Hi, my friend is having problems with his SRAM guide T brake pistons. The two pistons on one side of the back caliper are not returning anymore. We have tried pushing them back in but will not budge. I’ve heard putting DOT fluid on the pistons and cycling them a couple times can help? Any other advice is very welcome 👍
by Mediocre_Worker5644
6 Comments
If they are hard to love you should lubricate the pistons as you explained, if not I would not put any effort into that as it has a risk to it, if the piston moves nice and easy, you should push them all back with the bleed screw in the lever removed, also a smart thing to do is to put the lever 180 degrees, and ofc a paper towel cuz dit is really bad.
If only two of the pistons are stuck, there’s an internal corrosion problem – the caliper needs to be rebuilt/ replaced & the system flushed..worst case, you’re looking at a total replacement, as the master cylinder in the lever is likely just as corroded.
Replace the caliper or the brake. The work is frustrating and the pistons can get damaged during the process.
The brake isn’t so expensive that servicing it is viable unless you’re a bicycle technician.
[Here is the best video I’ve seen on how to easily service guide callipers](https://youtu.be/AY80Zt47M3A?si=aVreCfIQVNHREfeL). I’ve had completely stuck ones that I got back into great working order after doing the above twice.
The 4mm Allen trick is key.
Can also try using some isopropyl to clean the pistons and try and get them moving again
They will go back in. Make sure you are pushing in the center or they get wedged. Worst case, a caliper rebuild kit is cheap and easy on these.