Dragging the clutch and wheel spin... - The Unofficial BMW M5 Messageboard (m5board.com)

russell2002 · 11th July 2003, 20:28

Q, if you rev to 5000RPM and drop the clutch with DSC off, the rear wheels spin like hell almost immediatley, and shorley after you start moving forwards, are your dragging the clutch ???? assuming you let the clutch out as fast as possible.

And how about if you rev to 3500 and accelerate as you drop the clutch ?

Cheers,

M'nd · 11th July 2003, 20:57

Drop the clutch @ 5000 rpm = spin the wheels = No Sh!t Sherlock!=bye bye clutch!

russell2002 · 11th July 2003, 20:59

Is the clutch dragging, eg, would I be shortening the lenth of the clutch....

Teutonaddict · 11th July 2003, 21:08

If you can break traction by sidestepping the clutch at 2K RPMs, why in the world would you want to try 5K? or 3500, for that matter?

Not sure if this is the question you're asking, but Yes, you would shorten the useful life of your clutch.

greg · 11th July 2003, 21:44

Quote:

Originally posted by M'nd
Drop the clutch @ 5000 rpm = spin the wheels = No Sh!t Sherlock!=bye bye clutch!

Well, a launch at 5000 in the M5 is really, really worthless, it does NOT mean "bye-bye clutch".

Actually, the fact is that once the wheels break loose they have a lot less traction and the clutch may well hook up 100% pretty quickly - in which case there is no damage to the clutch. SOMETHING has to absorb whatever energy isn't converted into acceleration - and that energy is dissipated as heat. Much better for it to come from the tires than the clutch.

BostonRocket · 11th July 2003, 22:16

I did it once in an act of stupidity. I ordered new rear tires after it.

'Rocket

phillym5 · 12th July 2003, 01:21

ive dropped my clutch atleast 100 times at 5000 or higher. i still have no problems witht the clutch slippin. it feels as strong as it did the day i bought it. it wouldnt seems like the clutch would get messed up as long as you dont slip it. the wheel spinning would mean its pretty hooked. also, i usually make sure the clutch is fully engaged while racing(shifting) to make sure it grabs correctly. ive tried to shift while during a burnout, to burn through second and it slipped that time. i havent tried it since. but at 60,000 miles, the clutch still feels good.

josh.

MIB · 12th July 2003, 02:12

Greg Agreed, thats the point I think he was looking for.

Rocket: LOL

But true.

Quote:

ive dropped my clutch atleast 100 times at 5000 or higher. i still have no problems witht the clutch slippin. it feels as strong as it did the day i bought it.

Caution PhillyM5,

I spoke to a Master BMW Tech at length about the Clutch. I raised the point that a memeber raised about if you strengthen the clutch, you may be removing BMW fail safe soft point.

He disagreed, and said it was not intentionally weak and putting a stronger one in was fine.

You have just confirmed what he said in the following. "The reason why the clutch is the way it is, is because BMW want a clutch to feel like new all the Time. It will have the same pickup point from new as it does when it is three years old. To chieve this, they have this technical floating, delaying self adjusting thingy. He said if the clutch gets too hot, it melts these little plastic thingys and your clutch is screwed.

So bottom line, your clutch will feel the same until its Toast.

Also if you relace it with a strong one, as the clutch wears, the pickup point gradually gets higher and higher off the floor. I don't see that as a problem. It lets you know how much your clutch is warn

So I feel once this one is Toast, I'll put a stronger one in and a Lightened flywheel at the same time. I won't deliberately trash this one, but I intend on doing quite a few QM runs.

phillym5 · 12th July 2003, 03:05

i agree. i dont abuse the clutch all the time, but do my fair share(probably the whole boards share) of racing. i always read posts of clutches being torn apart really early. my point was i use it hard and it still seems strong. if im in 3rd, 4th, or 5th, at low or high rpm, i can nail it and it wont ever slip. im not sure, but thats usually a good way to tell. maybe the m5 clutch wont let you know till its out, but i doubt that. i will replace it with a aftermarket clutch once its fried and i read some posts of people who have done em.(outside of dinan) im waiting to hear about the uuc unit.

josh.

Need4Spd · 12th July 2003, 07:27

Quote:

Actually, the fact is that once the wheels break loose they have a lot less traction and the clutch may well hook up 100% pretty quickly - in which case there is no damage to the clutch.

I normally agree with Greg but I can't this time, unless he's talking about only after hook up. You have a flywheel that's spinning at 5000 rpm, the engine generating 300+ hp and about peak torque. You ask a clutch to go from essentially 0 rpm to 5000 rpm -- instantly. No matter how fast it hooks up, you're gonna incur abnormal wear. People underestimate the stress on aircraft tires, too. Jet aircraft land at something like 120-170 mph, depending on model. Before the tires touch down, they're essentially spinning at 0 rpm, but the moment they touch, they're instantly spinning at whatever rpm they have to at 170 mph. It's no wonder why there are so many black tire marks on runways.