Clutch slipping on my GTD

[gweitzel]

My clutch was slipping,particularly when suddenly accellerating and at higher rpm, particularly in 5th gear,
so I took the gearbox off to inspect.
The clutch plate and the friction surfaces at flywheel and clutch cover are basically in as new condition.
The back of the clutch cover has some wear marks where it rubs against the throw out fork.
The engine is a 302 with Renault bell housing and gearbox, the flywheel is a Ford?? with 121 teeth, the
clutch cover is Borg & Beck Type 9/ 9 1/2 519 MW,the clutch plate is Valeo.
Does anyone run this setup?
Is there an easy cure to fix the problem?
I was thinking of perhaps machining something like 3mm, off the flywheel where the clutch cover bolts on to
prevent the clutch cover from rubbing against the throw out fork and to achieve a higher pressure to the
clutch plate.
Has anyone done this? Would the flywheel need re-balancing?
Any other idea without getting a new clutch?

[gweitzel]

more pictures:

[gweitzel]

another picture:

[Bigend]

It looks as though your clutch release arm is rubbing against your clutch cover, stopping it from completely disengaging, thus the slip. Perhaps reducing the height of the clutch lever fulcrum would give you the clearance you need.
If you want to check the height of your cover, I will check the height of the Valeo version and let you know if that is the problem.

[Howard Jones]

If you do machine the flywheel, have it done at a shop that ballances them. The machinest can set you flywheel up record ballance setting, remove the material that you want and reballance to orginal setting on his machine. This will save you taking your motor apart.
Be sure he mounts you pressure plate on the flywheel when he does this.
If you can get the clearance you need this way you should be ok. If not a orginal renault clutch reworked by centerforce is good for 400HP. I have one in my GTD and it works very good.

[gweitzel]

Jasper,
I measured the height of my clutch cover. It is 54 mm.

[Julian West]

Gweitzel,

I had exactly the same problem on my GTD. In my case the cause was the clutch actuating arm not releasing properly. This was due to the hydraulic clutch line being to small & the forks struggled to release the clutch against the pressure in the pipe.

I made a temporary cure by adding an external return spring to the clutch arm, next to the slave cylinder to 'help' release the clutch.

A larger clutch pipe should solve the problem properly. During my re-build I'll upgrade the pipe from -3 to -4.

Hope this helps!

[gweitzel]

Thanks for the advise so far - it is actually not restricted to people who drive red cars.
Julian, I think my problem might be different to yours because the clutch cover is touching the release lever above the pivoting point. So if the arm would release further, it would reduce the clearance to theclutch cover again.

[Bigend]

The Valeo clutch cover is 42mm high to the shoulder of the cover (where yours is rubbing) and 49mm to the tips of the release fingers. I think that's your problem. The part no is Valeo 235 CP 6050. That is the clutch cover that the GTD factory supplied, and is perfectly OK for an engine of mild to moderate tune. For higher power you will need to consider upgrading to an AP Racing setup.......considerably more expensive. Incidentally, I would NOT recommend machining your flywheel.
Upgrading your clutch hydraulic pipe from the master cylinder to the slave cylinder to 1/4 inch (-4) will help the speed of release and take up, but not the pressure applied to the drive plate.
regards and best of luck, Mike @ jasperacing

[Malcolm]

I would agree with what Mike has said above, make sure your clutch pipe is 1/4 bore ie not the same size as your brake pipes which was how GTD first supplied them, and don't machine your flywheel (thinner flywheel may induce hot spots etc).

If I remember correctly, the various different forms of the UN1 box have different pivot lenghts for the clutch release arm to pivot on. On my car when I changed to a more beefy clutch release bearing which was a different size to the standard Renault unit, I had a terrible noise that was in fact the release arm on the clutch cover. It was a sporadic noise so came and went. Therefore it was only just rubbing. I left it alone and a tiny groove formed and the noise has never come back. Your situation looks a bit more serious so must make a racket! What if you filed out the release arm and welded in a reinforcement at the point where you have shaved off metal? Just an idea.

Malcolm

[gweitzel]

Chris Melia suggested to me that I should get a release bearing from a Ford Escort Mexico as it is narrower than my present one.
Does anyone know where to get this from?

[Howard Jones]

I can't see the face of the throw out bearing in the picture but is there any way to remove material from it to increase the "throw".

The only other place to add distance between the friction disk fingers and the throw out bearing would be to shim outward the bellhosing from the adapter plate.

I think that the best fix would be to replace the clutch with a thinner spec model.

[Bigend]

See my earlier posts, it's the simplest and most staightforward solution.
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