rjlawlor646

So i replaced my rotors with r1 concept premium slotted rotors all the way around..i'm very pleased with them..however, the rear calipers are not squeezing very hard..there is movement, so there not completely frozen, but there not doing much work..if i bleed them like crazy with this change? or do i need new calipers?

dlbehrns

"the rear calipers are not squeezing very hard" how do you know? when you say there is "movement" what do you mean? how many miles on your car and when was the last time you had your entire brake fluid volume changed? maybe changing the fluid/brake bleed is the next step?

mb_c55amg_guy

there are only a few things that could be wrong....number 1...you need to make sure that the actual rotors are fitted correctly...there should be no play with them..so you need to make sure they were tightened down correctly. 2...you always need to bleed the brake lines when you are replacing the calipers, as you probably have air in the lines that is why you are having issues. when you took the calipers off did you compress the pistons and drain the fluid? also are the calipers on correctly? i did a complete redo on my clk430 and will be putting massive brembos on the car in the next month or so. i would also recommend that when you do this to install stainless steel brake lines as well.

rjlawlor646

i was able to fix the problem by pushing the piston in and out a few times, putting a little bit of grease on it, pushing it back in, and bleeding the brakes ALOT..now they work like new..i am also very pleased with the r1 concept rotors

bobbyjo9

[QUOTE=rjlawlor646;4147773]i was able to fix the problem by putting a little bit of grease on it, pushing it back in,

Glad your problem is fixed but there is NOOOOOOOOOOOOOO grease involved in the hydro side of the system. You get grease in there and you have contaminated the brake fluid. If the seals on your pistons are good then there is no danger of grease getting past there.

rjlawlor646

well hopefully my seals are good, that would suck if i ruined the brake fluid..all i was trying to do was make it easier for the pistons to move because when i took the calipers off the pistons barley moved when i applied the brake..once i put a little grease on them they moved with a lot more ease, especially when i was pushing them back in with the c clamp. if the seals weren't good wouldn't fluid leak?

bobbyjo9

exactly.. if the seals were gone youd be pissing fluid. Only thing that is gonna move that piston is the brake fluid. If you have air in the line, which you must have, the air will need to compress first negating the action of the fluid. The fluid will not compress when properly bled and full movement of the caliper achieved. If you didnt do a full flush when you bled the brakes... now would be a good time. The moisture that builds up over time will have a definite effect on the performance as well as corrode sensitive parts. This is not an area you want to have "uhhh ohhhhh's" in!