Rear Brake help...

Brett

Brett

True Classic
OK, so I have multiple cars with failed rear brakes. Starting with what was supposed to be the simple thing. The Black '86 that I only drive occasionally started grinding at stops, so I parked it. Today I verified that indeed, the pads were shot, passenger side down to the steel, drivers not much better. Since I parked it as soon as the grinding started, the rotors were hardly scored at all. Bonus. Took them down to the local tire shop and had them resurfaced anyway.
(recently had a front caliper fail and replaced with a Wilwood set that I had been saving for another project - it's fine, this car was going to need an upgrade later anyway once I implement some of the other mods planned farther down the road).

BUT, when I went to reassemble, my rear calipers won't retract enough to slide over the new pads. They were also REALLY hard to get to turn in at first. I was using a regular screwdriver with a shaft of about the size that fits in the slot, and it took a lot of effort and the screw driver shaft was flexing a lot (not bending permanently). But they did rotate in. After a few turns they spin more freely and quit retracting. Both sides the same. I can spin counter-clockwise and they definitely extend. But retracting, they stop retracting about 1/4" too soon to clear the pads already installed on the carrier and against the rotors. Pic attached of how far it's retracting. Note in the pic I have the emergency brake cable partly disconnected in case that was not fully retracting. It didn't make a difference.
IMG_2672.JPG
Any ideas why they aren't retracting enough, and how to fix? I was trying to avoid rebuilding the rear calipers on this car right now, it has several other issues, and the brakes were working just fine other than the pads needing to be replaced. It'll get a better rebuild later.

I have several other sets of rear calipers (for other Xs) that need to be rebuilt. I have read several threads on the topic (referencing use of C clamps or eve block clamps) and the wiki page as well. Unfortunately I started taking taking them apart awhile ago and I don't know how many of the dished washers go in each caliper, nor how they are really oriented. If anyone can provide me more details on how they go back together, that would be most appreciated.
 
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that does not look all the way in.

I did buy a tool for doing that turn/push in. And I had to twist hard enough to bend the handle on the tool (replaced the handle with something I could put more torque on) and was able to twist it in more.
 
Rod, what kind of tool did you buy?

Mark, I don't appear to have any style of c-clamp that will fit AND still let me turn (fitting the screw driver in between the clamp and the piston into the slot). I have a poor selection of c-clamps. :( )

On the rebuilding front, I have not been able to get the pistons back in the cylinders no matter how much brake fluid I use for lube they hang up on the new seals. I ruined one new seal trying to force it. I even tried using the shaft with no spring washers or anything, figuring it would help pull things in straight, but it just gets to the point where it turns inside the cylinder like its supposed to do when fully retracted.
 
Brett,
there is pictures when i have done a couple years ago, I wish that will help.
I grinded the end of the C clamp to be more narrow.


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UT70cmy.jpg

hpBeNro.jpg

njBkcsR.jpg
 
Yves, thanks for the pics, it does help a lot. I better understand the c-clam modification now, and i get how it will help get all the e-brake pieces fitting back together. (looks bigger than the c-clamps I have, do you have a size that you would recommend, can't tell in the pics).
Also, did you have trouble getting the pistons seating past the new seals? Not sure why I'm having such trouble with that when no one else seems to mention it...

For the pad replacement on the calipers I am not planning to rebuild right now, THIS POST was most helpful - https://xwebforums.com/forum/index.php?threads/brake-caliper-wind-back-tool.32654/
Because the car is on stands where my wife likes to park I didn't want to wait for Amazon deliver so bought a "pro" version of the tool at Napa, for ~$72 (ouch!!) But it's amazing how the right tool can take a job from "I'm really frustrated and no longer sure how to do this job" to "hey, job is DONE!" :)

Would it be OK to use the above tool to seat the pistons while rebuilding a caliper, or is that again using too much force and likely to damage the new seals?

Thanks,
-Brett
 
Brett,
the Clamp I have used is a 5 inch size.
KIYROhO.jpg

aOyqTm0.jpg


For the pistons seating, it is sure is a tight fit but when I have rebuild my rear brake I also hone with Dot-3 oil the brake cylinder with a similar tool like this:

cDXhJ4v.jpg
 
I had this problem and decided a low-tech solution was to simply cut a piece of wood into a small semi-circle. I put this on the edge of the piston and then used the c-clamp. It won't work more than a couple of times before the wood is crushed, but it got the job done! Here is a picture of the little guy:

Wood.jpg
 
For the current pad replacement, I didn't have to disassemble the caliper, though I did need to go get a proper wind back tool.

I have other calipers though that need full rebuild. And I am still stuck at how to get the piston to reseat past the new seal without destroying the seal (ruined one seal by using a big wood clamp and trying to force the piston in. I swear it was going straight, but it didn't "feel" right and checking after I verified that I tore the seal). I have cleaned both the cylinder and the piston, am am using DOT 3 fluid as a lubricant.
Since this car didn't need a rebuild, just new pads, getting my other calipers rebuilt isn't a huge priority right now, but will be before spring...
 
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