Brake caliper refurb, worth it?

[SeriousSam]

The guide pins that hold the pads in place can be re-used, or you can buy a replacement set from Mazda easily enough. Greasing them is a very good idea. Did you fit fresh pads with the new discs? If yes, there's typically a bedding in procedure that you need to follow to make sure the two surfaces bond correctly for best performance. With Mintex M1144 pads, the recommendation is a few gentle stops from 30mph, followed by several firmer sets from 80 down to 30, then drive normally. If you just started using them as you normally would, there's a chance they wouldn't have been properly bedded, hence the chance of uneven wear.

[Lemon]

has anyone got any tips for freeing up seized bleed nipples? the ones on the new car are stuck good and firm and i'd rather not go all ham on them and shear the nipples off.

[PeteH]

Wire brush the hex part, so that the your spanner isn't on rust. Squirt with release oil and leave for a few hours. GENTLY tap the end of the nipple with a small hammer (the shocks help break the rust). Tap downwards, never sideways, because the hollow nipple will break. Then, most importantly, use a good quality six sided socket to crack it off. I have a good 1/4 inch socket set which has never failed.

[Kamys]

I had a seized nipple as well (sounds really kinky but its not), i just greased it and turn it with molegrips...as the sides colapsed and turned into a perfectly round and polished surface.

As for the bedding of the pads procedure...I just tested the brake progressively from low speeds to high speeds. I case I messed something up nobody else gets to pay the price. Are the disks compromised now?

One more thing...two nights ago I had to slam the brakes quite hard to avoid a cyclist...and the brake pedal feels slightly stiffer now. Also...in the spur of the moment I felt a delay in brake time, should a re bleed the brakes or was it just the adrenaline?

[ChrisHolmes]

has anyone got any tips for freeing up seized bleed nipples? the ones on the new car are stuck good and firm and i'd rather not go all ham on them and shear the nipples off.

One thing you must not do is Google "stiff nipples"

[warpc0il]

Do I need to delete my browser history?

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[SeriousSam]

If the pedal feels a bit stiffer that's probably a good thing, that's what you're aiming for. As for the delay you felt, that's normal enough on my other car when the roads are damp - takes a moment for the brakes to fully come online. And your discs may not be ruined, try doig the bedding in procedure I mentioned above. That will ensure the correct material transfer has happened, and may improve the discs. You could also buy some fresh discs, put those on and bed them in, then get the old ones skimmed by an engineering shop. OEM-spec discs can be bought from many sources, Euro Car Parts are decent enough if you've got a discount code, and that then gives you a spare set for the next time you need to change discs.

[SeanP]

To get the last bit of air out of the system, try parking the car on a steep slope facing down hill, handbrake on.
With the engine running press the brake pedal firmly and hold for a count of ten, then release really slowly.

The aim is to pressurise the system such that the tiny bubbles form one big bubble, which sits against the master cylinder piston.
The angle of the car and the slow release means that the bubble escapes up through the fluid in the reservoir.

You show feel an immediate improvement in the pedal firmness.
Repeat the action until no further improvement is noticeable.

Note that you can do this trick any time you find yourself stopped on a steep downhill slope, even just at traffic lights etc.

[Kamys]

Thank you very much for advice, I'll do the bedding procedure and the steep slope trick, as for the second set of disks... I'm not sure how much more my Mrs will tolerate XD

warpc0il - a clean browser history is a dirty history

[Kamys]

Hello guys, getting close to a year since I've done my brakes, lately they've been quite sqeeky (while rolling) so I checked the problem. After I cleaned the brake dust away, lubricate everything that's supposed to be slippery and so on, the problem continues to be present, but only on bumpy roads. I will change the little... things (what ever they are called, the tin things that the pads slide on), but I also want to know if this might cause the sqeeking:





The groove in the disk i'd class as superficial (less than 1 mm)

Also...the pad are Hawk performance (street / track version) but i find them a bit too hard for street. Can anyone recommend me a set of pads that are not too rough on the disks, perform well, and won't require me to sell a kidney to purchase them? Thank you.

[ChrisHolmes]

PM me your details an I can squeeze you in for a set of the Mintex 1144 pads. viewtopic.php?f=144&t=78927&p=1208683&h ... x#p1208683

[Kamys]

So...1 year and a bit into the Stoptech disks. I don't think I've covered more than 4500 miles with them, the front disks can do some more, but the new pads don't fit the the groove, the rear seem worned a little more than the front ones for some reason (same story with the groove). I'm now planing to go back on the standard disks, not because the Stoptechs are not good enough, but because I didn't get the chance once to get the car out on the track, and the investment is not justified. The braking was greatly improved and I got away with 2 close calls rather 2 nasty accidents.
I will post the pictures of the disks as soon as i get all the parts and start working on it, but until then, can someone please tell me from where can i get my hands on OEM Mazda sliding pins + rubber boots for all 4 calipers?
Thank you.

[SeanP]

Following on from this - and my "Intermittent VIbration" issue - I want to refurb my brakes - mainly the piston.
The slider PINs are all OK (in fact those were replaced / refurbed a couple of years ago)...
Are these OK for an R3 (same as S1 / 230 anyway?): https://www.bestpartstore.co.uk/1287676 ... ke-caliper
They're "cheap enough" - so may as well include Rears to do "at some point": https://www.bestpartstore.co.uk/1287659 ... ke-caliper
(@SeriousSam - I might come to you for advice before doing the rears! ;-) )

I did remove, clean "move / slide" the fronts a few weeks ago - and since then have not had a "Vibration Incident" - but the front right is clearly still a little binding as it's always "hotter" than the other side & after extended driving can hear a squeak.

[ChrisHolmes]

If the piston seals are old (older than an R3), or have been cooked by over-heating, or contaminated by the wrong grease used at some point, then they may no longer "grip" the piston.

The concept that they should "grip" is counter-intuitive, until you get into the details of how a caliper works.

As line pressure is applied then the piston should move out smoothly, pushing the pad against the side of the disc.
This becomes a clamping force as the reaction pushes the entire caliper back on the slide pins, and brings the passive pad into contact.

None of that is any surprise, until you consider that there's no return spring to pull the pads back when the line pressure is released.

This pull-back is achieved by the piston seal gripping the outside of the piston as the pressure increases, causing the cross-section to distort from a square to a lozenge. As the line pressure is released so the seal is allowed to return to a square section, and in doing so pulls the piston back - very slightly but just enough to release the brake.

This is what makes that first statement so important. You can have the piston nice and clean and shiny, and moving in/out of the caliper quite smoothly, but if there's no resilience in the seals then the pull-back doesn't happen and the brakes drag.

[SeanP]

Many thanks Dave. Deffo need to refurb them - boots on both sides have have nicks in them and they will have seen a lot of (sometimes excessive) heat cycles... Is there a guide to the process - i.e. Parts to grease / not grease etc.?

[Torque23]

There's no issue with grease, as long as it's the right grease.

"Red Grease" is often supplied in a sachet with seal kits, which is fine.
I tend to use CeraTec brake grease as it has better heat performance - fine for piston seals, the slider pins, plus the backs and ends of pads.

[Torque23]

I used this grease on a Brembo 4 pot caliper last time I changed discs and pads. Is this similar to CeraTec ?



Silverhook SGPGT70, Ceramic Grease

Also when replacing discs, what is the maximum runout?

[Torque23]

I'd say that's fine on the back of brake pads but there's no mention of it being suitable for caliper pistons and slide pins/bolts.

Ceratec is specifically for brakes.

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[SeanP]

There's no issue with grease, as long as it's the right grease.

"Red Grease" is often supplied in a sachet with seal kits, which is fine.
I tend to use CeraTec brake grease as it has better heat performance - fine for piston seals, the slider pins, plus the backs and ends of pads.

I have ceratek but expect grease is supplied. I'm thinking more ensuring grease applied to right area on piston and suppose this would be 'around piston, behind boot and there must be a seal / oring at the bottom of piston'?
OK with pins - done those before... I'll do one at a time and note on disassembly, keep one assembled for reference

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[SeanP]

Ok folks, follow up... I did buy refurb kits - and after taking another set of mintex to the metal on front right at Castle Combe (grrrr!)... I dismantled and prepared to rebuild them... Suddenly realising how out of my depth I am... Nothing to budge the pistons out... (no compressed air here, and I never thought of swinging the calipers out, sticking in a block of wood and pumping the pedal... I'd already removed them and drained fluid.) D'oh!

So after recommendations, sealed them up and shipped them off to Bigg Red for a refurb, and ordered new Hawk HP+ pads from RacingBeat / MRP / Shy Auto.

Everything returned this week and just spent evening cleaning the shims, fitting everything back with pads, ceretek etc. and ready to bolt back on this week.

Very pleased with the result - went for a basic electroplated gold - I'll *never* keep EM clean enough for fancy paint!

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