Clutches and Tremec gearboxes on 3.8's

[wynnski]

Hello
I need a bit of help with a clutch.
E type 89 vin number last of the 3.8's. It has a Tremec 5 speed box. The flywheel has 104 teeth. It has been drilled and pegged to accept the large 10" spring type pressure plate which does not look correct to me as there are a set of threaded holes and peg holes for the smaller diaphragm clutch.
I have both pressure plates and a 23 spline 9 1/2" clutch plate...all new.
Which pressure plate should I use with this gearbox?
Any help would be appreciated

[kingzetts]

My 3.8 had a T5 box when I bought the car. I found during restoration that it had the 10" pressure plate and a 9.5" clutch disc, which are mismatched - the pressure plate does not clamp on the full width of the friction material. As it is very hard to locate a 10" disc which will fit the T5 input shaft (I would have had to have one made up specially) I had the flywheel drilled to take the 9.5" pressure plate. By all accounts the 9.5" pressure plate is easier to depress and generally preferable anyway. Clutch works fine and feels fine in use so I'd recommend this approach.

If you do use the 9.5" plate, though, make sure you rotate the engine with the box fitted but off the car to check for fouling. I found the outer lobes of the 9.5" pressure plate fouled against the inside of the bell housing. A small amount of metal had to be ground away from inside the bell to provide clearance - not the sort of thing you want to discover once you've already refitted the engine to the car!

[wynnski]

Hello kingzetts

The clutch was slipping on this car quite badly although the clutch plate was OK so I think it was a bad mismatch all round. I will fit the diaphragm cover plate and 9 1/2" clutch plate and check for clearance as you said.

[64etype]

[quote="kingzetts"]

If you do use the 9.5" plate, though, make sure you rotate the engine with the box fitted but off the car to check for fouling. I found the outer lobes of the 9.5" pressure plate fouled against the inside of the bell housing. A small amount of metal had to be ground away from inside the bell to provide clearance - not the sort of thing you want to discover once you've already refitted the engine.


Is it correct that this is in reference to an aftermarket bell housing supplied with the transmission kit? I just did this change as part of a synchro gearbox installation in my 3.8 using the factory bellhousing. Still out of the car, but not a job I want to do again...

[PeterCrespin]

When I fitted a Getrag and diaphragm clutch as part of my S2 de-lumping I had to relieve the bulge inside the bell where the clutch slave sat. It foulded the three biggish lumps on the pressure plate where the torque straps are located inside. It was an early bell IIRC and if your bell is a correct part you should be OK.

Just one of the reasons I would never install a 'mongrel' powertrain until AFTER checking it all cranks freely out of the car.

[wynnski]

Thank you all.

The bell housing is the original E type. It has been mounted to an adapter plate on the front of the Tremec, so I should not have any trouble with clearance.
I just need to know the best clutch to use. I would like to use the 9 1/2" diaphragm unit as it is neater and I am going to build it up with this to check clearances.

[kingzetts]

My fouling problem was with the T5 box mated to the original Jaguar 3.8 bell housing.

[tinworm]

Just to clear up one mystery the late 3.8 flywheel was drilled for both the 10" and the 9.5" clutch.

Barrie

[wynnski]

Hello Barrie
Thank you for clearing up the fact that the flywheel can accommodate both clutch sizes.

[PeterCrespin]

Hello Barrie
Thank you for clearing up the fact that the flywheel can accommodate both clutch sizes.

Not ALL flywheels. Late 3.8 early/most 4.2. The giveaway is, err, two sets of holes :-)

[64etype]

I checked clutch to bell housing clearance over the weekend (9.5" Borg and Beck diaphragm). Clears 3.8 bell housing by a country mile (I removed starter and visually checked it). I wonder if clearance issues have been with a 10" Laycock diaphragm unit....sure isn't an issue with a B&B.

[kingzetts]

I can only report my experience, which was that a 9.5" diaphragm clutch cover plate fouled on the inside of my bell housing which was in my late '62-built 3.8 and my flywheel was only drilled originally for the 10" coil spring clutch cover. The 10" cover did not foul the bell. I do not recall the make of 9.5" cover plate I used. The fouling was minor, but enough to stop the engine being turned over by hand.

it may be that later 3.8 bell housings have more internal clearance, especially if Jaguar were at the time drilling flywheels to accept the 9.5" as an option to the 10" cover.

Anyway, my point remains that it is well worth checking for clearance before fitting engine and box into the car whenever fitting a new combination of drivetrain parts. Takes seconds and avoids the risk of hours of rework. The absence of fouling in one persons combination should not be taken to guarantee the same in all cases.

[PeterCrespin]

This is exactly how I found out about my fouling - cranking the engine by hand on the garage floor. Fouled in both directions, about a third of a turn apart IIRC.

I forget the brand of clutch. Probably AP or Luk

[64etype]

This is exactly how I found out about my fouling - cranking the engine by hand on the garage floor. Fouled in both directions, about a third of a turn apart IIRC.

I forget the brand of clutch. Probably AP or Luk

Definitely good advice to check it early. I've done so by hand on the garage floor, and will check it again after the long block goes in the chassis and I spin it on the starter to get it "pre-oiled". Also need to check the clutch hydraulics to be sure it's all correct as a result of the EJ gearbox conversion. If either is an issue, it's not a big deal to remove it before ancillaries are hung on the engine. Thanks for the advice.

[wynnski]

Thank you all for your replies.

Last week I put the 9 1/2" diaphragm clutch set up onto the flywheel and offered the gearbox onto the engine. Thankfully there was no fouling and it all turned freely.
One thing I did find out is that the thrust release bearing for the 10" pressure plate set up has a thinner piece of carbon on it compared to the 9 1/2" clutch set up. Initially I had the 10" release bearing with the 9 1/2" clutch and wondered why the release lever was fouling the back of the lever hole in the bell housing. Once the 9 1/2" release bearing was fitted, which has the thicker carbon face on it, the lever came back to the correct position with plenty of travel.
So full 9 1/2" set up it is.

[64etype]

Thank you all for your replies.

Last week I put the 9 1/2" diaphragm clutch set up onto the flywheel and offered the gearbox onto the engine. Thankfully there was no fouling and it all turned freely.
One thing I did find out is that the thrust release bearing for the 10" pressure plate set up has a thinner piece of carbon on it compared to the 9 1/2" clutch set up. Initially I had the 10" release bearing with the 9 1/2" clutch and wondered why the release lever was fouling the back of the lever hole in the bell housing. Once the 9 1/2" release bearing was fitted, which has the thicker carbon face on it, the lever came back to the correct position with plenty of travel.
So full 9 1/2" set up it is.

I believe the pivot arms on the carbon release bearing attach points also have a different offset for the 4.2/B&B clutch. Anyway, mine has the thicker/deeper arrangement to make up for the longer distance to the bearing surface on the pressure plate....bought it with the clutch 25 years ago (just now installed). However, the available throw before lever to bell housing contact still seems quite small...about 5/8"-3/4". Guess it doesn't take much throw to achieve a release, but it still concerns me. I'm curious if the gap/throw distance on your clutch lever is in this range? If it's significantly larger, I have a parts problem. Thanks.

[wynnski]

Hello Eric

I think there was more clearance than that on my release lever, but with the multiplication ratio of the lever it only needs to move a small distance to release the clutch plate. I cannot check it now as the the flywheel and pressure plate have gone away for skimming and balancing, but I can check again when they are back.
The release lever is the same for 3.8 and 4.2 as far as I can make out. I have the 3.8 parts manual and the part number is C9797.

[64etype]

Hello Eric

I think there was more clearance than that on my release lever, but with the multiplication ratio of the lever it only needs to move a small distance to release the clutch plate. I cannot check it now as the the flywheel and pressure plate have gone away for skimming and balancing, but I can check again when they are back.
The release lever is the same for 3.8 and 4.2 as far as I can make out. I have the 3.8 parts manual and the part number is C9797.

I have both levers...plus both bell housings and both flywheels. Yes, the levers are the same. I believe the length ratio on the lever requires more throw at the slave cylinder rod end for a smaller movement a the bearing. Anyway, I would indeed appreciate that measurement when you get your parts installed. As an aside, my original 3.8 bellhousing (with coil spring style clutch) had evidence of significant, long term contact with the lever at full throw. The entire end of the rectangular hole was mashed in. I had it welded up, but that's where my questions about the distance available/required for clutch release started. I removed the engine from the non-running car immediately after purchase thirty years ago, so I don't have an operational reference. But something was amiss in the clutch department.

[wynnski]

OK everyone, I have the flywheel back from being machine. It has been skimmed and balanced along with the pressure plate and pegged for the 10" diaphragm pressure plate.
I have had to use the 9 1/2" clutch plate from the Landrover Defender 300 Tdi, because this fits the Tremec input shaft, and also trying to get a 10" 23 splined clutch plate is nearly impossible.
I have fitted the correct release bearing for the 10" diaphragm pressure plate. The carbon on this release bearing is thicker than on the old spring type pressure plate release bearing.
This set up has given just over 1/2" of free play on the release lever arm measured at the pin holding the end of the clutch push rod in place. I measured this without the push rod attached so it gives the measurement of free play inside the bell housing. When the clutch is set up I will adjust the push rod to get the correct free play.
The pressure plate does not foul the inside of the bell housing.
I suppose I have just fitted the 4.2 clutch system to the 3.8 engine albeit with a 9 1/2" clutch plate for the Tremec gearbox.
If anyone wants pictures please pm me

[kingzetts]

I am puzzled. Why are you using the 10" pressure plate with a 9.5" disc? The 9.5" diaphragm pressure plate is the one to use with the 9.5" disc. If you use the 10" plate, check that the inner diameter of the friction material on the disc is not smaller than the inner diameter of the face of the pressure plate, otherwise you will end up with a step worn into the friction material which either will or could cause clutch problems down the line - why take the risk.

It is true that 10" discs with 23 planes are not readily available, although they can be made up to order. The 9.5" disc from Ford Granada/Scorpio V6 and from Rover SD1 V8 models will fit and are readily available.