Poor quality brake pistons?

Poor quality brake pistons?

Postby sixinoz » Mon Apr 01, 2019 11:35 pm

Rebuilt my front brakes 3 months ago with new pistons and seals. I have had a slight weeping from the seals so took the pistons out to have a look for any problems.
I found that the pistons already had plenty of pitting on them after 3 months?? I used new fluid and the calipers were dry so no moisture contamination to speak of.
I got the pistons at a good price but it appears they are junk. I contacted the supplier and attached photos but no reply. Am I allowed to name the supplier on the forum so others are warned?
I am now going to order some stainless pistons.
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Re: Poor quality brake pistons?

Postby daves79x » Tue Apr 02, 2019 6:15 am

Sorry for your luck. Sure, go ahead and name the manufacturer and/or distributor. Folks can weigh in on their experience with them and other brands.

Dave
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Re: Poor quality brake pistons?

Postby cbxchris » Tue Apr 02, 2019 5:40 pm

Not doubting your knowledge Sixinoz , are you sure you have the piston seals on the right way round, they chamfered ?
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Re: Poor quality brake pistons?

Postby daves79x » Tue Apr 02, 2019 7:15 pm

Not correct - the piston seals are perfectly square (or rectangular). The groove they ride in is stepped, creating the bevel that grips the piston and retracts it slightly upon lever release. Piston seals can go in either way.

Dave
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Re: Poor quality brake pistons?

Postby sixinoz » Tue Apr 02, 2019 10:16 pm

Thanks for the technical info. I was not aware that there was a step in the groove, Dave - more valuable knowledge from this forum.
Is there any way to inspect the groove - especially the front edge. Small dental mirror?
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