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John McCormack

Clutch shudder when hot

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I took the TR6 about 40kms today in light traffic with no issues.

On the drive back we got held up in very heavy traffic for much of the journey. Over time the clutch felt heavy, a bit like there was a restriction in the hydraulics or the clutch itself. If I didn't use a few revs on take off the clutch would shudder a bit.

I 'çleaned' the clutch by slipping the clutch for a second or two in 3rd. This helped but the clutch just didn't feel right.

When I got home I left the car for 10 minutes and when I got back in the clutch pedal felt perfectly normal. I didn't drive it but any feel of a restriction was gone.

Has anybody else experienced these clutch issues and what was the solution?

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If you are experiencing judder then that seems to rule out hydraulics, and if the pedal pressure has become variable that would suggest the cover or plate or possible release bearing mechanism/ shaft etc is faulty. I doubt the plate is hanging on the splines as you do not have engagement issues?

It could an outside chance of contamination with oil but that wouldn’t explain variable pedal pressure. You shouldn’t need to ‘clean’ a clutch by slipping it. I would suggest some imminent mechanical failure though worthwhile checking the hydraulics and release functions first.

Kevin

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Hi John,

when you say judder - is this with the pedal held in  for a moment or two or is the pedal juddering back to the foot off position.

In the first case it could be contamination on the friction plate.

In the second case it could be a mis-alignment of the GB on the engine. Are the two alignment bolts in place.

I had a strange issue four years ago on my 4A where the input shaft into the GB was not aligned with the GB extension that the release bearing slides on.

I ended up making a tapered shim to go under the GB extension. 

 

Roger

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Thank you for the replies. I called the Triumph specialist today and described the symptoms and also googled it.

It appears to be a reasonably common issue with the original type of clutch, exacerbated by a lack of lubrication of the throw out bearing and the shaft it slides on prior to installation. The mechanic says it isn't a major problem, it is just uncomfortable in a driving sense and can only be fixed by replacing the clutch with an improved one.

There might also be a bit of a contamination problem on the flywheel/clutch plate which the occasional slipping of the clutch sorts out.

Now I know what the problem is I'll put up with it. This clutch isn't that old and it is only an issue in the conditions I experienced yesterday, hours in heavy traffic, and is easily controlled with a slight change in driving style i.e. a few more revs.

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Definitely a case of driving around the problem being better than taking the clutch out!

However I would check the crankshaft end float as this can cause these sorts of issues and if it is the cause you need to sort it..

Tim

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1 hour ago, Tim D. said:

Definitely a case of driving around the problem being better than taking the clutch out!

However I would check the crankshaft end float as this can cause these sorts of issues and if it is the cause you need to sort it..

Tim

Thanks Tim. I recently checked the crankshaft end float and also had the Triumph man check it. All good.

This is an issue with the 6 cylinder engine that worries me. It is OK now but is it possible to lose a thrust washer without warning? 

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6 hours ago, John McCormack said:

Thank you for the replies. I called the Triumph specialist today and described the symptoms and also googled it.

It appears to be a reasonably common issue with the original type of clutch, exacerbated by a lack of lubrication of the throw out bearing and the shaft it slides on prior to installation. The mechanic says it isn't a major problem, it is just uncomfortable in a driving sense and can only be fixed by replacing the clutch with an improved one.

There might also be a bit of a contamination problem on the flywheel/clutch plate which the occasional slipping of the clutch sorts out.

Now I know what the problem is I'll put up with it. This clutch isn't that old and it is only an issue in the conditions I experienced yesterday, hours in heavy traffic, and is easily controlled with a slight change in driving style i.e. a few more revs.

Hi John,

Provided the gearbox has been properly fitted to the engine block/back plate I think that you have the classic case of ratcheting of the clutch bearing assembly sticking on the gearbox nose as indicated by your Triumph specialist. I suffered from this problem for over 40 years and it was only cured  by using a bearing carrier made from marine bronze and a new bearing made by RHP. Also the groove that the fork pins run in was modified to take the saloon slippers. This is a well known mod here in the UK by Revington but beware there are some UK suppliers that supply a brass bearing carrier and nor a bronze one!!!! It is quite a simple turning job to have one made out of bronze! Mine has now done 15K and there has been no signs of it coming back and I have been in plenty of traffic jams as I live near London

Bruce.

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In hot weather it is common,known fault the plastic pipe from the master will be repro or to long.

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Hi Neil,

can you explain why this causes this issue?

I’m eager to learn!

Thanks,

Waldi

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14 hours ago, astontr6 said:

Hi John,

Provided the gearbox has been properly fitted to the engine block/back plate I think that you have the classic case of ratcheting of the clutch bearing assembly sticking on the gearbox nose as indicated by your Triumph specialist. I suffered from this problem for over 40 years and it was only cured  by using a bearing carrier made from marine bronze and a new bearing made by RHP. Also the groove that the fork pins run in was modified to take the saloon slippers. This is a well known mod here in the UK by Revington but beware there are some UK suppliers that supply a brass bearing carrier and nor a bronze one!!!! It is quite a simple turning job to have one made out of bronze! Mine has now done 15K and there has been no signs of it coming back and I have been in plenty of traffic jams as I live near London

Bruce.

Thanks Bruce. That is what my Triumph man said. 

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This clutch ailment on my TR6 is testing my gear change/clutch technique. I had developed the habit of using my leg muscles on the clutch. I now need to use my ankle foot muscles to ease the clutch out incrementally.

It is annoying but I'm getting much better at it.

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On 6/27/2019 at 9:38 AM, John McCormack said:

I took the TR6 about 40kms today in light traffic with no issues.

On the drive back we got held up in very heavy traffic for much of the journey. Over time the clutch felt heavy, a bit like there was a restriction in the hydraulics or the clutch itself. If I didn't use a few revs on take off the clutch would shudder a bit.

I 'çleaned' the clutch by slipping the clutch for a second or two in 3rd. This helped but the clutch just didn't feel right.

When I got home I left the car for 10 minutes and when I got back in the clutch pedal felt perfectly normal. I didn't drive it but any feel of a restriction was gone.

Has anybody else experienced these clutch issues and what was the solution?

Hi John,

To me it sounds like the dreaded clutch ratcheting which gives the appearance of clutch slip when creeping along in heavy traffic? This in my view is caused by the bearing carrier rocking on the gear box nose. This problem plagued me for over 40 years and I only got rid of it when my whole power unit was removed for a rebuild. I went over to a Revington bronze clutch bearing carrier instead of the BL's M/S one and a double fixed clutch bearing fork. I have crept along in a large number of traffic jams since and have not had the problem again, although I still have a mind set that it will start again.

Bruce.

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11 minutes ago, astontr6 said:

Hi John,

To me it sounds like the dreaded clutch ratcheting which gives the appearance of clutch slip when creeping along in heavy traffic? This in my view is caused by the bearing carrier rocking on the gear box nose. This problem plagued me for over 40 years and I only got rid of it when my whole power unit was removed for a rebuild. I went over to a Revington bronze clutch bearing carrier instead of the BL's M/S one and a double fixed clutch bearing fork. I have crept along in a large number of traffic jams since and have not had the problem again, although I still have a mind set that it will start again.

Bruce.

Hi John,

I agree with Bruce,  this does sound like clutch judder. 

My reply on the 27th June suggests looking for the two close tolerance bolts that keep the engine/Bellhousing aligned.

I don;t believe your TRiumph specialists.

if the two bolts are present then you may have another problem whereby the GB splined input shaft and GB extension nose are out of alignment.

The judder (ratchet clutch) is caused by the following sequence -

with the engine running - press the clutch pedal and the Clutch Release bearing (CRB) releases the clutch.

The rounded face of the bearing pushes into the fingers of the diaphragm. If these are not on the same centre then the CRB carrier  try to twist (cock) towards the centre of the fingers.

When you lift the pedal the CRB carrier is now trying to return on a different centreline to the GB extension nose  AND it is still twisted (cocked).

One edge of the CRB carrierwill now try to dig into the GB extension nose and cause it to stop moving.

However engine vibration help to release it, but it jams again and again - judder.

 

Eventually you will need to remove the GB and examine the GB extension nose for subtle wear marks.

I made a cy;indrical gauge to fit closely over the GB splined input shaft with an O/D that of the GB extension nose (that the CRB carrier slides on)

This showed that I had 0.015" vertical misalignement - I fitted a tapered shim under the extension and bingo - no judder

Unlike Bruce I am now happy to use a steel carrier and it works beautifully.

 

Interestingly the TR4 uses a flat faced bearing and doesn't suffer the same problem.  Hmm new project coming on.

 

Roger

 

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I suspect that the bearing carrier is becoming tight on the nose and catching when hot so that the clutch doesn't disengage smoothly.

Likely culprit is the clutch release bearing or possibly the bearing carrier itself having insufficient clearance - sometimes as a result of a few burrs forming when someone has replaced the release bearing.

Either way it's a gearbox out job - replace the release bearing and gently run a file round the edges of the inside of the bearing carrier to remove any burrs formed when drifting the previous bearing off.

Naturally when reassembling make sure things are correctly aligned

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Here is a picture of the where the dowel bolts should be fitted.  I would check these before you decide to take the box out.

Picture supplied to me by another kind forum member, hope he doesn't mind me sharing?

John

Dowel bolts BellHousing2.jpg

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I agree with Bruce above, this most definitely sounds like what is known as a ratchet clutch. You will find it is worse when warm as everything expands. The nose piece that the release bearings slides up and down will be slightly out of shape, hence when you release the clutch pedal it does not release smoothly.  Been here before.

 

Good luck.

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On 6/27/2019 at 9:38 AM, John McCormack said:

I took the TR6 about 40kms today in light traffic with no issues.

On the drive back we got held up in very heavy traffic for much of the journey. Over time the clutch felt heavy, a bit like there was a restriction in the hydraulics or the clutch itself. If I didn't use a few revs on take off the clutch would shudder a bit.

I 'çleaned' the clutch by slipping the clutch for a second or two in 3rd. This helped but the clutch just didn't feel right.

When I got home I left the car for 10 minutes and when I got back in the clutch pedal felt perfectly normal. I didn't drive it but any feel of a restriction was gone.

Has anybody else experienced these clutch issues and what was the solution?

A similar thing happened on our recent tour in europe in VUX (our 72 TR6), after setting off from the South of France for Italy in 34C+ we hit mile after mile of stop-start slow moving lorries and caravans. Then after crossing into Italy we hit even more traffic and at one point sat for over 30+ minutes in more stop-start traffic in a fume filled tunnel at baking oven temperatures due to a lorry breaking down -  I dread to think what the temperature under the bonnet was, but VUX kept it's cool.

After a cooling down period the clutch was perfect for the rest of the trip through Italy, Switzerland and home via France.

Cheers, Andrew

Edited by Andrew Smith

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On ‎6‎/‎28‎/‎2019 at 7:04 PM, Waldi said:

Hi Neil,

can you explain why this causes this issue?

I’m eager to learn!

Thanks,

Waldi

See Andrews post,the plastic pipe can just about boil the fluid.There are ways to stop it but we are talking a lot of heat ask any BMW M3 owner.

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41 minutes ago, ntc said:

See Andrews post,the plastic pipe can just about boil the fluid.There are ways to stop it but we are talking a lot of heat ask any BMW M3 owner.

Spot on Neil, it was even worse on my 98 E36 M3 EVO.

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Thanks Neil and Andrew.

I found on wiki that wet DOT3 (with some water in it) can have a boiling point as low as 140 C. But if there is free water, it can be as low as 100C I guess. 

Regards,

Waldi

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Hi John

I had a similar problem with my clutch. I had the gearbox on the 4A rebuilt to cure oil leaks last year. When we went to the National Rally in Queensland in October, the clutch was a major challenge. It would judder on engagement and you could not engage first or reverse at a standstill. We became very good at turn engine off engage gear start engine especially when parking. We survived the 3000km  journey by taking up all of the play in the slave cylinder.

Earlier this year I finally bit the bullet and ordered a new clutch and bearing from Rimmers. When I removed the gearbox, it appeared that I had a rebuilt clutch - blue in colour with the word Triumph written in white marker. I do not recall whether I installed that clutch 20 years ago. (There is a lot I don’t remember.....)

Having replaced the clutch and bearing, cleaned the flywheel and replaced the ******* gearbox again, my diagnosis is that the gearbox rebuilder had quite sensibly replaced the throw out bearing whilst the gearbox was out. However he was not aware of the clutch in the car. The diaphragm on the new clutch is quite different from the old one. We now have a nice smooth clutch with a lighter pedal. I guess the moral is to buy the clutch and bearing at the same time and from the same supplier. 

Good luck

Rockie

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A bit of good news on this clutch issue.

The pedal rubber on the clutch was extremely worn, essentially smooth all over. When driving my foot wouldn't slide over the pedal as I released the clutch and when I felt it after a drive it felt very sticky to touch.

Owning a few of these cars I found a new pedal rubber in a box of bits and put it on the clutch pedal.

We just got back from a 50-60km drive and while there is a slight jerkiness the problem is 90% solved. The principal problem was the sticky rubber not allowing my foot to slide as I eased the clutch out. The new rubber allows a smooth sliding action.

It didn't cost anything and I didn't need to take the box out.  :-)

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That is cheating :P

 

Go on, take the gearbox out and THEN find it was the rubber :angry:

 

Roger

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2 hours ago, RogerH said:

That is cheating :P

 

Go on, take the gearbox out and THEN find it was the rubber :angry:

 

Roger

I'm not feeling too pleased.

The long door TR2 I am restoring to original condition is overheating, not badly but not good enough with summer coming. I fitted an original 4 blade fan to keep it original not knowing that the 6 blade fan as found on later 6 cyl Triumphs was a "tropical" option down under. I have had a 6 blade fan in my boxes of bits for 20-30 years so I measured it up and figured I could get the fans over the fan extension bolt, between the bolt and radiator.

I got the 4 blade one out easily and then found the new one wouldn't make it by about 1/4". Undid the radiator, drained it, disconnected everything and with my son's help to move the radiator as far as possible tried again. This time I got the new fan jammed between the bolt and radiator. It wasn't forced in, maybe 1/8" in it and it caught on something.

I got it out but did minor damage to the radiator cooling fins.

4 hours work and went backwards. The front apron will have to come off to do the job. With the new paint job I don't have the courage to do it.

Edited by John McCormack

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