I'm trying to get the brakes on the E21 bled and am failing. Not much feels better than a nice firm brake pedal. Not much is more frustrating than achieving that feeling.
I have sent close to half of a liter of fresh fluid though to the rear discs and have zero pedal with the car running. With no vacuum I can build pressure a bit but it's still soft. I have moments of big bubbles coming through but it's hard to say whether it's sneaking in through the threads of the bleeder or if it's actually coming out of the lines. On my most recent attempt I cracked the lines a quarter turn three times in a row on each corner with zero bubbles.
I'm wondering if how I had to re-route the hard lines just makes for a huge trap.
I've only tried so far with the Motive pressure bleeder and haven't had the chance for someone to manually pump the pedal for me.
Thoughts?
- Keep running more fluid through it?
- Try it manually?
- Attach a long hose to the bleeder and get it up above the MC height?
- Jack the rear end way up?
Help.
I think you just converted the rear from drums to disk, is the master cylinder matched to the new brake setup? I can't help with that but I know others here can.
I've had really good luck with my homemade pressure bleeder, I don't think your process is bad.
The calipers look upside down, the bleeders appear to be on the bottom of the caliper. You may have to take the handbrake cable off and rotate the calipers up. Or remove the caliper entirely and set it face down on the ground so the bleeder screw is pointed straight up.
The other fun thing with calipers with integrated handbrakes is that they have all sorts of air traps inside the piston. What I usually do is install the caliper, gravity bleed the system, pump the brakes to get the pistons out, which pushes the air from the line into the caliper, re-gravity bleed, actuate the handbrake a bunch of times to work some of the air out of the internals, gravity bleed again, and then start smacking the caliper with a hammer to shake more of the bubbles loose. Then, you guessed it, gravity bleed again.
This type of caliper also seems to usually need a break-in period, before which the pistons will over-retract. Sometimes, mainly on Hyundais, the new caliper is defective and they will suck back in no matter what you do.
In reply to adam525i :
That's correct, it used to have drums on the back. I asked the guy who developed the kit and he said all he's ever had to do was play with pad compounds for balance but the MC should work fine.
In reply to Pete. (l33t FS) :
This is the orientation the kit calls for but yeah it sort of ends up below the piston.
Questions for you.
If you take the caliper off to bleed it do you stick something in between the pads?
When you're gravity bleeding do you leave the MC cap on or take it off?
It probably doesn't matter but it's a VW caliper.
EDIT: I just did some Googling to see if I could find a specific procedure for the VW caliper. I didn't, but I did find the procedure for a Ford with an integrated parking brake and it's very similar to what you describe, Pete. Bleed, pump parking brake, bleed, pump brake, etc. etc.
If you don't push the brake pedal, no need for anything in the caliper. If you do push the brake pedal, you need to get inventive.
And yes cap off. Cap on while pumping the pistons out can also cause a low pedal!
I ran into this once when I swapped the left and right front brake calipers on an MR2 Turbo, such that the bleeder screw wasn't high enough. I agree with Pete it's upside down- take it off and zip-tie it up so that the bleeder screw is on top and stick a piece of stock or an old brake pad in between the pads, so the pistons don't over extend. I'd be tempted to let it gravity bleed for a while and then just a couple of pump and bleeds should finish it off.
AxeHealey said:
If you take the caliper off to bleed it do you stick something in between the pads?
Always make sure there is or you could eject a piston (if the brakes are pressed). I don't like to leave calipers ejection-ready at all, just in case something is pressed by accident.
Bleeding brakes is something that should be so simple, yet it almost never goes smoothly for me. I like taking the caliper off and just moving it around so that air can find its way to the bleeder. With a pressure bleeder you can let the bleeder apply light pressure while holding ht caliper at exactly the angle where the bleeder is highest. stick a chunk of wood or something between the pads just to be sure.
also, you may want to fasten the end of that hard line to something a bit harder.
Robbie (Forum Supporter) said:
also, you may want to fasten the end of that hard line to something a bit harder.
Agreed. I need to figure that out.
Two rounds of 20 minutes of gravity followed by pumping the handbrake resulted in zero improvement.
Next step removing the caliper to reposition.
This was my method.
An unbelievable amount of air came out. The car now stops pretty well on the second pump but a) that's not acceptable and b) pedal feel is still absolutely horrible. It's never been amazing in this car but it's definitely worse now. Before I go through this whole process on the rears again, I'm going to bleed the front and see if that improves things.
Thanks everyone for the suggestions!
Not that anyone is waiting for an update here but my wife helped me bleed them manually last night - no change. I've now put almost two liters of fluid through these lines using three different methods.
Hopefully today I'll have some time to try with the caliper flipped again and I'll get everything out.
Be patient and keep at it. Be happy you are not doing this monstrosity. 20 feet of brake line, a proportioning valve and 4 drums in the back. 
Any chance there is air in the master cylinder? As bad as that sucks, it might need a bench bleed. All the pumping, and/or the possibility of over-travelling the brake pedal could have finished off the MC. When I'm bleeding something that has a lot of air in it, I have always been told to put a block of wood under the brake pedal to prevent this from ocurring. I haven't always done that and I haven't had a problem, but YMMV.
This is a question to those with more experience but is there a benefit to using a vacuum style bleeder over a pressure bleeder? Pressure bleeders would shrink any bubbles while a vacuum bleeder would actually make them bigger, does that help with getting them out of the system?
I've always had good luck with my pressure setup on the car but from using a dual syringe setup on my mountain bike (one at the lever, the other at the caliper) putting vacuum on the system is an important step and can pull air out of fluid that looks pretty much bubble free.
In reply to Tyler H :
A reverse bleeder is the best/sometimes only way to get air out of a master cylinder.
Once you try it, you'll never go back.
I've only ever used a hand pump vacuum bleeder at the wheels and have never had any success with them. I'm sure the high-quality stuff is much more effective.
Point taken about the MC. Could be. At this point though, it's old enough that I'd just buy a new one rather than bothering to bench bleed this.
I flipped them over, moved them around and got more air out of them.
About to head out and see...
I was going to suggest a new master. There's a good chance that part of the bore in the master is rusted/pitted, and operating the pedal over more than normal travel while bleeding could have damaged the seals. Might as well look into a rear disc-specific unit if such a thing exists (I'm pretty ignorant in the ways of the E21).
The only thing I can say is I've NEVER had luck with speed bleeders or pressure bleeders.
The two man bleed has ALWAYS worked for me.
YMMV.
thewheelman said:
I was going to suggest a new master. There's a good chance that part of the bore in the master is rusted/pitted, and operating the pedal over more than normal travel while bleeding could have damaged the seals. Might as well look into a rear disc-specific unit if such a thing exists (I'm pretty ignorant in the ways of the E21).
yeah, crud settles in the far end of the bore where the pistons don't normally travel, then the pistons push through that crud when the pedal goes to the floor during a bleed, and the MC never builds pressure correctly again. i've seen it happen so many times.
In reply to AngryCorvair (Forum Supporter) :
I'm usually pretty careful to not let that happen but I'm also usually the one under the car opening and closing the bleeder.
I can't seem to get any more air out of the system and the pedal still sucks. Insanity, doing the same thing, yada yada...
The plan now is to try to order a MC for a 323i which had rear discs and try that but for now it has to go on the back burner so I can get Sven prepped.
Thanks again everyone for the suggestions.
In reply to AxeHealey :
Doesn't matter if the bore is rusted in the area where it doesn't stroke normally. As soon as you graunch the seals past that, it is game over for the master cylinder.
With all new fluid in the system, I always run multiple litres through and just recycle the fluid. Hope you are not buying a bunch of brake fluid to do it.
So. I got to the point with this where I was convinced I got all the bubbles out, the pedal feel was bad but it actually stopped well.
Problem was the rear brakes were dragging pretty badly.
I came to the conclusion that the OEM proportioning valve must be holding pressure to the rear because they were drums originally.
The decision was made to put in a new MC (to fix the horrible pedal feel), remove the OEM proportioning valve (to fix the dragging), run a new rear line with an aftermarket valve (in case needed for balance) in line and be good to go.
The master cylinder and proportioning valve are off the car and the rear brakes are still dragging.
What gives? Internal e-brake mechanisms stuck on? The handle is down and both cables have some slack.
In for tips on fixing my own similar situation.
