Alan Collins
CCCUK Member
Hi, I have a 1972 small block convertable which is giving me recurrent braking issues.
My front stainless steel sleeved callipers are starting to leak and have a history of repairs with lip seal service kits despite regular use, generally every two weeks:
First service kit fitted by previous owner in May 2017.
Second service kit by myself following sudden major leaks in May 2018, I found some seals twisted, some seal lips scored and white crystaline deposit around pistons inside the dust covers. I cleaned all parts meticulously, cleaned bores with 1200 wet and dry lubricated with brake fluid and replaced the fluid.
June 2019 brakes tested on a rolling road as part of general mechanical test, performing well, 273 and 288 kgf with wheels locking up.
February 2020, some pistons are leaking again! Looks like moisture has got past some dust seals, there is a greasy deposit containing soft crystals, and some seals have left a rubber lip deposit in the bore. Note I may have lightly lubricated the pistons with brake grease under the dust covers to prevent corrosion in May 2018. I now know this can cause a reaction with brake fluid.
Will fitting an O-ring seal and piston service kit rectify this? (I intend to split the callipers when fitting dustcaps this time to ensure they are perfectly pressed into place)
Should the bores be a dull matt finish as mine, or polished?
Or do I have a problem with my calliper bores and need remanufactured callipers?
Any help please
My front stainless steel sleeved callipers are starting to leak and have a history of repairs with lip seal service kits despite regular use, generally every two weeks:
First service kit fitted by previous owner in May 2017.
Second service kit by myself following sudden major leaks in May 2018, I found some seals twisted, some seal lips scored and white crystaline deposit around pistons inside the dust covers. I cleaned all parts meticulously, cleaned bores with 1200 wet and dry lubricated with brake fluid and replaced the fluid.
June 2019 brakes tested on a rolling road as part of general mechanical test, performing well, 273 and 288 kgf with wheels locking up.
February 2020, some pistons are leaking again! Looks like moisture has got past some dust seals, there is a greasy deposit containing soft crystals, and some seals have left a rubber lip deposit in the bore. Note I may have lightly lubricated the pistons with brake grease under the dust covers to prevent corrosion in May 2018. I now know this can cause a reaction with brake fluid.
Will fitting an O-ring seal and piston service kit rectify this? (I intend to split the callipers when fitting dustcaps this time to ensure they are perfectly pressed into place)
Should the bores be a dull matt finish as mine, or polished?
Or do I have a problem with my calliper bores and need remanufactured callipers?
Any help please