Brake weirdness

[tbd]

History....

1989 Vanagon camper.

1. Replaced flex hoses with braided steel variety.
2. Replaced both rear cylinders.
3. Replaced both front calipers.
4. Replaced the hard-lines.
5. Bled the system twice using the brake pedal, no bubbles.

At this point the brakes were working as well as they had when we purchased the Vanagon. At 25% pedal you can feel the brakes starting to grab, at 75% pedal travel you're stopping pretty good.

Soon after starting to use the Vanagon for short trips the front left brake began to squeal, loudly. Pulled the caliper off and found that the pads were wedged tightly against the disk, had to pry them away. Even after cleaning the dust and rust from the carriers and pads the pads would still bind up. These are the same pads, in the same positions, that came with the Vanagon, plenty of life left in them. I finally ground just a wee bit from each of the outer tabs on the pads which let them move freely sideways but not pull straight up. Added some more brake grease and no squeal. And no, I did not put the grease on the pad faces.

We took the Vanagon for a test camp this last weekend. Only 60 miles one way. On the way out, at night, cool temps, the brakes behaved as they had been. On the way back, during the day, much hotter, the braking changed. At 25% travel it was braking really well, at 50% it was stopping now. Almost like the brakes in the Saturn.

Today when I was out, the brakes are back to the 25/75 performance and the passenger front is starting to squeal. Sigh.

This is my first Vanagon. Is this normal brake behavior or is my master cylinder going bad?

Thanks.

[Wildthings]

If your brakes change with ambient temperature it could be that the rod between the brake booster and the master is a tad too long, and thus the brakes don't release fully when the rod lengthens just a bit more in the heat.

[insyncro]

Try cleaned out the proportioning valve.

[kaeferman]

Can I wake this old post up? I m having Similar symptoms as tbd with my 83 camper. My mechanic talked me into new calipers up front after discovering binding going on when I brought it in for a balancing. He used the wording 'seizing' , which helped make the sale. I knew the driver side would squeal sometimes, but it would go away for a while when I d tap the brake pedal. After the new calipers it was great for a year-ish, now it's back and doesn t seem to respond to my old tap trick either. I jacked it up and they both do rub some but they spin a bit then stop with rubbing sounds continuous. I will look into the two suggestions above, but read on I have more 'weirdness' with my brakes;

I recently became concerned about my brakes for another symptom that popped up and that was a pretty sudden firming of the pedal feel that showed up after I heated the brakes up on a mountain descent all loaded up with gear, beer and ice, etc. I was pretty sure that the pedal contacted sooner too but it's hard to know. The hard pedal condition seems to come and go oddly. My master cyl looks newish, it's chrome looking? They usually look rusty right? I don t know what would make these symptoms happen. Or what goes on inside one of these things either...

This is the also same master cylinder that had a strange short in one of its switch plugs that I found was draining my battery by turning on the drivers side brake light spontaneously when it was parked. The plug was also all melted up too, but I fixed the plug and swapped in a new switch and the lights/battery are behaving. Does this sound like I need to swap out the master cylinder, I hate to if it's been done by a PO and I just got all fresh brake juice in the system too!
Many thanks for any advice.
B

[Abscate]

This vehicle in the original post should have been parked. Brakes are not optional fun extras.

To new poster - some rubbing and friction with disc brakes is normal, but its tough to quantify on the inter webs.

If the wheel and rotor are not getting hot while driving (take it out at modest speed, 40 mph is fine for 10 minutes, then dowse the rotor with a cup of water, if it spits steam and hotness, thats too hot), the rubbing is probably ok.

Calipers do seize and they do it 'quickly' - working ok one week, then the piston sticks and things go downhill quickly.
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[Wildthings]

A bad caliper or brake hose is going to affect only one wheel, while a master cylinder problem will effect either two or four wheels.

Yes check the brake temps after a moderately drive. Unless you have had to brake hard the hubs should be only somewhat warm.

[kaeferman]

Thanks for the ideas. I'll check the temp after a short jaunt next.

So the funny intermittent, hardening pedal isn t alarming anyone? I was guessing the heating was expanding something, fluid? Or metal somewhere ?maybe that rod someone mentioned above...

Sounds like I might need to let the squeak ride then. I haven t really checked out the calipers since they were put on. Is there some gak I should put on the back of the pads if it gets unbearable, Anti squeak stuff maybe? I haven t done a lot of disc brake stuff yet.
Thanks
B

[Wildthings]

[kaeferman]

Ok Wildthings,
Am I reading your post correctly? Are you suggesting that I may need to adjust my play in those locations? Does a lack of play or 'slop' indicate that the component in question needs attention (replacement, adjustment or service). I really hope I don't have to get into the brake booster job. That sounds like a dash pull.
I still haven t really addressed this issue with my ride's brakes, but it's starting to bug me. They squeak intermittently now a lot more often and some days it seems that the van doesn t freely roll when I let off the brakes on a gentle slope as I might expect it to. But when I had that squeaky front right wheel jacked up I could spin it with my hand (hadn t driven it so everything was cold). There's some rubbing but it turns...
B

[Wildthings]

[kaeferman]

So then there must be an adjustment for that master cylinder pushrod that I can make somewhere right? under the dash I assume...

or is the master cyl. done? if I m experiencing this issue...

My fear is that I already replaced the calipers up front on the advice of a non vanagon, general mechanic who is a bit young maybe. I dropped off the bus to get its tires balanced and he got me when he said one of my calipers had seized or was seizing. I was in the lead up to a trip I was doing that involved steep winding mountain driving. I figured I would do them both and that was probably why they d been squeaking. Maybe that wasn t the problem's cause and it was only a symptom?

[Abscate]

The master cylinder push rod doesn't get out of adjustment normally unless someone messed with it. It's not unusual to get some new brake noises after heavy use. Really hard to give a definitive diagnosis
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[kaeferman]

So my brake system troubles persist. The condition is my pedal has odd and sudden rigidity at inverals after driving the van. This happens with short or longer drives. The brakes themselves work fine and bus stops well and good, but when the pedal has its rock like symptom the brake lights don’t turn off and battery runs down. More of a problem is that drivers behind me may not know when I m stopping and I could get smacked. The lights can also be off when I park it and turn back on spontaneously, which is fun.

Two questions (and a half maybe)
Is there any way bleeding brakes and or clutch system incorrectly could have produced this condition?

Is the pushrod of which you speak the one in front of the brake booster that cannot be even seen from inside the footwell? If I have to adjust it, can it be done from the footwell or does the dash and all need disassembled to get at pedal assembly and the booster? That frame crossmember and clutch master cyl make anything under there impossible...
Or is this pushrod adjustment made inside the master cylinder? I see two adjustment rods in the Bentley. One at the booster and one seems to be inside the cylinder between the primary and secondary pistons.

I m wondering about something else like the flex hoses or maybe something is screwed up inside the master cylinder? (But isn t how I ve experienced master cylinder issues before)
It seems hard to believe that this is something one would adjust each time a new master cylinder is installed. Dashboard disassembly really is a big hassle for something this minor like an adjustment. One post I read seemed to say I d have adjust it repeatedly to find out where to set the thing!
Thanks for any thoughts on this problem
B

[levi]

I think you're trying to focus on one aspect of the system (as being the cause), without understanding the whole system.

You haven't mentioned replacement of the flex lines.
They can fail internally, preventing that front right from releasing the caliper, which sings at a certain amount of held pressure.

Tapping on the brakes would change that pressure enough so it doesn't sing, but it's an indicator of too much pressure.

If you haven't changed out all of your flex lines, do that.
They're cheap and relatively easy to change out.

Also even though the new calipers were "rebuilt", I suppose it's possible that they were just given new seals.
If they weren't fully taken apart and had all the gunk removed from inside that could keep them from retracting = same results.

The rotors on these are solid, not ventilated, and can warp.

I've never had warped rotors so I don't know if it could cause your problem, doesn't seem like it would be too hard to check.
I wouldn't think that's your issue, seems likely that would give you a pulsing feel, but something to be aware of.
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[Abscate]

You definitely have residual pressure in the master as evidenced by the brake light problem.

It’s either a bad master cylinder or hoses
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[levi]

[kaeferman]

Thank you! That definitely helps me throw some more parts at this issue with a little more confidence. I was beginning to like the master replacement option but flex lines make a whole lot more sense to do first. People tend to overlook the important of those little guys. I learned that once before on my old super beetle. But rule is cheaper parts first then, work up to the bigger money items for any automotive conundrum with too many variables. My master looks newish anyway, shiny chrome looking with not a speck of rust, so I figur it’s a reman. Plus flex hoses are way easier to swap.
Also I really doubt that a bleeding fail would give me the symptoms I m having. I ve bled plenty of time for my rides over the years! I got my system. Bleeding poorly would leave air in the lines and be spongier not more rigid anyway.
Lastly, yes Levi I am also not suspecting rotors since I don t have one side pull or pulsing to speak of, these brakes are really pretty smooth all in all.
I ll get those hoses on the way soon and report back with the verdict.
Much gratitude as always!
B

[Abscate]

If it’s a long term runner New flex hoses should be in the safety replacement item list anyway, so you might as well do them first.

You can get junk New replacement parts , too, so dont assume new= functional.
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[Wildthings]

If your flex hoses are more than 10 years old then replacement is warranted, but bad flex hoses would not make your brake lights come on, only a problem with the master or booster would do that.

[kaeferman]

Ok so in the process of researching / ordering my flex lines I found a brake pressure regulator for sale @ busdepot. Sort of a lot of dough, so it’s probably what I ll need 6 months from now when i’m still stumped. Anybody think that it could be a suspect with this issue? I guess I m having a brake pressure issue, but I didn’t t know vanagon has such a thing. Where is it?
B