front caliper stuck

[bmw art car]

after overhauling the rear brake cylinder and after finding out how easily they come apart.
i am now stuck with the front ones...
they are seized as well and i don't really know how to them apart.
any ideas?

 

[HB Chris]

If they are seized then you are much better off buying new calipers, there are relatively cheap, why mess with them.

 

[bmw art car]

If they are seized then you are much better off buying new calipers, there are relatively cheap, why mess with them.

how much would i have to spend for a new set?

 

[bengal taiga]

after overhauling the rear brake cylinder and after finding out how easily they come apart.
i am now stuck with the front ones...
they are seized as well and i don't really know how to them apart.
any ideas?

I agree with HB Chris, that it may be a lot easier in the long run to replace the offending caliper (or calipers as this is something that is typically done in pairs). However, on a rare occasion, a seized caliper can be unseized and continue to function normally after that. Obviously, a lot depends upon the cause.

BTW, this is a topic that has been addressed before:
http://www.e9coupe.com/forum/showthread.php?t=3452
and indirectly:
http://www.e9coupe.com/forum/showthread.php?t=696
http://www.e9coupe.com/forum/showthread.php?t=3332

 

[x_atlas0]

Have you taken a large spanner to it? Undoing the bolts then giving it a whack can dislodge the halves. Of course, you will have to rebuild the calipers after, but that is a relatively cheap process.

 

[sfdon]

I have heard that those bolts are not to be re-used...

 

[bengal taiga]

Have you taken a large spanner to it? Undoing the bolts then giving it a whack can dislodge the halves. Of course, you will have to rebuild the calipers after, but that is a relatively cheap process.

The poster stated "I don't really know how to [take] them apart." Since he is uncertain, perhaps he only needs to free up one or more piston rather than completely disassemble everything or even partially rebuild things. This can sometimes be accomplished by removing the brake pads and compressing the pistons with a suitable tool, to work them free. I would be leery about splitting the caliper unless I had new fasteners available. In either case, it might be more prudent for the poster to consult a manual or at least review the guide available on this forum. :wink:

NB: SFDon, your hearing is quite good. :wink: :wink: The authors of Autobooks (and others) advise against reusing the four bolts that hold the caliper halves together. (See below) I believe the shop manual also mentions this.

 

[bmw art car]

The poster stated "I don't really know how to [take] them apart." Since he is uncertain, perhaps he only needs to free up one or more piston rather than completely disassemble everything or even partially rebuild things. This can sometimes be accomplished by removing the brake pads and compressing the pistons with a suitable tool, to work them free. I would be leery about splitting the caliper unless I had new fasteners available. In either case, it might be more prudent for the poster to consult a manual or at least review the guide available on this forum. :wink:

NB: SFDon, your hearing is quite good. :wink: :wink: The authors of Autobooks (and others) advise against reusing the four bolts that hold the caliper halves together. (See below) I believe the shop manual also mentions this.

well my manual is all in german... so apart from a few words i go by the pictures. but the manual assumes that the pistons are not stuck and will come out with pressure.
i was thinking of splitting the halfs and whacking the pistons some.
but if i don't do it right i can manage to bind them and have a bigger problem then.
what i tried now is to soak the whole caliper in blaster .
maybe i try a sandwich of two spanners and two c- clamps on each side to drive the pistons in a little and free them that way.
than with pressure push the pistons out. i have rebuild kits for the calipers.
but i don't have the bolts for the halfs that need to be replaced once you opened the caliper halfs

 

[Orangener]

Walloth & Nesch, the german part supplier has brakeparts on special offer at the moment, take a look :

http://www.wallothnesch.com/e/frameoffer.htm

 

[bengal taiga]

well my manual is all in german... so apart from a few words i go by the pictures. but the manual assumes that the pistons are not stuck and will come out with pressure.

maybe i try a sandwich of two spanners and two c- clamps on each side to drive the pistons in a little and free them that way.
than with pressure push the pistons out. i have rebuild kits for the calipers.

but i don't have the bolts for the halfs that need to be replaced once you opened the caliper halfs

Please don't take this the wrong way, but its sounds like you underestimate the power of compressed air. It can be very formidable. Have you ever seen what an air wrench or air chisel can do? Air can literally be the right tool for this job.

I'm not so sure I agree with your translation of the German manual and that it "assumes the pistons are not stuck and will come out with pressure." Calipers are rebuilt not just because they leak and don't hold pressure. Sometimes, calipers are rebuilt because they seize and won't release pressure too. If a caliper has more than light surface rust or corrosion or if it is cracked or warped, it may have to be replaced or sleeved. Calipers (like most mechanical parts that are subject to extreme use) are like a box of chocolates. You never know what you are gonna get . . . [until you open it].

If you don't have a source for compressed air, seek assistance from a machine shop or shop with a mechanic who has access to compressed air, (even someone who merely destroys lug nuts for fun). I think you may be as surprised as the kid who gets a new bike or bb gun for XMAS. On the other hand, its just a blast of air and there is not that much lost by the effort.

BTW, you did not mention "heat." Please resist temptation and do not use it. It may damage things beyond repair and since you are dealing with liquids and flammables, the dangers should be more than obvious.

hth

At random, I found someone else's documentation of a caliper rebuild for an Infinity. The brakes are not the same as the Ate's on your E9, but the same principles apply. Notice this comment:
"The unclamped piston will be pushed out by the compressed air. Don’t apply constant pressure, do it in short bursts… otherwise your piston may go flying across the shed!!! (And no, I didn’t figure this out by mistake!"

http://www.nicoclub.com/archives/rebuild-q45-brake-calipers.html

Look for a PM

 

[Honolulu]

just be sure...

Just be sure that what you think is a seized caliper, is not in fact the flexible brake hose gone bad.

Flex hoses croak, I believe, a lot more frequently than calipers seize.

And yeah, compressed air and a soak in some PBlaster or Kroil may do wonders. Be sure to have the piston blocked so it doesn't go shooting across the (whatever), I have used air and 100 psi into the brake fluid port can indeed result in ....

 

[m_thompson]

I made an adapter to connect a hand pump grease gun to the caliper. I could get lots more pressure behind a stuck piston and had a lot more control of the pressure.

 

[bmw art car]

I made an adapter to connect a hand pump grease gun to the caliper. I could get lots more pressure behind a stuck piston and had a lot more control of the pressure.

that sounds like a great idea

 

[bmw art car]

the grease gun worked well

...just on question... how can i stop one caliper from moving
whilst the other is still stuck?
most of them came out alright but with one i got problems... the last one of course

 

[m_thompson]

I used a combination of C-Clamps and blocks of wood.