Uneven Rear Braking

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vwlover77
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Location: North Canton, Ohio
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Re: Uneven Rear Braking

Post by vwlover77 » Thu Nov 21, 2013 6:34 pm

I was thinking that maybe the braking forces may actually be pretty close to equal, but the alignment makes it seem like the left side is doing more by steering the rear of the Bus? But I guess that doesn't explain why the left side drum gets warmer..... :-(

Which leads to another question.... Is it normal for the rear wheels on a Bus to lock before the front? I thought the proportioning valve was supposed to help prevent rear lock up.
Don

---------------------------
78 Westy
71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

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Amskeptic
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Re: Uneven Rear Braking

Post by Amskeptic » Thu Nov 21, 2013 10:07 pm

vwlover77 wrote:I was thinking that maybe the braking forces may actually be pretty close to equal, but the alignment makes it seem like the left side is doing more by steering the rear of the Bus? But I guess that doesn't explain why the left side drum gets warmer..... :-(

Which leads to another question.... Is it normal for the rear wheels on a Bus to lock before the front? I thought the proportioning valve was supposed to help prevent rear lock up.
It is "typical". Most replacement shoes do not have that trick short trailing shoe that the originals like the BobD have. I believe that short shoe was a "late engineering adjustment" to help keep the rears from locking.

Image
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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vwlover77
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Location: North Canton, Ohio
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Re: Uneven Rear Braking

Post by vwlover77 » Sat Jul 12, 2014 1:00 pm

Well, I think this is finally solved, but I'm not sure how or why. As you may recall, I transplanted all of the brake hardware from driver's side to passenger side and vice-versa and still had more braking action from the left rear. Oh, but now the passenger side drum is getting significantly hotter than the driver's side. WHATTTT???? I kept jacking up the rear wheels after drives to check for dragging shoes on either side, but nothing was evident.

I removed and greased the parking brake cable on the passenger side (again) and replaced the Chinese wheel cylinder with one of the original ATE cylinders. I now have much more even rear braking, and much more equal drum temperatures.

Weird!!
Don

---------------------------
78 Westy
71 Super Beetle Convertible Autostick

"When we let our compassion go, we let go of whatever claim we have to the divine." - Bruce Springsteen

User avatar
Amskeptic
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Re: Uneven Rear Braking

Post by Amskeptic » Mon Jul 14, 2014 8:35 pm

vwlover77 wrote:Well, I think this is finally solved, but I'm not sure how or why. As you may recall, I transplanted all of the brake hardware from driver's side to passenger side and vice-versa and still had more braking action from the left rear. Oh, but now the passenger side drum is getting significantly hotter than the driver's side. WHATTTT???? I kept jacking up the rear wheels after drives to check for dragging shoes on either side, but nothing was evident.

I removed and greased the parking brake cable on the passenger side (again) and replaced the Chinese wheel cylinder with one of the original ATE cylinders. I now have much more even rear braking, and much more equal drum temperatures.

Weird!!
Do a "cc" test on the chinese wheel cylinder and compare it to the Ate. Brake application pressure depends on piston surface area. You can GUESS that the chinese wheel cylinder would have been made just as small as possible with as little material as possible and the other side would have the greater braking.

Did we not have this chinese crap vs oem Ate discussion?
Colin

Here is an October 2013 quote . . . :cyclopsani:
Advanced Diagnostics

Pressure gauges on each rear brake line. Have someone apply brake pedal while you read them. Stomp brakes and LOOK at actual pressure rise rates for each.

Replace all rear brake componentry with German-sourced parts.
Colin
BobD - 78 Bus . . . 112,730 miles
Chloe - 70 bus . . . 217,593 miles
Naranja - 77 Westy . . . 142,970 miles
Pluck - 1973 Squareback . . . . . . 55,600 miles
Alexus - 91 Lexus LS400 . . . 96,675 miles

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