Many thanks for the replies, lots of very useful information there, including that I now know the broken part is called a 'strap'.
The BMW thread was really useful, thanks
@clio tyres
I can now visualise that with the flywheel turning the clutch the strap is stretched and would be very strong in that situation.
As soon as you reverse the forces by engine braking, in my case changing into second for the elbow when the road speed is still too high, the stap is effectively put into compression, which would separate the leaves, and put a shock force onto the rivets.....the point of failure here I think.
The LUK reasons for failure book backs up the above with the very polite description of clutch abuse:
• Incorrect driven practice Tow starting in 1st or 2nd gear
• Wrong clutch fitted Engine rotation incorrect (Renault)
Yes, I am guilty of
incorrect driven practice, reckon I can live with that shame.
What's that 'engine rotation incorrect (Renault)' comment about? Does the flywheel on a Renault rotate the opposite way to most, so a non-renault specific clutch will drive the straps in the wrong direction all the time?
@NorthloopCup and @Yorkshire Pudding I will have a good look at the casing to see how much metal has been scored away, maybe take some close up pics and come back for more advice. If it does need the casing replaced I do have the original box ( huge thanks for the offer of your spare
@Yorkshire Pudding, very much appreciated), but not sure that's a job for an amatuer like me, and at the moment I'm not trusting anyone other than Mark to touch my box and precious gripper....no innuendo!
So I think the issue is very much related to my home circuit, Lydden Hill. the standard gear ratios, and the relatively feeble standard clutch.
( I only feel justified in calling the OEM clutch feeble because I've subjected Impreza clutches to 'incorrect driven practice' repeatedly and they've lasted well. But tbh they were aftermarket ,exeedy etc, and similar cost to the Sachs for the Clio. Maybe there's a hint right there!)
I think the big killer is the braking and change down from 3rd at 93mph to 2nd at about 43mph for the elbow at Lydden.
I reckon 43mph is too fast to change into 2nd, and I could actually hold a higher speed through the corner on decent tyres.
But even on decent tyres staying in 3rd loses 0.6sec laptime as the track goes steep uphill after the elbow, so you need to get into the torque zone to maximise the blat up the hill.
Add to this the Gripper Diff has given me a huge advantage in this corner against more powerful, heavier cars, and over 200bhp+ Clios that don't have a plated diff.
So in summary I'm not changing my driving style here to lose 0.6 seconds.....although with my new pedals I will force myself to heel and toe, which will mitigate the problem to some extent.
The real problem is then either the gearing, or the lack of torque in 3rd at around 43mph
2 solutions: change the gearing, or increase the torque so I can take that corner in 3rd
I always planned some power upgrades, so maybe now is the time.
(I've manged to get 176bhp on B list tyres down to 49.3 at Lydden, normally 200bhp+ clio cup/slicks territory. So maybe up against a brick wall anyway)
I think a big change of plan might be in order here, particularly now the engine's out.
Forget the remaining events this year and put that money towards the folowing upgrades:
Sachs clutch......having talked to PMS about compatability with the flywheel and max power/torque capabilities.
Throttle bodies and cam upgrade, the increased power and increased revs should open up completely different options around the track.
ABS delete.......always wanted a bias valve I could play with, and probably kill myself.
New slimline rad'fan assembly to faciltate the throttle bodies.
New exhaust manifold, just to maximise the throttle bodies intake.
New or piggy-back ECU to deal with all the above.
So I reckon that's £4-5K right there. any other estimates welcome!
Maybe I'll just take up gardening!
