Front brakes - caliper and piston condition

[olr159w]

I just managed to removed the old seized pistons through a combination of hydraulic pressure followed by slowly drifting them out by tapping around their rims.

The pistons are history anyway. The intent is to get stainless ones.

My question concerns the calipers themselves. While the pistons have surface corrosion the calipers also have a rusty residue within the piston recesses. See photos below.

Is that a problem? Is it recoverable/removable and if so by what method? What are the calipers made of anyway? Is this rusty residue a parting gift from the pistons or actual corrosion of the calipers therefore?

I know I could get recon calipers but I'd prefer to use the ones I have. The main reason being they are supplied on an exchange basis and shipping back two 1kg+ calipers would likely neutralise the exchange surcharge .

Thanks

[olr159w]

Also, while we're on the subject, what do we think of this :

http://www.cheapbrakecalipers.co.uk/car ... e-calipers

and second, are there supposed to be locking washers on the caliper mounting bolts?

thks

[marko]

In future for parcels try parcels2go.com as they're cheap as chips and easy to use.

[Magenta Auto Sprint]

when ever I have stripped down a pair of brake callipers, I have a put them in a bucket of vinegar.

Every couple of days give them a brush with a small brass wire brush to remove the excess, then soak for another day and repeat.

Use in a well ventilated area as the gas this process gives off can make you feel unwell.

They come out like new, also to be sure to clean the groove where the square section fits, re-assemble with with red brake grease.

pistons and seal kits available from James paddock at reasonable prices.

[SprintMWU773V]

Well they definitely need a refurb, you'll need new pistons and a seal kit. Let's assume that the bores on the actual callipers are OK then you could easily do the work yourself. If the bore are not so good then a specialist might be required. Perhaps give them a lick of paint at the same time?

Pistons are usually steel and not very expensive but you can upgrade to stainless steel ones for quite a bit more money.

I dare say there must be a calliper reconditioners in your neck of the woods. The pistons and seals will be identical to those fitted to other cars taking a Girling Type 14 calliper, though the actual calliper is different to say a Spitfire.

[xvivalve]

You'd surprise yourself how well they would clean up using methylated spirit and a cotton rag...pistons and callipers both.

I'd overlook the 'exchange' demand if a request came from down under!

[olr159w]

Thanks.

Since posting I have read something that leads me to understand that the pistons don’t have to be a super accurate fit in the caliper bores – they sit against the seal and are “suspended” thusly.

So I feel ok with the idea of some 1000 grade on the inside of the bores to clean off the surface deposits.

They definitely do need a refurb and per opening post I will use SS pistons this time. I’m fine doing that work. It’s just the 2w waiting for bits to arrive from the motherland that is time-consuming…..

I couldn’t see seal sets on J Paddock site so I guess it will be RB along with a number of other items.

Right, this vinegar idea. I’m not separating the two halves so what is this acid wash going to do to an inner seals? And how long does it taken to fully clean the surface? I must say I’m a bit suspicious about the vinegar on those inner seals.

Likewise the use of methylated spirits. Would that clean up the rusty outer surfaces? And would it affect the inner seals?

The idea of painting them is good. Problem one comes back to surface prep per above. Any further thoughts welcome. I see there are suitable paint products available that withstand high temps so it’s a possibility. But what colour…… red….

What are the calipers made out of anyway – just steel?

Finally, just as another alternative does anyone do a recon caliper with stainless pistons already fitted?

[mahony]

I have cleaned up worse pistons than that and resealed with no problems, reuse them after a good clean up and new seals

[Magenta Auto Sprint]

Thanks.

I couldn’t see seal sets on J Paddock site so I guess it will be RB along with a number of other items.

Right, this vinegar idea. I’m not separating the two halves so what is this acid wash going to do to an inner seals? And how long does it taken to fully clean the surface? I must say I’m a bit suspicious about the vinegar on those inner seals.

They are not listed under Dolomite, but type 14 brake calliper.
The vinegar will not affect the bridge seal in the calliper either, it is only 5% acidic not like sulphuric acid, the vinegar removes the rust that you can not get too and does not remove the base metal.

[olr159w]

OK. You've done this right ? With no ill effects to the bridge seal?

I see the parts on Paddocks thks. More expensive than RB although I daresay it all comes from the same factory. And yet their brake pad fitting kit is substantially less expensive. Interesting that they also have new calipers for less than recon ones

[olr159w]

Ok well they are in the vinegar brewing up.

I might paint the calipers. They don't do the colour "old iron" so what do you reckon? I'm not genuinely keen on red yellow or blue. Or white.... although with it being a white car...

But otherwise silver or gloss / satin / matt black. I guess silver was the original colour before the parts went rusty.

m

[SprintMWU773V]

I painted mine Gold as I thought it would look nice. Often callipers are refurbed and gold zinc passivated so I figured it would look pretty good painted Gold as it's similar. Be sure to use a calliper paint as it's good for hot things like brakes. Usually comes in a tin or aerosol.

[xvivalve]

Likewise the use of methylated spirits. Would that clean up the rusty outer surfaces? And would it affect the inner seals?

It cleans up the outside of the pistons and insides of the calliper bores, but you don't soak them in it, you use it by soaking a cotton rag and rubbing!

It doesn't affect the inner seals because you don't use enough to reach them!!

If the pistons are too badly corroded then replacement is the only solution.

[olr159w]

Here's a couple of pics showing the calipers after they'd had a 3 day vinegar etch and then today, after a top coat with Dupli Color caliper paint.

[SprintMWU773V]

Wow, they've come up really well. Did the pistons clean up OK or are you still going to fit new ones?