I get this on my Sport Black with the front offside wheel. It binds enough to be noticeable but doesn’t lock up completely. The disc is over 100 degrees Celsius after a drive. Sprayed water boils immediately on touching the disc but I can actually put my finger on the others. The next day or when it has cooled everything is fine.
How does it release itself on cooling? That’s the bit I can’t figure.
I’m going to take the caliper off and lubricate the slider in the next few days. Is there anything else I should be looking for? Could the heat warp the disc and dry out the main bearing if I leave it too long?
Had a very similar thing on nearside front caliper. Had to jack the car up in a car park to have a look at the brakes as the disc was really hot (wife had gone out in the car and then called me that there was a problem so we met at car park and I’d loaded up some tools).
Got the car home safely (only about 5 miles away) and when cool I got the slide pins out. The heat had clearly affected the the slide pins. At the end of the pin(inside the caliper bore) there is a rubber collar. This had become deformed and jammed at the end of the bore hole which prevented the pin moving freely. The slide pin was quite firmly jammed and took a bit of pulling to get it out and the collar stayed at the end of the bore hole. A bent piece of coat hanger wire got it out.
New pin and regrease with red rubber grease and all was fine.
I would not leave it long at all as will likely damage the bearing and the hydraulic fluid will get boiled if things get extreme.
Hope its just the slide pins as they are really very easy to sort. I re-grease mine once a year now to keep all in good shape.
As said strip it, clean it, lube the pins see how it goes.
At best the pins need lube, worse a new or refurb caliper. Calipers can bind too if not properly serviced each year. In serviced I mean clean up and apply lube around the rubber caliper boot (red rubber grease) Done mine each year and pins and they’ve never given a problem. I’d guess most service centres would cast an eye over the brakes for wear on an annual service unless they are down for replacement or its noted to do them on the schedule, not really good enough.
Because of the friction within the defective components.
The friction will cause it to heat up and therefore expand which will in turn cause the binding.
When it cools down the components will retract and therefore release.
So as above, probably either defective slide pins, seized piston, warped disc are the normal culprits.
So it’s a combination of things. Once one item warms up and the disc gets hot it accelerates the recycling of heat until things start to physically seize.
I’ll do the obvious things first and see how it goes.
The MK 3 brakes are not far off the same as the so called MK 2.5 “large sports brakes”, ( same design) and fail as easy as blinking, most of the time it is down to the lack of proper servicing over the years which can pre long their life span on the roadsters, and lack of use, Miles mean nothing, but if it as not been done from the word dot , it is a hit and miss if you can get them back without changing calipers and starting form scratch correct.
Personally with all the roadsters i put right the " large sports brakes" MK 3 calipers are the worst for failing and design, they need to be kept on top of to work and last a little longer.
M-m
I checked the sliders yesterday afternoon. No corrosion and plenty of grease
The top one was fine but the bottom one was stiff and this appeared to be down to the ridged rubber seals three parts of the way down the bottom slider only. Can’t see what they do. Putting on extra grease helped only very slightly.
Went for a short run and braked hard a few times and still the same heat build up. Gave the piston a few sharp taps but it didn’t move. There’s only about 3mm of cruddy piston sitting proud of the caliper. Pads are pretty thick and the car has a full service history. I suspect the pistons haven’t had to travel too far over the years.
You could try working the caliper piston in and out after a clean up and lube but it sounds like it’s already start to bind with corrosion in there.
I got away with doing this on a Mk1 brake caliper it freed up. Had a rear slide pin completely seize too on that car, had to be cut off it was that bad.
Keep them lubed is the way, annually.
grease wont fix that. I had the same issue and did exactly what you have done but it bind again in two weeks time. order replacement guide pins (I got them from ebay and keep stock in case one of them pins goes again) I am checking if the calliper is moving freely every couple of months and definitely check brakes and the pins before a trackday.
Mazda don’t do replacement guide pins for the callipers or refurbishment kit (I went to my local dealer and have asked for the part numbers and prices). unless you intend to buy new callipers from Mazda the only economic option is to buy the aftermarket stuff (probably Chinese made)
Forget the dealerships and the service from them on the brakes, because 100% they are drier than a nuns ch*ff ,their service is not proper maintenance.
Just speak to and ask the right people that have been solving the issues with these roadsters for years and get straight no nonsense advice.
M-m
It will all need stripping down, cleaned properly with the correct rubber friendly grease as above.
IF it was my car I would perhaps look at trying to save the CALIPER and new seals etc.
Best to get it all off and on the bench.
If not get a refurbished item.
Also new pads and discs at the same time as they are not that expensive.
I have ferodo on the shelf waiting to go on, (actually have them on from last time).
If that’s what you want I can send the part numbers/links you will need.
Good luck and it’s a relatively easy fix.
It is a collection of it all Richard the slider pins are a big issue also that causes sticking,
Just cr* p designed calipers and bits that need more caring then the other designs on the MK 1 and 2’s
M-m
