Rear caliper replaced

toddr124

toddr124

Hagerstown, MD
I finally started working on the rear brakes of the blue 86 X1/9. Rear passenger brakes were frozen in place. Removed the pad, yes only one side still had any pad. Went to turn i the rear piston and it was frozen in place. Took a real long pipe and I was able to turn the piston. Now the piston turns hard, but does not go in.
Any idea beside replacing the rear caliper?
 
I'm no mechanic, but when it did happened to me, I used a large C-clamp to compress the piston and a screwdriver in the slot, Under the C-clamp to turn the piston. every 1/4 or 1/2 turn, I tightened the C-clamp. It worked...sometimes.
 
For goodness sakes, take it to John and let him and Gildo get it out. Using tools with long pipes attached on brakes is probably not a great idea....on crank shaft nuts it's a great idea...…….
 
I had the same problem when I rebuilt my calipers. I found what looked to be a cut off piece of old shift linkage laying around the shop. This worked for me, to screw my pistons off and back on. When trying to compress the piston, you have to apply a good deal of pressure (while turning the piston clockwise).

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This is what you're screwing on to. You have to turn the piston until it draws the threads at the end of the E-Brake actuator shaft all the way into the back of the piston. It is a course thread, but takes more turns than you would think to seat the piston. Go slow and take your time.
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If it's that stuck...you really should take the pistons out to inspect them for any scoring, and see if the seals are okay.
Also, the calipers aren't difficult to rebuild, but they're a little finicky if you've never done it before. I have lots of photos if you need them for reference.
 
Todd, I didn't realize that you've been working on these for waaaaay longer than me,and probably don't need any help from me!
But in the event you haven't cracked the rear calipers before, the offer still stands.
 
I have never rebuilt the rear caliper before. I need to pull the piston tomorrow and than decide what parts I need.
 
I seem to recall some older threads that detail the rebuild process for rear calipers. Hopefully someone has them bookmarked and can add links here. That might help to review them and see what's going on before tearing into things (at least it does for me).
Actually I need to get into rebuilding four rear calipers and like you, have never done one before. So I'd like to review any "how to" threads as well.
 
toddr124 said:
I have never rebuilt the rear caliper before. I need to pull the piston tomorrow and than decide what parts I need.
Click to expand...
I haven't had the opportunity to write up the caliper rebuild with photos, and unfortunately I'm leaving shortly for a Holiday Party.
I may be able to put something together tomorrow, but I don't know if it would be in time to assist you.
 
toddr124 said:
I finally started working on the rear brakes of the blue 86 X1/9. Rear passenger brakes were frozen in place. Removed the pad, yes only one side still had any pad. Went to turn i the rear piston and it was frozen in place. Took a real long pipe and I was able to turn the piston. Now the piston turns hard, but does not go in.
Any idea beside replacing the rear caliper?
Click to expand...
If the piston is frozen in place it's probably because there is corrosion behind the seal in the caliper. The corrosion builds up (usually water gets in because the boot is torn/ripped) and presses the seal out tight against the piston. Because it's normally such a tight fit it doesn't take much corrosion pressure to freeze the piston. You'll probably have to remove the piston (take care to note how it comes apart), remove the seal, and scrape the corrosion out of the seal's groove. I use a dental pick, but I'm sure there's a better tool to scrape all that crud out.
Here's the tool I use to turn the piston in and out.
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It's just a flat bar that's the right thickness to fit into the slot on the piston.
When you screw the piston back in make sure the line on the piston is on top when it's all the way in. (see service manual if this doesn't make sense.)
When you rebuild the caliper you might not have to replace the seal on the shaft in back that the parking brake actuator uses. If it's not leaking you might be able to leave it in place. If you decide to replace that small seal I advise you get a tool that will allow you to compress the beveled washers to reassemble the parking brake actuator - before you disassemble it all. I've seen several different versions, most use a large c-clamp.
 
I haven't been into the rears yet either but they are similar to other Italian cars I've worked on. So until Tom heals up from last night's social activities to enlighten all of us I suppose it's better than nothing.

If the piston is spinning freely but not moving in the bore one of three things are possible.
  1. You broke the shaft you gorilla! Ok, not likely but it's not often I get to use gorilla in a post.
  2. The piston has disengaged from the shaft and you're golden. Pop that puppy out with "a little" compressed air into a big rag you'd like to get filthy. About 20 psi should be enough. You don't want to shoot it across the street into the neighbor's Lexus.
  3. The shaft is spinning. Unfortunately, this is rather likely after hearing about that big cheater pipe. Pop the rubber boot off the back and see if you can hold the shaft from spinning and keep trying. Hopefully the parking brake cable was disconnected before this happened.
Once everything is apart you can take lots of pictures and tell us about the gory bits you found. Good luck Amigo!
 
I have recovered!
Attached please find my best effort. I created it in WORD and saved it as a PDF file.
If any one has any additional edits, tips, comments, or suggestions please let me know and I'll be happy to make the changes requested.
If you all deem it worthy, I'd be honored to have it included in the wiki.
Let me know if anyone has any difficulty opening or navigating the document.

Edited again, to correct more typos
 

Attachments

  • Rear Caliper Rebuild(rev4).pdf
    1.9 MB · Views: 273
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Tom, it opened for me. Thanks a million. On quick review it appears to be fantastic. I'll have to go back and read it in detail, but it is definitely Wiki worthy - will someone that knows how please add it there. Awesome buddy!
 
Here's a tool I've used regularly on my older cars for brakes and clutches which works brilliantly (Brake Cylinder Honing Tool) , and then finish off manually with your good ol' finger and a bit of 320.
Just attach to an electric drill, variable speed preferably, and it cleans up the cylinder nicely. Just keep the heads completely in the cylinder with a gentle in/out motion.
HoningTool.JPG
 
I also use cylinder hones like that. Don't take off any more than needed to just clean things up a little, use lube (eg. brake fluid or light machine oil), and keep the speed low. Clean everything well after. ;)
 
Okay I gorillaed the piston to death. A 4 ft piece of pipe makes me strong. I will now order a rear caliper, rotors and pads on Monday. Not bad for a weekend of "repairing" my car.
The driver's side piston is fine. I will now loosen the ebrake cable to make removing the caliper easy. This I have done before.

Thanks for all the ideas. As anyone who "helped" me work on cars will tell you, waiting for the right way is not my way.:cool:
 
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