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Jesus
08-05-2015, 03:30 AM
Hello,

I made an error and ordered standard caliper pistons instead of stainless-steel ones. The pistons I got are not chromed but have a matt dark grey finish that is supposed to be less prone to pitting. I could send the pistons back and change them for the SS, but twice shipping costs and VAT between Spain and UK is going to be expensive, I guess more than 50 pound.

Are SS pistons so superior and recommendable? My TR3A is driven only very occasionally, and brakes components stay still during weeks.

Thanks for your responses.

Jesus

trrdster2000
08-05-2015, 06:56 AM
Jesus, I think you are over cautious, the matt black ones will do fine for years to come. Make sure to use a good lube when putting them together.
It's a special grease for this, don't just use anything.

Wayne

martx-5
08-05-2015, 07:41 AM
Yeah, I agree, just use the pistons you have. Maybe in ten or fifteen years you'll have to approach the subject again. You might also want to think about using DOT 5 silicone brake fluid, if you have it in Spain. It's not hydroscopic so the chances of getting corrosive water in the system is lowered considerably. Or you could just change out the brake fluid every couple of years.

CJD
08-05-2015, 08:25 AM
I agree. What kills the standard steel pistons is that most people don't ever change their brake fluid, and it eventually absorbs a lot of water, causing rust. The steel pistons should last 15-20 years if you do nothing, and even longer if you change your brake fluid every 5 years or so.

dklawson
08-05-2015, 10:06 AM
This is one more vote for use the parts you have and change the brake fluid regularly.

AZTR4a67
08-05-2015, 10:35 AM
I'm sorry but I have to disagree. You need to have the SS in there just in case someone is checking out your car, and decides to crawl under the vehicle, peer down with a flash light and checks out your brake calipers. I mean, we have a reputation to uphold, as Triumph owners! :chuncky: Ok, all kidding aside, use the steel pistons and see about the DOT 5 fluid mentioned above. The steel pistons will be no problem.

Don Elliott
08-05-2015, 04:40 PM
I have 195,000 miles on the original chromed caliper pistons that are in my 1958 TR3A from new. During the restoration from 1987 to 1990, I noticed that some of the chrome plating had flaked off. I put these slightly rusted pistons back into the calipers with new seals and in the past 25 summers of driving 113,000 additional miles, I have never had a problem. I have used silicone fluid all this time and this keeps everything lubricated. It prevents rust and every spring after long storage over the winter, I have never had them freeze up. They are still like new. It also applies to the rear brake cylinders too.

Jesus
08-07-2015, 03:09 AM
Thank you all for your interesting and useful comments. I will use the standard steel pistons and change the fluid. Silicone brake fluid is available in Spain (everything is but at its cost…), but I used initially DOT 5.1, so I will stick to mineral fluid.

This all started because jerky braking at low speed. When restoring the TR3A I used the original discs (rotors) and some NOS pads. I cleaned the calipers, the chromed pistons and put new seals.

Now I plan to install new discs, new green-stuff pads and the said pistons with a new seal kit. Hope to get a better and uniform braking by then.

Jesus

Don Elliott
08-07-2015, 11:18 AM
Over a 10-year period, I had driven 40,000 miles on my Michelin 15" radial tyres. As I would apply the brakes to reduce my speed, I would get a thumping feeling from my front wheels. I got out and checked the tyres, There were bumps (like bubbles) in the tread area. This condition is known as ply separation. The tread was still there but the tyres were finished. I bought new tyres which resolved the problem.