Hot rear brake

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yondermtn
Old School!
Location: IL
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Hot rear brake

Post by yondermtn » Tue Sep 04, 2012 7:17 am

Last night towards the end of our 250 mile drive home I noticed the driver's side rear brake was EXTREMELY HOT. We were stopped by about 3 lights immediately after exiting the interstate which required moderate braking. I could smell burning brakes and when I got home the driver's rear wheel was very hot to the touch. The passenger's side was warm but I could hold my hand on the wheel if I wanted to.

I didn't notice anything else unusual about the braking performance. What could cause this and what is my diagnosis/repair procedure?
1977 Westy 2.0FI
1990 Vanagon MV 2.1 Auto

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sped372
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Location: Waunakee, WI
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Re: Hot rear brake

Post by sped372 » Tue Sep 04, 2012 7:28 am

Your brakes are hanging up. Since it's the rear it could either be the parking/emergency brake or the hydraulic brake. Sometimes the hydraulic hose can deteriorate on the inside and prevent the fluid from returning to the reservoir when you let off the pedal. You'll have to investigate. I have a new noise back there that I'll be checking into, too... probably time to pull the drum and poke around.

Jack that corner of the bus up and see if you can easily rotate the wheel by hand (have it in neutral, e-brake off, block the wheels be safe...). If you can, have a friend work the brake pedal to lock the wheel, then release the brake pedal... does the wheel free up immediately or does it stay "sticky" for awhile (hanging up)?
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX

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yondermtn
Old School!
Location: IL
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Re: Hot rear brake

Post by yondermtn » Tue Sep 04, 2012 1:31 pm

Ok, I will attempt to diagnose this asap.

I replaced the shoes and MC about 1,500 miles ago and adjusted them more recently. Is there a way to tell if the brake hose is bad? I would think that if something were bad in the MC then both rear wheels would be overheating.
1977 Westy 2.0FI
1990 Vanagon MV 2.1 Auto

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sped372
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Location: Waunakee, WI
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Re: Hot rear brake

Post by sped372 » Tue Sep 04, 2012 2:06 pm

Run the test I described, a symptom of the hose being "bad" will be a brake that doesn't release right away. The springs that are trying to pull the shoes back together aren't strong enough to push the fluid back through the "bad" hose. Your foot at the pedal is much stronger than those return springs. Make sense?
1971 Karmann Ghia - 1600 DP
1984 Westfalia - 1.9 WBX

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Amskeptic
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Re: Hot rear brake

Post by Amskeptic » Fri Sep 07, 2012 3:48 pm

sped372 wrote:If you can, have a friend work the brake pedal to lock the wheel, then release the brake pedal... does the wheel free up immediately or does it stay "sticky" for awhile (hanging up)?
Get your 7mm box wrench and crack loose the bleeder. Close it. Have assistant press on the pedal and release. Crack open bleeder into a wadded up paper towel. Does wheel spin freely now? Brake hose.
Does it remain hard to turn? Grab ebrake cable under spring plate and try to "flatten the curve" of the sheath. This will release a sticky cable enough to know that it is a rusted ebrake cable.
Update us.
Colin
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 94,615 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,990 miles

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yondermtn
Old School!
Location: IL
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Re: Hot rear brake

Post by yondermtn » Tue Sep 11, 2012 10:03 am

Ok. I'm just reading Colin's procedure now.

I did lift the rear and had the wife apply the brakes and then release. I had no brake contact, wheel spun easily. Did the same with the ebrake and that didn't seem to stick either.
1977 Westy 2.0FI
1990 Vanagon MV 2.1 Auto

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Amskeptic
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Re: Hot rear brake

Post by Amskeptic » Sat Sep 15, 2012 7:17 am

yondermtn wrote:Ok. I'm just reading Colin's procedure now.

I did lift the rear and had the wife apply the brakes and then release. I had no brake contact, wheel spun easily. Did the same with the ebrake and that didn't seem to stick either.
You are not spelling out for us whether or not you did the bleeder screw procedure. You did not spell out of your wife applied-then-released the e-brake before you reported an easily spinnable wheel.

If the foot brakes released perfectly without your doing anything, and if the ebrake released perfectly, then we now have to ask if normal operating warmth is a necessary ingredient to make the brake heat up. So, go drive it and use the brakes firmly a few times and get hiome and retest.

If the brakes still release perfectly, then YOU MUST HAVE DRIVEN IT WITH EBRAKE ON, DID TOO.
Colin :alien:
BobD - 1978 Bus . . . . . . . . . . .111,130 miles
Chloe - 1970 bus . . . . . . . . . . . 206,787 miles
Naranja - 1977 Westfalia . . . . . 94,615 miles
Pluck - 1973 Squareback . . . . . 55,510 miles
Alexus - 1991 Lexus LS400 . . . 72,990 miles

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