Need to kill something or someone..........

Stoat · Post by **Stoat** » Sun Jan 28, 2007 7:48 pm

I've had clutch problems for several months, the clutch has been inconsistant sometimes disengaging, sometimes not sometimes partial disengagement. When there is no disengagement the clutch pedal feels light. There has been no loss of fluid and the hydraulic system bleeds ok.

I removed the engine (RV8 with, I think, a LT77 box) from a Scimitar which had been converted ran for, I believe 10 or so years then written off. I dropped the engine into my Scimitar without fiddling with the clutch, it was supposed to have run ok before so I don't fiddle with what isn't broken.

I ran the car for several months when the clutch problems started.

I've rebuilt clutch and slave cylinders, both look ok and bleed ok, each time I did something the clutch seemed to be ok then the problems started returning.

I replaced the master cylinder just before Xmas and just after Xmas I had complete clutch failure, no pedal pressure, no fluid loss and when I bled the clutch there was no air in the system.

So, has to be the clutch itself???, I've heard of rusty / worn release arms.

Pulled the RV8 out of the Scim this morning, pulled the gearbox off and.....nothing looks wrong, only thing I can see that looks odd is some marks on the back (clutch side) of the release arm as though its been contacting the the clutch pressure plate.

What the ***heck*** is up with this???

Any ideas where to look or what to look for before I take my frustration out on my cat!!!

toughy V8 · Post by **toughy V8** » Sun Jan 28, 2007 9:31 pm

whats the thrust bearing like, i had a one collapse and go through the centre of the diaphragm once, some times it would engage and sometimes it wouldnt

Post by **katanaman** » Sun Jan 28, 2007 9:34 pm

when it failed did it fail completely even when cold again? The Scimitar is well known for heating the clutch fluid because the line runs so close to the headers. It usually starts working again tho when everything has cooled down or you would find bubbles when you tried to bleed it again.

ian.stewart · Post by **ian.stewart** » Sun Jan 28, 2007 10:04 pm

Another thought, with the pushrod removed from the slave cylinder, how much free play is there before you come in contact with the clutch, I am also wondering if the pressure plate is worn beyond limits, losing plate pressure and allowing the clutch to slip,
Is there any unusual wear in the splines on the input shaft or in the friction plate, The reason I ask is the Rover shares the same pitch and shaft dia as the Cosworth, But the spline angle is different allowing the friction plate to jam, and the plates were sold by RealSteel as replacements.

stevieturbo · Post by **stevieturbo** » Mon Jan 29, 2007 1:02 am

maybe it has been contacting it ??

was there ever noise ? There are different lengths of ballstud pivots used on LT77 boxes, although I dont know whats what.

Stoat · Post by **Stoat** » Mon Jan 29, 2007 8:08 pm

Thrust bearing is ok.

Now have no clutch warm or cold.

Marks on release arm, on inspection, are not contact marks (not striated enough) and no corresponding marks on the pressure plate.

No odd noises when engaging, disengaging, or attempting to disengage.

Pressure plate has plenty of material on it, though if, as suggested, the pivot arm is the wrong length (too short) then it may stop short even with friction plate material still present?

How do I ascertain what length of pivot arm should be fitted?, what lengths are available?

You'll be glad to know I don't actually have a cat :-}

Stoat

ian.stewart · Post by **ian.stewart** » Mon Jan 29, 2007 9:01 pm

Clutching ar straws a bit here

sorry had to say it

Funny marks on the clutch arm, Although I have never seen it, I have heard of clutch arms bending

jrv8 · Post by **jrv8** » Mon Jan 29, 2007 10:46 pm

Hi,
There are a lot of different parts out there for RV8 clutches and LT77 boxes. The trick is getting the all the correct parts together for the job. There are two different types of release bearing available. Using a mismatched bearing and pressure will result in erratic clutch operation, and early failure.
If you want to give me a call, I'll at least be able to tell you if you're using the correct parts.
Regards
Jim

Stoat · Post by **Stoat** » Fri Feb 02, 2007 6:06 pm

Small world, not only is a work colleagues father in law a previous owner of my engine but another, completely unrelated, knows the person who rebuilt it.

Spoke to him, gearbox and clutch are completely standard Rover SDI parts.

What he did say though was that differing clutch plates had different thicknesses, he thought that the difference between Borg & Beck & Lockheed was as much as 1/8th inch.

He states that he fitted the thicker clutch type.

Does anyone else know of this and also what is the thicker clutch plate?

Stoat

ihatesissycars · Post by **ihatesissycars** » Sat Feb 03, 2007 9:10 am

I had a problem weith my clutch not engagin full which meant a slipping clutch sometimes. I had to keep releasing fulid from the slave cylinder to engage the clutch fully.

This time round after rebuildign everything i hade to space the slave cylinder away from the bellhousing by approx 1/2"

Does this sound like your fault?

I put it down to the master cylinder i'm using. Its too small really and doesn't allow the slave cylinder return fully due to too short a stroke in the master cylinder.

stevieturbo · Post by **stevieturbo** » Sat Feb 03, 2007 11:12 am

ihatesissycars wrote:I had a problem weith my clutch not engagin full which meant a slipping clutch sometimes. I had to keep releasing fulid from the slave cylinder to engage the clutch fully.

This time round after rebuildign everything i hade to space the slave cylinder away from the bellhousing by approx 1/2"

Does this sound like your fault?

I put it down to the master cylinder i'm using. Its too small really and doesn't allow the slave cylinder return fully due to too short a stroke in the master cylinder.

I put it down to your pedal not releasing far enough, and opening up the MC, so it allows fluid back into the reservoir.

The same happened me, when I made a small rubber stop for the pedal to stop an annoying rattle when the pedal was at its normal postion.

The piston must just about have been covering the hole in the MC that allows fluid into it, and after a while, it started to hold the clutch open ever so slightly because the fluid couldnt drain back fully into the reservoir when you let for foot off.

Adjust your pedal or mastercylinder so that fluid can travel through it freely and out the slave when the pedal is at its normal rest position.

Stoat · Post by **Stoat** » Sat Feb 03, 2007 7:48 pm

Looks like this is my problem.

However, I wish to replace the clutch before I put the engine back into the Scim.

Does anyone know if this clutch plate thickness thing is true and what the thicknesses of different manufacturers plates is?

Stoat

Stoat · Post by **Stoat** » Tue Feb 06, 2007 7:43 pm

May I assume no-one knows about this???

Stoat

ian.stewart · Post by **ian.stewart** » Tue Feb 06, 2007 8:37 pm

Have a word with this lot, Ive found them useful and helpful over the years,
http://www.helix-autosport.com/

Ian

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Need to kill something or someone..........

Need to kill something or someone..........

Replies

Clutch plate thicknesses

Clutch plate thicknesses.