M Possible

I just ran my M pretty hard for about 20 minutes and I noticed that the clutch began to slip from 2nd to 3rd close to the end. Is this because it's getting hot or because it's getting done? I then put it on the freeway and made sure to lock-up 3rd, 4th and 5th and it held fine at low rpm and full throttle. I'm just confused on why it would slip on a clean shift at high throttle. Does the clutch plate get hot and "slippy" over a short time of hard driving or is this a sign of $1,800 in pain comin' my way??? BTW - friend in a '91 ZR1 wanted to sprint and I left him back in the '90s (this was earlier, however ).

MIB

Hey M Possible,

I've been taking a good look at the clutch setup lately.

Mine is being taken out tommorrow. The Clutch, Pressure plate and Dual mass (POS) flywheel.

All being upgraded. This is about a five hour conversation, so I'll just give you an extremly brief overview of the problem that E39 M fivers face.

The clutch plate is solid. Yes it has holes drilled in it to lighten it, but by soild, I Mean it does not have any springs in the centre like a normal clutch plate. Therefore it is ridgid and without flex.

BMW moved the flex to the Dual Mass flywheel. And boy does that POS flex. This is the real problem. It is filled with a special Grease. Because this flexy POS moves so much, the seals flex and allow a little grease to get passed. With the great heat, the grease becomes almost a liquid. The force of the thing spinning allows the now liquid grease to travel and get all over the Clutch plate.

This starts to cause Hot spots and Viola Clutch slip and shudder.

That was real quick.

O.K. I have had the entire setup re-engineered the way I recon it should have been.

I am using the Centre of an 850 BMW, Are those mean mother springs, bigger and stronger than the E28's I was originally thinking of using. I have combned this with a 5 Button Carbotic compound Clutch plate. So it now has a sprung centre.

Therefore the flrex is where it should be. So I now can the POS dual mass and replace it with a Super strong Thick Steel Single mass flywheel.

Yes I said Steel and thick. This baby is solid as a rock, zero flex. Now it is much lighter than the stock one, with huge strength and rated above 9,000 rpm. I drag race, so under certain times you are not allowed a Aluminium flywheel as they have a habit of decintergrating.

O.K. I combine this with a Customised Pressure plate with above 4000lbs of clamping force. The stock one has 2,600 lbs.

Positives, I will be able to burn tyres on command. It will take everything I can give it. It will handle 750 BHP + . Although Yoda will never see that sought of power.

It will increase pedal pressure but, the M5 could use a little more, its a bit light.

There will be a little noise only at idle. This is unavoidable with Single mass Flywheel. One of the main reasons why BMW went with the Dual mass, they are quiet.

But as I will have a Tubi, it should drown out most of the noise, also a blip of the throttle and its gone.

I am using the stock Ring Gear so it has to be smashed off tommorrow. If all goes well, I should be driving hard core this weekend.

__________________
///Mark 03 E39 M5 MIB He's in Apples hands now.

M Possible

Wow, that's a lotta info but I got my answer. Thanks and good luck on the new Dinan equipment. I'll want to buy that clutch myself when mine keels over.