BMW 2002 : Caliper rebuild?

foret

Any advice re: brake caliper rebuild on a '75 2002.

Brakes are ok for a while then become soft after 20 mins driving..

Mechanic changed brake fluid etc and says pistons are free to move on both calipers.

Master cylinder should be good as there is initially good braking.

However calipers are sticking and the front disc are heating up and boiling brake fluid.

I'm not going to risk working on brakes so my questions are ....

Likely cause?

Advice re mechanics that can do an overhaul in west dublin / kildare.

(Have bought braided brake hoses which I intend to replace..)

Thanks!

8~)

Likely cause? You've answered the question already:

"However calipers are sticking and the front disc are heating up and boiling brake fluid."

So one or both of the calipers are not free.

Don't bother fitting braided hoses or doing anything else with the brakes until you've got free calipers.

Plenty of garages won't bother rebuilding calipers now - it is not cost effectve for them and the potential for comeback is too great. I.e. it takes longer to rebuild a caliper than to bolt on a new one. And say they rebuild a caliper and it gets sticky again 3 months later (because the car's hardly been driven). One unhappy customer.


I can't recommend a place; it's not my area. Have you equipment to consider DIYing it? Not particularly difficult to do.

welder

Google bigg red in the uk,they will supply overhaul kits if You want
to diy or recon your own if You send them over. I have found them
very good to deal with for the kits and have rebuilt My own,Its not
difficult as already said.

milod

foret wrote: »

Brakes are ok for a while then become soft after 20 mins driving..

Sounds like a temperature based leak which points to seals/grommets etc, or possibly the lines to the calipers. The fact the the brakes go soft means air is getting in or fluid is being lost due to a leak somewhere...

Sticking calipers may be a secondary issue cause by fluid leaking into the calipers/pistons etc...

Might be worth asking the chaps who know these things, on www.bmwireland.ning.com

MercMad

You will find that your problem is deteriorating brake flexi pipes. They degrade over time and the passage becomes blocked.Fluid wiull get through under pressure but will not flow back. If you dissasemble you will find the piston may well be free.

As a test, after a drive feel the wheel to see if its hot, jack it up and see if it is stiff to rotate, then confirm it IS the hose by opening the bleed nipple.If the hose it the problem then the fluid will squirt out and the caliper will release.

It is a good idea to replace flexi pipes on a car of that age unless you have a receipt for a failry recent replacement !

8~)

That's a good point about the flexible pipe.
I had that happen just once - one was collapsing internally.
Easier to check that first before rebuilding calipers.

... so I retract my earlier statement about not fitting hoses...!

foret

Much appreciated .

Will update once hoses replaced.

Itsfixed

Hi foret

+1 on the flexi brake hoses. I have the same problem on my 2002 - although its just on my left side one, but have braided hoses all set to go in, just a matter of getting the chance to put them on.

Its good news if the pistons are free, as your mechanics asserts, as they're a complete bugger to fix.

Like Milod, I'm part of the bmw classics group (caters for sharknoses mainly), and we meet up on the second tuesday of every month. Next meet 13th Oct at the underground car park in radisson stillorgan. You'd be more than welcome to come along. Lots of collective expertise on the mechanical side.

MercMad

Itsfixed wrote: »

Hi foret

+1 on the flexi brake hoses. I have the same problem on my 2002 - although its just on my left side one, but have braided hoses all set to go in, just a matter of getting the chance to put them on.

Its good news if the pistons are free, as your mechanics asserts, as they're a complete bugger to fix.

Like Milod, I'm part of the bmw classics group (caters for sharknoses mainly), and we meet up on the second tuesday of every month. Next meet 13th Oct at the underground car park in radisson stillorgan. You'd be more than welcome to come along. Lots of collective expertise on the mechanical side.

.............is there a website for that BMW Club ? Is there some way to join it ??

8~)

Ha... drove my E28 for the first time in over a year the other day. Brakes a bit sticky. 20 mins / 10 miles down the road the driver side wheel is getting pretty warm. Anyway, when I stop the wheel is very warm and car cannot be pushed. 30 mins later I can push the car, though not as freely as I'd like.

Wheel off, piston was sticky, flexi hose looks okay but who knows. Anyway, freed off the piston, cleaned off the rust and dust and reassembled. Still have to bleed the brakes and try again.

What d'you reckon? Slightly sticking caliper warming fluid or flexi hose collapsing, or both?

Henry Ford III

I was able to send off my old callipers last time for an exchange set. Cost about STG£100.

Johnboy Mac

Buy new if reasonably priced and look for twin pots from the Tii/Turbo iirc or from an E12 (528?). Sorry can't be more specific as it's a long time since I ran 2002's. Also the twin servos's pack up, very common so it would be worth checking your one's out.

MercMad

8~) wrote: »

Ha... drove my E28 for the first time in over a year the other day. Brakes a bit sticky. 20 mins / 10 miles down the road the driver side wheel is getting pretty warm. Anyway, when I stop the wheel is very warm and car cannot be pushed. 30 mins later I can push the car, though not as freely as I'd like.

Wheel off, piston was sticky, flexi hose looks okay but who knows. Anyway, freed off the piston, cleaned off the rust and dust and reassembled. Still have to bleed the brakes and try again.

What d'you reckon? Slightly sticking caliper warming fluid or flexi hose collapsing, or both?

.........drive it, when it stick, jack it up, open the bleed nipple.If it releases its the pipe !

8~)

Must do that... I got a 'pedal pusher' to help me bleed the brake line, took it for a spin and didn't the bugger bind again after a few miles with regular braking. Parked up for 10 minutes, then set off again. Same trip home and the car rolled freely on my return.

It was dark by then so I didn't investigate further since.