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  #1  
Old 01-13-2007, 07:27 PM
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Question (Help) Brake job: assymetrical gap size for pads in caliper?

Finishing off the front brake job I started last weekend and doing the right side now. (rotors, bearings, pads).

Everything was going MUCHO smoother this time until I got all the way to the part that I fit the new pads in. Now, these PBR pads have always been about a 1/16" too thick and that's expected (I sand them down).

But....look at these pictures. The inner side pad gap is WAAAAY smaller than the outer side. I have the pistons pushed all the way back in as far as I can tell. Anyone know what the heck is going on? I've changed these front brakes once before a couple years ago and definitely don't recall running into this.

The only thing that looks funny is how the inner piston rubber shield seems to not look like the outer side.

(Help) Brake job: assymetrical gap size for pads in caliper?-front1.jpg

(Help) Brake job: assymetrical gap size for pads in caliper?-front2.jpg

(Help) Brake job: assymetrical gap size for pads in caliper?-front3.jpg
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Chris
1985 300SD - 'Grace' (198K mi.)
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  #2  
Old 01-13-2007, 07:40 PM
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The piston on the left in the pictures is not pressed all the way in.
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Old 01-13-2007, 07:41 PM
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OMG it looks like you have D pads instead of SD pads. that is a LOT of pad to sand off.
possible your pistons are not going all the way in? I gotta pull the wheel off my SD and look at the pistons... I can't believe it's that thin.
John
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  #4  
Old 01-13-2007, 07:46 PM
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That inner side "boot" seems like it's from outer space...........???

I cannot make any sense of what I'm looking at..........there should be a piston with a rubber boot that sits flush with the casting face on the inside.........just about what the outer side looks like............what's all that brown material surrounding the piston that doesn't appear to belong there???
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Old 01-13-2007, 07:49 PM
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Originally Posted by Brian Carlton View Post
what's all that brown material surrounding the piston that doesn't appear to belong there???
Dirt.

The left boot is cracked so the piston may be rusted. Time for a new caliper.
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  #6  
Old 01-13-2007, 07:52 PM
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Originally Posted by ForcedInduction View Post
Dirt.

The left boot is cracked so the piston may be rusted. Time for a new caliper.
.......what a mess.......

Yep, both the left and right boots are cracked. I agree......time for a replacement caliper.
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  #7  
Old 01-13-2007, 09:02 PM
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Yep...piston wasn't all the way in.

I really need to invest in one of those piston spreader tools
...and yes, that's a bunch of dirt in there that I've now cleaned up.

Anyway, the metal piece that sits on top of the rubber boot came off while getting the piston back in. What a PITA. I had to get the metal piece re-positioned EXACTLY and then slip the new pad in.

So...new caliper??? I thought you could just rebuild these things with a caliper rebuild kit.

Chris
'85 300SD
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  #8  
Old 01-13-2007, 09:09 PM
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Originally Posted by ck42 View Post

So...new caliper??? I thought you could just rebuild these things with a caliper rebuild kit.

Chris
'85 300SD
Yep, you can.

But, be prepared for an adventure the first time you do it. Getting the pistons out of the bores is no cakewalk and getting them back in is also a PITA. Part of the problem is no good surface to apply force from a C-clamp.

The heat shields use a special tool to seat them below the piston surface without completely mangling them. I got them on the piston but never fully seated them. They should not sit above the piston face.

You need three hands to get the boot in place...........

Finally, if the piston has any corrosion that won't fully polish out, the rebuild won't be successful (leaks). Usually the polished chrome won't have permanent corrosion, but, with a long term boot failure, nothing is assured.

Last edited by Brian Carlton; 01-14-2007 at 02:09 PM.
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Old 01-13-2007, 09:53 PM
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Sounds like a PITA enough job to justify paying for a rebuilt caliper. Thnx.
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Old 01-13-2007, 09:56 PM
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Originally Posted by ck42 View Post
Sounds like a PITA enough job to justify paying for a rebuilt caliper. Thnx.
Yep, I'd probably not rebuild a front caliper again. The rear calipers, however, seemed to go much easier..........no heat shield........
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  #11  
Old 01-13-2007, 10:24 PM
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So...looking at pricing for reman. calipers...

Do the prices listed include the full caliper ready to drop in (just add pads?)
Or are these just the basic caliper bodies? (need to add pistons and whatever else?) I ask because the pix of the reman. calipers look incomplete.

Also, I'm not seeing any matching brands of reman. calipers for front left & right.
Is this a big deal if I have one brand on one side and a different brand on the other? Intuition says 'no' but I'm asking just in case.

Chris
'85 300SD

Last edited by ck42; 01-13-2007 at 11:17 PM.
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  #12  
Old 01-13-2007, 10:37 PM
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Yes. Two different brands on opposite sides might have different working pressures and cause it to pull when you apply the brakes.
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  #13  
Old 01-14-2007, 12:04 AM
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Quote:
Originally Posted by ck42 View Post
Intuition says 'no' but I'm asking just in case.

Chris
'85 300SD
Actually, intuition says to keep them from the same manufacturer. Small differences in manufacturing tolerance might just stack up to slightly more grab on one versus the other.

Cannot be positive........don't know of anyone who attempted it and failed.
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  #14  
Old 01-14-2007, 12:26 AM
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There isn't really a shortage of either the Bendix or ATE so why mix them up?
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Old 01-14-2007, 09:45 AM
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Originally Posted by Ara T. View Post
There isn't really a shortage of either the Bendix or ATE so why mix them up?
Because from the parts places I've checked, they'll have one brand that list availability for only the front/left and a different brand for the front/right.

If they had a listing for the same brand for both left/right front, the question would not have been raised. Hopefully when I call them, I'll get a different story and will be able to get the same brand for both sides.

Chris
'85 300SD
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