M5 brakes / clutch are bollocks! - The Unofficial BMW M5 Messageboard (m5board.com)

slider · 5th October 2002, 12:42

There, that got your attention!
I took the 5 to Donnington a littole whiel ago ran out of brakes on lap 2 at the end of the main straight. Pedal went all wobbly as something in the disc/caliper/pad department had warped with the heat.
Wasn't a bad trip out though, the 5 certainly does amazing oversteer slides on demand, best was through teh Melbourne loop where, from 1/2 way through the corner all the way up the hill, you can light the rears up and its smoke (and unfortunately tyre wear) city!

A few weeks ago we were holidaying in France and the usual autoroute 'progress' was being applied. After the first slow down from 165 (VMAX it seems) to about 100mph teh brakes were fine, during the 2nd which was just a minute or so later - same distortion feeling - same lack of brakes.

Took it into the dealer last week - they are fitting new engine (at 17000 miles) due to excessive oil consumption, chief technician said (after prompting regarding blocked up brake ducts) "Oh yes, the original spec was with brake ducts but the discs were getting 'overcooled' brakes not being there when drivers wanted them - so they modded out the duct system" - needless to say they will be on the cat when I pick it up.

Clutch: apparently with this special type of pressure plate (sachs self adjusting) there is a run in period which if you dont abide by, will ruin it for life. My clutch is quite soft, big power changes from 2nd to 3rd induce a little slippage, hooligan starts wont light the tyres up at all - just spin the clutch.

Just thought you'd like to know my problems !

gmajor · 5th October 2002, 15:03

Hopefully you can come to some winter track days at Bedford, where it will be nice and wet. It will make a nice change to see another M5 with the wheels out of line.

I've opened my brake ducts, put big expensive brakes on the car, and they still go away in a couple of laps or so. The only place where the new set-up has worked so far is Spa (where the originals had had it in just a few laps), presumably because of the long stretches without braking.

geoffrey

DZeckhausen · 5th October 2002, 15:07

Quote:

Originally posted by gmajor
Hopefully you can come to some winter track days at Bedford, where it will be nice and wet. It will make a nice change to see another M5 with the wheels out of line.

I've opened my brake ducts, put big expensive brakes on the car, and they still go away in a couple of laps or so. The only place where the new set-up has worked so far is Spa (where the originals had had it in just a few laps), presumably because of the long stretches without braking.

geoffrey

Your AP racing brakes are fading in just a few laps? What sort of pads are you running on the track? How about your brake fluid? Are you swapping it out for fresh Motul 600 before each event?

What are the symptoms of your brake failure? Does the pedal still feel hard but just no braking power? Or does your pedal get all soft and spongy and go to the floor?

slider · 6th October 2002, 19:36

Quote:

Originally posted by gmajor
Hopefully you can come to some winter track days at Bedford, where it will be nice and wet. It will make a nice change to see another M5 with the wheels out of line.

I've opened my brake ducts, put big expensive brakes on the car, and they still go away in a couple of laps or so. The only place where the new set-up has worked so far is Spa (where the originals had had it in just a few laps), presumably because of the long stretches without braking.

geoffrey

Hi Geoffrey!
Hmmm, even APs dont hack it eh? What setup did you put on - 4 pot or 6?

I'm V interested in the Bedford events - could you give me some details of when they are - or point me in the right direction please?

cheers
james
PS had a look at the engine block yesterday at the dealers - 2 cylinders very badly scored and 3 or 4 others with score marks.
They blamed the high sulphur petrol we used to have in UK. Reckons that the nicasil lining was eaten off by it...

gmajor · 7th October 2002, 23:46

I've got the CP5555 6-pots on 343mmx32mm I think. Fluid is AP's Ultra 5.1 with jolly high BP of 250 deg C dry I think. Was going to get my temperature paint out and go testing but I just got bored of the whole idea. I have no complaints whatsoever about the AP parts, but 'laws of physics' still apply, sadly. Solution is not to brake! Pads are Ferodo DS2500 compound, track/road compromise.

Do a search for Bedford Autodrome and you'll find their website, it's also the home of PalmerSport. They run their own open pit lane track days which were, last winter at least, £195, much less than the big track day companies. Nice wide track plenty of slidey turns.

Hopefully see you sometime. Mine's Carbon black with millions of stone chips and will be pointing at an angle to the racing line!

geoffrey