Rear Brake Drum Won't Go Back On

[scodari]

1970 GT - We've been working on the brakes for a while....replaced the calipers, turned the rotors, replaced the brake lines....while doing this we left the right rear brake drum off (probably the wrong thing to do); After we finished bleeding all the lines, we attempted to put the brake drum back on and it no longer fits. We can't get the drum over the shoes. We thing we have the eccentrics all the way in. We've taken off all the slacke on the parking brake cable but it still won't fit. We tried the left drum on the right side, but that won't go on either.

1) Anyone else ever experience this problem?
2) Any suggestions?
3) Is there anyway to confirm that the eccentrics are all the way in other than just "eyeballing" it.

Thanks in advance
Bob

[markandson]

When you have the eccentrics all the way "in" as you say, are the shoes contacting the pin that IS the eccentric? If not then you have too much fluid in the lines, open the bleeder and push the shoes back in, if you attach a short hose to the bleeder nipple, and put it into a cup of brake fluid you will not allow air to enter the system a mess up your bleeding job.

[Dmcbrass]

You can't get too much fluid in the lines. The lines are always full of fluid. If you push the wheel cylinder pistons back in, the excess fluid will go back to the MC reservoir. Sounds like the brake shoes are hung up on the back plate. Make sure that the eccentrics are rotated toward the axle and then pull the shoes slightly toward you as you push them together.this will push the pistons back into their resting position. Also make sure that the return springs are all still in place and not broken

[markandson]

Taken to literally-----of course the lines are always full, sorry if I stated it improperly. Sometimes, depending on MC design, you can't push the fluid back into the reservoir, and if the brakes were bled with the drum off then the wheel cylinder extended, (filled with fluid) and pushed the shoes outward, so you can't get the drum on. Cracking the bleeder will allow the fluid out easily when the wheel cylinder pistons are pushed back in. If in fact the entire bleed job was completed, then the MC is already topped off to full, hence my statement that there is too much fluid in the system. So he might not want to push the fluid back into the MC, or it will be too full.

[sbarc]

On this topic.....it is always best to open the bleeder vlaves to drain "excess" fluid through a bleeder hose inot a "used" brake fluid container, especially concerning the front disc brakes. Do NOT reuse this old brake fluid. Dirt and other contaminments get in the brake fluid especially in the calipers. Attaching a hose to the bleeder valve and opening that valve before you back off the caliper drains this dirty brake fluid out of the system and keeps the brake fluid much cleaner. Since I started doing this my brake fluid remains much cleaner throughout the system on all my vehicles.

Steve B

[oldopelguy]

How did you bleed the brakes with the drums off? Any pressure in the system would have blown the cups right out the ends of the wheel cylinders.

You need to at a minimum pull the rear shoes off and inspect the rear wheel cylinders for damage and proper assembly. Having been over-extended there's no telling how they ended up when the springs jammed them back down their bores.

[sbarc]

Originally Posted by oldopelguy How did you bleed the brakes with the drums off? Any pressure in the system would have blown the cups right out the ends of the wheel cylinders.

I must admit I was wondering that myself.

You need to at a minimum pull the rear shoes off and inspect the rear wheel cylinders for damage and proper assembly. Having been over-extended there's no telling how they ended up when the springs jammed them back down their bores.

Very good advice. I would suspect the rear wheel cylinders have popped the ends out of them and possibly some air got into the system. It should be possible to put it back together....wipe up any fluid and re-install the drums.....adjust the brake and bleed the system if the pedal feels soft. If no fluid has leaked out then it is possible the rear wheel cyclinders haven't popped the ends out completely and there might not be air in the system. Also before installign the drums make sure your brake shoes are centred left <--> right and up<--> down.

And of course.....keep brake fluid off the paint work.....brake fluid is a brutally effective paint stripper.

Keep brake fluid off the brake shoes as well......brake fluid it is not an enhancer of braking performane if spilt on the brake shoes.....or so I've heard.

Steve B

[nobody]

Actually Opel uses a check valve at the MC for the rear brakes only. Bleeding off excess fluid in the cylinders almost has to be done with the bleed port.

[sbarc]

Originally Posted by nobody Actually Opel uses a check valve at the MC for the rear brakes only. Bleeding off excess fluid in the cylinders almost has to be done with the bleed port.

Yup.....that is the only way to go.

Steve B