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Clutch or Overdrive Slip

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T

toxi

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I had to be low loaded after what I thought was a slipping clutch. I was on a long journey involving many steep climbs without any problem. On another steep climb the revs started to rise and the car came to a standstill in second gear. I rolled back down and tried it in first gear and just made it to the top. However, after making a steep decent there was no drive at all.

I have since taken out the gearbox and inspected the clutch plate. It has some wear, but plenty of meat left on the friction surface and no signs of overheating.

I am now thinking that it could be an overdrive problem. I had noticed that on the odd occasion when I had forgotten to disengage the o/d there is a slippage as too much torque is being transmitted going up the gears, but stops as soon as I ease off the accelerator a little.

The o/d was not engaged when this incident happened as I was in second.

There is no drive at all now.

Can anyone make a suggestion, please?

Mike
 
Did you check the pushrod on the slave cylinder to make sure the hole for the clevis’s pin is not oval instead of round .
What was the condition of the release bearing
 
There are apparently conditions when the overdrive can slip even when it's not engaged. See "Part Four" of this vintage Mr. Finespanner article (which I'm not able to find online anymore?)
 

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  • Del Border (Mr Finespanner) The Overdrive.pdf
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Healey Nut said:
Did you check the pushrod on the slave cylinder to make sure the hole for the clevis’s pin is not oval instead of round .
What was the condition of the release bearing
Click to expand...
Hi thanks for the reply, the clevis pin is not oval but does look home made. however it has worked well for many years. I checked the movement and when the clutch pedal is depressed it extends a good half inch so I don't think the problem is there.
the release bearing is the carbon type and it looks ok. but don't know how it would compare to a new one, there is still a few mm of carbon left and all surfaces are clean and shiny, clutch plate also has a few mm off the rivets and does not look like it's been subject to excessive heat.
This is what is making me think that the clutch in the o/d could be causing slippage even when not in engaged, when in first or second gear. Do you know if that is possible - or not?
I don't want to put it all back together with new plate and release bearing only to find the problem is still there.
 
kozelding said:
There are apparently conditions when the overdrive can slip even when it's not engaged. See "Part Four" of this vintage Mr. Finespanner article (which I'm not able to find online anymore?)
Click to expand...
thanks I will try to find this article.
mike
 
I was able to download the article from the provided link. 'Part Four' describes what happens when the unidirectional clutch in the OD is damaged, and it fits your symptoms. Also, the lined cone clutch that enables the OD to propel the car can wear and slip, which also would probably create your symptoms. The only source for these clutches that I have found are relined ones from Denis Welch (who also offers a 'race' version, which is both riveted and bonded). FWIW, when I rebuilt my OD a few years ago the cone clutch was still serviceable at over 200K miles.
 
Bob_Spidell said:
I was able to download the article from the provided link. 'Part Four' describes what happens when the unidirectional clutch in the OD is damaged, and it fits your symptoms. Also, the lined cone clutch that enables the OD to propel the car can wear and slip, which also would probably create your symptoms. The only source for these clutches that I have found are relined ones from Denis Welch (who also offers a 'race' version, which is both riveted and bonded). FWIW, when I rebuilt my OD a few years ago the cone clutch was still serviceable at over 200K miles.
Click to expand...
Hi Bob
After reading the article part four I am fairly convinced that there has been a failure within the o/d. This happened with very little warning and there was some clunking noises after a complete lack of drive, there is usually quite a bit of warning when the flywheel clutch fails, there was also lack of the usual burning smells.
I am going to take the o/d apart and see if there is any obvious damage and following the manuals I will try the repair myself. but may have to send away if it gets too technical I am going on holiday so won't be able to report my findings for a few weeks.
I am very grateful for your help.
Many thanks Mike
 
When you start, let us know. I learned a couple things rebuilding the OD in my BJ8 I'd be happy to share. It's a straightforward process, but there's some gotchas, not the least of which is mating the OD to the gearbox.

Here's a good watch (but some things weren't mentioned):

 
Del's article is online at > The Overdrive <. As I put the article on the website, Del's nom de plume of got me in trouble with the actual Mr. Finespanner - Doug Reid and team.net's Mark Bradakis.
 
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