Standard AP 2-pot front caliper refurb - any wisdom?

I’m just after the combined wisdom of the collective before I start the next project (and hoping to avoid doing something silly along the way)

My car just had its MOT and I was advised that the front brakes are pulling to one side (which I could also feel) and the tester said they need servicing. I’ve got new pistons and AP seals and I’m about to start looking at them, but after all the horror stories about airlocks recently, I’m probably getting myself overly worried…

Are there any ‘tricks’ I should be aware of? Incidentally, I had new braided hoses fitted a couple of years ago, if that’s of any relevance.

Thanks for any useful input guys! :+1:

If you’re mechanically minded you’ll be fine. A good air compressor will be useful for popping out the pistons and make it easier for you. Every caliper I’ve reserved/replaced I’ve filled with fluid on the bench rotated and twisted to remove what air I could, re filled etc then bolted all back up on the car.

I recently had my 4 pot fronts refurbed, you might have seen my thread on here.

I didn’t do the work myself, but in hindsight I wouldn’t have had the inner seals replaced as the new rubber seems to be retracting the pistons more than before and it’s creating longer pedal travel.

It makes sense from a good practice point of view to replace the seals whilst your in there, but if they’re not letting fluid past the pistons I would be tempted to leave them.

If your issue is piston corrosion, I would of course swap these out.

This is just my experience, so take it with a pinch of salt :wink:

Aye as above, not too many pitfalls with these. I did my Exige ones and totally split them apart to paint (in hindsight I probably wouldn’t have split them, as since heard from loads of people who ended up with knackered calipers from doing this due to seized in bolts. I got lucky).

Pistons pop out dead easy with some compressed air, I did replace seals on mine - just made sure everything was lubed up with fresh brake fluid before reassembling.

As for rebleeding afterwards, I still haven’t cracked it after countless times now on the 111 platform. My only solution is to keep throwing cheap fluid through it and just bleed, bleed, bleed. Get it vaguely driveable, then try to get out and lock the brakes up a few times, back home, repeat. Once you have a decent pedal, do one more flush with some decent stuff.

Some things that definitely help are a decent pressure bleeder, clamping the pistons back when bleeding (reduce the air capacity of the caliper as much as possible), inverting and tapping the caliper/hose, etc etc.

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Thanks guys, I’ll get cracking when I have time… I did buy this at the same time as I thought it might help, but it sounds like it’s basically brake fluid after all, lol!

I did the passenger side in about 30 mins this evening, waiting for an opportunity to do the drivers side, then will put loads of fluid through whilst wiggling, knocking and inverting the calipers :slight_smile: Seems to have been very straight forward so far - and the original seals look like they’ve perished, so I’m glad I’ve replaced them :slight_smile:


I seemed to have acquired a workshop helper during the process too… lol

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Car looks awesome. Cat looks either sad or guilty about something :smile:

Turns out that the driver’s side piston seals looked much newer - I suspect one side had previously been refurbed but the other was original. Anyway, all done now - and a CRAZY amount of air evacuated. Need to drive it around and get the ABS busy next, then bleed again and see how we go :slight_smile:

I’ve reassembled it all with my other alloys on - they’ve got sufficiently large gaps between the spokes that you can easily bleed the calipers without needing to take anything off, lol!

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Bonus. Great idea!

Just went out for a 15 minute drive for the first time since doing the job. The ABS was kicking in a lot and the pedal seems good, but a touch lighter than it was before, but I’ve changed a number of things, so can’t tell what’s causing it, lol! To be clear, with the window down, I could hear the tyres chirping as they locked for a moment as the ABS came in, so I’m encouraged that it’s working, but wondered why the ABS might be seeming more ‘active’ than I’m used to…

  • It could be that I’m using my AD08R tyres from 2018… The first thing I did as I pulled out of my drive was a very unexpected power slide despite the fact that I was at marginal throttle - so I suspect they’re VERY brittle…
  • It could be that the CL RC6 pads are much more effective as I’ve just put them on all 4 corners and never used them before
  • New caliper pistons and seals, so they’re probably just gliding more smoothly, hence the braking effect is increased for less effort?
  • It could be that there’s air somewhere there shouldn’t be? Maybe? But I’m not convinced it would cause that?
  • Any or all of those things?

I’m going to try bleeding them again just to be sure, but the pedal didn’t feel spongy. Other than the obvious ‘just bleed them to see if air comes out’ is there any other way to know if there’s still air in the lines/calipers?

Perhaps just that you are not used to the braking power due to the calipers being gummed up and binding?


Honestly hoping that’s what it is - they fundamentally felt good - just keen to lock up, lol!

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If you managed to powerslide out of your driveway I’d wager those tyres are just not up to it!

I have no experience of the RC6 pads but perhaps they’re a bit grabby when cold, combined with some mahogany tyres.

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Obvious point. Did you do the Caliper rotate thing on the fronts? I expect you did as the brakes don’t work at all well if you don’t. They fill on the inside top, bleed on outside top, you must rotate them to get air from the inside top, through the joining pipe, to the outside. I tap the Caliper with a rubber mallet as I do it to dislodge bubbles.

I think you have done that as your brakes work!

I have just refurbed my S1 brakes and they certainly feel different, I think that’s because the pistons move freely at the start of travel.

Like others, I suspect your tyres are dead. Exige brakes have plenty of feedback so you should be able to threshold brake with a bit of practise.

I bled the tiny remaining bubbles out and used the car for the commute yesterday. Tyres are awful. Brakes are wonderful! Thanks everyone! :+1:t2: