
"only occurs in some angular positions of the sleeve."
Did you replace/renew the bearings for the cross shaft in the tranny case? Did you renew the fork pins?....is one fork pin much flatter than the other?
The jamming only occurs when the sleeve is rotated to certain positions - operation is smooth in others. The cross shaft bearings were left as found - they were deemed OK. The new release fork came complete with new fork pins.
|I would say maybe ,possibly flat spots on the bearings|
It kinda sounds like your fork pins are not parallel to the sleeve (or visa versa). Or, is the sleve "wabbling" on the bearing (not running true)? Unfortunately you can not see what is going on when it happens. Is the input shaft running true? Are the pressure plate fingers causing the bearing and sleeve to skew?
|Don & Rick|
The problem is evident whilst the gearbox is still out of the car - hence no impact from the pressure plate fingers. For the same reason, the bearing cannot have any influence since it is just sitting on the sleeve and there is no contact to the outer race. The sleeve is a very nice fit onto the inner housing support (what do you call this piece?) and as mentioned slides and rotates freely by hand before the fork pins are engaged. My only conclusion is that the groove in the sleeve isn't true, causing the pins to lock in certain angular positions. If the fork pins were not parallel to the cross shaft, and hence to the groove shoulder in the sleeve (my first thought), the problem would be evident for all angular positions of the sleeve.
I will try dressing the sleeve back face and if all else fails probably source another replacement locally. After waiting for this beautiful weather to arrive, I don't wan't to be stuck in the garage longer than necessary!
Thanks for your thoughts.
|I did a litle checking in some of the articles that I have in my book of knowledge and found an article by Nelson Reidel on "Sticky clutches"|
Some points jump out.
1. The "sleeve attached to the transmission" casing that the "release bearing inner sleeve" slides on should have a smoothly polished surface and a smoothly rounded front edge. Lubrication with a high temp grease is suggested.
2. The "release bearing inner sleeve" inner surfaces should also be polished smooth and the ends smoothed over so there is minimal chance for the 2 parts to dig into one another.
3. There appears to be a number of different "release bearing inner sleeve" designs out there. One thought is that the shorter design is actually the preferred style as it doesn't tend to hang over the end of the "sleeve attached to the transmission" when at the end of its travel. (ie when the clutch would be fully released) A suggestion presented in the article is to not replace the "release bearing inner sleeve" if its not worn.
4. The clutch fork also came under scrutiny in the article as they were found to be finished somewhat poorly resulting in the forks pushing on the "release bearing inner sleeve" unequally. They didn't seem to think there was much of an binding effect caused by this fact as every fork inspected was like this and as long as 1, 2, & 3 above were followed, the cluthes worked smoothly
I hope you find this of help.
|I think the current problem has been resolved. Some local car enthusiasts agreed that the problem was associated with the new sleeve. Since it is fairly common practice to just replace the release bearing, why not press out the sleeves and reuse the old one? This was done and there is now free movement in all angular positions of the sleeve. (It helps when you have a hydraulic press at your disposal). Now to reinstall the gearbox!|
|I purchased and installed the Sachs/Koyo clutch last winter. If I understand correctly you state that when the sleeve is installed on the fork it will stick in some positions when it rotates. I was my understanding that the sleeve should not necessarily rotate. I noticed that the sleeve from BPNW did not have a "roll pin" Moss #325-335 which is meant to keep the it from rotating. I took the new and old assemblies apart and installed the roll pin from my old sleeve. Have put on a couple hundred miles so far without any problem. FWIW|
|A follow-up to report that all is well. The gearbox went back in with a struggle after realigning the clutch plate for a second time. It was found to be off centre even though the alignment tool had been used originally - conclusion was that you have to make sure that the tool slides in and out freely otherwise it is an indication of binding due to slight offset. Everything else went back together well. Took a while to bleed the clutch system due to air in the top loop. I finally pushed the piston back into the slave cylinder and believe this displaced the air bubble back into the reservoir. A test drive indicated nice pedal action with the SACHS clutch - much improved over the heavy feel of the original which turned out to be a Borg & Beck replacement. No overdrive action initially but this was soon traced to an incomplete electrical circuit. I will put some photos up on a web site shortly for general info.|
Thanks again for all the feedback during this mini-project.
|I have uploaded some photos to a hosting site - let's see if the link works!|
|One more time - it this doesn't work I will go back to working on cars!|
Back to the cars Barry.
Try again though. I would like to see the pic's
|HP Henry Patterson|
|Here is a picture of the old B&B clutch. Note the wear on the release fingers.|
This thread was discussed between 20/04/2007 and 02/05/2007
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