Rebuilding Calipers

[Sevada_230]

Hello, i recently purchased another e30, and the brakes were pretty crappy, so i noticed the rear disks and pads had to be changed, so i put an OE parts, and it is still the same crap. I haven't yet bled the system, because i purchased caliper rebuilt kit for all 4, and when i took it to the guy who would do it for me, he said, you don't need to change it until it leaks oil and you will have 0 effect on braking feel.

I have read different cases, however, did not notice anyone mentioning their calipers leaking when they changed it.

What are you thought? Will the brakes improve if i rebuild them?


Thank you
Sev

[jlevie]

It is unlikely that rebuilding the calipers will have any affect on brake feel. But, they are probably way overdue for new seals and I'd rebuild them. Then flush & bleed the brakes.

Suck all of the old fluid from the reservoir with something like a turkey baster or large syringe. Starting with either rear wheel, push a measured 300cc of fluid out of each rear caliper. Then push a measured 150cc through each front caliper. At this point the system has been flushed and bled.

Since the flush needs to be done every other year, investing in a pressure bleeder will make the job easier and will be well worth the cost.

Check to see if the brake pedal sinks when you hold a good bit of pressure on it. You could have a failing master cylinder. If so, use a rag on the end of a wire to check for fluid in the booster. If there is any fluid in the booster it must be replaced as the fluid will destroy the booster diaphragm before long.

[///M42 sport]

then again, it is pretty cheap to buy rebuilt calipers already.

[TobyB]

...and even cheaper to clean and reseal them yourself. I made up an adapter to use a bike
pump to pop the pistons out.

Clean them well, new seals, lube with a bit of brake fluid and reassemble. Now you KNOW
it's done right.

OP, 'pretty crappy' meaning they don't stop the car? Try different pads.
Someone might have put MetalBastards in there, and they don't work nearly
as well as the backing pads they're attached to.

If 'pretty crappy' means, instead, long pedal, then follow Jim's excellent advice on bleeding. Twice, just for good measure. Then replace the master if that doesn't do it.


t

[Ether-D]

I thought I needed a new booster because my brakes were so bad. I started with new fluid, rotors, stainless lines, and stop tech pads all around ($350 for the works from Turner). Completely solved the problem. It stops absolutely fantastically now.

[fight4life28]

I rebuilt my brakes, The seals around the pistion. I used air composer to get the pistons out.

[Sevada_230]

Thank you guys, i have been a little busy at work, however, these couple weeks, the car will be changing dramatically.
I purchased new stainless steel lines, and front brakes, and ill keep you guys posted.

[jlevie]

I think that SS lines are okay, if you get top quality product (like from Bimmerworld), but aren't really any better than the OE lines. I have seen SS lines fail (line separating from the fitting), but I've never heard of that happening with OE lines in good condition.

[dude8383]

I think that SS lines are okay, if you get top quality product (like from Bimmerworld), but aren't really any better than the OE lines. I have seen SS lines fail (line separating from the fitting), but I've never heard of that happening with OE lines in good condition.

I had an OEM line burst from the fitting at Lightning last year... that sucked.

Rubber lines are good as long as the manufacturer you choose is reputable!

[jlevie]

I only use BMW OE soft lines and I've never seen a failure on the street or track if you replace the OE soft lines when you see surface cracks on them (or before).

On a race car I figure on at most 3 years for caliper rebuilds and new soft lines. For a street car, 6 years with fluid flushes every other year. I use ATE Type 200 fluid. It is the same as ATE Blue, but won't stain the reservoir. It has proven (by direct testing) to be resistant to moisture absorption. Moisture in the fluid causes rust (a bad thing) and can cause boiling of the fluid under very heavy brake use, which results in a loss of braking. Better to be safe and stick with a good maintenance schedule.