850 LR caliper seizing up..

salts850 · Post by **salts850** » 26 Oct 2009, 23:07

Does anyone know if there is a common problem on 95 850's with the LR brake caliper seizing up? The bcm was bad for a long time. I've replaced and fixed that problem. The issue is that I keep having to replace that particular cailper. 3 times now to be exact. RR is fine so i'd say that fluid pressure isn't a factor and the lines do not appear to have damage to them. Any one ever hear about this or experience it?

Post by **polskamafia mjl** » 26 Oct 2009, 23:49

As far as I know it's relatively common for the calipers to stick on the 850's. There's another thread about someone having a similar problem. 1 cause is that the rubber brake lines deteriorate after a while and can't sustain the pressure of the system so when you release the brake pedal the lines constrict instead of "sucking" the caliper piston back in. If your lines are "old" then replacing them may help. Also, re-grease the guide pins and the piston itself.

salts850 · Post by **salts850** » 27 Oct 2009, 09:21

oh ok, yeah the lines are all origianl to my knowledge. I think i found my weekend project, thanks.

Post by **polskamafia mjl** » 27 Oct 2009, 14:36

I'm pretty sure I have the same problem and I'm replacing my lines with stainless steel lines sometime in the coming months.

voodoorobaz · Post by **voodoorobaz** » 27 Oct 2009, 18:36

I also added the braided the lines to my car but I also bought the bleeder tank from IPD. was well worth the money for it.

Post by **tjts1** » 27 Oct 2009, 20:49

Mine seized up too. Replaced it with a JY caliper. My brake lines were relatively new. Its a flaw in the design of the piston bore in the caliper. Its a very common problem. most people don't realize they are driving with a seized rear piston because there are 2 on each caliper.

salts850 · Post by **salts850** » 27 Oct 2009, 21:35

good to know tjts. I'll keep an eye on the new one I just put on. I'm still going to install new front hoses since they are original.

Post by **outdoor7or24** » 12 Jan 2010, 10:12

How do you regrease the piston on the caliper?

I have a problem with my front disks warping. I just got them turned and after a 1,000 mile trip they started developing the shuddering during stopping. I did lube the sliding pins.
I did notice that my front right side caliper seal is not all the way in, or it is not seated properly. Should I look into rebuilding them?

I do know my front brake lines do not look the greatest, it looks like the outer part has some cracks. Maybe this is a cause?

Thx.

Post by **polskamafia mjl** » 13 Jan 2010, 08:12

I guess the best way to regrease the piston would be to just barely tap the brake pedal until the piston slides out enough to apply grease. I usually just slab grease on w/e part of the piston is sticking out. Was that 1000 mile trip highway or city driving? Also, turning rotors inherently warps them, there is a discussion about that somewhere on this forum. Warping also happens when your brakes are hot and you sit at a light for a while with the your foot on the brakes.

I think it was MIJ who suggested rolling forward a bit every 5 seconds if your stopped at a light or putting the E-brake on istead of keeping your foot on the brakes the entire time.

Post by **outdoor7or24** » 13 Jan 2010, 08:47

polskamafia mjl wrote:I guess the best way to regrease the piston would be to just barely tap the brake pedal until the piston slides out enough to apply grease. I usually just slab grease on w/e part of the piston is sticking out. Was that 1000 mile trip highway or city driving? Also, turning rotors inherently warps them, there is a discussion about that somewhere on this forum. Warping also happens when your brakes are hot and you sit at a light for a while with the your foot on the brakes.

I think it was MIJ who suggested rolling forward a bit every 5 seconds if your stopped at a light or putting the E-brake on istead of keeping your foot on the brakes the entire time.

1000 mile trip was mostly hwy driving. The car stopped fine with no shuddering or pulsating the first half.
Got back from my trip after feeling the pulsating and jacked the car up. Turning the wheels, I can hear/feel the pads touching the rotor on about a 1/4 of the whole turn. Both sides. Now, each side differs where the pad touches the rotor.

I had just replaced the front struts (yellow konis, IPD spring seat, OEM strut mounts), had the tires rotated, and had an alignment done.

Now I am wondering if an A arm bushing is worn. I checked this when the car was jacked up, I tried to feel vertical and horizontal movement. None felt. I lubed up the sliding pins and on a test drive you could hear the calipers slide back and forth! hmmn...

So this leads me to believe my RF caliper may be suspect with the seal being partially out. Also, I suspect A arms (they appear fine) and maybe the axles / CV joints (I checked those too and they appear fine)?

I am kinda stumped. I know when I replaced my RF lower engine mount it made a huge difference as it was completely worn out.

Any ideas?