T9 clutch woes

[TimW]

Hi All

Some may know me some may not but I have a 1974 modified GT6. Restored 11 years ago. I fitted a type 9 gearbox kit supplied by frontline (though jigsaw) at time of restoration. The supplied kit included a saab99/900 clutch cover and TR7 clutch plate. I've always had a very high biting point on the pedal. 

Last year I pulled the engine and box to replace the 6-3-1 Pheonix manifold and big bore exhaust for a new TLD manifold and custom 2.25 inch exhaust. At the same time I had to change the TR7 organic clutch plate as it was badly worn so installed  a ford Sierra organic plate. 

Finally managed to have the bespoke exhaust fitted 2 weeks ago and took it for a test. My biting point is even higher now and the clutch now slips badly under heavy acceleration. 

 

Last Saturday we pulled the engine and box again. I replaced the saab cover (as the fingers were worn) with a Borg & Beck cover that's done 3000 miles and is at least 15 years old. I kept the Sierra plate. 

I can't figure out why my bite point is so high on the pedal. The clutch arm doesn't sit in the centre of its travel at rest its much further towards the rear of the bell housing. Slave is at least 3/4 stroke if not a bit more at rest. It's like the cover isn't deep enough and the diaphram spring is compressing too much so it takes very little movement to disengage. 

I'm lost for an answer other than the old Laycock covers look like they are much deeper. 

Any thoughts anyone?

 

[Nick Jones]

Hi Tim,

Nice to hear from you on here   Sorry you have problems though.

The joys of hybrid clutches and their actuating mechanisms.  Familiar issue (and ongoing) in this neck of the woods........  Though assuming your T9 conversion is done the usual way with an adapter plate between bell housing and gearbox, you should actually be using pretty much all Triumph parts.

Two main areas this can go wrong.

1. Clutch itself.
 - Weak pressure plate spring, or over-skimmed pressure plate friction surface (recons only) - which you have pretty much ruled out by fitting another pressure plate
- mismatch between pressure plate and cover plate.  In my experimentations with mixtures of Toyota and Triumph parts I have found friction plates in two thicknesses.  The Triumph (also Ford and Saab) from the likes of B & B, LUK and Sachs seem to use a friction plate that is around 7.5mm when new (it's done by about 7mm IIRC) whereas the Japanese ones (Exedy) are almost 1mm thicker.  You can use the thicker Japanese friction plate with the European cover (though you probably shouldn't), but you need to increase the stroke of the release mechanism or it won't clear.  On a Vitesse, a 3/4" m/c does it.  You need a strong leg and presumably your could wear the friction material all the way to the rivets and beyond.  The other way around doesn't work as there is not enough clamp - barely grips a new disk.

What you need to look for, is how the angle of the diaphragm fingers changes as you bolt the clutch up to the flywheel.  In their relaxed state the fingers point rearwards in a shallow cone.  With a new, compatible thickness friction plate they should end up nearly flat when the bolts are tight.  With an over-thickness plate they go slightly concave.  As the clutch wears the fingers gradually move back rearwards and form the cone shape again.  With the Triumph mechanism this also has the effect of bringing the outer end of the actuating arm forwards and compressing the slave cylinder.

From what you say, yours is the opposite.

2. Actuating mechanism.
- The hydraulics is dead simple.  About all that can wrong and cause your symptoms is that the slave cylinder bottoms out.  At estimated 3/4 extension that isn't your problem.
- The tricky bit is getting the operating arm to work around the centre of it's range and achieving this means you need the release bearing carrier to be the right length to put the resting position of the outer end of the arm forward of it's mid-position with a new clutch installed.  This isn't entirely straightforward as even with the standard gearboxes there are several factors that can affect what the right length is.  Long or short back crank, flywheel thickness.  Clutch working thickness.  Release bearing working thickness.  Consequently there are a number of different lengths from the factory - more than you might expect because the saloon ones look the superficially same. 

A very important thing is that with the box fitted to the engine, there needs to be some spare travel.  That is, there needs to be room for the carrier to move back a bit (lever comes forward), proving that the carrier is not trapped between clutch and gearbox with insufficient room to fully disengage.  This could be your issue if your carrier is too long.  It might also explain the worn fingers on your Saab clutch plate.  In you case, it might also be that the T9 conversion is restricting the rearward travel of the carrier.

The other possibility is that you have (at least) two faults: A carrier which is too short, in combination with a friction/pressure plate duo which don't give enough clamp.

My favourite theory at present is an over-long bearing carrier trapped between clutch and gearbox, maybe made worse by the conversion restricting rearwards motion.  An absence of free play.  This might be a bit hard to detect for sure due to the rather free-floating nature of the arm!  If this does prove to be the case, you might want to check your crankshaft endfloat (with gearbox off or at least sure that the  clutch is not compressed at the time of test) as the thrust washers might have been working a bit harder than usual.....

Hope this is useful.....

[TimW]

Hi Nick

Thanks for your detailed response. Let be address the bearing sleeve theory first. With the gearbox attached to the engine but without hyralics attached the bearing carrier has at least an inch of travel. The clutch arm starts at just under midway (towards engine) in the bellhousing opening and moves towards the gearbox until there is about 1/2 inch of opening remaining. The clutch fingers are most likely worn because I have to ride the clutch in very slow moving traffic due to a kangaroo motion at very low speed in 1st, this is probably a combination of a lightened GT6 flywheel and 3.27 diff. I have a short back, late Mk2 PI bottom end. 

I am sure that I am over extending the clutch diaphragm spring when I fully depress the clutch as the biting point is so high on the pedal. I have a standard late mk3 hydraulics setup of 3/4 master and 1 inch slave. 

The Sierra clutch is about 8mm thick. The very worn TR7 clutch, both Helix organic, is about 6mm (in round figures) 

I regret I didn't fit the worn TR7 plate back in at the weekend as although this still had a high bite point it didn't slip previously just to see if the slipping is the increase in torque that I think I can feel with the recent exhaust/induction mods. 

I have 2 bearing carriers. The first is the origional (I know the complete history of the car and can confirm this is origional to the car) and made of steel. The second is a used item I stumbled across years ago that looks like a phosphor bronze or similar. I think it could be an early GT6 or 2l vitesse possibly. They are both the same length and have the same shape and size release bearings.  I swapped to the bronze one last year as it was a better fit on the bellhousing tube. My clutch arm pins that engage the sleeve have gone flat on the thrust face resulting in a little play between the 2.

 

Thrust bearings were changed about 10 or 15k miles ago and haven't been checked since

[Nick Jones]

Hmmm......  Fairly sure the clutch master is 5/8" as standard......  They sometimes get changed for  a 0.7" (or swap the slave to 0.7") due to lack of travel.  So 3/4" could explain your high biting point...... but not the slip.  You will be overstroking the clutch, but my experiences suggest that though undesirable, this isn't a massive problem.

As for the position of the  arm, has your flywheel lost any meat from the clutch face that would move the clutch assembly forward?  Arm itself in decent condition?  Fulcrum "mushroom" ok  This normally bottoms out on the front face of the gearbox, so should be coming up against the adapter plate now - in effectively the same place?  Most of the modern (and this is going back a bit now) are too shallow.  Should be 19mm IIRC and many are 3 - 4mm less

Bottom line though - none of this does anything to explain the slip as it doesn't sound like anything is leaning on the clutch.  Presumably the hydraulics do fully release?  (can't think of anything that would stop it).

Therefore I'm thinking your original high pedal is the 3/4" m/c.  But the slip,  If  the release mechanism, hydraulic and mechanical are fully releasing, seems related to the Sierra friction plate - though I cannot explain why.  At 8mm it seems a bit thicker than what I remember as usual for the European clutches but it didn't cause a problem for me.  I have much less torque though.  Perhaps bite the bullet and buy a matched clutch set?  There's supposedly a Sachs cover with a good clamping force and a light action which is a great upgrade for Triumphs...... I'll see if I can find what I did with the part number as I might be wanting one too.

Probably not directly related but my hybrid Toyota/Triumph arrangement (uses mostly the Toyota release mech, not dissimilar though) is weird in that with a brand new clutch plate a 5/8" cylinder easily clears it with a nice, light action.  After a few 1000 miles, it no longer clears.  Fit a 0.7" m/c and all is good again, for about another 6 - 8k, then it no longer clears again.  Fit 3/4"....... Now at about  18k and getting short of travel again.  And it's heavy....  That's a Helix 8" clutch plate with a B & B pressure plate.  Going to have to deal with it quite soon.......  Would have liked more than 18k.  Quite hard miles, but not that hard!

[TimW]

. My helix organic TR7 clutch has only done 10 - 15k miles. Its still got a little meat on it but not enough for me to want to put it back in. I'm guessing here as its not been on the dyno in its current trim but as it had 200ftlb torque before changing the 6-3-1 (dyno confirmed) it could have 220 or so now. It's come quite far since your help with the original EFI conversion. Now has Peter burgess big valve race head, 280 inlet /300 ex duration cam. And ms2 v3 with edis delete rather than the ms1 v2.2 you kindly built for me. Put one of those blackline LSD's in the 3.27 last year. 

I've now have a 4 paddle clutch on the way to me and was considering a referbishrd Laycock cover as they look far deeper than the saab/borg & beck covers which I think may solve the high bite point.  Still can't find any info on spring strength for these though 

My apologies on the hydraulic sizes I quoted earlier. I actually have 5/8th master and 1 inch slave fitted. 

 

[Nick Jones]

IIRC, back in the day there were different pressure plates listed for T2000/VIt/GT6 vs 2.5PI/TR5/TR6 with the latter having a stronger spring for more clamping force and higher torque capacity.

These days one size (nearly) fits all.

This thread has some part numbers from Sachs and LUK.  Quite likely the Sachs one is what you started with

 

[TimW]

Thanks Nick

Yes I've read that topic. When we looked up the part number on the saab cover I'm sure it said it was a Borg&Beck. 

I'm going to try a Laycock cover and paddle clutch. I can always sell the Laycock if it doesn't work. 

[Nick Jones]

Looking online Sachs describe the 3082 100 041 as NLA.  There is also the 3082 100 142 which shows as being the supersession to 3082 100 042...….

Laycock is good gear as a set.  Have heard reports they don't respond well to mix 'n match but no personal experience.

[TimW]

I guess only time will tell Nick. Its all sellable in the end. Just a pain the engine has to come out everytime just to change the clutch. 

[Nick Jones]

52 minutes ago, TimW said:

Just a pain the engine has to come out everytime just to change the clutch. 

 Why?

[John I]

51 minutes ago, TimW said:

I guess only time will tell Nick. Its all sellable in the end. Just a pain the engine has to come out everytime just to change the clutch. 

Hi Tim, a little while ago I followed up on the thread which Nick highlighted and found that they were allegedly available from " onlinecarparts.co.uk" price quoted was £71.16 think that was inc VAT. 

Be interested to see if they still have them for offer.

john

[TimW]

8 minutes ago, Nick Jones said:

 Why?

Because the gearbox doesn't come out from the inside. There's absolutely no way unless I cut the propshaft tunnel which I don't want to do. It took us an hour to get the engine and box out last Saturday. 7 hours in total from driving into workshop to driving back out. 

[TimW]

8 minutes ago, John I said:

Hi Tim, a little while ago I followed up on the thread which Nick highlighted and found that they were allegedly available from " onlinecarparts.co.uk" price quoted was £71.16 think that was inc VAT. 

Be interested to see if they still have them for offer.

john

The sachs ones John?  If so I'm not really looking to fit one. Had a saab and a GT6 cover so far and both aren't really suitable. 

[John I]

2 minutes ago, TimW said:

The sachs ones John?  

Yes Sachs. Sorry hadn't picked up that you had already tried them.

[Sprint95m]

Firstly, I don't have a parts catalogue for a GT6 so cannot compare the master and slave with the Dolomite 1850 numbers
but I do know the clutch plate, cover and release bearing are all the same.

Dolomites have 5/8" bore master cylinders and 7/8" bore slave cylinders.
There are two versions of 7/8" bore cylinder, the position of the  mounting flange is the only difference.
The early 1850s had the GT6 'box with a slave which had the mounting flange nearer the middle (Vitesse type) 
but the other slave (T2000/Dolomite Sprint type) does work too (I have used this).

There were two flywheels used on 1850s. The early version is thinner and gives a much lower biting point.

Anyhow, the point of my post is this question...
Do you have the correct release bearing? 
I have one here (somewhere) which is supposed to fit but it had has quite different dimensions to an original RHP
think it is Quinton Hazel boxed SKF?

 

Ian.

[TimW]

49 minutes ago, Sprint95m said:

Firstly, I don't have a parts catalogue for a GT6 so cannot compare the master and slave with the Dolomite 1850 numbers
but I do know the clutch plate, cover and release bearing are all the same.

Dolomites have 5/8" bore master cylinders and 7/8" bore slave cylinders.
There are two versions of 7/8" bore cylinder, the position of the  mounting flange is the only difference.
The early 1850s had the GT6 'box with a slave which had the mounting flange nearer the middle (Vitesse type) 
but the other slave (T2000/Dolomite Sprint type) does work too (I have used this).

There were two flywheels used on 1850s. The early version is thinner and gives a much lower biting point.

Anyhow, the point of my post is this question...
Do you have the correct release bearing? 
I have one here (somewhere) which is supposed to fit but it had has quite different dimensions to an original RHP
think it is Quinton Hazel boxed SKF?

 

Ian.

Hi Ian

Thanks for your reply. I have 2 different bearing carriers. The original has a replacement I fitted after the one supplied with my type9 kit became very noisey. I also have a used carrier with bearing that's the same size, and shape. I have also just obtained a NOS AP Borg & Beck. All three bearings look the same and the AP one matches the part number in my parts book. I'm therefor assuming I have the correct bearing. 

[Nick Jones]

Thickness of the OE one is 19mm IIRC.  Some of the substitutes are less, some quite alot less.  If you are close to 19mm, it's not the issue.

[TimW]

23 minutes ago, Nick Jones said:

Thickness of the OE one is 19mm IIRC.  Some of the substitutes are less, some quite alot less.  If you are close to 19mm, it's not the issue.

Haven't got one to hand but almost an inch thick sounds about right. I'm confident I have all of the correct mechanical components as I've used most of it from the origional car. Could my high bite point be associated with the lightened GT6 flywheel? My thoughts are no. 

[spider]

Tim I have a nos laycock on its way to me at present, I can take some measurements for you when it arrives.

 

[Sprint95m]

9 hours ago, TimW said:

Could my high bite point be associated with the lightened GT6 flywheel? 

Hi Tim, is this a standard flywheel that has been lightened
or is it a new bespoke flywheel?

 

Ian. 

[Nick Jones]

9 hours ago, TimW said:

r. Could my high bite point be associated with the lightened GT6 flywheel?

If the flywheel thickness has been reduced, yes. If it’s still at or very close to the original thickness then no.

[TimW]

5 hours ago, spider said:

Tim I have a nos laycock on its way to me at present, I can take some measurements for you when it arrives.

 

Hi Mike. I have a referbished Laycock being delivered to me today. Spill the beans where did you find a NOS one? 

[TimW]

19 minutes ago, Sprint95m said:

Hi Tim, is this a standard flywheel that has been lightened
or is it a new bespoke flywheel?

 

Ian. 

Standard GT6 one

[spider]

Tim I have a nos laycock on its way to me at present, I can take some measurements for you when it arrives. Twas on ebay for £75 . I had been looking for one for ages then when one did I could not justify the cost at present, so I bought it. I was in the middle of messaging you to buy it when I hit the buy it now button on impulse.

 I am glad you have one sorted I don't feel so bad now. Hopefully it will see me out as I can't drive far these days anyhow.

 

[TimW]

32 minutes ago, spider said:

Tim I have a nos laycock on its way to me at present, I can take some measurements for you when it arrives. Twas on ebay for £75 . I had been looking for one for ages then when one did I could not justify the cost at present, so I bought it. I was in the middle of messaging you to buy it when I hit the buy it now button on impulse.

 I am glad you have one sorted I don't feel so bad now. Hopefully it will see me out as I can't drive far these days anyhow.

 

Did it come with a reserfaced friction plate from Lloyd? If so I saw that yesterday but he wouldn't split the two. I didn't need the friction plate. I also didn't like the condition of the pressure plate. It was cheap though. I paid £160 delivered for mine. Its referbished so like new.