Front Drivers Brake Hot - Thoughts?

[wagohn]

Hello all,
Back around December. the master cylinder went out on our '76. We bought and replaced the master, bled the system, and the brakes seemed perfect. However, there was a new (we think new) slight binding on the front drivers disc brake when spinning the wheel. We didn't think much of it and used the vehicle locally on running errands. I would feel each wheel hub after initial drives and everything was cool to the touch.
Fast forward to today and we went on a 100 mile round trip and somehow burnt through 2/3rd tank of gas. It was a hilly drive so I thought maybe we needed a timing tune up. On getting home, I touched each wheel and all were very slightly warm (it was an 85 degree day and 50 miles) but the drivers front hub was super hot, too hot to touch.
I'm thinking either a collapsing hose on that wheel OR the pushrod on the master cylinder is ill-adjusted and keeping the brakes slightly "on". But wouldn't ALL the brakes be binding and hot? Also, super hot day could contribute to a tight caliper getting tighter?
Any ideas to test, guys?
Thank.
_________________
1976 VW Transporter, 2.0 FI Engine

[camino70]

My first guess would be a stuck caliper.
_________________
Ron
1974 Westfalia
Goal: get the 914 1.7 running

[aeromech]

The rubber brake hoses fail from the inside out. They swell and prevent the free flow of fluid in both directions. When you press the brake, let’s just say you’re pushing 1000psi through that restriction into your brake. When you release, it’s just free flow for return so if the hose is bad, your brake will stick
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[wagohn]

Thanks guys. That's where Im leaning too, new hoses required. I was suspicious of a misadjusted master cylinder rod as that's the last thing we changed, but then all hubs would be hot, correct? The other three hubs were barely warm after 50 miles. Also, perhaps the slight binding on the drivers front was there for some time, but only noticed after bleeding all brakes for the master cylinder swap.
Anyways, I will jack up the front tomorrow, test both sides for binding, and, assuming the drivers front is still binding, I will relieve the bleed screw and see if the binding stops.
Thanks! I will report back.
_________________
1976 VW Transporter, 2.0 FI Engine

[aeromech]

Front brake hoses cost less than $20 each. If you’ve already changed your master cylinder then you know how to bleed the brakes. You’ll only need to do the front since you have a dual MC so front and back are separate systems. I’d just change them since they are the next step and a whole lot easier than the step after that which is the calipers

Edit: don’t get fancy with new hoses
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[wagohn]

[aeromech]

Please update this thread when you can
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[wagohn]

[aeromech]

You should update your profile with more info like your location
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[wagohn]

[Wildthings]

Once you have driven 10 miles or so on a road that requires you to use the brakes frequently crawl underneath and loosen the bleeder on the side that is getting hot and see if there is any pressure in the line. A slow seepage of brake fluid is normal, but a pulse of fluid as you first open the bleeder is not. However if the bleeder is all clogged up with rust and dirt, you will not get a good test.

[wagohn]

[mikedjames]

If the caliper is rusted up, then you may have to use more than a rubber hammer to knock the pads sideways out of the caliper (remove the pins first !) . If it is rust, then you can file off the rust from the caliper where the sides of the pad rest against the caliper. The pad should be a loose fit on the pins so it can move.
At that point, buying new pads, fitting them and checking the brakes actually work is a good idea.

I once had a car with a rusted caliper - gentle braking and it would pull hard to the kerb side of the road as the pad stayed put on that side.
Press really hard on the brakes, and it would bend the pads back into contact with the disc, and stop straight.
Some work with a hammer and a file and it had one less bad problem. (also 150 miles to the gallon of engine oil, carpet wrapped round steering column that snapped suddenly causing fish tailing at 70mph , starter ring fell off flywheel daily, carburettor float jammed down in the rust at 100mph .. ... Good old British Leyland 1974 car , rusted through by 1985)
_________________
Ancient vehicles and vessels

1974 VW T2 : Devon Eurovette camper with 1641 DP T1 engine, Progressive carb, full flow oil cooler, EDIS crank timed ignition.
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[danfromsyr]

yeah you can put it in the box you get the new one in and return it as a core..
that's the best thing you can do for/with it.

Brakes are too important to squabble over $100~150 for a 5~20 year life item.

*I used autozone as a example because it's easiest on core returns.
but go with a favorite VW vender if you prefer.
https://www.autozone.com/brakes-and-traction-control/brake-caliper-front/volkswagen/transporter

[wagohn]

[busdaddy]

While the pads were out did you try prying the pistons back?, did they move freely?, or did one put up a fight?
Maybe it's not hot now because it's stuck and not doing much braking?
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[wagohn]

[busdaddy]

Try prying both back into the caliper a 1/4" + , be prepared for the pedal to go to the floor a couple pumps before they reseat themselves after you get it back together, pump the brakes before driving anywhere.
If one (or both) don't move you have a problem.
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[wagohn]

[wagohn]