Bleeding rear brakes

[rjkoop]

Just finished the install of the e-brake cable on the rebuild calipers and now I'm going to bleed the system. Even though I have the rear axle jacked up as far as it will go before the entire rear end of the car starts to lift I'm not getting any brake fluid from the brake bleed screws. The system was completely empty of brake fluid. Would this take a while before the fluid flows? It's just below freezing here so maybe it could take a while. I filled up the reservoir, saw a few bubbles of air come up and now nothing is flowing. Could this point to a clogged compensator? I might try loosening the brake hose in front of the compensator and see if I get fluid seeping out from there. Any other ideas? All hoses were replaced.

Or maybe I should get a brake bleed vacuum and this might help start things moving again?

[4uall]

This might help

http://www.youtube.com/watch?v=L0oUejw5Edc

http://www.youtube.com/watch?v=MfTmlOZbXgs

Brake Bleeding in the Fiat 124 Spider:

Like many cars that use compensators to prevent lockup of the rear brakes under hard braking, the Fiat 124 Spider rear brakes must be bled with the rear axle supported. Otherwise, the compensator valve will fully close, and no fluid will be allowed to flow to the rear brakes.

On the 124, jack the rear of the car at the differential pumpkin. You can use a block of wood in between the jack and pumpkin to prevent damage. Place the jackstands as far outboard as possible on the rear axle tubes. Bleed the brakes farthest to closest (i.e. RR, LR, RF, LF) from the master cylinder.

Alternatively, if you choose, you can bleed the brakes with the car fully on the ground. Though, using this method, access is tricky and it takes nearly as long as jacking the car in the first place.

Note:Only get under a car that has been supported with jackstands; a jack alone is only meant to lift and can fail if holding a car up by itself.

[rjkoop]

Thanks jay. I didn't have jackstands on the axle so I'll try that.

Eventually I got some fluid a one of the blled screws so this is a good sign that the compensator is working.

[rjkoop]

Jack stands didn't help. I also removed the steel brake line from the new rubber brake hose near the caliper. Nothing there either so no fluid is going into the caliper at all. I even put the wheels back on, lowered them onto car ramps and loosened the bleed screw. No fluid still. I'm thinking the rear passenger side brake hasn't been working for a while.

So if I'm getting fluid from the driver's rear side but not on passenger side I'm thinking compensator is not working for the passenger side. I examined the steel brake line from the compensator to the passenger caliper and no kinks/bends in the line.

I think I have to understand how the compensator works. Maybe the lever that opens it up is not opening the compensator enough or something.

I saw a few posts on the mechanism so I'll take a closer look I guess.

http://www.fiatspider.com/f08/viewtopic ... &sk=t&sd=a

Or maybe do the controversial bypass.

http://www.allisonsautomotive.com/image ... bypass.jpg

[rjkoop]

And after further examination the steel brake line goes into the compensator 1st (which is mounted passenger side up high) and then back down to the top of the axle, does a 180 degree turn and then splits into the left and right steel brake line. So because I get fluid on the driver's side that must mean that the splitter has an issue or the steel line from the splitter to the passenger caliper is blocked. I guess next I'll remove the steel lines from the splitter and see if I can narrow down where it might be blocked.

[spider2081]

I had a similar problem with my 81. The cause in my case was a clogged rubber brake line feeding the "T" splitter on the rear axle.
Once I replaced that I was able to gravity bleed the rear brakes. If the bleeder is below the reservoir, just open the bleeder and wait for the fluid to come out.

[rjkoop]

I had a similar problem with my 81. The cause in my case was a clogged rubber brake line feeding the "T" splitter on the rear axle.
Once I replaced that I was able to gravity bleed the rear brakes. If the bleeder is below the reservoir, just open the bleeder and wait for the fluid to come out.

Yep. I already replaced that rubber hose. I actually took out the T and cleaned everything out there. When I took things apart there was very little brake fluid at all. So at this point I was pretty sure the compensator was the issue. When I was under the car (rear wheels on car ramps) I was able to push the rear of the car up/down and noticed that the bar that goes from the axle to the compensator didn't twist correctly. The angle would change from the axle to the point on the body where the bar attaches but the other end didn't move at all. In other words the bar was twisting but the compensator wasn't being moved. So I think I have a rusted compensator. I'm in the process of removing the compensator now (all bolts are loose, just have to get the steel brake lines loose) and I'm pretty sure lubricating this or replacing it will fix the issue.

[darksider415]

Well, since I'm about to do my 81 for the third time... (First time, tried rebuilding calipers myself. Don't do that. Second time, the reman left rear was defective. Third time's the charm??) I suggest arming yourself with plenty of Italian swear words, and doing it with the car on the ground. Also, plan on having about 5x the brake fluid you think you'll need. I learned this one the hard way, when the bleeder for the reman left rear wouldn't seal off and covered everything in a 3 mile radius in brake fluid. (Measurements taken purely by guesstimate.)

[spider2081]

I think you have it figured out.
The steel brake lines at the coppensator can be difficult to remove. I heat them with a propane torch and spray PB Blaster to help. Also be sure you have a good quality flare nut wrench.

[rjkoop]

I think you have it figured out.
The steel brake lines at the coppensator can be difficult to remove. I heat them with a propane torch and spray PB Blaster to help. Also be sure you have a good quality flare nut wrench.

Yep. I didn't have a flare wrench. I found PB, wait, then using vice grips and a quick tap with a hammer worked well. I should really get a flare wrench!

[rjkoop]

So I loosened the compensator linkages up, spray everything with silicon lube, moved things around and now I'm getting a flow of brake fluid from both rear calipers! Bled the rear brakes and reattached the brake shield pieces. Phew! I also noticed that the fuel line was actually too low and rubbing against the compensator bracket/linkage. So I moved that back to where it should be in the plastic clip against the underbody. Now I just have to bleed the front brakes.

[rjkoop]

So unfortunately I have a leak from the passenger side rear caliper! 1 drip every 20 seconds or so.

Doesn't look like it's coming from the rubber hose attachment or the bleeder valve. So must be an issue with my rebuild for the piston seal or where the e-brake cable lever.

Once I remove the caliper from the rotor I'll have a better idea. So I guess I'll narrow down the area and then maybe remove the piston and ensure the seal is seated correctly. Otherwise I'll probably have to purchase a rebuild.

[rjkoop]

So took the piston out of the caliper that was leaking and the o-ring seal (that I replaced as part of the caliper rebuild kit) was torn slightly. Argh! This must have happened when I forced the piston back (with a C-clamp) in before I started to screw it in. I thoroughly cleaned out the groove the o-ring sits in (brass wire wheel on a dremel tool), cleaned the piston carefully, etc... How hard do I have to push that piston in before I can start to screw it in? Maybe I shouldn't have used a C clamp at all? I had brake fluid inside and outside on the caliper and covered the piston in fluid before I tried to insert it. Still needed the C clamp. Any advice would be appreciated before I try this again.

[raysorm]

I just did rear brake rotor and pad replacement and E brake line. Vacuum bleed did not work but old fashion helper pumping breaks worked like a charm for me bleeding my 81 spider brakes just now. I think compensator will not allow vacuum bleeding. I did also replace the compensator and it linkage and bushings I noticed they were all wasted away doing this brake job.