[MBZ] 124 Rear Calipers
I found an unusual (to me) situation when replacing the rear brake pads on one of my '95 E300D. A dealer replaced the disks and pads at some point just short of 300k mi, perhaps 2-1/2 years ago. It's now at 352k mi. The rear brakes started making noise, so today I started replacing the pads myself. When I removed the old pads on the left, the outboard pad was gone and metal was rubbing the disk. The inboard pad was still like new and seemed to be siezed in the caliper. The right rear brake is in similar condition, but not quite as bad. The outboard pad is down to about 1/4 and the inboard pad is maybe at 3/4. To sort this mess out, I removed both calipers. There is no evidence of leakage. And when I forced each pistion back (two per caliper) it squirted fluid out the hose connections. So the pistons don't seem to be siezed. But there is a lot of rust/corrosion around the pad guides and pressure surfaces. Has anyone else experienced this? What is the source of this problem? How do I correct it and avoid a repeat? Can I cleanup and rebuild the calipers? Thanks Ned Kleinhenz '95 E300D x2 '85 300D '80 300TD
Re: [MBZ] 124 Rear Calipers
sounds like maybe your brake hoses are bad and need to be replaced. This is likely because you couldnt push the pistons in with hose hooked up but could when you removed then. ned kleinhenz wrote: I found an unusual (to me) situation when replacing the rear brake pads on one of my '95 E300D. A dealer replaced the disks and pads at some point just short of 300k mi, perhaps 2-1/2 years ago. It's now at 352k mi. The rear brakes started making noise, so today I started replacing the pads myself. When I removed the old pads on the left, the outboard pad was gone and metal was rubbing the disk. The inboard pad was still like new and seemed to be siezed in the caliper. The right rear brake is in similar condition, but not quite as bad. The outboard pad is down to about 1/4 and the inboard pad is maybe at 3/4. To sort this mess out, I removed both calipers. There is no evidence of leakage. And when I forced each pistion back (two per caliper) it squirted fluid out the hose connections. So the pistons don't seem to be siezed. But there is a lot of rust/corrosion around the pad guides and pressure surfaces. Has anyone else experienced this? What is the source of this problem? How do I correct it and avoid a repeat? Can I cleanup and rebuild the calipers? Thanks Ned Kleinhenz '95 E300D x2 '85 300D '80 300TD ___ For used parts email [EMAIL PROTECTED] For new parts see www.buymbparts.com For repairs see www.oldworldauto.com To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net -- Kaleb C. Striplin/Claremore, OK 89 560SEL, 87 300SDL, 87 300SDL, 85 380SE, 85 300D, 83 300TD, 81 300TD, 81 240D, 81 240D, 76 450SEL, 76 240D, 76 300D, 74 240D, 69 250 Okie Benz Auto parts-email for used parts
Re: [MBZ] 124 Rear Calipers
You need to rebuild the calipers, it's easy on this particular set (you can push the pistons back in by hand!). Quick fix. I would do the fronts as well, and check the condition of the pin and bushings the floating caliper slides on -- if they rattle or move sideways, replace them too (kits available). I would also take a wire brush and clean up the bearing surfaces for the pads, they CAN stick if there is lots of corrosion in there, although that usually causes excessive pad wear rather than no pad wear! I suspect what happened is that the calipers actually needed rebuilding last time the pads were replaced, so you have a pair of pistons that are stuck. The rubber goes bad eventually, and although the caliper does not leak, you are not generating enough pressure to move the piston during normal use. Working the piston free doesn't help, it will only stick again, or worse, leak. Bad hoses cause BOTH pads to wear, not just one, but I would replace all four hoses at 300,000+ miles anyway, they are MUCH cheaper than failed brakes! Peter
Re: [MBZ] 124 Rear Calipers
I just had a caliper failure on a 123 and the hoses were not letting the fluid return so they held pressure on the calipers and thus the pads. Now with new hoses, the new calipers and pads are not sticking as they were when I put them on without changing the hoses at the time.. Dwight Giles 1979 240D auto 244k + miles Wickford, RI Bissell Cove Quahog & Auto Salvage Co. - Original Message - From: "Kaleb C. Striplin" <[EMAIL PROTECTED]> To: "Mercedes mailing list" <[EMAIL PROTECTED]> Sent: Sunday, July 31, 2005 9:18 PM Subject: Re: [MBZ] 124 Rear Calipers sounds like maybe your brake hoses are bad and need to be replaced. This is likely because you couldnt push the pistons in with hose hooked up but could when you removed then. ned kleinhenz wrote: I found an unusual (to me) situation when replacing the rear brake pads on one of my '95 E300D. A dealer replaced the disks and pads at some point just short of 300k mi, perhaps 2-1/2 years ago. It's now at 352k mi. The rear brakes started making noise, so today I started replacing the pads myself. When I removed the old pads on the left, the outboard pad was gone and metal was rubbing the disk. The inboard pad was still like new and seemed to be siezed in the caliper. The right rear brake is in similar condition, but not quite as bad. The outboard pad is down to about 1/4 and the inboard pad is maybe at 3/4. To sort this mess out, I removed both calipers. There is no evidence of leakage. And when I forced each pistion back (two per caliper) it squirted fluid out the hose connections. So the pistons don't seem to be siezed. But there is a lot of rust/corrosion around the pad guides and pressure surfaces. Has anyone else experienced this? What is the source of this problem? How do I correct it and avoid a repeat? Can I cleanup and rebuild the calipers? Thanks Ned Kleinhenz '95 E300D x2 '85 300D '80 300TD ___ For used parts email [EMAIL PROTECTED] For new parts see www.buymbparts.com For repairs see www.oldworldauto.com To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net -- Kaleb C. Striplin/Claremore, OK 89 560SEL, 87 300SDL, 87 300SDL, 85 380SE, 85 300D, 83 300TD, 81 300TD, 81 240D, 81 240D, 76 450SEL, 76 240D, 76 300D, 74 240D, 69 250 Okie Benz Auto parts-email for used parts ___ For used parts email [EMAIL PROTECTED] For new parts see www.buymbparts.com For repairs see www.oldworldauto.com To Unsubscribe or change delivery options go to: http://striplin.net/mailman/listinfo/mercedes_striplin.net
Re: [MBZ] 124 Rear Calipers
Thank you Peter. Your advice makes sense. If the pison stuck, can it be fixed by replacing just the piston? Or do just the o-rings need replacement? Is the cylinder of the caliper body usually OK? I haven't looked at the front caliper yet. Does the front caliper have a floating side? Each rear caliper has two independent pistons. Is there a caliper rebuilding article somewhere? Thanks, Ned On 7/31/05, Peter Frederick <[EMAIL PROTECTED]> wrote: > You need to rebuild the calipers, it's easy on this particular set (you > can push the pistons back in by hand!). Quick fix. I would do the > fronts as well, and check the condition of the pin and bushings the > floating caliper slides on -- if they rattle or move sideways, replace > them too (kits available). > > I would also take a wire brush and clean up the bearing surfaces for > the pads, they CAN stick if there is lots of corrosion in there, > although that usually causes excessive pad wear rather than no pad wear! > > I suspect what happened is that the calipers actually needed rebuilding > last time the pads were replaced, so you have a pair of pistons that > are stuck. The rubber goes bad eventually, and although the caliper > does not leak, you are not generating enough pressure to move the > piston during normal use. > > Working the piston free doesn't help, it will only stick again, or > worse, leak. > > Bad hoses cause BOTH pads to wear, not just one, but I would replace > all four hoses at 300,000+ miles anyway, they are MUCH cheaper than > failed brakes! > > Peter > >
