'71 Westfalia Bus brakes

[qball]

Ok you guys, please help me out! I've searched your experienced responses here already but I just need to ask. I've driven serviced many VWs and I am surprised that I'm to be undone by a stupid "brake booster". Yes, somehow after all these years I find myself with a servo with which I am completely unfamiliar. After reading the forum here, I was planning on ignoring the servo (not hooking up the vaccuum lines). I've replaced the master cylinder, front calipers and all the brakes lines. I adjusted the pushrod length, as the brake arm was not being returned to the brake stop by the spring (as outlined in the VW Service Manual). I was not able to verify that the pushrod just barely put pressure on the servo, as described in the manual, because I can't see this area. It would require removing the plastic cover (which has the nipple for connecting the front air line to the servo) which by the way is cracked, as well as the rubber boot fitted to the front of the servo. I have bled and bled and bled and I have no brake action whatsoever. I get fluid and some air at each bleeder valve, and I bleed in the order the book outlines (Front:right, left; Back:right, left). At this point, I need to ask: what the hell am I doing wrong?
Please help although this isn't very sexy and I know it's been covered I just can't find it here in the forum. I'm wondering if it's a matter of the pressure regulator,which I could adjust as the manual shows, but I can't see this preventing ANY fluid compression and brake action.

[odecom5]

I think the books have it incorrect (I know, confusing when everybody here yells at you to refer to the manuals), but you bleed the rear brakes first.

No idea if that is your problem, but here is more complete info on a brake job:

http://ratwell.com/technical/BrakeJob.html

[busdaddy]

Welcome, first off are you sure you're allowing the lower reservoir to fully fill before proceeding? Where did you get the master cylinder and what brand is it? rebuilt or new?
Sometimes just letting things settle down a while and coming back for round 2 later helps as well.
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[VDubTech]

Definitely bleed from the furthest brake from the M/C to the closest, and also make sure your rear brakes are cleaned and properly adjusted before trying to bleed the system.
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[jpeters]

I had this same problem once, I think. Turned out the rear pads weren't adjusted correctly and couldn't reach the drum so it couldn't build pressure. I'd double check the rear pads are adjusted correctly.
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[Jody '71]

May be that the pushrod is not adjusted correctly. See figure 4-1, page 5, chapter 8. It may have helped somewhat if you bench bled the new master first prior to install. I would not ignore the servo, get it fixed. You will really appreciate its proper function. The regulator is unrepairable, but it can be tested as outlined. The previous replies are good advice.
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'66 Beetle
2011 Hyundai Elantra Touring

[qball]

All right all right all right. Thanks folks. Um: MC is new, don't know brand, came from Airhead Parts, or Wolfsburg West. One caliper from W'burg, then a similar one from O'Reilly's to save $100. Both are ATI (?) rebuilt units. Pretty sure the lower reservoir filled since I did that weeks and weeks ago (before I realized just how much this would involve). Now that you say it, seems I've known for decades, per the Idiot's guide, that bleeding proceeds from the wheel furthest from the mc. Ok,ok, no: I wimped out and have not removed the rear drums. I cannot believe that anything I find in there could produce outright failure (e.g., braking won't stop the front wheels spinning at all) but I am in no position to argue. I'll get into the rear and get back to you guys. I guess I'm heartened, at least, that none of you hollered at me to respect the servo and quit thinking this will fly without it, or that it may be the source of this trouble. With the diffculties I've read about repairing the servo, if needed, it will bring this project to a quick end. I just don't have the money.
Couple other thoughts. Has anyone considered removing the servo and installing a standard two chambr MC as on my ''67 where the servo pushrod passes through (looks like the same place that the mc is in the old bus), and obviously running the lines a bit forward to this mc. Do front disc brakes really require a boost?
Also, I would think that you who do this reglarly would immediately remove the rinky dinky little bleeders at the rear wheels for something that actually lends itself to servicing? A longer stem? With a larger hex pattern than 7 or 8mm? No?[/b]

[busdaddy]

I can't say I've ever had an issue with the size of the bleeders personally.
As for deleting the booster? it was optional on Euro delivered 1600 powered buses and it stops OK without it, but it's sooooo much better when it's working. You could use a Euro master cylinder and pushrod but if you went shopping at O'reilly's for brake parts you don't seem the type who's prepared for the sticker shock the correct parts may induce

You really should remove the drums for a look at least, as other have said the shoes must be adjusted to bleed properly and now's the time to fix anything back there.
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[kreemoweet]

1. The booster connecting rod, frequently miscalled the "pushrod", can prevent successful brake bleeding if it's way out of wack. Your description of adjusting
the "pushrod" sounds way wrong. There is nothing under the booster front boot involved. You need to adjust the length of the connecting rod coming from
the front of the booster so that there's a small gap where the conn. rod and the brake pedal assembly meet (at the clevis pin), i.e. so that the resting brake
pedal exerts NO force on the connecting rod. The actual pushrod in the booster is not accessible and is not adjustable.

2. The bleeding order given in the Bentley manual is not wrong, has always worked perfectly for me, and seems much more logical IMO.

3. Since you have a dual-circuit system, having misadjusted rear brake shoes should not affect either bleeding or operating the front disk brakes.
You do not need to pull the drums to adjust the shoes, but it's a good idea, so you can know the condition of your rear brakes.

4. It is not all that unusual to have a defective new master cylinder, which could be causing your symptoms.

5. Some folks claim their brakes work OK without a booster. Myself (and others), I might consider running my bus around the block, in an emergency,
there is a night-and-day difference in braking, and running without the booster seems dangerous as hell to me.

6. If you don't have the bucks to keep your brake system in good working order, maybe you should consider just leaving in parked until you do. For the
sake of all of us.
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[Amskeptic]

[old DKP driver]

qball, Along with what everyone else here I will add another item.
and that is,Did you bleed the front calipers properly?

build pressure,open lower bleeder till fluid comes out.then close.
Then build pressure again and open top bleeder to remove any
trapped air.
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[qball]

thanks again everyone. You guys are great. Sorry to whine so much here. I may have had great luck in the past with my VWs, inasmuch as raising them from the brink hasn't been too troublesome. And this includes, better sit down, lighting fluid-contaminated shoes on fire to dry them out a la John Muir. But I am not going to argue any of this good advice. Of course it's time to bring the back up to speed, so, yes, I will go ahead and pull the drums off and r & r anything that's in need. I guess I thought air would be driven out of anywhere and everywhere once the system was all connected. I can certainly bleed the master as described. As for the connecting rod, I was under the impression that the point of contact/possible pressure was at the other end which, as pointed out, is inaccessible. What I did was observe that the pedal assembly was indeed not returning all the way to the stop. I removed the cotter pin and clevis pin, broke the seriously tight bind at the locknut, and turned the rod counterclockwise to lengthen it until the rod's hole, when viewed within the two arms of the clevis, was aligned while the assembly was resting on the stop. This allowed me to slide the clevis pin through without any resistance, replace the washer and the cotter pin.
I'm happy to hear that with the dual chamber system the front brakes should function even in the presence of poorly adjusted rear wheels. Happy because that sounds logical to me. Of course, while bleeding, the fact that fluid is present at each brake makes me think that the pistons should be getting compressed SOME. I think I'm bleeding effectively. I pump the pedal, usually seven times cuz I think it's lucky, and I retain the pedal at the floor with a bar against the driver's seat. Then I open the valve and let fluid/air pass out, close it, and repeat. I don't use the bottom bleeder on the right front since y'all pointed out elsewhere that it's a drain.

[qball]

Oh, btw, I'm all for buying good material. I don't have other options than the rest of you. i used to buy most everythink at Western Auto, or when in the Bay area, Tassi's. Out here it's a hassle to go to THoff in Raleigh or Bob Hicks' place over in Durham (I always enjoy seeing Bob, though). So I go to the web to BusBoys or Wolfsburg West or AirCooled or RMMW, etc. Another post mentioned ATI rebuilt units at O'Reilly's. Exactly the same product as from AirHead Parts, but $47 after core return compared to $161.

[qball]

I'll check for more advice, but won't be back to work on the Bus until the weekend. I'll post my findings. Thanks again.

[kreemoweet]

The point of adjusting the connecting rod has nothing at all to do with the brake pedal stop. Whether the pedal reaches the stop
depends on the strength of the return spring, and it doesn't matter if it's a little weak. The purpose of this adjustment is to
ensure there's NO PRESSURE AT ALL on the connecting rod when the pedal isn't being pushed down. The valving in the booster
is very sensitive, and just a little pressure on the connecting rod can cause pressure to be exerted on the piston in the M/C. If the piston
in the M/C moves just a tiny bit, the compensating port, which connects with the fluid reservoir above the M/C, will be covered up
and prevent normal fluid flow/pressure equalization.

There is no call for violent pumping of the brake pedal when bleeding. The sealing cups at the wheel cylinders are not designed
to withstand much vacuum, and too much can suck air back into the lines.

Your method of bracing the brake pedal may not be effective, because you need to maintain pressure on the pedal when you open the
bleeder and the fluid starts flowing out. That's why the 2-person method works so well, as does pressure bleeding. I've seen guys
rig up a system with a rope so they can pull on the rope to operate the brake pedal while they loosen the bleeder under their bus, so
no 2nd person is needed.
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[Desertbusman]

Qball, your method of connecting rod adjustment sounds possibly a bit fishy. At least the way you describe it sounds real fishy. Kreemoweet explained it correctly in both of his posts. And it's the way the service manual instructs. Do it that way. Your pedal arm pivot and return spring might be suspect. The connecting rod clevis and pin on mine have a bit of slop which relates to about an 1/8" slop in the arm where it contacts the stop. In other words that amounts to just a tad of looseness between the connecting rod and it's contact with the valve on the nose of the booster. And the pedal spring snaps the pedal arm up sharply against the stop. That's spring pressure and not related to the connecting rod. Good chance you might want to pull the pedal arm pivot apart, clean it up, lube and reassemble it. That pedal arm pivot can get junked up or damaged and not work smoothly or not provide the spring return force. I had to replace the spring holder on mine.

Your method of working the pedal while bleeding sounds bogus. If you're not versed in coordinating the valve and pedal then read the book again. Again, like Kreemoweet mentioned, you don't need a helper. With the fronts you can pull the pedal arm down with one hand and work the bleeder wrench with the other. And I use a heavy cord to pull the arm when bleeding the rears. Loop the cord around something to get a down pull instead of a straight back pull.

When using a pressure bleeder there is no concern with which bleeding order. But with manual bleeding there is a concern and you were correct in the order you used. R.F., L.F., R.R., and L.R. Ignore the "do the rears first" advice. Then sometime when you do your Ford, Cheby, Kia, or Moped do the rears first the way other vehicles do. Yours is a VW Bay bus so do it the VW Bay bus way. It makes a difference. Everyonce in a while here someone can't get them bled using the other vehicle rear first method. Then they do it per the book and it's a snap. But be sure and inspect the rears first and adjust them per the book. As far as bench bleeding a new master cylinder I've never had to do that.

You will need about a quart of brake fluid. Don't just bleed the air out but rather flush old fluid out. That's where a calipers bottom valve is great. With your rear cylinders you can flush them until you see new clear fluid come out.
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[busdaddy]

You may also try bleeding by using a 2' length of fishtank hose with the end submerged in a jar of old brake fluid, leave the bleeder open and give the pedal 6-7 long slow full pumps, close the bleeder before removing the hose and don't forget to refill the reservoir before moving on or repeating.
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[qball]

Yes, I always have the end submerged which should allow me to close the bleeder without worry. I see the point of keeping pressure either with a helper or the rope. I will allow the fluid to flush through next time I bleed, also, after I've reconditioned the back wheels.
Yeah, my immediate suspicion was the return spring itself. It seems logical that if I can push the arm the last little bit to contact the stop, then it's not being prevented by the length of the rod but by the weakness of the spring. In adjusting the rod I was probably just 1)being foolish and lazy to not do the rear wheels in the first place, and 2)grasping at straws because I just want to put this baby on the pavement. It's no big thing. I turned the rod 2 revolutions, so I can replace it to its original position and instead remove, clean, inspect the assembly and maybe replace the spring. How can a spring lose it's tension after only several decades?

[mills66]

I had the same problem too. I checked and double checked everything. Turned out my rear brake shoes weren't adjusted out far enough and it wouldn't build any pressure. Kind of embarrassing but it happens.

[VDubTech]