Brake woes

[vannin]

Can I ask here I have bad brakes and need 2 pumps but Im sure its a vaccum leak as I can hear hissing when I hold down the pedal.
Ive replaced the booster & checked the seal between it and the master cylinder and it looks good.
Ive tried to check the one way valve in the engine bay but I cant get the hard plastic lines off is there an easy way?
I will still check everything else listed here as Im sure it could all be improved.
Thanks Nik

[Gizmoman]

To get off the check valve, you might try a hair drier or heat gun to warm (and temporarily soften) the hard plastic lines - don't get too carried away. The valve is not prone to fail though and if you have power assist, it's probably fine. I ran without one for two years and noticed no difference.

If you can hear it leaking and have no cracks in the line, it's time for a new booster. I've heard that there are BMW boosters that can be used to increase power but you'll have to search for the details.

I believe removing the dash is in order and if you do that, there are other things you might want to inspect/replace while it's out - again, more searching. I've never removed one myself and get the chills thinking about it. Lots of folks here do it and make it sound like a piece of cake.

The good news is, the problem is fairly obvious and you will gain a better running engine as well.
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82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).

[j_dirge]

Removing the Vanagon dash is a pleasure compared to more modern cars..
I know guys who claim they can get one out without breaking anything in less than 30 mins. Maybe it should be added as an event at Vanagon meets!
"Take out a dash and win a..."

That said.. the OEM booster can be swapped out without removing the dash. I was able to swap in the bigger BMW booster without taking out the dash, too.. but in 20/20 hindsight, it would have been less work/frustrstion to just remove the dash.. and that would allow one to work on the pedal assembly, which is likely pretty gunked up.. And you can do nifty things like swap out the windshield squirters.. and trim the vent boxes.

DO NOT FEAR THE DASH!

The BMW booster provides better pedal feel.. less foot pressure to apply same brake.. but does not increase braking power.. more braking only comes with bigger brakes.

Worth the effort in my opinion. Give yourself a day to do the task and take lots of breaks.
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[crazyvwvanman]

My timed record for complete dash removal is 16 minutes working alone, breaking nothing, and trying to go as quickly as possible. It was not my first time with a Vanagon dash and there was no radio installed. People make a much bigger deal over it than it deserves. That leads other people to put off doing it until they are ready to do a bunch of stuff all at once and that other stuff adds up to the big deal, not the dash part itself. I consider that a trap, like some other jobs on vans that people expand into massive projects.

Mark

[Christopher Schimke]

[VANGAUX]

[Gizmoman]

Awesome feedback!
I agree that the BMW booster won't improve the brakes because the pads are what does the work and if they don't change, the "stopping" won't either.

However, my (or my wife's) foot is still part of the equation, and if it's easier, it's better . The diaphragm is possibly twice as large (sq.in.) as the stock booster and it does make for a very nice feel. I drove Rubbachinken's unit a few weeks ago and the improvement is sweet - just don't have time to mess with it myself currently. I may just give him a call. . .

I will want to remove the dash someday though, and you guy's just convinced me to relax a bit about it (say that three times real fast)
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82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).

[Gizmoman]

Just an update,
Installed a new German (expensive) master cylinder - no improvement - still requires two pumps to get decent pedal.

All there is left is the diverter/proportioning/regulating valve which is NLA.
I got a possible source for a guy who may be able to rebuild mine.

I may have mentioned it already, I took mine out and it rattled when I shook it. As it's such a simple device (so I've heard), I figured it was OK.

I may also look for a female connector sleeve that would allow me to by-pass it. At least then I'd know if it was a problem.

Very frustrating. . .
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82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).

[crazyvwvanman]

What about the problem with the pedal continuing to drop under steady pressure?

It shouldn't be hard to get a decent used one of those regulators. Maybe from here:
http://sandiego.craigslist.org/csd/pts/4507483234.html

Mark

[insyncro]

If the ball in the P valve rattled, it is still working.

Do your rear brake cylinders have the internal springs?
If not, at this point I would be focused on the rear assemblies as the issue.

How many clicks does the emergency brake handle make before it is firmly seated?

Mark and TK may have more to add.

[Gizmoman]

Here is a quote from this thread which is way longer than it should be;

[Gizmoman]

[insyncro]

[Jake de Villiers]

[Gizmoman]

With the engine off and the check removed, the pedal feels quite stiff and doesn't travel far at all.

I don't have a vacuum gauge but the vacuum pump is brand new.
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82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).

[insyncro]

If I had a dollar for every "brand new" part I sent back because it was faulty....

[Christopher Schimke]

I just skimmed over this thread, so if some of this has already been covered, I apologize.

What is the amount of initial brake pedal stroke before it starts pushing on the master cylinder? Your pedal should move a small amount (just a few millimeters - 3mm to maybe 7mm max) prior to building hydraulic pressure via the master cylinder. If your pedal requires too much stroke prior to hitting the hydraulics, it will cause excess pedal travel in order to build full hydraulic pressure.

Since there is almost always a little bit of clearance in the system before the pads and shoes (especially the shoes) make full contact with the rotors/drums, a quick pump of the pedal will raise the pedal height before the pistons have a chance to retract. If you let off the pedal and give it just a bit more time, the pistons have more time to retract and when you push on the pedal again, the travel of the pedal is back to having a longer throw. If the pistons in your rear wheel cylinders are sticky and or the springs are weak or missing, this scenario is compounded since those pistons may be retracting too far and or reacting slowly when the pedal is pumped at a relatively quick speed.

So when you combine a bit too much initial pedal stroke (which creates too much overall pedal stroke) with a quick pump and hold of the pedal, yeah, the pedal will be higher in the stroke after that quick pump.

On the other hand, and I have never seen this with a Vanagon master cylinder, but I have with a GM-type master, if the pedal has zero initial stroke prior to pushing on the master cylinder, it may be that the piston assembly inside the master is already pushed part way into its stroke do to the push rod/clevis being adjust too long. Then when you press on the pedal, the seals(s) on the piston assembly are reaching the pressure port in the cylinder prematurely causing a small amount of pressure bleed-off at full stroke. Again, I have never seen this with a Vanagon master cylinder, but I have experienced it with another type of master cylinder where the rod assembly between the master cylinder and the booster was too long and was pushing the piston assembly inside the master cylinder too far into the bore at rest.

Assuming that the above scenarios aren't the problem, do you have any pedal pulsation when braking? If you do, even if it is small, wherever the pulsation is coming from (warped rotors, material build up on the rotors, out of round drums) is pushing the pistons back inside the calipers and/or wheel cylinders too far. Then when you push on the pedal, it takes some additional pedal travel to push the piston(s) back out to the point where the pads/shoes can make contact with the rotor/drum.

One last thought! You can pinch off the two rear brake hoses and see if the situation changes. This would obviously disable the rear system from the front in an effort to try to isolate the issue to being in the front or rear.

Oh, and don't forget that your problem could very well be multiple small issues adding up to a bigger problem.
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[Gizmoman]

Just checking in to review the reference photos before I button things up on the right rear.

I DID find that the the slave cylinder (LH side), had no springs inside. The right one does as I checked it already.

Not sure yet if that's been my issue but I'm betting it was - that's what I get for assuming.

I'll update as soon as I'm done and have results.
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82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).

[insyncro]

I hope that is the issue

Way to stick with it.

[Gizmoman]

OK, that was it. Brakes feel good now.
My sincere apologies for all the head scratching, pulling, etc.

There were NO springs in the RH slave which caused me to have to pump twice. After finding one in the LH side, I assumed the right was fine - WRONG.

Thanks to the two new slaves Mark sold me a few weeks ago, I was prepared. BTW Mark, I haven't forgotten I still owe you 10 bucks.
On the glass half full side, the brake system is practically brand new now - even have stainless steel hoses.

Kudos to everyone for all the input and patience. It was no "mystery", just laziness on my part to actually check everything thoroughly.

Now, on to that pesky valve cover leak (for the sixth time). . .
_________________
82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).