Rear brake caliper rebuild question

fiatmonkey

fiatmonkey

Tim Hoover
Hi,

So I had to do some brake work and found one front caliper needed a re-build and so did a rear so I decided to re-build all four.

Fronts are done and started rears last night however I am running into an issue with the first one I started.

I did the dissasembly and putting back together (BTW - I modified a c-clamp to get the e-break bolt in - worked first time):

PIC-0005.jpg

The shape catches the edge of the large side of the back of screw and doesnt slide off.

So now my problem. I have all the hardware assembled but I am not able to get piston all the way in (at least it doesnt look like it). It screws in and although I can continue to turn it with my massive flat head screw, it will not go in any deeper:
PIC-0004.jpg


All of the rubber seales are in the right spot and not pushed out of position. What am I doing wrong?

Thanks,
Tim
 
fiatmonkey said:
So now my problem. I have all the hardware assembled but I am not able to get piston all the way in (at least it doesnt look like it). It screws in and although I can continue to turn it with my massive flat head screw, it will not go in any deeper:
PIC-0004.jpg


All of the rubber seales are in the right spot and not pushed out of position. What am I doing wrong?

Thanks,
Tim
Click to expand...

If you have the piston engauged on the parking brake rod threads & it still is not screwing in, then there is something wrong with the piston's internal mechanisum.
 
As Chris says...

Use the exploded diagrams in the WIKI section if you need help in its assembly.

One thing that MAY help, leave the seal and 0 ring out and just assemble the metal parts. Once you have tha mastered and the piston is now FLUSH the the cylinder face... then take it apart, lube the 0 ring and seal with brake fluid, and reassemble.

Secondly... as I think about it... the SPRING WASHERS (I believe) can get hung up on a shoulder of the "shaft". Make sure the washers are FACING each other correctly and are free on the shaft.

HTH...
 
yeah...

I'm not feelin' ballsy enough to take my rears apart. I think I'm just gonna order some from Midwest or IAP once I got the means :rolleyes:
 
Black-Tooth said:
Use the exploded diagrams in the WIKI section if you need help in its assembly.

One thing that MAY help, leave the seal and 0 ring out and just assemble the metal parts. Once you have tha mastered and the piston is now FLUSH the the cylinder face... then take it apart, lube the 0 ring and seal with brake fluid, and reassemble.

Secondly... as I think about it... the SPRING WASHERS (I believe) can get hung up on a shoulder of the "shaft". Make sure the washers are FACING each other correctly and are free on the shaft.

HTH...
Click to expand...

Thanks Tony and Chris. Tony - the "dry" run without the o-ring and
seal is a good idea (and something I have done in the past mainly by mistake!!). It's been a while since I have re-built the rears calipers of an X.

I will let you all know how it goes when I can get some time to wrench the breaks.

-Tim
 
Not me, buddy.

I run screaming like a little girl from rear calipers. I know rebuilts can be pricey but it's worth it in time and lack of frustration and anxiety. I just buy em and slap em in. No muss, no fuss.

The fronts are a breeze, same calipers as the 124's, rears too I believe. Well, 'cept for the real early X's with the small units up front.

Mudge
 
Finally got some time tonight between work and kids and fixed the stuck caliper piston and rebuilt the other rear. The new seal wasn't seating properly it seems so I think I was squishing it all funny when I would install the piston. I also re-inspected the cylinder and it needed a slight honing.

All buttoned up now and the brakes are right as rain. Nice to have brakes :)

Thanks,
Tim
 
Early front calipers

Mudge said:
I
The fronts are a breeze, same calipers as the 124's, rears too I believe. Well, 'cept for the real early X's with the small units up front.
Click to expand...

The later calipers fit the earlier cars - just have to take off the cast-iron mounting bracket that the early calipers use. Only thing to watch out for is that the banjo bolts use a different thread on the early calipers.
 
Yep...

Good work Tim... I found that I always hadta use a bit of Scotchbrite on the pistons and cylinders to get them to operate smoothly... then lubed with fluid and they would go back together easily.

After doing this 4 or 5 times in 20 years, its a snap! HA!
 
Am I missing something?

The piston has to be forced back into 'retracted' position. Just had to do this the other day on the Spider. You just use a c-clamp and something to span the piston, and just crank away until the piston surface is flush with the housing. Then everything will fit on.

I might be missing the point of what you're talking about here. I don't remember the rears on the X being any different than the fronts, or the Spider, the pads are all interchangeable.

Sorry if I've missed the point.
 
Parking brake

The difference is the parking brake. On the rears you can't just push the piston in, you have to turn it to thread it onto the parking brake actuator rod.
 
Black-Tooth said:
Good work Tim... I found that I always hadta use a bit of Scotchbrite on the pistons and cylinders to get them to operate smoothly... then lubed with fluid and they would go back together easily.

After doing this 4 or 5 times in 20 years, its a snap! HA!
Click to expand...

Tony - how "easily" should the piston fit into the cylinder? I ask as I still had to muscle the piston into the cylinder pretty good and I didnt want to hone or scotchbrite any more than I should. The other 3 were a little easier but not much. Or maybe I am just being a girly man... ;)

ng_randolph said:
The difference is the parking brake. On the rears you can't just push the piston in, you have to turn it to thread it onto the parking brake actuator rod.
Click to expand...

And in my case the problem was not the threading of the pistion to the hand-brake mechanism bolt but actually the piston and o-ring not working together properly. Honing the caliper cylinder and scotchbrite'ing the piston (probably really the latter) did the trick on the sticky pistion.
 
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