M3 bits

[Stuart]

Yo Dudes

I have a few of BMW M3 specific questions;

1) What gearbox oil are you using that is good at coping with track toot
2) What clutch fluid are using as above
3) Do you know where I can buy the little rubber grommets that control the vacuum side of intake.

Thanks in advance

I'm quite happy for you lesser Japanese and French owning folk to contribute but don't expect me to take your answers too seriously

[Gerry H]

OK, I know sweet FA about BMWs and hope to keep it that way but......

The last time I peered, in disinterested fashion, under your bonnet, I'm pretty sure the brake and clutch systems were served by a common reservoire. Unless you've split them, shouldn't the brake requirement take priority?

[Stuart]

Gerry, you know you secretly covet a Bavarian missile

My brakes have always been more than powerful enough but maybe their potency is robbing the clutch of it's full scope of operation when the fluid heats up? I think there is a shared pot under there (I don't look that often as you know) I'm not even sure if I have an M3 brake cylinder as opposed to a 318 one thinking about it......

Off to search Google.

Your point about the brakes though.......I don't really understand. If the reservoirs are shared, wouldn't good quality fluid do both jobs well?

What do/did you use in the Impreza?

[Gerry H]

Gerry, you know you secretly covet a Bavarian missile

I'll ignore that as you're probably right.

Your point about the brakes though.......I don't really understand. If the reservoirs are shared, wouldn't good quality fluid do both jobs well?

What do/did you use in the Impreza?

My point was. If the fluids are shared between clutch and brakes, then I'd be more interested in the requirement for the more important system i.e. brakes. The theory being that stopping is a greater requirement for a hurtling mass of metal than getting it going.

Stupidity aside, I'd re-phrase the question with the focus on brake fluid.

As for what I've used. TBH almost anything that wasn't too old, half empty or had been shaken up too much. Good quality dot 4 and renew it if and when the opportunity arises or after a couple of years.

I don't think that what I do necessitates a fancy 'race' fluid.

Why do you ask? Are you still having gear selection problems?

[Stuart]

Very occasionally and only then after the most severe provocation. A couple of people suggested it could be the clutch fluid.

[Gerry H]

I'm trying to remember back to that last Cadwell where it was playing up and whether the clutch tubing ran alongside any hot bits.

Unlike the brake fluid, which ends up being rather close to the heat source and so runs the risk of being overheated or any contaminants being boiled, the clutch fluid is nowhere near the clutch friction material. The slave cylinder, operating the release bearing fork is on the outside of the bell housing, well away from any heat.

I've never checked but I doubt the brake fluid reservoire gets particularly warm as the fluid only moves back and forth and doesn't circulate. There'll probably be some convected heat but most will remain near the source.

All IMO of course

Is it a conventional push clutch? Have you had the box out and inspected the clutch mechanism?

[Stuart]

I've never checked but I doubt the brake fluid reservoire gets particularly warm as the fluid only moves back and forth and doesn't circulate. There'll probably be some convected heat but most will remain near the source.

Is it a conventional push clutch? Have you had the box out and inspected the clutch mechanism?

No idea whether it is push or pull (the net didn't help) I've not recently removed the gearbox and clutch although when APT did, they said there was some clutch wear but everything else looked OK.

I also think it's heat related but felt that maybe the fluid may not be man enough for the grief I give it. Full fluid change needed I think.

[Tommy]

It is indeed a shared reservoir and the slave cylinder does sit outside on the side of the gearbox.

Gearbox oil we have in the 328 is standard BMW stuff and it'll be the same in the M3 when the box gets changed on Thursday.

Brake fluid I have is ATE Super Blue Racing (DOT4) which I mentioned I bought from Euro Car Parts. These are its boiling points.

Dry 536F 280C Wet 396F 198C

Compare that to the top spec Castrol SRF, which is very expensive:

Dry 590F 310C Wet 518F 270C

Not much difference in the dry point but there is in the wet point.

EDIT: Did you put in a braided clutch hose yet?

[Stuart]

Yeah Tommy, pretty sure Gary fitted that when the clutch was changed. I'm also looking into some Redline shockproof or similar for the gearbox.

[Mr Fletcher]

for bmw parts i use motomec in lowestoft