Seized callipers

I'm in a bit of a tight spot. I've got a long-ish journey to do tomorrow evening (150 mile round trip) and I was intending to use the supra, but I found out today that 2 of the callipers are very likely sticking. 2 of the wheels are affected, nearside front and offside rear. The front one is easily the worst. Symptoms are excessive heat from wheel after driving, and the wheels not turning when jacked up (rear turns a bit but stops, but I can't budge the front one by hand at all).

Now, I've never done brake work before. Is it straightforward to free up the callipers as a DIY job? Or, is there someone in the Basingstoke area who's got some spare time tomorrow and who could lend a hand?

Is it up in the air with wheels off now? J-specs i presume?

If so I would undo the top 14mm slider bolt and loosen the lower one and check the bolts slide in and out easily ie is it these that have seized or the piston in the caliper itself. If its one or both sliders then it should be easy to loosen them with the correct spanner and penetrating fluid under the rubber bellow section.

Could be the sliding pins, thats fairly common and easy if youre handy with a spanner.

Thanks guys for the posts, really appreciate it.

Yes, they're standard J-spec NA brakes. I've dropped the car back down and put it away for the night.

Graham S has a part which could sort the problem out for the front wheel and hence save my bacon (not entirely sure what, as I said I've never done brake work before). I'll look at your posts again when I'm about to fit it.

I'll need to leave the rear as is for the journey unless your suggestions fix it, but that should hopefully be OK if I drive sedately.

Scooter, is there any particular penetrating fluid you'd suggest? I've heard WD40 can eat into rubber.

How do you get to the 14mm slider bolts? i.e. do any other parts (apart from the wheel, obviously) have to come off before I can access them? I've searched for a how-to on here but couldn't find one.

Could you go into a bit more detail about the slider bolts please? Is the aim of it to loosen them off and leave them loose? It might be clearer in my head when I see it, but I'm a tad confused at the moment.

It's much easier with pics lol. The 14mm nuts need to be removed to access the pins, don't leave them loose. The pins slide into the caliper body and should move easily, if they don't move theres your problem. The pistons can also seize which is a whole different problem.

I would say from bitter experience that the sliders will be seized but won't be the main part of your problem. I would hazard an educated guess that the pistons are seizing due to the dust seals being split and letting crap in there. If you are in a rush I would get some spray brake cleaner in behind the dust seal and give them a good clean out, I would only use red rubber grease near my brakes as it won't affect your seals. I certainly would'nt use copper grease etc near any rubbers or seals. Remove the cap from the brake reservoir and push the pistons in on one caliper at a time with a g-clamp or similar then push them back out with the brake pedal being careful not to push the fluid out of the reservoir on the way in, and also that you don't run the fluid low or push the pistons too far out when using the pedal. do this until they free up. It is safer to push the pistons out a bit before cleaning so that on the way in the crud doesn't damage the seal.

This has been a monthly ritual for me for the last 2 years until I sorted new pistons/seals etc(ta CW) If you are in any doubt over any of this either ask or get someone qualified to do it.

Thanks Robzki. Are there any other gotchas I need to be aware of when trying to free the pistons? I've read somewhere about pistons coming out completely and are a pain to put back in. How do I know when to stop when pushing the piston out?

Thanks Robzki. Are there any other gotchas I need to be aware of when trying to free the pistons? I've read somewhere about pistons coming out completely and are a pain to put back in. How do I know when to stop when pushing the piston out?

when you have undone the 14mm nut and pivoted the main caliper body back you can put something inbetween the now free pads that is just a bit smaller than the brake disk. Push the brake pedal a little and the pads will clamp on that something and then you can lever them back and repeat. Look closely at the fronts as sometimes/usually one piston will be more free/siezed than the other and you should see this easily if you are gentle on the brake pedal.

An update: this is no longer urgent but the problem still persists.

Over the weekend I swapped the brake pad carrier on my car for another: one of the sliders on my carrier had seized, or at least was very sticky/stiff. I put my pads on the new carrier (to preserve the pads/disc pairing). I also tried to ensure the pistons were free by cleaning them up a bit, and pushing them in and out by a few mm a couple of times. It's possible I didn't push them enough distance to get the full effect. They were fairly easy to squeeze in with a G-clamp though, and easy to move out with the brake pedal.

I also ensured the pads were free-ish to move in their slots. One of them was super-tight before I did anything.

Despite doing that, I was still getting excessive heat. I guess the pistons are the main culprit still, because most other things have been checked.

You have to clean the crud from the pistons and then move them all the way in an almost all of the way out. they move a fair way. I can measure a piston if you like so you know how far they can come out. If the sliders/pistons and the pads are all free to move then you shouldn't have any problems. Just for information, with newly rebuilt calipers you can fairly easily push the pistons in using your thumbs.

Thanks Robzki, the piston length would be very useful. What would you suggest cleaning the pistons with? I used a basic kitchen cleaner.

I'll get the length later, I would use a can of spray brake cleaner. others may have a different opinion. Then use a very small amount of red rubber grease to lightly coat the piston(this is about the only grease that won't swell the seal in the caliper) before pushing back in. You could use a little brake fluid if you don't have any red rubber grease but be careful on painted surfaces as it will remove paint.

Are your dust seals knackered?

disclaimer:) This is a temporary measure as your calipers could probably use a complete refurb.

Thanks again Robzki. The dust seal around the pistons looked OK to me.

Bump for Robzki: do you have the piston length handy? I'm going to do a refurb on my calipers soon.