E30 Zone

I'm about to renew my brake system on my m52 powered 2 door (ABS, full interior, mainly street use and occasional track work hopefully this year).

After a bit of research I found that there are different size rear calipers available for the touring. I also have a large lpg tank in the boot and always felt the rear could do a bit more braking...

I've calculated some numbers and came up with a front brake bias of 65.1% on the standard set up of 48mm front and 33mm rear with a standard 22.2/17.46mm master cylinder.

With the rear calipers changed to 35mm touring calipers this changes to a front brake bias of 62.3%.

Theory is all good and well and quite probably incorrect too, are my numbers in the right ball park and what real world difference would swapping the rear calipers make to braking and stability?

Current set up was new discs pads and shoes all round. DS2500 front and rear which I managed to create heat cracks in the front discs so these were replaced and now I'm giving yellowstuff pads a go in the front with DS2500 rears still going strong. Tyres were michelin pilot exalto 2's but I will be trying to get something stickier for this year.

sorry to high jack this but does anyone know what size m3 rear caliper pistons should be?

sorry to high jack this but does anyone know what size m3 rear caliper pistons should be?

I'm fairly sure they too are 38mm. Although they are mounted further out on bigger discs so will have even more leverage.

cheers for that. i recently won some cheap off ebay. the carriers are different but the calipers appear to be the same as a my original 325i ones. marked with number 33 on them.

If they're marked with a 33 they may be 33mm? Easy enough to check if you have them in front of you though.
From what I've read, the carriers are supposedly difficult to get hold of. So maybe worth a fair bit more than "cheap" ;)

Supafly wrote:I'm about to renew my brake system on my m52 powered 2 door (ABS, full interior, mainly street use and occasional track work hopefully this year).

After a bit of research I found that there are different size rear calipers available for the touring. I also have a large lpg tank in the boot and always felt the rear could do a bit more braking...

I've calculated some numbers and came up with a front brake bias of 65.1% on the standard set up of 48mm front and 33mm rear with a standard 22.2/17.46mm master cylinder.

With the rear calipers changed to 35mm touring calipers this changes to a front brake bias of 62.3%.

Theory is all good and well and quite probably incorrect too, are my numbers in the right ball park and what real world difference would swapping the rear calipers make to braking and stability?

Current set up was new discs pads and shoes all round. DS2500 front and rear which I managed to create heat cracks in the front discs so these were replaced and now I'm giving yellowstuff pads a go in the front with DS2500 rears still going strong. Tyres were michelin pilot exalto 2's but I will be trying to get something stickier for this year.

There is also a bias valve in line to the rear callipers.

I've read about this but haven't checked on my car yet. Is this standard on all e30's? Mine is an 88 facelift but it is a LHD German import.

I was also going to post up on your LSD thread as I have a 3.46 z3m diff currently fitted with an m52b28 mated to its original non overdrive fifth gearbox, and I'm happy with the ratio but was thinking of getting a torsen diff as other cars I've driven with this type of diff seem to generate more traction. In fast road driving I find I have to be more careful applying throttle coming out of a bend, if there is wheelspin it locks up and puts it sideways which is fun but I feel I lose more forward momentum compared to a torsen on say an mx5.

If you like I can post up on your other thread?

Does this happen regardless of what the direction of the turn?

A Torsten LSD won't do much for your troubles, they work on preloads which is normally applied by the traction control system on modern cars. They use the brakes as soon as the wheel speed sensors sense slip to apply preloads.

There are of course Torsen LSD's that have a little preload applied such as the latest ATB Quaife offering. But in my limited experience I still feel the clutch LSD wins hands down.

You might have worn rear axle bushes, this could be causing your washouts.

Andrew

It is only slightly more so on left hand turns. However to put it into context, it is when at almost 10/10ths e.g keeping up with a 997 carerra s. I find that I just have to hold the acceleration off for a fraction of a second coming out of tight bends, so I am chasing a very diminishing gain in performance. Come to think of it I don't think I'm getting inside wheelspin, more that I'm reaching the limit of traction on the axle. In the torsen equipped mx5 I found that I had better drive out of a corner, which could also be due to better suspension design and lower engine output...

I know I'll never has much drive out of a corner as a rear engined car, but I'll still look forward to further improving my car.

As for bushes I've fitted all new lemforder bushes throughout the car and had it aligned to m3 specs. I'm also about to fit new springs and shock absorbers to the car to almost finish off the suspension for now.

Thanks for taking the time to reply.