Most friendly road clutch for 250bhp VX

[sd2]

Hi All,

 

I have received the quotes from both Swindon and QED for a lovely 250 bhp conversion including dry sump system for a VX engine which I will be going ahead with in January. The car will be mainly used for the road with the occasional track day blast, probably about 2/3 times a year.

So far I have been looking at the ultra lightweight 5.5" flywheel and clutch system which requires a special starter but from what I have read it’s not that friendly for the road and you certainly would not want to be stuck in heavy traffic with it!

 

My question is what is the most road friendly clutch that I can get that will handle this sort of power and will still be durable? I don’t mind going to a 7.25” system btw and have no preference on brand. My concern is I will do 3 hill starts and burn it out!

 

Btw I will be running an R&R supplied Type 9 HD Quaife box.

 

Thanks,

 

SD2.

[Chelspeed]

What is the car? What does it weigh? Whats the first gear ratio in the box? Whats the diff ratio? What size rear tyres?

[Swiss_Tony]

I have used a quarter master 7 1/4 twin plate clutch for the last 5000 miles.

Its the organic drive plate one.

No problems despite my best efforts to break it. Its done 3 or 4 track days a couple of days at brooklands brighton speed trials etc and lots of general abuse. Its a bit heavier to use than a standard one but is pretty good in traffic.

I have not measured the plates yet but there seems to be a bit of life left in it. Having said that I will probably put some new plates in to be on the safe side.

 

James

 

[sd2]

Chelspeed,

 

The car will weigh around 525-550kg when complete and run a 2.39 first gear with around a 4+ diff (havent decided yet) on 15" rears with 225's (havent decided brand of wheel but probably image at this point). I didnt want a particular tall 1st gear like a 2.04 which I believe can add difficulty in pulling away.

 

Thanks James,

 

Is that the 'Sport' type your running then? When you do arrive in traffic does your brain say 'oh no its traffic' due to the clutch or are you fine with it?

 

Thanks SD2

 

[Swiss_Tony]

It is the sport type clutch.

No problem to drive in traffic at all.

I use a cable operated clutch but imo a hydraulic setup would be much easier to use ie lighter etc and no problem with the cable breaking. Also I am sure it would be a bit more progressive.

 

James

 

 

[sd2]

Thanks James.

 

I had spec'd a hydralic clutch so its looking good thus far!

 

It seems to be a compromise between a track day versus road car when spec'ing these sort of engine powers, ho hum. Bring on the delivery of goodies!

 

Regards,

 

SD2.

[Chelspeed]

A coupole of years ago I was on 13 inch wheels and 22 inch ACB's but otherwise similar spec. I ran an AP Racing 7 1/4 inch CP3912 clutch which is intended to take sintered metal clutch plates but I ran a pair of organic plates from Helix. It was very user friendly and ran the whole year (7 sprints and a couple of thousand road miles) without significant wear.

 

I then changed to a 5.5 clutch (still AP Racing) and Helix didn't make organic plates, just sintered so I now run them, it's not as user friendly and not nice in traffic. But it's lighter and I don't do much traffic so it's staying.....

[Peter Carmichael]

My only experience is with a twin plate 5.5 Quartermaster clutch with Quartermaster plates. It was tricky until I had the mapping right around idle, but now it is fine and easy enough to use in traffic. I do worry about the wear rate and I am careful to engage it briskly with the minimum of slippage.

 

The alternator I run is more responsible for the car being road-unfriendly than the clutch.

[sd2]

I had ago in a similar spec'd VX powered car with an SBD supplied 5.5" AP clutch with their lightest flywheel and found it a bit awkward. Plus as you say I was very conscience of the fact it wears away quickly.

 

I believe the only route I can go is the AP Sport 7.25" one so its now on the list with the other goodies.

 

Peter, I was planning on purchasing a nice lightweight alternator how does it effect things then?

 

Cheers,

 

SD2.

[Marius]

I´m using the same clutch-setup as our flying doc Alex Wong, a 7.25" Quartermaster clutch with sport plates which are the most "soft" ones. You can put in Rally (phase 2) or Race (phase 3) plates, too, but I´m absolutely happy with the sport ones on the road. They´re sharp enough for a competition get away and quick shifts but still docile enough too avoid bunny-hops on the traffic lights.

 

The clutch is fitted to the QED full-steel-flywheel which improved engine pick-up significantly in combination with the 7.25" clutch. Will take the clutch out this month to check wear but Alex has done many many miles before it failed so I don´t expect it to be a problem.

 

If you´re still using it on the road mainly, stick with the 7.25".

 

My car: 240BHP, 1st gear 2.04, 4.11 Diff, 13" ACB10. Lovely setup.

 

Give Dave Kimberley a ring at Demon Tweeks, he sold me the clutch for a good price and will offer you help in choosing the right components (so as any club member does).

 

Marius

 

 

[sd2]

Appreciate the insight Marius its reassuring to many views on this subject.

 

My current shopping list is:

 

7.25" AP 'Sport' twin plate clutch kit

Suitable Release Bearing

Hydralic clutch setup with fairly small cyllinder to increase pedal feel

Superlight flywheel (looking for around 2.1-2.4kg with weight, not fussed about lack of inertia)

 

I will see what sort of prices I get back from QED and the like and then maybe contact DT about it.

 

Thanks,

 

SD2

[Peter Carmichael]

SD2,

 

The alternator I have is the baby Nippon Denso one. It is a triple wire install and can chuck out 45 amps or thereabouts. Weighs 2.5 kg.

 

Unfortunately, the ratio between the revs at which it starts to produce useful output and its maximum revs is very small. 1:4.

 

This is no good for a car with an engine that has a rev range from idle to max of 1:9 (or even 1:8) if that car is ever going to spend significant time in traffic. You have to gear the alternator so that it doesn't disintegrate at high revs and this means that it doesn't do anything useful at idle. The problems are especially bad once the fan has cut in to keep the engine cool and at night with the lights on and in warm ambient conditions where it is prone to overheating anyway.

 

I believe there are a number of options at the ~4kg point that are more viable, but the most important feature of a "roadgoing" alternator is the ratio between first useful charging and max revs.

[DaveK]

The clutch you are refering to is made by Quarter master NOT Ap.

As your primary use is road use then go for a std 7.25 steel flywheel approx 2.8 kgs weight as the engine will be more driveable with the small amount of extra inertia.

 

You have to be very single minded in the pursuit of performance to put up with the impracticle nature of a ultralight flywheel clutch assembly with would not be right for a mainly road use car.

 

Dave

 

 

[sd2]

Peter,

 

Thank you for the insight. I must confess that aspect of alternators had never occurred to me but I will certainly keep it as a consideration when purchasing one.

 

Dave,

 

Be the looks of things SBD's 7.25" 2.6kg Flywheel (model FLY-W4) might be a good alternative to give some extra inertia compared to the others then?

 

http://www.sbdev.co.uk/Clutches_&_Flywheels.htm

 

I’m pleased I got to drive a car with the 5.5" assembly because as you say, it has meant that I have geared the car towards road use. Certainly SWMBO would not be happy otherwise!

 

All the best,

 

SD2

[Alex Wong1697456877]

I use the FLY-W2 (3.8kg) with a twin plate 7.25 "sport" quatermaster clutch. This is on a 240BHP engine and the combination works well although it's already tricky for people who are used to normal cars to use smoothly on the road. SWMBO took three days of long distance endurance driving to get used to it (about the same as I did). The lighter flywheel (FLY-W4) requires a special starter so that means extra cost. I would guess that my flywheel is about as light as you'd want to go for a road car. It already feels great on the track but it get's harder to match revs and down shift smoothly with a light flywheel, contrary to what some people think. I preferred the heavier flywheel apart from the fact that the car accelerates quicker with the lighter one.

[sd2]

Thanks for the insight Alex. I was kinda hoping that this would be as close as I could get to road clutch but I guess there just isnt one on the market to do it.

 

Cheers,

 

SD2.