My nearside front caliper has seized and the offside is sticking as well. I thought they would free up as it has been standing for a while, so foolishly I drove it to the nearest Kwit Fit to get them checked out, and it was smoking badly when I got there. They tell me both sides need replacing and due to the heat, I’ll also need pads, discs, fluid and hoses. At a total cost of £740
Frankly, I can’t afford that right now, so I’m considering getting some reconditioned calipers from MX5 parts and doing it myself. I’ve had a look at the FAQs and various other guides, and it doesn’t look too difficult (easy to say).
I should say I’m not experienced mechanically – I’ve changed the oil and brake pads on a couple of previous cars, and the choke cable on a mini (what fun that was) and I’m not completed useless at DIY. I’d like to give it a go, and I guess if I make a mess of it, I can always get a mobile mechanic to finish the job
Is it as straightforward as it seems? I’m also concerned at how easy it will be to remove the old calipers and/or discs given the heat. What do you think? And any advice you can give me?
Hi, It might be the hydraulic part of the caliper or it might be the slider pins or even a collapsed flexy hose. I would dismantle the bad one first for a look at the piston and slider pins. If needed clamp the hose and remove the complete assembly for rebuilding or replacing. Pins boots, pistons and seals are all available or get a recon unit if you need to but it will cost more. Complete each in turn with new hose, disc, pads, and bleeding, rather than try to do them all(?) together.
I would look at the hoses, pads and discs yourself before ordering new ones, and as already said have a look at the calipers, you may get away with cleaning or renewing the slider pins and or piston.
Go to Bigg red (www.biggred.co.uk) for the parts and give them a call, don’t order online. I can’t remember if it is the top or bottom pin but Mazda do not sell one of them but Bigg Red stocks them and at a very good price.
If you are in the South Essex area there is help at hand.
I’m in Wolverhampton, not a million miles away from Malvern, but too far to expect you to come over. If the car had been drivable, I’d happily have had a run over, it would be good to get some help. Thank for the offer though.
Thanks for the replies, some useful thoughts. It looks like the first thing to do is get the calipers off to have a look. Then if I can see where the problem is, I can have a go myself … or perhaps take 'em over to Mal’s for some help! I had a look at a guide to refurbing calipers and didn’t read further than the bit about needing compressed air.
If I’m getting the problem on the front brakes, what are the chances of having a future problem with the rear ones?
If you lift the boot and do find the piston needs changing you don’t need compressed air. Just pump it out very slowly with the brake pedal til you see fluid just start leaking. Then clamp the hose quickly and keep the master topped up. Remove the caliper from the car to clean up and change the piston and seals.
Give the rears a good inspection but if they’re working well and seem free, with no torn boots, and pads and discs ok, I’d leave them.
Expect it to be rusty outide the boot where it contacts the pad but not under the boot where it needs to be clean to slide in and out the caliper body, yes usually obvious if there’s a problem. Note it can be tricky to see inside and the piston has to come out to replace the internal seal and external boot. Use meths for cleaning up and red rubber grease for assembly.
Keep the master topped up at all times as it is so much easier to bleed through than if you get air in there especially if you have abs. To stop the fluid flowing out you can trap cling film under the cap or arrange a stick to bear against the seat to hold the brake pedal down. (The first part of the pedal movement closes the port to the master reservoir.)
Thanks, Rich, that’s just the kind of useful advice that makes jobs much less frusrating! I’m quite exited aboout doing this now, though it will have to wait a week or two till I have the free time.
I’ve just watched a youtube video on how to replace the seal & boot on an MX5 caliper, so at least I know what it all looks like now. Incidentally, he used brake fluid to lubricate the piston, seal and boots during reassembly, is red rubber grease a better bet then?
Hmm, whilst it isn’t always a hard job to strip the caliper to the extent of taking the piston out, if you aren’t all that confident then I would definitely go the complete replacement calipers and just bolt them on and bleed them - job done.
However definitely check out the sliders first though because, as said, if it is them that have seized there’s a good chance you can free them off and you’ll be on your way again.
Whilst you have the caliper off but still connected to the brake hose, check the piston can move readily in and out by gently pumping the brake pedal with a mate watching the piston move - but not too far! Then get a big G cramp or maybe a piece of wood and a large lever and gently lever the piston back into the caliper. If it moves smoothly with no sticking and no leaks then that part should be ok.
As far as the discs and pads are concerned just look at them. If the disc seems shiny all the way round and doesn’t have any runout (ie it looks as though when you spin it it is flat) and the pads have plenty of meat on them, then just clean everything with emery paper or a coarse sandpaper, put it all together and try them out on the road… carefully at first!
Don’t see why you should need new hoses unless they look cracked when you bend them and a good bleed will change the fluid nicely.
Hi Andy, yes all good advice on here, if you’ve done pads and bled brakes before you’ll be fine. No special tools needed, maybe a hose clamp (and a G clamp possibly to refit the piston), go carefully and do one corner at a time
Fit the seals into the caliper body with a smear of rubber grease then a wipe of fluid on the piston to help it go in. They are both compatible and miscible but grease is better inside the dust seal to keep muck and water out.
Not for assembly or on any rubber parts Steve as it is mineral oil based, will rot rubber, and is not compatible with brake fluid.
We need Red Rubber Grease for all assemblies involving rubber inc slider pins and boots. Loads on eBay now as folk seem to have woken up to this the last couple of years.
A thin smear of Copaslip or Ceratec on the external metal rim of the piston which contacts the pad backs, and on the metal shims, pad backs and edges, is ok.
