AP clutch failure - Anglesey

[Stuart Miller 7]

Just a quick note - thought it might be useful for anyone else experiencing gear selection issues on the six speed box. I've heard grumbles from varoius people in the paddock this year.

 

As many of you know, I failed to finish Anglesey because my clutch blew up. I have the engine and gearbox out of the car now and found the following:

 

The friction material on the plate has completely gone - it has also distorted the cover. I thought about a paddle clutch but I will be fitting a new AP clutch instead. I have taken the opportunity to pull the gearbox apart (well, Tom New has) as I have been moaning about gear selection all year. The internals are in good shape I am pleased to say.

 

Gear selection difficulty is down to the following: The "detent" spring is fine but the bronze collar and ball-bearings that centre the lever (3rd and 4th) is badly worn. This, combined with a sticky spherical bearing on the lever means that the lever sticks in the 1st/2nd, 3rd/4th and 5th 6th planes and there is no feeling as to where the lever is when driving the car. Bottom line is that from 2nd, I have no idea if I'm going to get 3rd or 5th and from 6th, selection of 3rd or 4th is nigh on impossible. I'm going to replace these parts and stick it all back together. I am testing the car at Oulton next Friday so I'll let you know how it goes.

 

Stuart

 

p.s. I'll also be testing the new ZZV700R's 😬 😬 - I'll send you the report, Mr Bowler so you can keep up to date.

[skydragon]

Glad to hear you've got it sorted Stuart

 

 

[Mowerman]

So Tom's a dab hand with gearboxes as well.......?

[lotusdave]

stuart, what make of clutch was in their ? i am running the caterham ap so mine may go the same way i dont do as many events as you i am also in class 4 , 190 bhp should not bother this set up

[Stuart Miller 7]

It was an AP racing clutch in there, however, it has done two seasons and I have given it some abuse. I have a habit of slipping the clutch when Tyre warming and in fact set it on fire at Curborough!

 

I'll put the failure down to user error ☹️

 

Stuart

[david nelson]

Too much Torque if you ask me. 😬 😬 😬

[Alan Bowler]

Tyres are too sticky. Get some List 1As.

 

[Richard Price]

I think a clutch failure such as Stuart suffered is most likely to have been caused by excessive friction plate speed.

I'd guess that, during braking from high speed, the clutch was pressed, a low gear was selected but the clutch was not engaged again until the car was slow enough to prevent engine over revs, but once the gear was selected the friction plate was spinning much faster that the engine ever would.

If, whilst braking from the 6th gear approach to "Rocket", second was selected whilsy still traveling at 80mph, then the clutch friction plate would be spinning at around 10k rpm .

[Simon.Rogers1]

That might make sense Richard.

 

I have now lost 2 plates in the same way - friction material disintegrating.

 

I can't say how the first one failed exactly as it wasn't instant but given my "style" to release the clutch early particularly on fast approach slow speed corners eg into the bus stop at Llandow so that I deliberately lock the rear wheels to get the back out/loose to aid turn in I suspect that over time your reason adds up.

 

The second failure in Spain this year was whilst enjoying some spirited road driving and I touched the down change paddle twice in one hit so she dropped 2 gears instantly - BANG - foot to the floor.

 

Therefore I concur 😶‍🌫️

 

However I have also been told that the current plates do suffer from the rivets failing.

[Stuart Miller 7]

Gentlemen

 

I refer to my earlier "user error" as most likely explanation. I do have a habbit of selecting early, mainly due to the fact that my gearbox is such a pain in the ****!

 

I hope that this will be resolved by the replacement of the spherical bearing on the lever and a new set of brass ramps and balls on the selector shaft, meaning I will have more confidence in finding a gear when I need one at the corner rather than well before. I'll let you know if the repairs are successfull next week.

 

Stu

 

p.s. The rivets are all intact and tight (which surprised me) - just the friction material missing.

[Stuart Miller 7]

Just returned from Oulton Park. The day was organised by Lotus on Track, who, I can recommend highly. Very well run with mainly exige and elise's, a couple of other Caterhams and a couple of GT3RS cup cars testing.

 

Aways puts a smile on one's face when the full blown Porche race cars (on slicks) get shown a blue flag to let you past 😬

 

Gearbox repairs spot on. A revelation to be able to select gears! Roll on 2012 Speed Championships.

 

Sorry I can't make it tomorrow. Hope you all have a good time.

 

Stuart