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MG Midget and Sprite Technical - Rechroming caliper pistons

has anyone ever had experience with rechroming caliper pistons? Not that I am going to, but it seems that the standard chrome is quite poor, and rechroming an other good piston would make it last a lot longer?
Tarquin

Get some S/S ones?

Howie
Howard Wright

are there no stainless pistons available?
more suited to the job than chrome i think
Onno Könemann

I am getting s/s replacements for the 2 that have started to rust, just wondered if anyone had gone this route.
Tarquin

i obviously had not read Howards's response ;)

Onno Könemann

Tarquin. The pistons would have to be stripped of their old chrome/nickel/copper plating (called "triple plating"), then polished out, then copper plated, then polished, then nickel plated, then polished, then chrome plated. And, when finished, they would have to be within a few thousandths of an inch of the original size. All the work being done on two pistons, which means that you are not going to build up the experience base that is built up when doing thousands of pistons every month.

So, the down side is that it is going be be rather expensive. Second down side is that it is getting very hard to find a good plating operation because of governmental restrictions on the hazardous process which uses dangerous chemicals and produces contaminated waste which is expensive to get rid of properly.

The old triple chrome plating (copper, which can be plated directly to iron/steel and forms a base coat, followed by nickel which will bond to copper but not steel and provides a moisture barrier, and chrome for the bright, shiny, pretty surface finish) was one of the best things going in its day. As a result, its use was expanded to areas, such as the brake caliper pistons and inside bores of various components, which did not have to meet some cosmetic standard of beauty. Today, a Brit process called NP-3, a nickel plating with embedded teflon for lubricity, would be the ideal plated finish for things like the brake calipers, inside wheel cylinders and the master cylinder bores.

If you do decide to experiment, please keep us informed.

Les
Les Bengtson

Tarquin,
Speak to AP Racing, or, there might be someone on this web who can be more specific. The master cylinders in the blue Frogeye I had had been sleeved with SS, but,someone did say to me that surface finish of the SS needed to be of a very high order to ensure it did not degrade the seals and give short life expectancy. It's worth following up, there may be a specific seal spec to conform to if you do use SS pistons.
Peter
PJ HOBSON

Teflon coating is the way to go - try JEMS brakes.
d brenchley

I quote "Not that I am going to"

I am in no way going to experiment. I also already have bought some s/s ones as mentioned above!

I was just curious as 2 pistons in the new calipers I bought have rusted after only a few thousand miles. The chrome plating seems very thin.
Tarquin

did you ever use those MG Metro ones I almost gave you?
Shawn

Tarquin
There is a guy down here that does them, He manufactures and reco's hydraulic rams and cylinders and has a hard chroming setup as part of his business. He also makes calipers
I've heard that it is a bit expensive 'cause they have to grind the old pistons to a smaller size to allow for the extra thickness of the hard chrome, it would probably only be worth it if a new piston wasn't available. You've got me interested now, I'll go and find out how much it costs
PJ
The problem with SS lined cylinders seems to be that when the fluid supply holes are drilled through the sleeve it leaves a sharp edge in the bore and all that is needed is a light fine hone after drilling--never had a problem with them. BUT I have heard stories, and it is usually that the holes have been drilled too big allowing the edge of the cup to get in there, or as mentioned before not cleaned up properly. I guess it's like a lot of car repairs there are them that do it properly and there's them that don't Cheers Willy
WilliamRevit

Shawn, I didn't think it worth it to refurb them, bought new ones in the end.

Willy, thats what I thought, rechroming would make them oversize, and/or different sizes between pistons.
DOn't see the point in chromed pistons as s/s are so widely available.
Tarquin

Like William said, it has to be hard chromed. The soft chrome like on bumpers will not work.
tomshobby

You could get them 'hard chromed' and then centerless ground to size.... but is it really worth the effort?

As Matt has said, the stainless ones should be fine.

Although, someone did try to argue the point for NOT using stainless pistons, but I can't remember why....

Mark.
M T Boldry

This thread was discussed between 25/11/2009 and 27/11/2009

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