clutch slip

[Julian West]

My standard GTD is suffering from clutch slip, especially in the higher gears. It's only done 2300 miles from new so I guess the plate can't be worn yet....

On initial inspection, the slave cylinder doesn't seem to return very quickly & the whole clutch operation is very slow. Despite bleeding (alot!.

Has anyone got any suggestions on the set-up (other than get a new clutch!)

 

[Guest]

Change your clutch pipe to 1/4 diameter instead of haiving the same diameter as the brake pipes. The fluid is taking too long to return to the reservoir. Typical sympton of early GTD this. Then you are into clutch plates and covers which are now standard upgrades. I can show what is what when we meet up if you can still get here.
Malcolm

 

[Julian West]

Excellent, thanks Malcolm. Am certaiunley hoping to pay you a visit & tie it in with a trip to Silverstone.

Regards,

 

Hi julian

Try a return spring from the slave cylinder to the top of the arm also the length of the push rod is citical.

Chris

 

[Guest]

The slave and master cylinder must return freely, if they do not it will sometimes damage you trow out bearing and clutch. In most cases you need some free play and this tells you the clutch is fully released. I have had slave cylinders where the piston and seal frooze in there bore, and the clutch would slip. Another thing that can happen is the flex line can have a blockage inside. Brake lines have also had this problem inside the rubber hose that goes to the wheel.

 

[Guest]

Julian,
Check your clutch for free play if you can, it may have a rod that you can adjust. This depends on what kind of slave cylinder you have. Another adjustment can sometimes be found on the master cylinder, the rod from the pedal should have some play and not be under constant pressure.

 

[MWGT40]

Julian

When are you guys going to Silverstone? Subject to timing, I would be interested in joining you guys if that's ok.

Thanks, Martin

 

[Guest]

I have a pass out for Donnington for a Willie Green track day on 29th April (monday) so if you want to meet up....

Malcolm

 

[Robert Logan]

Julian,

Fully concur with Malcom as regards the diameter of the clutch lines. We use the larger lines on our clutches.

The other area that you should investigate is the fitting of a heat sheild between the slave and the exhause if you have a Renault box as the are really close and this can harden grease, reduce the efficiency of poor quality fluids. I also like the idea of a return sprind as every little helps.

Good luck and best wishes,

Robert

 

[Guest]

The heat sheild that Robert mentioned is pretty much standard issue on GTD's as the exhaust cooks the slave cylinder when it is mounted on the top of the gear box just under where all the exhaust pipes converge.
Malcolm
PS I haven't got anything happening this weekend (just the honey-do list) if you want to come up Julian. However if you phone up I shall sound surprised to hear from you, so lets make it look natural!!!!

 

[Paul Thompson 'Hooligan']

Malc, wait till I next see Wendy ....
ho ho ho

 

[Julian West]

Thanks chaps, the clutch pipe will have to be increased. However I may wait until I strip the car so the new pipe can be routed more easily.

Presumably the master/slave cylinder connections stay the same size (dash 3?) but connect immediatley to an adaptor to increase pipe size....

I'll hunt for a spring & try & live with it at the mo. It only slips when acccelerating from low speeds in high gears. The heat sheild sounds like another good idea, when I bled the clutch, the old fluid was pretty mank.

Malcolm, thanks for your kind offer to visit, however I too have a Wife to consider & will be busy earning brownie points for future 40 activities!

Martin, March 23 is SR & GT racing at Silverstone & I *think* there will be a couple of 40's racing. It would be great to meet up!

 

Hi Julian, the advice everyone has given is good, however the correct size of the pipework is 1/4 pipework with 7/17 unions on -4 fittings. You will have to change the flexy line also. The lines are not the only reason for slipping.. The old style GTD clutch was a mixture of Renault cover and plate or renault cover and metalic tilton plate. either way, these are not used as standard now. The cover plate was far too low push pressure, this, when the plate wears a little, was not man enough to clamp the plate in drive. The best solution is to do the pipework mods and have a billet steel flywheel and AP Racing clutch upgrade. Best money spent to rectify that problem. This will hold up to 400-450 hp no problemos. If you need one or further advice, E-mail me.
All the best
Mark

 

What I meant was 7/16 unions, i really must take my gloves off when typing on the pc!!!

 

[Guest]

Hi Guys, Saturday March 23rd is Silverstone but whether any GT40s will race is debatable at present as we're revolting (Malcolm knows that already) due to politics twisting the tyre regulations against mid-engined cars again. This was all sorted out but have learned today that it's all changed again - no post historic tyres, just 225 or list 1a (road tyres) and L or M section historic (7.5" width maximum). It ain't looking good and five cars are not entering. Trevor Taylor might turn up to demonstrate to our esteemed organisers the mass dynamics of piloting a 1200kg (minimum weight for us also guys!) mid-engined car is akin to driving in wet and on ice at times - ain't no warning that's for sure. We're fed up with repairing the painful results of unexplained unpredictable erratic behaviour when racing at very high speed which is not experienced by the front-engined cars.
Rant rant rant etc.
That's why I'm off to race in Europe and am making enquiries in the US for the odd race, thanks GT40MkII for that.
Kind regards, Bob.

 

[Julian West]

Mark,

Thanks for your advice. The tappings on my Master & slave cylinders are -3. I'm a little unsure about drilling & tapping the hose connections.... is this the way forward or is it a casse of buying new cylinders?

The steel flywheel sounds like a good idea, presumably there is a weight saving & safer at higher RPM?

On the GT40 racing front, I'm gutted for you guys... all that preparation & investment wpied out by a stupid rule change. So I guess there is no suitable race series for a club level GT40 rep in the UK?

 

[Guest]

Hi Julian

When you get here I can show you how to change the bore sizes on the cylinders without the need to buy new ones. Again it is easy.

Sorry to hear about the racing, Bob. I thought politics only went in F1. What do I know? Mind you, I was at an arrive and drive go kart endurance race at Daytona Milton Keynes, and a team had taken legal advice on the interpretation of a rule! A bit OTT. Come hillclimbing with the club. None of this politics rubbish there.

Malcolm

 

[Guest]

Mark,
I would agree with you that if the pressure plate and disc, are not matched properly to the engine you are going to have clutch problems. If you have free play and the clutch is new, and it slips you have a problem with the clutch assembly. In order to make a satisfactory repair you have to analyse the problem correctly, if you cant do this you are only guessing. Always check a clutch for free play and oil if it slips, assuming that the clutch will hold the engine.