No Pedal Pressure

Manfred · Post by **Manfred** » Mon Jun 08, 2009 8:07 am

I was installing new rear brakes shoes on to my 78 bus over the weekend. I started with the driver side rear. When I pulled the drum off everything looked fine. I didn't see any fluid anywhere. The cylinder seemed to be holding fluid. The pedal pressure felt fine before I started this.

Fluid started leaking from the wheel cylinder as soon I removed the shoe. Not a lot of fluid leaked out, but enough to let me know I need new cylinders.

I then went over to the rear passenger side to replace the brake shoes and check on the status of things. The cylinder looked completely destroyed. There was tons of dirt surrounding the cylinder clumped together with brake fluid. I decided not to mess with it until I have some new wheel cylinders.

During the drive home I discovered I had no brake pressure. I thought they would pump up as I drove because of the fluid lose. I expected a weak brake, but the pedal went down to the floor. However, I did hear the front engaging. Needless to say I drove very slowly.

I didn't check the rear reservoir. I'm guessing the little fluid that was in there leaked out of the driver side wheel cylinder. I figured there would be some pressure from the front brakes.

Anyone know what gives? I haven't had a chance to check the rear reservoir. Should I just fill it up to get back pressure or is there something bigger going on here? I'm so glad I found this problem. I think these brakes were about to fail on me.

chitwnvw · Post by **chitwnvw** » Mon Jun 08, 2009 8:21 am

You can get cylinders at Autozone or Murrays.

Did you adjust the start adjusters? IIRC you turn them til you get some light rubbing.

I have a pretty nice setup for bleeding the brakes, let me know if you'd like to use it.

hambone · Post by **hambone** » Mon Jun 08, 2009 8:21 am

Check your metal lines underneath, and the flex hoses. Also make sure the master cylinder isn't leaking. I would not drive that bus until you get the brakes working right. At least parts are cheap!

chitwnvw · Post by **chitwnvw** » Mon Jun 08, 2009 9:01 am

Manfred wrote:
chitwnvw wrote:You can get cylinders at Autozone or Murrays.

Did you adjust the start adjusters? IIRC you turn them til you get some light rubbing.

I have a pretty nice setup for bleeding the brakes, let me know if you'd like to use it.

I bought a vacuum pump for bleeding. What is your set up? I could use another hand doing this.

Do they stock the wheel cylinders or do you have to order them?

Go to the autozone on touhy, it's their superstore, they had them in stock.

My bleeder screws on to the reservoir under the front seat and you pump it up. All you have to do is open the bleeder screws out comes the air and old fluid. Totally a one man show at that point.

Post by **Amskeptic** » Wed Jun 10, 2009 7:13 pm

Manfred wrote:I was installing new rear brakes shoes on to my 78 bus over the weekend. I started with the driver side rear. When I pulled the drum off everything looked fine. I didn't see any fluid anywhere. The cylinder seemed to be holding fluid. The pedal pressure felt fine before I started this.

Fluid started leaking from the wheel cylinder as soon I removed the shoe. Not a lot of fluid leaked out, but enough to let me know I need new cylinders.

During the drive home I discovered I had no brake pressure. I thought they would pump up as I drove because of the fluid lose. I expected a weak brake, but the pedal went down to the floor. However, I did hear the front engaging. I didn't check the rear reservoir.

Couple of problems with this account.

If brakes were fine before your operation, then it is possible that removing one brake shoe from the wheel cylinder may have forced the other shoe IN due to spring pressure, and that may have forced the first piston out enough to allow fluid to escape. It is tricky but important to monitor the pistons in the wheel cylinders when you are removing or reinstalling shoes. The return spring can be a PIA but you must get both shoes pushing their respective pistons in the wheel cylinder towards each other simultaneously, or make very sure that you do not let one shoe to pull in too far.

Next problem is the remaining brake circuit. You would expect that the pedal would sink pretty low, yes, but the remaining circuit should have pulled the car to a halt with nothing more than a longer stopping distance, and you should even be able to lock up the wheels.

Your reservoir is designed to share the first half of the reservoir's volume with both circuits. If one circuit is leaking badly, the reservoir will finally let it drain down, but the partition will keep a fluid reserve for the remaining circuit.

Get this squared away, brakes are THE critical system in a VW bus with a headlamp bucket 6" from your shin.
Colin

Manfred · Post by **Manfred** » Thu Jun 11, 2009 7:12 am

I replaced the wheel cylinder of the driver side rear...worked great...got pedal pressure back. Is there anything that needs to go on the threads of the brake line? I have some Teflon tape, but left them bare.

Since I was working on the left side, I decided to install my new front brake pads and rotor. Low and behold the outer piston is seized in the caliper. So I'm guessing it needs a rebuild or needs to be replaced. I'm going to check out the ones on my parts van and see if they are working.
And swap them out if they are.

Vdubtech · Post by **Vdubtech** » Thu Jun 11, 2009 7:44 am

No sealant or teflon tape on the threads of brake lines please. I would hope you also replaced the wheel cylinder on the other side of the Bus as well. They're cheap, they should be replaced in pairs.

Manfred · Post by **Manfred** » Thu Jun 11, 2009 8:33 am

I didn't yet. Long story, but my parts van takes up most of the space in my garage right now and it was easier just to the driver side front and rear.

Thanks for the advice. So if I see any fluid should I just tighten up the hoses?

I'll be doing the passenger side tonight and bleeding. Wish me luck.

RSorak 71Westy · Post by **RSorak 71Westy** » Thu Jun 11, 2009 8:11 pm

Manfred wrote:So if I see any fluid should I just tighten up the hoses?

Yep

Manfred · Post by **Manfred** » Fri Jun 12, 2009 7:04 am

Both rears breaks and wheel cylinders are installed. I'm getting more pedal fell back now.

I didn't install the front pads and rotor. Both calipers have seized pistons. I could not even turn the old rotor with my hands with the old pads installed.

As with the driver side caliper, I could not get the outer piston to budge. I decided to cut my losses for the night. I'll install the calipers off my parts van tonight.

Since the old passenger side rotor was so hard to turn I decided to only re-install the break pad on the side with the working piston. The trip home is only a 7 minute drive. The pad seemed to stop the rotor fine.

I couldn't believe how much easier the van accelerated during the drive home. Can't wait till everything fixed.

One thing I've noticed since I've let some of the brake fluid drain out. The car is having trouble holding ideal. The van has been dieing for no reason with and erratic idle. Is this behavior due to air in the lines and the brake booster? Am I creating a vacuum leak? I didn't have this issue until started working on the brakes.

Manfred · Post by **Manfred** » Tue Jun 16, 2009 1:08 pm

Brakes are working great! I just need to adjust the rears and I'm all set.

I have one question. So I had a lot of air in my lines from installing new brake cylinders and swapping the front brake calipers. The ignition timing seemed off while driving the bus in this condition. Then once I bled the brakes, I got my timing back and the bus stop stalling on me.

Did all the air in the brake hoses cause a low vacuum to my advance? I notice that my brake booster hoses connects directly into my air intake.

Manfred · Post by **Manfred** » Mon Jun 22, 2009 2:39 pm

Finally got back from New York (Business so I could drive the bus) and got a chance to adjust my rear brakes and E-brake. Wow! What a difference. Couldn't have done it without you guys.

Post by **Amskeptic** » Tue Jun 23, 2009 9:01 pm

Manfred wrote:Did all the air in the brake hoses cause a low vacuum to my advance? I notice that my brake booster hoses connects directly into my air intake.

If your old booster has to travel too far because of air or bad adjustment, it might be leaking at long extension, and it might be behaving when it only has to do a little extension.
Guessing here . . .
Colin

Manfred · Post by **Manfred** » Wed Jun 24, 2009 10:24 am

Amskeptic wrote:
Manfred wrote:Did all the air in the brake hoses cause a low vacuum to my advance? I notice that my brake booster hoses connects directly into my air intake.
If your old booster has to travel too far because of air or bad adjustment, it might be leaking at long extension, and it might be behaving when it only has to do a little extension.
Guessing here . . .
Colin

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