E30 Zone

Has anyone else had any issues with the feel of their brakes when using the Clio servo with a 750i master cylinder?

They bite well and there's a nice hard pedal with a nice amount of travel (minimal) but when you really stand on them they seem to get to a point where they're not getting any more effective despite being at the point where you feel like you're standing on a block of wood. I think I'd have to pull the steering column off to get enough leverage to lock them up properly at lower speeds too. Maybe it's just me, but I was expecting them to have bigger balls.

Aside from the servo and M/C the rest of the system is as follows:

17mm slug of metal in the M/C (started at 20 but they were binding, went to 17 but fear the sweet spot may have been missed)
Braided lines to replace all rubber sections
E36 328i vented front discs and calipers
Z3 solid rear discs with E36 328i calipers

Has anyone else had similar issues? I've asked in this section of the forum as it's an M52 engined car.

I'm considering biting the bullet and fitting the E36 M3 Evo discs and calipers I've got in the garage but would rather solve any other issues first so any help or suggestions would be greatly appreciated!

Cheers,
Russ

What size MC does the E36 328i use?

The E36 328i one is 23.8mm as opposed to 25.4mm for the 750i one I believe. I'd have stuck with the standard one from the donor car had it fitted inside the Clio servo but it's a fair bit larger than the opening so I decided to go for the 750i one for a firmer pedal given that I had to buy a new one in any case.

It's just weird that they're great at first but don't seem to want to really dig in at the end. Any ideas James?

Cheers!

Well, or anyone for that matter...?!

Could it be anything to do with the rear disc, as a solid Z3 one, now being much thinner than the vented ones that caliper is used to compressing on the E36 they came from meaning there's more fluid / pedal effort going to the rear for less actual gain / braking effort and having the knock-on effect that not enough effort is able to go to the front, or is that just my mind making up a load of boll**ks? I'm good at that, you see.

What pads are you using?
Did you fit new discs?

russ325i wrote:Well, or anyone for that matter...?!

Could it be anything to do with the rear disc, as a solid Z3 one, now being much thinner than the vented ones that caliper is used to compressing on the E36 they came from meaning there's more fluid / pedal effort going to the rear for less actual gain / braking effort and having the knock-on effect that not enough effort is able to go to the front, or is that just my mind making up a load of boll**ks? I'm good at that, you see.

It is possible that your brake bias is all to c*ck - bias being a function of disc diameter, piston size, m/s size, wheel/tyre size, pad/disc coefficient of friction etc. But measuring relative front/rear braking effort is difficult to do without a set of rollers - and braking hard from speed to see if the rear locks up before the front isn't to be advised! It would be worth trying to find out whether or not this is the issue, as bigger front calipers/discs won't necessarily fix it.

If this does indeed turn out to be the issue, a bias valve that limits fluid pressure to the rear could be the way forward. Cheap enough, but a pain to plumb into a standard brake system if you want easy access to adjust from the driver's seat.

Thanks for the responses guys, I'm just using off-the-shelf pads as it stands with both new pads and discs on the rear and I've re-used the pads and discs from my donor car on the front (plenty left in them at the moment whilst I decide whether to fit the E36 Evo ones) Dan.

Braking hard from around 30mph I can't get anything to lock up, but now you mention it I did hear a small chirp (but no feeling of the physical effects of a lock-up) when beginning to brake heavily from probably around 50mph which could possibly be the rears as the weight transferred forward so I reckon you might be onto something there Motorhole.

A few of my lot have fitted brake bias valves to their E36 & E46 M3s (the latter of which had significant issues with the rears locking up on track following a big brake conversion all round) and ultimately I'd like to fit one in any case as I'm sure it'll come in handy for track work so that could well be an avenue worth exploring.

It just seems weird that they seem bang on but just run out of balls when you really expect it. I'll take her for another spin this evening if it stops raining and see what I can determine when it comes to the bias.

Cheers both!