Brembo refurbishment. Semi-HOWTO

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mjb
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Brembo refurbishment. Semi-HOWTO

Post by mjb »

My Brembos are knackered, and need refurbishment. I also have an MOT due next week and know the brake balance is so far out it'll never pass (got an advisory for it last year). In a stroke of pure genius, I decide to buy a pair of calipers and a refurb kit off ebay so I can refurb the "new" set without risking the car being off the road for more than an afternoon.

So the stuff arrives (the refurb kit being for a Fiat coupé, but I know they're the same brakes) and I get to work. Then stop and go to Machine mart for a vice. Then stop and go to Halfords for a couple of bolts to attach said vice to the worktop. A vice is essential for this job. In fact, I'll list the tools I used:

Vice, 6" opening
10mm allen socket, Halfords Professional, 1/2" drive. Tough enough for impact wrench use
1/2" drive mains powered impact wrench, >500Nm. Utterly essential.
2 foot, 1/2" drive breaker bar
24oz ball pein hammer
T27 bit, 1/4" socket holder
4mm allen socket
Metal files
11mm open-ended spanner
11mm crow's foot socket
11mm 1/4" socket
Jacks + axle stands.
T55 socket, 1/2"
Punch
Hacksaw
Chisel
Threadlocker
Copper slip
Strips of cardboard, about 6"x12"
Pliers
Toothbrush (actually, sold with wire brushes, has stiff plastic bristles)
Dust mask.

1. Put the dust mask on and attack the callipers vigorously with the toothbrush. Get as much brake dust off as possible.

2. Put the calliper in the vice, bleed nut upwards. Use the cardboard to protect the calliper. Remove the bleed nuts then put the new ones in. Carefully. It's VERY easy to cross-thread these buggers. They're something like M10x1mm, which isn't a thread you can buy a tap for at Machine Mart. Guess how I know... The thing to remember is the calliper is an aluminium alloy, and the bleed nuts are a lot harder, so they have a tapping action. Your callipers will also have a lot of corrosion and age-related issues, so chances are your new nuts won't go in smoothly. Good luck. If you mess this up, you may well have written off the calliper. Don't bother with the dust caps.

3. Grab the hacksaw and cut the short pipe which joins the two sides of the callipers. Cut it both sides near the ends, so you can use a socket to remove them. You want to have the calliper in the vice with the pipe facing upwards unless you want everything to get wet.

4. Use the 11mm socket to remove the pipe connectors. If they start to round, grab the chisel/punch and give it a good smack. If it loosens the connector, great. If not, just destroy it. Given the construction of the brake pipe, you've not got to worry about needing to drill anything - once the nut part breaks up, the rest will come out easily.

5. Remove from vice, turn upside down, and allow to drain. Good time to do the other one...

6. Put the knackered connectors back in the callipers, or some bleed nuts, or something, just to block the hole.

7. Now it's time to break out the heavy duty kit and get the four big allen screws. I had absolutely zero success using hand tools - I felt like the breaker bar was delivering enough torque, but was getting seriously worried about rounding the screws. The impact wrench did well though, but those things are in tighter than wheel hub nuts.

8. Let's get those shims off. Hammer the T27 socket into the screws - hard, to shock the screws loose - then unscrew while putting as much pressure as you can on the wrench head. Once they're off, scrape off as much of the corrosion as you can (hint: if it's not visible, it's under the paint!), then attack the sides with a file to get rid of a load of the corrosion and level things off a bit.

This is a good time to give the callipers a good clean. If you want to get them painted, I suggest screwing them back together and doing it now.

9. Lever the pistons out. There's a groove in the sides which the seals fit into. That's where you do your levering. No idea how to get the seals out without knackering them, but they're going to be old and knackered so it's no big worry. Once out, clean 'em up, clean up the wells, then replace the dust seals. Lubricate the new seal rings with some brake fluid, then smear more fluid around the pistons and wells. Gently hammer the new pistons in and push the dust seals home. I used the ring of a ring spanner to push them down.

10. Apply a generous amount of copper slip to the bottom of the new shims then screw them in. Wipe off excess grease

11. Screw the two halves back together then have fun putting the new brake pipe in. All I can say is that you need the two connectors to screw straight in - they can't be at an angle. Also, you want a slight bend near both connectors in order to get the pipe into the slot. I guess after you've bent the pipe correctly, you should really paint it to protect it from the elements. I haven't though...

12. Fit the new bleed nut dust caps.

Now the callipers are ready to go back on the car.

If you've survived this far, expect the brake hose connector to round off :evil:
<steve_earwig> I think this forum is more about keeping our cars going with minimal outlay than giving our cars more reason to go bang
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Re: Brembo refurbishment. Semi-HOWTO

Post by mjb »

Ahahaha brilliant

Got the new hoses today, fit one to replace the one with the rounded nut, hooked up the pressure bleeder, and ARSE! Little fountain from the bleed nut I thought I'd narrowly escaped cross-threading. Tried tightening it harder and it just spun. Arse.

So my next job is refurbing the caliper that came off my car. Turns out this one has 10mm fittings, not 11mm! all going well until it came to removing the rounded hose. Ended up having to drill it out and use a screw extractor on it. Unfortunately I may have drilled a little far. F**K! The hole drilled neatly in the middle, and isn't wide enough to take out the whole conical section, but I'm nervous.

Just need to separate and clean it, then figure out how the hell I'm going to get the seals out of the knackered calliper without damaging them, else it'll be a couple more days and a load more money to wait for the ebay seller to shift a new set.

Fun.
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Re: Brembo refurbishment. Semi-HOWTO

Post by jasper5 »

You should be alright with the conical fitting.

As for getting the seals out without damaging them....

Push or pull out the pistons, get a small flat blade screwdriver and gently ease the outer seals out from their slots by levering the rubber from the inner part....if the pistons are tight blow compressed air into the bleed screw or brake pipe hole and the piston will pop out.....or you could grip the outer part of the piston where the hole is with mole grips and ease them out.

To get the inner seals out just get the same screwdriver and gently ease the seals from their slots by sliding the screwdriver blade into the slot where the seal sits.....take note which way they came out.

Clean the rust from where the inner and outer seals sit and clean the inner portion of the caliper with brake cleaner.

Wipe off the old seals after spraying with brake cleaner and refit the inner seals and refit the outer seals after cleaning out the slots where they fit.

Clean off the pistons and refit after coating the inner seal and the piston with rubber lubricant.....I carry condom lube for this job, it is perfectly safe with rubber seals.

To fit the piston open the outer seal and place it all around the piston then gently locate the piston into the caliper and push it all the way in.
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Re: Brembo refurbishment. Semi-HOWTO

Post by mjb »

jasper5 wrote:You should be alright with the conical fitting.
I'm hoping so. If I can get the new screw in without cross-threading, the 2mm or so of remaining cone (along with the screw thread of course) should provide enough of a seal
As for getting the seals out without damaging them....

Push or pull out the pistons, get a small flat blade screwdriver and gently ease the outer seals out from their slots by levering the rubber from the inner part....if the pistons are tight blow compressed air into the bleed screw or brake pipe hole and the piston will pop out.....or you could grip the outer part of the piston where the hole is with mole grips and ease them out.
The pistons are tight, especially with the brand new seals in them. I've already popped the 8 pistons on the ebay callipers, so I'm hoping I've got the knack of prying 'em out without ripping. I don't particularly want to use a small screwdriver on the dust seals since it's easy to cut/rip the rubber. I think I'll pry the pistons (with two blunt pry bars) to the point the dust seals pop - either at the base (would be excellent), or they'll pop off the pistons in which case I'll have to try gently pushing them out from underneath
To get the inner seals out just get the same screwdriver and gently ease the seals from their slots by sliding the screwdriver blade into the slot where the seal sits.....take note which way they came out.
They're just big rubber rings, about 3x3mm cross-section, not tough to get out at all
Clean the rust from where the inner and outer seals sit and clean the inner portion of the caliper with brake cleaner.
Actually, the inside of these Brembos has been nearly immaculate! Christ knows what I'll find in the one from my car though...
Wipe off the old seals after spraying with brake cleaner and refit the inner seals and refit the outer seals after cleaning out the slots where they fit.
Re-read what I put above - I'll be re-disassembling a calliper I refurbished (and destroyed :evil:) over the weekend, and using the new bits (seals, screws, stupid bloody shims, etc) on my old calliper
Clean off the pistons and refit after coating the inner seal and the piston with rubber lubricant.....I carry condom lube for this job, it is perfectly safe with rubber seals.
Hmm. I've just been using fresh brake fluid to lubricate everything. Is that not sufficient?
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Re: Brembo refurbishment. Semi-HOWTO

Post by jasper5 »

Nothing wrong with brake fluid, I use the other stuff cause it's very slippy and helps with the outer seal when fitting the pistons.
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Re: Brembo refurbishment. Semi-HOWTO

Post by mjb »

Hahaha it just gets better. I refurbished my original calliper (spending about an hour grinding/chiseling/filing the corrosion off), bolted it on, connected up the hose, put the bleeder on and it immediately dumped a pint of brake fluid all over the garage floor.

This time it's the hose connection. Stupid braided hoses have a ring+bolt arrangement instead of just a simple screw-in jobbie. This requires a flat surface on the calliper. Unfortunately mine is that corroded there's hardly any of the original flat bit left. f*ck.

I have no idea what to do. Buy yet another pair of callipers off ebay with £150 I don't have and then go through the whole rigamarole of refurbishing again? Buy a pair of Lucas callipers and hoses for about the same amount of money (after the cost of the hoses has been factored in), then buy new pads and discs? I dunno. This f*cking thing's worn me down that much I'm thinking of just scrapping the whole f*cking car. I'm really that f*cked off with it.
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Re: Brembo refurbishment. Semi-HOWTO

Post by mjb »

Would Araldite putty save me? I don't care if I lose the ability to disconnect the hose in future...
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Re: Brembo refurbishment. Semi-HOWTO

Post by steve_earwig »

Depends if brake fluid eats it :shock:

Is there enough meat left for a new seat to be machined into the caliper?
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Re: Brembo refurbishment. Semi-HOWTO

Post by mjb »

urgh. google says araldite and brake fluid don't play well :cry:

Wonder if I can get it welded in... EDIT: aluminium isn't really mig weldable, is it? :cry:
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Re: Brembo refurbishment. Semi-HOWTO

Post by mjb »

OK So I hit ebay and replaced the fancy braided hose with it stupid (imperial sized!!!) banjo bolt with an oem-style hose with the proper connection. It works!

Went to bleed it and found the pressure bleeder has failed, flattening my tyre in the process. Some superglue to make one final use of the bleeder, and I have leak-free brakes. Awesome.

Get the wheels on, put the car back on the ground and my god the pedal feels weird. :shock:

A bit of experimentation later and I realise that for most of the pedal's travel there's very little resistance, then it feels normal. This is the rear brakes kicking in. Yep, the front brakes do nothing.

I have no idea what's causing this (huge air pocket or the master cylinder or abs unit failed somehow?), but I've completely lost the will to go on with this damn thing :(
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Re: Brembo refurbishment. Semi-HOWTO

Post by madmadmax »

keep going mjb you will get there its hard but keep going, i could come and help but its a long way on a push bike 50ish mi a nice but long bike ride

could you not use jb weld to make the Surface flatter
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