Clutch diagnostics

[Jason]

At long last I am fitting the new interior I have for the TR - new carpets, underfelt, door panels, vinyl, recover the H frame etc - so it's all stripped out now.

I've been chasing a clutch issue for a while, occasionally the clutch pedal seems to "stick"making smooth take up of drive very tricky. I found a missing pedal return spring and that improved things but then it came back so I replaced all the hydraulics, this didn't cure it but again it was a little better. I then suspected that the pedal bushes might be worn so I've just stripped the pedal box out to replace them but they are only very slightly worn not enough to be causative.

So, clutch cross shaft maybe? What tests can I do to see if this is the likely culprit before I bite the bullet and pull the box out? I really didn't want to get into that but I'll do it if I have to - might as well throw a clutch kit in too unless it looks really good but I'll cross that bridge when I come to it.

[mikew]

Sometimes its the clutch bearing carrier sticking slightly on the gearbox nose piece - check for sharp edges / rough edges etc.

Also wear where the slipper pins fit in the bearing carrier - check the grove is uniform with straight edges.

You can double up the cross shaft bearings in the gearbox too

Have fun, pull the box you know it makes sense  :)

[Jason]

Yeah Mike, I know it makes sense :-) I've never pulled a TR6 box out before, it looks just as much fun as a Herald/Spit/Vitesse!

When you say double up the bearings - do you mean just stick two in there?

[mikew]

Its more fun than a Herald Spitfire etc etc as the box is so much heavier  :-/

Yes just fit 2 bearings each side - the alloy housing is about 25mm thick, and a bearing about 10mm, so 2 fit each side without issue, and with a larger surface they wear more slowly

[Andy Flexney]

Jason,

We had this on a TR5 and a TR6 last year and both times it was the bearing carrier. This was made out of cast (?) iron and after changing to a brass carrier all was well. It appears the iron carrier wears, the hole becomes oval and starts to jam on the shaft. This is especially noticeable on the TR5 and TR6 were it cannot spin freely as on the TR3. During the rebuild we left the pin out of the bearing carrier on the TR6 to see if this will help.

First we were told it was because of aftermarket clutches and clutch covers but could not find any evidence to back this up. Although it did slightly improve when we put in a reconditioned original Laycock cover and new plate.

Beware there are 2 different size bearing carrier and if I manage to find the bad picture I took I will add it here. The one on the left is the one I used in the TR3 albeit with TR6 gearbox and overdrive so I presume this is the one you will need for yours. The gearbox flange to engine is thinner on the original TR3 box therefore the slightly moved back bearing carrier.

As Mike says take you gearbox out you know it makes sense and replace the bearing carrier. If you have the seats out already for the carpet refit it is only a couple of hours and you have the box out repaired and back in

Cheers
AndyF

[Jason]

Right well that's settled then, I'll get the box out - I've rebushed the pedal box, feels a lot better now but it wasn't notchy so I'm positive that isn't my problem but at least it's done and going back in the car now.
I'll pull the box tomorrow and see what delights I find in there. The car was restored 20+ years ago and done on a budget as the money was spent in funny places - new floors, wings, etc but a patchwork of old trim back in, some with the mud splashes from the holed inner wings still on it! The structure is sound and the mechanicals good so it's only silly things that need rectifying - I suspect that 20 years ago the quality of the some of parts wasn't that great either - or at least there might have been cheapo options used. I've been rectifying the short cuts and most are sorted - this clutch issue is one of the last I hope.

The bronze carrier is available new from Paddocks (as is the cast one) and it does look like the left one in your picture



Oh and Mike - I've seen "double" bushes for the cross shaft like this



Looks like an easy worthwhile mod.

Thanks for the input guys.

[Hogie]

Hi Jason,
                  when you have it apart have a look at the fork taper pin - replace this as their life is interesting - consider putting in the extra cross bolt to help the taper pin.

Roger

[Jason]

Thanks Roger, everything so far suggests that the taper pin should be replaced when your have the opportunity!

[Nick Jones]

Jason,

If you haven't discovered the Buckeye Triumphs site, a wealth of information awaits you.

Just one small corner of it
http://www.buckeyetriumphs.org/technical/clutch/StickyClutch/StickyClutch.htm

Nick

[Jason]

Thanks for that, there's soooo much on that Buckeye site, I always feel I'm missing something when it comes to finding what you need :-)

[Jason]

Right, gearbox is out. God knows how I'm going to get it back in there but that's another problem! Photos on my blog - it all looked OK to me. It's a cast iron carrier but not excessively worn, it does have some wear "dents" in it though from where the fork touches.
I think the issue may be the cross shaft bushes, they are single width and knackered, whether this is actually enough to cause my issue I'm not so sure.
I'm going to have a look at the cover and plate next, see if I can find anything obvious there.
Any thoughts?

[thescrapman]

the little hat things on the ends of teh forks look quite worn in the pictures.

Or are there no little hats.

Or .... is it the version that uses square hats

And just push in some double width cross shaftbearings, no need to take the old ones out.

Also the pin should have been wired.

Cheers

[Jason]

No little hats on the fork, the marks look a lot worse in the photos I think. There was no sign of any locking wire but it'll get some when I reassemble. The driven plate looks fine, loads of meat left on it, the plate looks OK too, the fingers are worn but not excessively so. Apart from the release bearing carrier and the cross shaft bushes I can't really see much wrong with it all, which is a pain!!

[mikew]

Bearing carrier and fork is (are) shot.

Those marks on the fork and the indents in the carrier are all it needs to spoil the clutch action.

The pin needs wiring too, (thats what the hole is for) on refitting to stop it coming loose

[Andy Flexney]

Jason,

there should not be any dents in the bearing carrier and certainly not in the position where it is. Is there one at the other side too? The bearing should spin until the little pin through the carrier is pressing against one of the pins on the fork.

I would replace the bearing carrier and the bearing, the fork pin and the cross shaft bearings and the complete clutch. In other words just about everything. The fingers on the clutch look quite worn and could be contributing to your problem.

I would not only wire the fork pin but drill a 3mm or 4 mm hole in the middle of the fork at 90 degrees to the pin position and tap a roll pin through. It offers support to the pin and will hopefully not break before you have had chance to take the box off again for clutch replacement or whatever.

AndyF

[Jason]

Thanks guys, I'm guessing that defects here and there mount up. The clutch action wasn't awful but it did spoil the drive a bit. Andy, there is a smaller dent one side of the carrier than the other, looking at it again, it's not right and obviously means that the carrier isn't operating "square".
The Yanks seems to want to lubricate this carrier but that seems to go against what you'd normally do in a clutch and what would you put in there that would stay put for the life of the clutch?

So the shopping list is new everything then, with a bronze release bearing carrier then?
Is all this the same on the TR6 as on the saloon and Stag?

[mikew]

Jason wrote:

So the shopping list is new everything then, with a bronze release bearing carrier then?
Is all this the same on the TR6 as on the saloon and Stag?

Yes bronze carrier is good.

Saloon and Stag both have differences to the length of the bearing carrier from each other and the TRs, and the good stag clutches have a longer gearbox nose piece, but all a similar system.

Don't grease, the factory didn't and it just gets sticky and full of old clutch lining

[esxefi]

you can actually redrill another hole for the anti rotation pin,just do it less than 180degrees and the fork contact pads will press on new metal.(no good if the bore is shot though)

for the taper pin I would go belt and braces and drill and tap for a decent allen bolt.

I fitted a 12mm one which is tapped right up into the fork and that was 20years ago and have had no problems at all.

[Hogie]

12mm cross bolt !! What is the diameter of the cross shaft?

Roger

[piman]

Hello Andy,

my feeling an additional pin, particularly a thin roll pin will do nothing, likewise the fitting of an extra bolt as is often advised. Roll pins are flexible so a solid pin would be better but 3 or 4 mm is tiny.
The critical thing is to ensure the taper pin is a very good fit, If the cross shaft hole is worn then the pin won't sit correctly and the shaft needs reaming. If it's not worn it's worth lapping the pin in the shaft to ensure it contacts over it's length. (Also make sure the head does not meet the fork)
The whole idea of a taper pin rather than parallel is that, fitted correctly, there is no clearance whatsoever. Simply drilling a hole for a bolt means the bolt is loose(relatively) and does rock if the taper pin is a bad fit. It may delay things but it is not a cure (In my view)

Alec

[thescrapman]

Jason

Were the fork contact pads missing??

I am intrigued now.....

[Jason]

There were no other parts of evidence of other parts - no debris in the bottom of the casing etc so I don't know what a "contact pad" should look like! The fork touches the carrier, nowt else was there - it looked like this
which doesn't show any pads, just a fork and it's replaceable pins (I didn't realise they were replaceable and available!)
Can you show me a picture?

[piman]

Hello Jason,

here's a copy of the later style thrust.

I doubt if the cross shaft is more than 3/4" diameter so I'd say you were lucky to get away with a 12mm bolt, it only leaves a wall thickness of 4mm or so ech side if drilled dead central.

Alec

[Jason]

Nope, no sign of anything like that ever having been in there, what are they made of?

[Jason]

Could it be that there's a mismatch of components in my setup? I'm only guessing here but could it be that the early set up is bronze carrier and no pads? The later set up is cast iron carrier and slipper pads, ie cheap.
In my car, by using the later cast carrier but no slipper pads it has worn a 'dent' in the carrier and, combined with the wear in the cross shaft bushes, there is enough movement to create binding of the carrier on the nose extension leading to drag?

Or am I taking bollocks (again)?

Oh and if I take the nose piece off, will the gearbox oil drop out? I have not yet drained the box and would like to do it after the box is back in and I can get it warm.