Rear pads wearing very quickly

[MrChris]

Hi all, did a track day yesterday at Donington Park and went through 3 sets of new pads very, very quickly, with the final set only lasting 10-15 mins maximum track time:



Calipers were new items I'd installed lately.
The brakes were fully bled with RBF600 fluid.
The driver's side wore more quickly than the passenger side.
The problem seemed to get worse as the day went on (i.e. wearing quicker and quicker).

The discs were old but seemed fine to me.
The pads were cheap pads admittedly (but, I have always used cheap pads and they have lasted me at least 2 track days).
The sliders on the calipers were working/moving.
Every time I changed the pads the pistons were winding back okay.
When I came off track the car was rolling fine (i.e. not a binding caliper).

I used chatGPT AI to try and diagnose this and all it says is:

Check brake hoses for kinks (I think they're fine but I guess I could change them).
Check brake bias (no idea how to do this).
Change for new (track appropriate) pads and discs.

Any thoughts on this? Could I have a duff caliper?

By the way, front pads absolutely fine. They have "old" calipers, new MTEC standard pads and new MTEC J hook discs. Still looked like new pads at the end of the day.

Also: At the beginning of the day and for most of the day pedal "feel" was absolutely great, the brakes felt really good. The final pad change of the day, the brakes were super spongey.

[Alex Knight]

This is a very unusual problem. Three sets of pads in one day (how many miles on track?) is unheard of.

My gut tells me that whilst your callipers are moving freely, this is almost certainly a binding caliper issue.

Whilst the wheels may move freely when static, that doesn't mean that they are not binding dynamically.

This is further supported by the fact that the wear is uneven across the same axle.

If it were me, I would change the rear callipers for new ones, and then test.

I know it's an expensive way to diagnose a problem, but you cannot mess around when it comes to brakes.

Go for a pair of high quality callipers too, not some cheap shit from Autodoc et al.

[Iain]

Has to be a sticking caliper or handbrake not adjusted right. 

[thetyrant]

If your coming in with red discs like that there is either a caliper issue or restriction in the hydraulic lines stopping/slowing pad releasing fully send temps through the roof, these cars do use rear brakes hard but thats excessive i think

[MrChris]

This is a very unusual problem. Three sets of pads in one day (how many miles on track?) is unheard of.

My gut tells me that whilst your callipers are moving freely, this is almost certainly a binding caliper issue.

Whilst the wheels may move freely when static, that doesn't mean that they are not binding dynamically.

This is further supported by the fact that the wear is uneven across the same axle.

If it were me, I would change the rear callipers for new ones, and then test.

I know it's an expensive way to diagnose a problem, but you cannot mess around when it comes to brakes.

Go for a pair of high quality callipers too, not some cheap shit from Autodoc et al.

Did about 150 track miles in all (3 sets of pads).

Anywhere you'd recommend getting decent calipers? Brakeparts have them from about £50 for "Bremtech" and they go up to £100+ each from other places.

I think I'm going to do a full rear brake refresh including calipers, discs, pads, braided lines.

Took a couple of pics this morning.

Near side:


Offside:

[thetyrant]

I used the Brakeparts Bremtech i think on my 2 and they were decent enough, looks like prices for the facelift 6speed calipers have shot up mind! 

I know its been discussed before on here but cant remember what difference is between those and earlier 5speed carsm maybe something to do with handbrake mech as cables are different, might be interchangable but cant remember, pads are all the same between the 2 though so that helps.

[Alex Knight]

Honestly, I'd source a set of used OEM calipers from J-Spec or similar and get them rebuilt.

Probably your best value for money/reliability ratio.

[Iain]

Honestly, I'd source a set of used OEM calipers from J-Spec or similar and get them rebuilt.

Probably your best value for money/reliability ratio.

This

[MrChris]

@Alex Knight @Iain

Thanks, this makes a lot of sense. I've actually got a few calipers kicking around, do you know of a way to tell if a caliper is OEM vs non-OEM?

[Iain]

@Alex Knight @Iain

Thanks, this makes a lot of sense. I've actually got a few calipers kicking around, do you know of a way to tell if a caliper is OEM vs non-OEM?

Im sure there will be some way of telling but i dont know unfortunately.

However if you speak to Andy @jspec he will sort you out some good ones, very good service from him/them.

[boor]

Just beware with these companies refurbing calipers - I did ordered two rears and got them working ok, but are not oem, some other brand. Never asked about it, so my fault. Either send your oem for refurb, or check what you will be getting before purchasing.

[MrChris]

Honestly, I'd source a set of used OEM calipers from J-Spec or similar and get them rebuilt.

Probably your best value for money/reliability ratio.

Just bought the virtually brand new set of calipers (all 4) plus discs and track pads from J-SPEC.

[Alex Knight]

Just bought the virtually brand new set of calipers (all 4) plus discs and track pads from J-SPEC.

Which pads?

[MrChris]

Which pads?

Some EBC pads, tbh even if they're not the best EBC pads they're better than the Apec ones I've been running (and I've found the Apec pads to be great).

[thetyrant]

Some EBC pads, tbh even if they're not the best EBC pads they're better than the Apec ones I've been running (and I've found the Apec pads to be great).

Apec ones will probably be better 

[normanh]

When I had my 2 I replaced the front and back pads/discs with Pagid ex Halfords for around £60 an axle mail order never a problem this was last year
.

Norman

[Alex Knight]

Some EBC pads, tbh even if they're not the best EBC pads they're better than the Apec ones I've been running (and I've found the Apec pads to be great).

Depends on how hard you drive of course, but I've literally melted EBC Yellows. I will never use their pads ever again.

[MrChris]

Thanks for the vote of confidence in the EBCs guys 

In all seriousness, my main reason was because I'm getting 4 good as new calipers and discs and the pads are a bonus (kinda, maybe... maybe not).

[Alex Knight]

Thanks for the vote of confidence in the EBCs guys 

In all seriousness, my main reason was because I'm getting 4 good as new calipers and discs and the pads are a bonus (kinda, maybe... maybe not).

You have been warned:

[Iain]

I'll stand up for using EBC pads for track days. Never had a problem when i used some on the fronts, lasted ages aswell.