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Caliper Honing

  • Thread starter Thread starter jwhelan65
  • Start date Start date
J

jwhelan65

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Wondering if anyone has honed brake calipers? I have them apart from 80 750E, they are not pitted but have some discoloration in the bore. I would like to salvage them if possible, pistons look really good.....
 
jwhelan65 said:
Wondering if anyone has honed brake calipers? I have them apart from 80 750E, they are not pitted but have some discoloration in the bore. I would like to salvage them if possible, pistons look really good.....
Click to expand...

I take some 800 grit wet dry sand paper and clean the bores up use some wd-40 to keep it wet and then clean well.

used 1500-2000 grit on cam caps/saddles

I take the chromed pistons over to the buffing wheel with some Roche and get them real spiffy.

Don't let them fly across the room though.
 
posplayr said:
I take some 800 grit wet dry sand paper and clean the bores up use some wd-40 to keep it wet and then clean well.

used 1500-2000 grit on cam caps/saddles

I take the chromed pistons over to the buffing wheel with some Roche and get them real spiffy.

Don't let them fly across the room though.
Click to expand...

thanks Jim

I started to use 400 on them , I think they will be ok with new boots and seals. Just wondering if there were some kind of fancy hoing device. ;)
 
jwhelan65 said:
thanks Jim

I started to use 400 on them , I think they will be ok with new boots and seals. Just wondering if there were some kind of fancy hoing device. ;)
Click to expand...

Oh there certainly are fancy hoing devices!!! :-\\\
 
jwhelan65 said:
thanks Jim

I started to use 400 on them , I think they will be ok with new boots and seals. Just wondering if there were some kind of fancy hoing device. ;)
Click to expand...
If you already hit it with 400, I would go back over them with something a little smoother
 
Mechanically speaking, the bores only need to be smooth enough for the pistons to slide freely. They don't need to be anywhere near polished. They can even have pits and gouges as long as the bore is mostly good. Just get all of the brake fluid residue out and test the piston action by hand. The pistons need to be smooth because they are a sealing surface. As long as the machining under the chrome is good, the pistons should be OK. The seal groove also needs to smooth over some contiguous surface around the OD (deepest part). Pits in the groove are permissible if they leave enough good material for the seal to, um, seal.
 
Dogma said:
Mechanically speaking, the bores only need to be smooth enough for the pistons to slide freely. They don't need to be anywhere near polished. They can even have pits and gouges as long as the bore is mostly good. Just get all of the brake fluid residue out and test the piston action by hand. The pistons need to be smooth because they are a sealing surface. As long as the machining under the chrome is good, the pistons should be OK. The seal groove also needs to smooth over some contiguous surface around the OD (deepest part). Pits in the groove are permissible if they leave enough good material for the seal to, um, seal.
Click to expand...
It is still a rubber seal running over metal, it needs to be pretty smooth :|. I would still go for nothing less than 800.
 
posplayr said:
It is still a rubber seal running over metal, it needs to be pretty smooth :|. I would still go for nothing less than 800.
Click to expand...

I'm not really following you here. The piston should be good from the manufacturer or as long as the chrome is intact in the sealing area. More polishing (without launching) won't hurt. The bore never interacts with the seal, so I guess that's not what you're referring to.
 
Dogma said:
I'm not really following you here. The piston should be good from the manufacturer or as long as the chrome is intact in the sealing area. More polishing (without launching) won't hurt. The bore never interacts with the seal, so I guess that's not what you're referring to.
Click to expand...

I undrstand, the piston actually floats in the bore. The seal acts as a seal and a spacer so really the condition of the bore is not as crucial as the condition of the piston. Worse case as long as there are no serious rust pitting in the bore, replacing the dust boots , seals and pistons should work.
 
Dogma said:
I'm not really following you here. The piston should be good from the manufacturer or as long as the chrome is intact in the sealing area. More polishing (without launching) won't hurt. The bore never interacts with the seal, so I guess that's not what you're referring to.
Click to expand...

Yea sorry, it is the static seal in the bore sliding against the polished piston.

Still no reason to rough up the bores.

I was having a Mojito ; it is Fiesta :p

http://www.thedailysound.com/080510FIESTAFIRST
 
Dogma is correct, smoothing the bore does nothing. Just make sure the groove area is clean and smooth. The pistons need to be smooth too. I don't polish but rather use a gray (fine) scotchbrite on the pistons if there is any crud.
 
Nessism said:
Dogma is correct, smoothing the bore does nothing. Just make sure the groove area is clean and smooth. The pistons need to be smooth too. I don't polish but rather use a gray (fine) scotchbrite on the pistons if there is any crud.
Click to expand...

Ed,
You should try buffing the chrome, it works real well on fork stanchions as well. And from what I have heard the more polished the surface is the less likely rust is to form.
Jim
 
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