Why Can't I Keep No Friggin Brakes???

[TheWedge]

I replaced the bearings, stub axle assembly, and all the misc. nuts and bolts on the passenger side of my RHD Ex-MOD SIII. Before I started my brakes were always fine. Since the repair, I can't seem to get the brakes going. I have adjusted the brakes per the manual, bleed the brakes per the manual, checked the fluid, and checked everything else I can think of. When I bleed the brakes I can get good pressure on the pedal, then the very next time I press the pedal it goes to the floor and I have to pump it up to get any brakes. I also went ahead and bleed all four wheels while I was at it. I can't find any leaks, all the air is out of the lines, and I have plenty of fluid. What the hell is going on???

[jimfoo]

Either the shoes are on wrong, or the springs are on wrong. The top spring goes from the shoe to the post on the backing plate, not shoe to shoe. Make sure the pin on the shoes are in the right place to contact the snail cams, otherwise the shoes are in the wrong place.

[TheWedge]

Maybe I went wrong in the way I did it, but I didn't remove the shoes to remove the backing plate. Did I "F" it up?

[zed]

IT doesn't seem to have saved my post.. so this may end up doubling.. if its just slow..

Anyway.. what I said was...

It may be the master cylinder. I've had them go bad without leaking but not building pressure either. I'm not sure the inner workings .. but it seems a valve or something breaks.. allowing the fluid to just squish back up into the reservoir instead of down the lines to the brakes.

But check your brake assembly against the manual.. maybe you knocked something loose or something. Not too much could make them not work at all though.

[zed]

Originally Posted by TheWedge

Maybe I went wrong in the way I did it, but I didn't remove the shoes to remove the backing plate. Did I "F" it up?

I've done the same with fine results.. but it doesn't mean you didn't eff it up.

[jimfoo]

What exactly do you have as far as brakes go, single slave like on an 88" or dual, like on a 109? The 109's can be a bitch to bleed because of the arrangement. I have heard of people using a thin feeler gauge between the seal and cylinder to allow the air out.

[TheWedge]

I have a dual system b/c I have a 109". I finally know what a love hate relationship is. Please continue trying to help.Thanks.

[TerryS]

For the time being, assume that since you only worked on your brake system at the wheel, rule out the master for the time being.

First off, I have found that despite thinking you have all the air out of the system, that is almost never the case, and the only foolproof way of bleeding the system is with a power bleeder, or Handy Vac pump at each wheel cylinder.
The next thing to remember is that ALL the individual brakes have to be adjusted for minimum takeup. The MC itself moves very little fluid with each stroke, so if one or more brake shoes have excessive gap, all the fluid (as in 'pedal goes to the floor') is used to just move them outward, but still not coming up against the drum. Each shoe not yet to the drum will require more pedal travel (and fluid) until they are all to the drum (within each circuit)
A pedal going to the floor, and not able to be pumped up is usually indicative of a bad check valve of the end of the MC piston, but that doesn't sound like your porblem.

[pickuprover]

If you have a 109 with the dual cylinders, then chances are it is air. They are noted for being hard to bleed. I finally gave up on my 109 and reworked the piping. Now the pipe goes into the bottom cyclinder, then up to the top cylinder with the bleed screw on the top of the the top. It now bleeds like an 88". The only disadvantage is that you have 2 pipes exposed on the bottom of the axle. I put them so they are running side by side using the idea that if I were to rip one well then the second one being beside it would not matter as I already would have no brakes on that side. (I also keep a ten penny nail to put in the flex line incase this happens to block off that side, just incase I need brakes on the way home) .

[p76rangie]

Originally Posted by TerryS

For the time being, assume that since you only worked on your brake system at the wheel, rule out the master for the time being.

Not necessarily. The pumping to bleed the brakes over the full stroke of the pedal can sometimes stuff up the master cylinder.

But agree with others that it is air in the system and they are a prick to bleed. Two ways are to pressure bleed, as already suggested by others, or to pump like buggery and then get them to hold it down with force while another person opens the bleed valve.

[TheWedge]

I have bleed them both ways, if the air is that hard to get out, is there another way?

[jimfoo]

Try taking the shoes off, and the pistons out, but leave the cups in. Then try to work a thin feeler gauge between the cup and cylinder, and let gravity bleed the air out.

[zed]

Originally Posted by TheWedge

I have bleed them both ways, if the air is that hard to get out, is there another way?

You have a bleeder or doing it the "olde fashioned way"? I'm never going back to the olde way.

[zed]

Originally Posted by p76rangie

Not necessarily. The pumping to bleed the brakes over the full stroke of the pedal can sometimes stuff up the master cylinder.
.

That was my point. Like finding out you have a bad wheel cylinder when you try to push it back in for the new shoes.

He didn't just mess with the hubs.. he pumped the brakes beyond their normal operating range. Its always "the other part" that breaks at the same time as something on which you worked that gets ya.

[TerryS]

Originally Posted by p76rangie

Not necessarily. The pumping to bleed the brakes over the full stroke of the pedal can sometimes stuff up the master cylinder.

That's a good point. Junk can accumulate in the back end of the MC over years , and not be a problem until the check valve is forced into it and, when the junk gets caught beneath the valve. He did, however say that it does build and hold pressure after succesive pumping, which would indicate that hasn't happened (yet).