5.5 inch clutch life

[Chelspeed]

Some of you may recall that my clutch failed last year at the marshals sprint at Curborough on August bank holiday. This caused me to miss the L7OC event on the Sunday and another event at Colerne on bank holiday Monday.

 

This was after 5 sprints and a perhaps a thousand road miles. It was an AP6002 140mm (5.5 inch) twin plate clutch but fitted with Helix sintered metal plates. There was some discussion after and various people, Dave K, Arnie and Peter C spring to mind, said that their similar clutches lasted much longer.

 

This year I finished the engine about the same time, mid April, with the same clutch, a bit more power and genuine AP plates (CP3414). After 7 sprints and similar road miles the bank holiday weekend is coming up, the clutch feels fine but I didn't want to risk losing 3 events again.

 

The engine was popped yesterday and, good news, the clutch plates have only worn approx 0.08mm from a max permitted 0.38mm (last years were completely gone, approx 0.6mm wear).

 

So what do I conclude? AP sintered 140mm plates are as long lasting as Quartermaster. Helix aren't, either generally or I had a duff set. Clutch wear on a 5.5inch AP racing type is insignificant for this kind of engine. It won't do 50,000 miles but it will last long enough to not be the limiting factor, ie the engine will be out for an upgrade or refresh before the clutch is knackered.

[Peter Carmichael]

I have pre-emptively replaced my clutch plates twice now, but am now running on the original set once again. These plates were first run in October 2000, so the clutch is getting on for being the oldest component in the car...

 

*thumbup*253 bhp, up and running *thumbup*New boingy bits

[Gridgway]

apart from the driver!

Graham

[EFA]

Seems there is a high initial rate of wear as the plates bed in - my QM plates did 0.20mm in 600 miles and then only 0.08mm in the 2500 which followed.

 

I changed them at 3100 miles, but only because I had a new set in the garage. I kept the old set ready for re-insertion next time!

 

QM claim to have a much harder wearing sintered material. Compared to what though.....I think they suggested AP.

 

 

 

Fat Arn

Visit the K2 RUM site

See the Lotus Seven Club 4 Counties Area Website here

 

[Mike Biddle]

I can confirm the short life of the helix plates, now have a set of QM plates in my 5.5" AP clutch, and they have already survived much longer than the helix items.

 

Can't give you any mileage figures because I hav'nt had a speedo for the last two years, no drive on the Quaiffe box.

 

Mike.

[Paul Ranson]

I had a drive in a car with a carbon/carbon clutch last weekend. Much nicer noodling around the paddock than a sintered sort. I didn't stall it once...

 

And I believe you can shim them to adjust out wear for quite a while.

 

Paul

[Chelspeed]

When the helix plates wore so quick myself and Mike looked at carbon carbon clutches. They were 2 grand new (!!!) but allegedly last 10 x as long as sintered.

 

At 120 quid for a pair of clutch plates the 10 x life would go a fair way to offsetting the new price. If that meant not keep pulling the engine to change plates I think I would have gone for it. Unfortunatly the 10 x life includes reshimming the plates every 0.5mm (with a total wear of 4mm). So instead of pulling the engine 10 times to fit new plates you need to pull it 8 times to reshim the clutch. Never even bothered finding out how much the shims cost, bet they're as dear as the sintered clutch plates too.

 

Now I know I can leave the clutch the whole season I'm even more pleased.

[Paul Ranson]

I guess the only real argument for carbon/carbon is excess power. But it did noodle nicely.

 

(and handled 500lbft...)

 

Paul