Rebuilding calipers need advice
04-08-2003, 08:01 PM
#1
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Rebuilding calipers need advice
my calipers seem to be binding up on the front, the car is a 1986 944 turbo, do you think that the slider plates could have corrosion under them thus causing the binding up of the brake pads? has anyone bought new slider plates and replaced this part? How hard is it to do? also if i was not going into the process of replacing the pistons in the caliper but i want to replace any other part that my be causing my brake binding what other parts should i get and replace on each caliper? I have new pads, rotors, stainless brake lines, super blue brake fluid as a side note already, but this lack of proper full brake power is from binding and if the slider plates can be changed id like to know who its done, thnaks
04-09-2003, 01:19 AM
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I'm not sure what part you're referring to. There is a sliding frame and a mounting frame. A good cleaning and a little caliper grease on the contact parts might help if they are binding.
04-09-2003, 02:17 AM
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I've just rebuilt my M030 option calipers. Don't know if yours are the same, but assuming they are of the same design......
The easiest thing is to take the calipers completely off. It's a pain trying to do anything with the dangling by the brakeline! Make sure you have EXACTLY the right size torx bit to remove the plates. Mine were T27 screws. Obviously make sure the screw heads are clean first. If you mess up the screws, they can be a bit of a pig to find, and even more of a pig to get out. Access is very limited as they are at 45deg to the pad surfaces.
The reason I rebuilt mine, is because I had a build up of crud under the slider plate. The grit/stones they use in Winter here in Sweden is like grinding paste, and it finds it's way into everywhere. I basically had the same problem as you. One side was actually OK (according to the man who did the 'yearly check' (MOT in the UK)), but turned out to be borderline.
When you have the plate off, obviously clean it all up, and you can actually bend the plate 'down' towards the mouting surface on the OUTER edges. [b]just a little though!!!![b] When you then bolt it back up, the outer edges will sit on the caliper to start, and the inner edges will pull down when you do up the screw. Make sure you use copper or aluminium grease both on top and under the plate. It helps a lot, and will actually help stop brake squeal a bit.
I actually also rebuilt my pads without the stickon plate - the one with the two 'towers' for the piston, and just used a standard anti-squeal stickon liner, and greased it a bit. Works just fine, and makes pad changing a five minute job!
Somewhere there is a link on here to a guy who sells parts for caliper rebuilding if you get in a bit of bother. I'll try to dig it up!
Good luck.
The easiest thing is to take the calipers completely off. It's a pain trying to do anything with the dangling by the brakeline! Make sure you have EXACTLY the right size torx bit to remove the plates. Mine were T27 screws. Obviously make sure the screw heads are clean first. If you mess up the screws, they can be a bit of a pig to find, and even more of a pig to get out. Access is very limited as they are at 45deg to the pad surfaces.
The reason I rebuilt mine, is because I had a build up of crud under the slider plate. The grit/stones they use in Winter here in Sweden is like grinding paste, and it finds it's way into everywhere. I basically had the same problem as you. One side was actually OK (according to the man who did the 'yearly check' (MOT in the UK)), but turned out to be borderline.
When you have the plate off, obviously clean it all up, and you can actually bend the plate 'down' towards the mouting surface on the OUTER edges. [b]just a little though!!!![b] When you then bolt it back up, the outer edges will sit on the caliper to start, and the inner edges will pull down when you do up the screw. Make sure you use copper or aluminium grease both on top and under the plate. It helps a lot, and will actually help stop brake squeal a bit.
I actually also rebuilt my pads without the stickon plate - the one with the two 'towers' for the piston, and just used a standard anti-squeal stickon liner, and greased it a bit. Works just fine, and makes pad changing a five minute job!
Somewhere there is a link on here to a guy who sells parts for caliper rebuilding if you get in a bit of bother. I'll try to dig it up!
Good luck.
04-09-2003, 10:44 AM
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If you're going through the "trouble" of replacing everything else, replacing the pistons along with them is just a matter of the money. You'll have to do all the same work. The piston is pounded in to the sliding bracket (why didn't they just make it all one (*&#&@ing piece?!).
I put my calipers back in last night after painting. It was sooooo not worth the work.
I put my calipers back in last night after painting. It was sooooo not worth the work.
04-09-2003, 12:26 PM
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Tecart,
Like Mike said, removing the screws that hold the plates to the calipers can be a real PITA! In my case (1991 944S2), I used a MIG welder to weld steel nuts onto the heads of each screw, and then easily removed them with a wrench while they were still hot from welding. Worked a treat, and took about an hour to remove all 8 screws from the front calipers. I managed to get replacement screws from a specialist here in Sweden for about $10. Porsche only sells the screws as part of a kit, including new plates. The plates are not necessary since they are stainless steel and clean up perfectly with a wire brush. The Porsche price for the kits for the front calipers was over $100.
Be careful to use the correct screws, as they have a very shallow head. The screws I initially found at a fastener specialist had thicker heads, and these would have eventually fouled on the pad backing plates as the pads wear, preventing the pads from contacting the disc properly.
Mike,
Where in Sweden are you located?
cheers
Derek
Linköping, Sweden
Derek
Like Mike said, removing the screws that hold the plates to the calipers can be a real PITA! In my case (1991 944S2), I used a MIG welder to weld steel nuts onto the heads of each screw, and then easily removed them with a wrench while they were still hot from welding. Worked a treat, and took about an hour to remove all 8 screws from the front calipers. I managed to get replacement screws from a specialist here in Sweden for about $10. Porsche only sells the screws as part of a kit, including new plates. The plates are not necessary since they are stainless steel and clean up perfectly with a wire brush. The Porsche price for the kits for the front calipers was over $100.
Be careful to use the correct screws, as they have a very shallow head. The screws I initially found at a fastener specialist had thicker heads, and these would have eventually fouled on the pad backing plates as the pads wear, preventing the pads from contacting the disc properly.
Mike,
Where in Sweden are you located?
cheers
Derek
Linköping, Sweden
Derek
04-09-2003, 03:05 PM
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Check the brake lines. As they age, they can produce the same symptoms if the rubber has swollen thus reducing the ID of the line. When braking, fluid is pressurized pushing against the caliper piston. When the brake pedal is released pressure is held against the caliper piston.
