Weak brake booster? [advice needed]

[ALIKA T3]

Aloha folks!

I have a little problem with a brake booster on my 84 Automatic Westy.

Freshly polished ( 8 hours of work )

The brake pedal feels partially non assisted since I had the van. I changed the fluid, the brake pads, brake lines because it was needed but I still have that problem.

When I brake, if I apply too much force it seems like I loose assistance.
The brake pedal gets harder, it feels normal at first but if I ask too much braking power then it seems like the booster runs out of vacuum kind of like if the engine was off.

I made the engine off type of test to waste the vacuum. Then I start the engine, but I only get partial assistance for a little bit of travel, then it gets freaking hard!

If I keep applying pressure on the brake pedal with the vehicle non moving, if I rev' the engine, I can get past that hard spot that I previously reached.

This makes me think the vacuum is weak. I have a report of low compressions on the engine from 2 previous owners. The engine was indeed sluggish until I adjusted the valves and the lockdown and throttle cable the other day... it's definitely not to the point where it's dying and not going uphill at all anymore.
It runs cherry.

So, what should I do? Replace the booster or I don't know? I don't hear any leaks by the booster when the engine is running, the engine doesn't have a vacuum leak either....


Thank you for your help!
_________________
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Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[MarkWard]

Two things to check. I would disconnect the vacuum hose at the booster and measure the vacuum. There is also a check valve in the system that could be not functioning properly or installed backwards. I would also see how the brakes feel without the vacuum line connected to be sure you don't have something else going on.
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☮️

[ALIKA T3]

[ALIKA T3]

Ok I went to unplug the elbow fitting at the booster and tested the vacuum with a finger to plug the hose. It's pulling vacuum damn fine I would say!

I shut the engine off and kept my finger on it for a few minutes to try to see if the hose held vacuum. I held it for 2 min until I got bored with no drop in vacuum. So it's definitely pulling vacuum rather fine.

It can only be the booster then. Dammit, like I had nothing else to do than to drop the dashboard right now

With engine off, the pedal is hard but doesn't hit a stop though.

With engine on, if I press the pedal twice, it comes to a stop somehow feeling like it hits something metallic if I press repeatedly fast, like the throw is too short? If I keep reving the engine, that stop disappear and I can go past it....
_________________
Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[Dwighia]

I have that similar "metallic" sounding brake pedal on the last 1/2 inch of travel on my '84 1.9 camper. I've also replaced all the parts except the brake booster, but I also get good results in testing the booster.

So I'm at a loss.

Did you ever get your brakes to work with confidence and without that hard clunk metallic sound at the end of the brake travel?
Thanks,
Dwight
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'71 Ghia Sedan
'68 Ghia Convertible
'84 Vanagon
If you dismantle a VW engine and reassemble it enough times, will you end up with enough extra parts for another engine?

[ALIKA T3]

Hi!
The clunk must be a worn pedal. I don remember I had it.
No I gave up, I learnt to drive like that, sold the van recently. It was working but never as good as others.
_________________
Silicone Steering Boots and 930 Cv boots for sale in the classifieds.
Syncro transmission upgrade parts in the Classifieds.
Subaru EJ22+UN1 5 speed transmission
http://www.thesamba.com/vw/forum/viewtopic.php?t=416343
Syncro http://www.thesamba.com/vw/forum/viewtopic.php?t=4...num+gadget

[Dwighia]

Thanks ALIKA T3,
Anyone out there with this weird metallic clunk at the end of their brake pedal? Van stops but I just feel like I'm not getting 100% braking power.

'84 Vanagon 1.9 automatic w/o AC or power steering. All new brake parts except for booster.
Help!
Thanks
_________________
'71 Ghia Sedan
'68 Ghia Convertible
'84 Vanagon
If you dismantle a VW engine and reassemble it enough times, will you end up with enough extra parts for another engine?

[Gnarlodious]

You don’t have to drop the dashboard to fix the booster. Take off the cluster, unbolt the mounts and the whole assembly pulls out the top. Would be a good time to look at the clutch clevis too, and lube things up. I put in a larger BMW booster over the summer and finally getting a modern brake feel.
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Vanagon ’83 diesel AAZ w/Giles injection, 5spd 4.57R&P+TBD and a '78 diesel Rabbit

[Dwighia]

Thanks for the encouragement on removing the dash. I'm only slightly intimidated by the the dash, but I mostly would really hate to replace the booster if the problem is really something else. Here's what I have:

1) I have replaced all the brake components except the proportioning valve and the booster.
2) I don't have any hissing or anything that would suggest a vacuum leak.
3) My pedal does the following:

Engine off:
1/8" initial play in pedal
3/4" to start engaging the brakes
2" to what feels like the end of the braking
With engine on:
3" to a hard metallic sounding clunk
No amount of pumping the brakes makes any difference.
Also full disclosure: I did not make any adjustments to the booster push rod when I installed my new master cylinder.

Any help would be muchly appreciated.
Dwight
_________________
'71 Ghia Sedan
'68 Ghia Convertible
'84 Vanagon
If you dismantle a VW engine and reassemble it enough times, will you end up with enough extra parts for another engine?