Race starts with a racing clutch

[Tim Falce]

I have recently fitted a 7.25 inch triple plate clutch to my car and find the race starts are now a nightmare.
With my old road clutch I could build the revs to about 1500/2000, slip the clutch and as I started rolling I would floor it, controlling the wheel spin. I would always manage to make up at least 3 or 4 rows within the first 100 yards or so (I just wish I could have qualified nearer the front to make it worthwhile).
With the new setup, I seem to have no control at all, it's either in or out , at Brands yesterday I found no matter how I tried I ended up with mega wheel spin (even starting at low revs and trying to build up) and the rear of the car falling sideways before it started moving too far.
Has anyone got any tips to help me improve?
Car, for those that don't know, is a 1000kg Jaguar with a 4.2 engine.

[Al Weyman]

Well I found quite the opposite after years of using a double or triple plates I stuck a conventional clutch in my yellow car as it is not a particularly powerful engine and found it would not deliver off the line like I was used to eventually failing all together but that may have been for something else. I suppose a lot of it is down to how well you car hooks up but just get off the gas a bit once the clutch is home if it is lighting the wheels up, also your car is very light on the rear I would have thought which is always going to be a bit of a problem. What rear axle set up do you have as a matter of interest. My black car has a long torque arm type rear axle location which actually tries to lift the car or plant the tyres so it hooks up very well.

[Rod Birley]

Do races with a rolling start, saves a lot of aggro.

[greenamex2]

I have a single plate 5.5 inch racing clutch.

It's useless, if you were to try 'slip it' it would last about two races.

I have had to become adept at getting the timing of revs, clutch and throttle right to spin the real wheels instead. Tricky with a zero torque 1600.

I guess the 'tip' is practice, it took me over a year to get a decent start!

Before anybody chips in with "why don't you fit a normal clutch" I can't fit because my crankshaft will break (long story).

[Al Weyman]

You are right Dennis even for the triple and double plate jobs they tell you catagourically not to slip it.

I have a clutch down the shed that may suit you Falcemob. It is an American job called a 10,000rpm clutch and is basically an all alloy thing with no steel inserts and includes the flywheel, the difference is it uses conventional organic clutch material not sintered and although I have never used it properly (another story but a cock up by the guys who installed it and it held open, I can see it being far more gentle than a sintered clutch and still holding up to abuse.

[greenamex2]

Originally Posted by Al Weyman

You are right Dennis even for the triple and double plate jobs they tell you catagourically not to slip it.

I have a clutch down the shed that may suit you Falcemob. It is an American job called a 10,000rpm clutch and is basically an all alloy thing with no steel inserts and includes the flywheel, the difference is it uses conventional organic clutch material not sintered and although I have never used it properly (another story but a cock up by the guys who installed it and it held open, I can see it being far more gentle than a sintered clutch and still holding up to abuse.

Just how big IS your shed Al!!! Got any race Corolla bits or a Countach hidden away you don't want?

[Al Weyman]

Oh its big, very big so is my garage!

[quickbadgers]

Launch control, easy press right foot as hard as possible dump left. Couldn't be simpler!

[greenamex2]

Originally Posted by quickbadgers

Launch control, easy press right foot as hard as possible dump left. Couldn't be simpler!

I am going to get to play with launch control on my kit car (if my engine ever gets built).

Unfortunately most race series ban it so it isn't an option for falcemob.

Unless he cheats

[Tim Falce]

Originally Posted by Denis Bassom

I have a single plate 5.5 inch racing clutch.

It's useless, if you were to try 'slip it' it would last about two races.

I have had to become adept at getting the timing of revs, clutch and throttle right to spin the real wheels instead. Tricky with a zero torque 1600.

I guess the 'tip' is practice, it took me over a year to get a decent start!

Before anybody chips in with "why don't you fit a normal clutch" I can't fit because my crankshaft will break (long story).

I guess I'll have to practice my starts more, I think I would be better with lower revs and wait until it picks up before flooring it. There's no chance of slipping it as it now seems like an on/off switch, also it is a pain getting the car back on the trailer in the wet and I had to winch it on a few weeks ago.

A normal clutch is out as they don't last long, and go out of balance. I destroyed 3 engines before I found the cause, the cover plate is the problem as they can't take the torque of a heavy downshift or a spin (quite common with me) and bend the pressure plate mounting arms putting it all out of line.

Al, The rear end is standard V12 E-type with a single lower wishbones and radius arms going forward.

Originally Posted by Rod Birley

Do races with a rolling start, saves a lot of aggro.

I'll leave that to you wimps with roofs over your heads.

I see we actualy have a thread related ad at the bottom.

[Al Weyman]

Yeah cheap as well at ONLY £864! Falcemob don't drive the car on the trailer in the wet or dry with these things, OK if you can get a run out at it and get it halfway up then winch the rest but dont slip it to get it on (blimey what am I talking about here sounds a bit rude) as you will blitz the thing in no time flat and it may be cheaper to get an electric winch.

Also be careful driving around the paddock. Its a pain but worth it, the Muncie boxes in my cars have huge first gears on them and will do 70mph in 1st so it is a real pain and one of the reasons I stuck a conventional clutch that was with the engine in the Yellow car but as I said they don't hold up and I reckon having to go easy with it cost me a couple of places at the start at Pembrey last year that had to be won back the hard way!

[Peter Mallett]

I dump the clutch at around 4500 and then play with the wheelspin until it matches the gearing, then I change up. There's really no hard and fast rule for starts but changing the clutch does mean you have to learn all over again. Now that I've got used to it I find it works pretty well but it took ages to get it right.

[Al Weyman]

Another idea if you have a road box in the D-Type i.e wide ratios, it may be worthwhile dumping it in 2nd gear instead of 1st. As I said I have a huge 1st gear on the Muncie Close Ratio gearboxes and that kills the spin a bit. I can see an IRS Jag backend not hooking up as well off the line as a live axle but you would probably more than make that up around the twisty bits. I don't use as many revs as Peter off the line but I guess it depends where your power band is on the V8's it is very flexable.

[aland]

Originally Posted by Denis Bassom

I am going to get to play with launch control on my kit car (if my engine ever gets built).

Unfortunately most race series ban it so it isn't an option for falcemob.

Unless he cheats

nope Falce wouldnt cheat, if it was his mate Oily Oaf then it would be a different matter

Its ok I know Oily from another forum and he has mentioned you falce

[Tim Falce]

Ah, you Oily do you, there's a man who can spin a fable or two, I do pop in there now and again to keep up with his missives.

[Eric Falce]

Never mind Tim, now what you should do is take some lessons from someone who wins his class although he has'nt raced for fourty years. Formula is take one bowel of rice, (long grain of course to increase clutch travel) pour it into the bell housing just before the start

[Chris Y]

Oh dear - Eric's on about his bowels now. I don't like the way this is going

[aland]

Originally Posted by falcemob

Ah, you Oily do you, there's a man who can spin a fable or two, I do pop in there now and again to keep up with his missives.

Think everyone knows Oily, decent bloke but totally fecking mad. Question?? is he that mad in real life or does he become a nutcase on the internet

[Tim Falce]

Originally Posted by aland

Think everyone knows Oily, decent bloke but totally fecking mad. Question?? is he that mad in real life or does he become a nutcase on the internet

He's a total pussy in real life, the internet is just his alter ego.

[graham bahr]

as has already been said tim, dont slip the clutch its life will be shorter than one of erics twincams staying leak free and in one piece,

what i've found with mine is to come quickly off the clutch with only around 1500 -2000 revs, the wheels will spin a at first, once i sense a reasonable amount of forward motion i give the throttle a bit of a blip which will spin the wheels a bit more but stops it bogging down as i immediatly grab 2nd, usually once the clutch is up again i usually have real forward motion, but it is hard to get right, even once you've learnt the technique that best suits your car

[zefarelly]

Originally Posted by Peter Mallett

I dump the clutch at around 4500 and then play with the wheelspin until it matches the gearing, then I change up. There's really no hard and fast rule for starts but changing the clutch does mean you have to learn all over again. Now that I've got used to it I find it works pretty well but it took ages to get it right.

What he said !

Any more than 5000 and its 2 small clouds of smoke like an american drag race while everyone else dissapears in the distance !

[Tim Falce]

Originally Posted by Peter Mallett

I dump the clutch at around 4500 and then play with the wheelspin until it matches the gearing, then I change up. There's really no hard and fast rule for starts but changing the clutch does mean you have to learn all over again. Now that I've got used to it I find it works pretty well but it took ages to get it right.

Originally Posted by zefarelly

What he said !

Any more than 5000 and its 2 small clouds of smoke like an american drag race while everyone else dissapears in the distance !

If I dumped my clutch at 4500-5000 I wouldn't have any back tyres left by the time the car eventually started moving, 1500 is about my limit now

[greenamex2]

Originally Posted by falcemob

If I dumped my clutch at 4500-5000 I wouldn't have any back tyres left by the time the car eventually started moving, 1500 is about my limit now

If I dumped my clutch at 4500-5000 I would have lots of rear tyre left but no rear of car, because my engine would have stalled!

[R59]

Tim, I use a 7.25" triple plate on my chevy powered contraption. When it was new, it bit like a snapping terrier, but now it's done some miles, it feeds in much better.

Must be mellowing with age.

Rob.

[Peter Mallett]

Originally Posted by falcemob

If I dumped my clutch at 4500-5000 I wouldn't have any back tyres left by the time the car eventually started moving, 1500 is about my limit now

Unfortunately I'm not on cam until around 4k.