Spongy pedal on rear disc brakes (1 Viewer)

Joined
Jul 8, 2009
Messages
226
Location
Melbourne, Australia
Hi all,

I have recently installed a TSM kit with the El-Dorado calipers that have the parking/hand brake (e-brake to most of you).

I haven't put the hand brake cable on the system yet as thats a different weekend job, and I now have a spongy pedal. I have an 82 with a 7/8" master cylinder bore.

I have bleed the lines a few times and still the same. I have put in the residual valve (2lbs) and it improved slightly, but still leaves me with pedal to the metal stuff, but not in the good way.

I read somewhere on here about the hand(e) brake operation and how the brake needs to be applied regularily to keep the pad/piston closer to the face of the disc, but can't seem to find that even after searching.

Can anyone give me some insight as to how to solve this problem. I can goto the 80 series bore size, no issues, but will I then just be hiding the problem, rather than solving it.

Lawrence. :cheers:
 
Joined
Dec 8, 2003
Messages
1,013
Location
So Cal
Good luck on getting the parking brake to work. I tried and tried, and finally gave up and went back to the stock location.

I have never heard of the e brake needing to be used to make the brakes work properly. I have now had my e brake on the calipers totally disconnected for months and have had no problem, hell it never worked for me.. However, my brakes work fine.

I have mini disc in the front, El-Dorado in the rear, with a Non ABS 4 wheel disc LC master with no external valves of any kind, and it works great.

Shawn
 
Joined
Mar 5, 2009
Messages
18
Location
Roden-The Netherlands
I will give my exerience;
I have the same with a 1980-BJ40, mounted with standard drum brakes front/rear. Put all new brake shims on the rear even new brake cilinders and a revised master brake cilinder. I did air bleed for days without any result. My supplier assumed that there was trapped air somewhere in the system.
I pushed the brake all down to the floor. After removal and dismanteling the master brake cilinder I found out that te supplier did not a good revise job. The front plunger was damaged by the stop screw......:mad:
Cees
 

dgangle

total rice
Joined
Nov 24, 2004
Messages
4,012
Location
Heart of Dixie
yea, we expect the parts we buy to be good. Tha't one reason I would NEVER rebuild or consider buying a remanufactured mastercyclinder. It simply is not worth the hassle of having to do the job twice or again soon.
 
Joined
Oct 3, 2008
Messages
12
I had the same problem on my 1980 FJ-40 with Monte Carlo calipers and aftermarket master. I ended up purchasing a new Toyota master cylinder from C-Dan. Per the recommendations on this site, I removed the 10-lb residual valve from the master cylinder and installed a 2-lb residual in the brake line after the proportioning valve. This time the brake system was easy to bleed and they now work perfect. OEM parts if available are worth the extra dollars.
 
Joined
Jul 8, 2009
Messages
226
Location
Melbourne, Australia
Well, I went out and got an 80 series master and it appears to be working fine. Hand/e brake not working yet but will look at that next week.

Going wheeling on Sunday to see how the discs go, they'll get covered in mud and water and all sorts of things, and hopefully the'll work straight afterwards. The old drums were full of crap by the way.

Cheers

Lawrence
 
Joined
Mar 30, 2008
Messages
255
Location
Pagosa Springs, Colorado
Lawrence

The Cadillac brakes, like the lincoln versaille brakes use the E brake to keep the pads adjusted to the rotor. When you put them on the first time, you could/should have cycled the e brake a few times to tighten the pads up against the rotor. You can also "screw" out the piston cap manually with some homebrew tool that will take up the slack. All that being said, your spongy pedal is air as noted by Pinhead. There's nothing preventing you from bleeding the brakes upside down or not, by removing the caliper and flipping it over so the bleed valve is up, putting back on rotor. Bleed and then put back in the mounting position. No big deal. you probably didn't need the residual value as you master cylinder is high compared to the brakes, but it doesn't hurt either. How's your pedal travel. If it's alot, you may consider moving to a larger bore MC.

Don

WWW.wolfcreekrodworks.com
 
Joined
Jul 8, 2009
Messages
226
Location
Melbourne, Australia
Well guys,

After some moments thinking that the weekends wheeling was not going to happen, I went out and had a great time complete with rear disc brakes. The swap to the 80 series master cylinder was the fix, the old one was not upto the volume required for the new rears.

Tracks were mud filled and slippery as. We followed an 80 series up this slope where the guy was doing at least 5000 with the thing popping off it's rev limiter, and a 75 series that spent more time on the side of the track at all sorts of weird angels in readiness to tip over. My car went up there doing 3500 revs, front locker in and a glorious V8 sound echoing through the valley. Made it up in one go, much to the disgust of the 75 and 80 owner.

The brakes worked a treat. I'm working on method for the hand brake (read e-brake) and well see what eventuates there.

Thanks for all your help. I'll have some footage on youtube when I get around to putting it together.

Cheers

lawrence
 

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