Why do my rear brakes appear to work great but squeal so bad?

[SCM]

I rebuilt my rear brakes about 12k miles ago, new drums, shoes, cylinders, and all the springs. After that, the driver's side would squeal loudly juuuust before the van would come to a complete stop. I thought maybe they needed to break-in but it didn't go away. After a while I put a little more high-temp grease on the backing plate contact points but that didn't help anything.

Last weekend I swapped the shoes out with new set of ATE brand shoes. The new shoes visually appear to match the curve of the drum perfectly. I noticed one of the old shoes on the driver's side had a cracked lining and the brake internals were covered in brake dust while the passenger side brake looked almost as clean as the day I rehabbed it. I figured that must have been my problem.

Nope, the driver's side still squeals! The van stops great, pedal feels good, E-brake holds at 3 clicks, van holds a straight line braking with the pedal or the E-brake.

What in the world could be making the squeal?
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'91 Westfalia GL Automatic (GTA "Turbo" Rebuild w/Peloquin) and 2.3L GoWesty Engine

[SCM]

Just one bump before I leave on the first Westy trip of the year!
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'91 Westfalia GL Automatic (GTA "Turbo" Rebuild w/Peloquin) and 2.3L GoWesty Engine

[dabaron]

possible rubbing on the backing plate?
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1991 Vanagon GL Camper
i had no idea i wanted to be a mechanic
"burnin oil and cookin coils" -- Destructo

BiWerks Design, LLC

[dobryan]

Slap a new drum on the driver side and see if that makes a difference?
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson

MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
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Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794

[SCM]

[SCM]

Hmmm, the plot thickens. Not only does that brake squeal but it's heating up a lot more than the others. I need to verify this but I think it only heats up after stopping from a high speed (i.e. highway off ramp) and not from just driving around.

I'm wondering if the non-squealing rear brake isn't engaging and that's allowing the other to get overworked and overheated.

Does that brake proportioning valve under the van control front/rear bias or does it have an effect on right/left function?
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'91 Westfalia GL Automatic (GTA "Turbo" Rebuild w/Peloquin) and 2.3L GoWesty Engine

[crazyvwvanman]

The rear brakes connect to a TEE near the tranny nose. Only 1 line from the front feeds both, via the tee.

I would consider replacing both rear rubber hoses as that is a known cause of problems and expected to need periodic replacement. They don't cost much and are not hard to replace unless you have a rusty setup.

Mark

[SCM]

[Igeo]

Squealing drum brakes are usually glazed linings or a polished drum friction surface. If it were me, I would pull the off the offending drum, then with some 150 grit emery cloth, give the linings a good de-glazing. Do the same to the drum to knock the polish off. This will not affect your adjustment. No greasy or oily finger marks allowed!
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1987 Westfalia 2.1 WBX Manual

[SCM]

[Igeo]

Unequal adjustment may be your issue.

A 70 degree temp reading after a hard stop sounds low. That's ambient.
170 is more like it. I would back off both sides untill there is no drag. Put a dab of white lithium grease under the shoes where they contact the friction pads on the backing plate so they are free to pivot nicely. Just a dab. Then adjust the brake on one side until it's essentially locked up, and you can't rotate the drum. Then, back off on the adjustment until you can rotate easily with the wheel on, but to a point where you can still hear and feel drag. Confirm that your e brake is still working at 3-4 clicks and you should be good.

Also- You might have to bleed both sides. If there is air in one side, that side will be ineffective.
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1987 Westfalia 2.1 WBX Manual

[SCM]

Those all sound like good ideas guys. Thanks. I'll report back once I get around to checking those things.

First I need to catch up on my day job and also post a trip report!
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'91 Westfalia GL Automatic (GTA "Turbo" Rebuild w/Peloquin) and 2.3L GoWesty Engine

[E1]

Unlikely being that you've "gone back in there," but......

We once had the same symptoms in our Jetta. It was a tiny piece of gravel floating around, then re-embedded.

Ten-Second Test:
Back up the bus (literally, Haha) at a decent clip, and stomp the brakes.

Again, may not apply, but worth a try!

(rhyme unintentional, apologies)
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[handjammer]

Did you buy the cheaper rear drums? Check if they are round.

I had similar issues with my rear brakes after I did a full rebuild with GoWesty parts using the less expensive, non-finned drums. One of the drums got so hot it caused the rubber in the cylinder to melt, eventually leaking.

Took a while to find the problem, even had a few shops look at them. Finally discovered that the new drums were way out of round. Learned my lesson the hard way, don't buy cheap parts!
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'87 tintop syncro w/ EJ22

[E1]

Wouldn't that be obvious in pedal pulse, plus make inconsistent sounds?
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[Abscate]

[E1]

Thanks, and curious... Because the shoes adjust to the egg shape quickly enough to not wobble, nor screech just once per rotation?
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‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[Jake de Villiers]

[SCM]

Man, this is puzzling.

I drove the van today for the first time since our 1500 mile trip and noticed that the E-brake is now not holding at 3 clicks, more like 6, and the pedal travel has increased a bit.

I confirmed that the driver's rear brake heats up much more than the passenger side during braking - not just driving around.

I pulled the drum and found that the front brake shoe, replaced just 1500 miles ago, is worn down to about 30% of it's orginal thickness. The rear shoe looks like new, which it is.

The drum spins freely after pumping the pedal and actuating the E-brake so it seems doubtful that anything is dragging while driving.

Both brakes were adjusted per the Bentley when I first did the job (spaced 1.5 mm less than the drum ID) and brakes felt great so I don't know what would be going on there. The passenger side brake engages with the pedal and E-brake so it's not like that isn't working at all.


If I somehow botched the adjustment making the passenger side drum engage later than the driver's side, would that cause this? It seems unlikely to me that that would cause the one brake shoe to wear so quickly but maybe I'm wrong?
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'91 Westfalia GL Automatic (GTA "Turbo" Rebuild w/Peloquin) and 2.3L GoWesty Engine

[Abscate]

You probably have hydraulic issues o the cold side

Plugged lines
Rusted. Wheel cylinder
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.ssS!