Paul H Posted June 11, 2023 Report Share Posted June 11, 2023 I changed rear brake cylinders about 5 years ago just stripped down to replace the rubbers as moving across to Silicone . Good job I did this as one cylinder was seized solid They were new when fitted . The brand was TB3 . I’ll clean out and see if the surface is corroded . Any suggestions as to a reliable replacement ? What causes the corrosion , the other 1 again new was fine Paul Link to comment Share on other sites More sharing options...
dougbgt6 Posted June 11, 2023 Report Share Posted June 11, 2023 (edited) Traditional brake fluid absorbs water and should be changed every 2 or 3 years, any steel in the system and you're gonna eventually get rust. I'm guessing you've left it a little too long! However, Silicone doesn't absorb water so you're doing the right thing. Silicone shouldn't be used on ABS modern system as it can boil, but we ain't got ABS so that's OK. There are cheap test devices on Ebay for those sticking to DOT3/4 and 5.1 Doug Edited June 11, 2023 by dougbgt6 1 Link to comment Share on other sites More sharing options...
trigolf Posted June 11, 2023 Report Share Posted June 11, 2023 Yes, Dot 3,4 is hygroscopic - i.e it absorbs moisture. I've never had a siezed cylinder since swapping to silicon. 1 Link to comment Share on other sites More sharing options...
johny Posted June 11, 2023 Report Share Posted June 11, 2023 Does depend where the corrosion is: inside the seal is the hydraulic fluid and outside is ingress from the road. Either/both can seize your cylinder☹️ Link to comment Share on other sites More sharing options...
Paul H Posted June 11, 2023 Author Report Share Posted June 11, 2023 The corrosion was throughout and now scrap . This is the state of the cylinder Paul Link to comment Share on other sites More sharing options...
Steve P Posted June 11, 2023 Report Share Posted June 11, 2023 Sadly some of the new ones are rubbish, I had 2 fail within months on my cars dumping fluid into the drums. S Link to comment Share on other sites More sharing options...
Paul H Posted June 11, 2023 Author Report Share Posted June 11, 2023 22 minutes ago, Steve P said: Sadly some of the new ones are rubbish, I had 2 fail within months on my cars dumping fluid into the drums. S My thoughts Steve , mine were repros so replacing with NOS Girling Paul Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 11, 2023 Report Share Posted June 11, 2023 they all need a good dose of brake grease on the road side under the boot to keep moisture away from the "open " end of the cylinders Pete Link to comment Share on other sites More sharing options...
johny Posted June 11, 2023 Report Share Posted June 11, 2023 57 minutes ago, Paul H said: The corrosion was throughout and now scrap . This is the state of the cylinder Yes thats on the outside of the seal so from the road and not down to lack of fluid changes😅 As Pete says a coating of red grease inside the dust boot and bore will help.... Link to comment Share on other sites More sharing options...
Paul H Posted June 11, 2023 Author Report Share Posted June 11, 2023 40 minutes ago, Pete Lewis said: they all need a good dose of brake grease on the road side under the boot to keep moisture away from the "open " end of the cylinders Pete Is the red rubber grease ok with silicone Paul Link to comment Share on other sites More sharing options...
Pete Lewis Posted June 11, 2023 Report Share Posted June 11, 2023 as its the other side of the seal i dont see why not , any lip seepage wont have much effect whatever Dot /grease you use in a cylinder just they are not well sealed to the outside world as you have found Pete 1 Link to comment Share on other sites More sharing options...
Unkel Kunkel Posted June 11, 2023 Report Share Posted June 11, 2023 I was always under the impression that wheel cylinder failure and seizure was a sequence that began with a failing seal leaking tiny bit of fluid.The fluid being hygroscopic and exposed to air, absorbed water making it corrosive.That is why the corrosion is mainly on the ‘wrong side’ of the seal.Resulting roughness of the bore perhaps promoting more leakage, and more corrosion progressing to complete seizure of the outer parts of the piston/ cylinder. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted June 11, 2023 Report Share Posted June 11, 2023 My 13/60 came with a load of spares, two of which were wheel cylinders that had been resleeved in stainless. I haven't used them yet, but it's a nice idea. Link to comment Share on other sites More sharing options...
johny Posted June 11, 2023 Report Share Posted June 11, 2023 Interesting idea Unkel but it seems to happen so quickly that the seals hardly have time to deteriorate that much... And of course stainless sleeving wont stop piston corrosion☹️ Link to comment Share on other sites More sharing options...
Peter Truman Posted June 11, 2023 Report Share Posted June 11, 2023 (edited) A couple of master cylinders that I've had sleeved weren't S/S sleeved but used a chromed brass sleeve there've been there 20 years and no problems. Sleeving over here has got very expensive used to be around the $100 mark ie cost effective but recent quotes were $240 to $260, I brought a new County brake master for a Mk3 Spit for around $150 mark! Re rear brake slaves I got a pair of NOS Girling from Mick D for the same Spit last year, re brakes I don't compromise. esp with a single pipe system Edited June 11, 2023 by Peter Truman Link to comment Share on other sites More sharing options...
Paul H Posted June 12, 2023 Author Report Share Posted June 12, 2023 As a follow on the pistons are different on the Girling and TB3 so Girling rubbers won’t fit . The pics below show the end rubbers and the Girling seems more substantial which supports the theory my issues could have been rubber seepage . Whilst the piston had corrosion there was corrosion in all of the piston cylinder . Just bought 2 Girling NOS Brake Cylinders for £15 each Paul Link to comment Share on other sites More sharing options...
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