Hi Folks
Can anyone see any problems with replacing the alloy pistons with stainless in alloy 4 pot brake calipers?
Nick


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....Doesnt stainless corrode Ali...

So if you put them both together its going to corode....

No not saving weight
My son has bought a mini van with 4 pots on and one has decided to deposit all its fluid onto the drive overnight caused by corroded alloy pistons.

Nick

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I think wilwood have some of their pistons in stainless and they are alloy body, so I don't see why not.

quote:

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Originally posted by x_flow57
No not saving weight
My son has bought a mini van with 4 pots on and one has decided to deposit all its fluid onto the drive overnight caused by corroded alloy pistons.

Nick

<<<<For Sale

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they shouldn't be in contact so shouldn't corrode; unless the brake fluid casues some chemical reaction between the two.

but then the LR master cylinder is alloy as well as clcuth master /slave and I have never heard problkemns weith the alloy; stainless brake pistons are avaialble so either someone has not tdone the electro-chamistry homework or else it is ok.

It depends....

i was under the impression that alloy callipers with a stainless piston had a coating on the bore of the barrell to stop corosion...

So if you dont have that coating, it might corrode..

Then again I might be talking out of my arse!

For road use alloy calipers are bad news.

Stainless steel pistons should be OK

BT, apart from the obvious (corrosion) are there any other drawbacks with alloy on road cars?
Nick

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quote:

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Originally posted by x_flow57
BT, apart from the obvious (corrosion) are there any other drawbacks with alloy on road cars?
Nick

<<<<For Sale

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Yep, I think maybe somebody better tell Mazda, Nissan, Mitsubushi, Porsche and a few others that they better stop using alloy calipers!!

Back to the question, no there's no problem with stainless pistons in alloy calipers, as long as the car's not being stood for long periods. There is an issue with dissimilar metal corrosion but as said above, the two shouldn't be in contact in normal use, but can be once its been stood for a bit.

Realistically though, it will be fine, just go for it!

Fiat used alloy calipers on some models for a long time -- in wet salt laden UK roads they used sized after 2 years use. PGA group used alloy calipers on some models as a production alternative to steel/CI, the alloy ones were nothing but trouble.

Alloy calipers and wheel cylinders have always been a problem when exposed to salt --- back in the 50s and 60s' alloy wheel cylinders were the norm and replacing seizied wheel cylinders kept a lot of garages going.

Thank you all for the replys.
Stainless pistons now fitted and stopping well.
I'm sure the car is not handling as well as it was before what with all that extra unsprung weight.
Being serious for a mo, the stainless are incredibly heavy compared to the alloy.
ATB Nick


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Usually steel pistons are hollowed out not solid.