16 replies to this topic

[finch661]

hey every one, im having some braking issues at the mo. every so often my front brakes come on, affecting the cars performance. the brakes dont come on so much, that the car doesnt move, but enough that when coasting down a hill the car slows down . i also notice that the brake pedal gets very hard when this happens, and the brakes still sort of work.

this seems to of happened after replacing my rear subframe, the first drive after smoke started to come out of the pads, and into the cabin

the brakes have been adjusted, and there is still plenty of friction material on the pads/shoes.

whats going on?

thanks

[The-Womble]

This is probably a way off idea, but just thinking about basic physics - when a liquid gets hot, it expands; If one of your brake hoses is somehow getting hot, the brake fluid inside may be expanding and therefore pushing on the brake pistons and applying the brakes.

It would also explain the smoke coming from the pedal. I'd check the brake lines to check theyre not touching anything hot or rubbing on anything that is turning or whatever

[finch661]

thats an interesting thought, i will double check everything. any other thoughts whilst i am checking this out

[me madjoe 90]

Are they all ajusted up properly and not binding when you spin them with car jacked up?


if its fronts could be sized piston causing pad to stay against disc

rears shoes could be sticking / binding. Take the drums off and give them a good clean with break cleaner cheack eatherythings ok and all the mechanisams move and re geases all movin points and where the shoes touch the back plate.

hand brake could be sticking.......

[il-barba]

do you have a servo fitted?

[finch661]

the wheels spin freely, it just kinda happens now and then. its really odd....

[finch661]

still having issues with this checked over the brakes, every thing seems ok, but still happens, the car really struggles when the pedal goes hard!

[billyboy83]

Have you re bleed the brakes as air in the system can course this.

[Cooperman]

Check to see if one of the front wheels is hot when this happens. If one is, then it's a sticking brake calliper. I had this on my BMW and that was the cause. It was intermittent and would clear itself when I cornered hard and the pads got 'knocked back' a bit. Then it would all cool down and work OK, until the next time. Changed one of the callipers and all was fine again.

[finch661]

yup the wheel was quite warm!, sticky calliper, is there anyway of checking apart from the wheel test, the wheel spins ok when jacked up

[Cooperman]

Almost certainly a sticky calliper. With our Minis we are lucky that rebuild kits with stainless steel pistons are available at low cost and it's an easy job to do (until you come to fit the outer dust seals, that is!). On the BMW a new calliper cost me £75 plus VAT and postage.
When it's in bits you'll probably find that the old piston is badly corroded.
If you need more help with the calliper re-build come back on here.
You need the re-build kit, some brake & clutch cleaner and a bottle of new brake fluid of the right specification - probably DOT4.
Push the old pistons virtually out of the callipers before disconnecting the hydraulics or removing the callipers from the car. To do this, take out the brake pads and replace with pieces of wood about 3/8" thick. Do this a on both callipers, then pump the pedal until the pistons are against the wood. That makes it much easier to get the pistons all the way out in order to change the seals. I always split the callipers and replace the small rubber seal between the two halves. After installing the seals and new pistons you must fit a new rubber seal and torque the calliper joining bolts to 45 lb.ft. with a spot of Loctite (a torque wrench is thus vital).
The key to brake rebuilding is cleanliness, cleanliness, cleanliness.

[finch661]

cool i will have a look at rebuild kits and have a look at the calliper. cheers for the advice

[bobs]

it's an easy job to do (until you come to fit the outer dust seals, that is!).

Does anyone have any tips on doing this job, I've already done it, but any ways of not bending the new metal dust seal when fitting it in the calliper might be helpful?

Is there a special tool (asked a trader once at a mini show he said they just "pop in", about five people around the stall all laughed and commented "yeah right"! Guess they've done it also!), I know you have to really clean up the edge of the pistons housing, especially if your old chromed pistons have rusted away to get a good seat, and liberally apply fresh brake fluid.

I bent a few and replaced them, also my father (retired blacksmith) managed to reshape a couple using the base of a spray can! But these were eventually replaced.

Is there a way of just getting them to pop in like one did, or was that just luck?

[finch661]

it happened again on my way back from work. i found out that both the front wheels are heating up. this has only started since my rear subframe was replaced?

[Ethel]

It's obviously the front brakes binding, the question is why. I would start by opening the bleed screws on the calipers when it's misbehaving to see if there's any trapped pressure there.

You could also strip the pads out and push the pistons back in (with the bleed screws closed); the pistons should move quite freely, pushing the other piston out, but with both going back in to the caliper with just a few shoves.