Rear Wheel Binds

[RONIN10]

I did some searching and couldn't find anything relevant. I hope this isn't already documented elsewhere.

I just completed replacing the rear shoes/pads and springs on my newly acquired 1976 Westy; the drums were old, but still hadn't reached maximum inner diameter yet. I did a brake adjustment and bled the system and the brakes operate fine during normal operation. Two issues remain however:

1) When doing the adjustments and backing off the adjusting stars after I could no longer rotate the wheel, the wheel would be tough to turn for about 1/2 of a wheel rotation and then rotate comfortably for the rest. When bound up, I could still manually force the wheels to rotate, but it took a fair bit of muscle to do so.
2) The parking brake holds the bus, but it does so only with the parking brake handle pulled fully out; not the 6-8 clicks recommended.

My guess is that these two issue are related and might be tied to old parking brake cables, but thought I'd put it to the wise minds here and see what suggestions arose.
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Andrew

Oscar: 1976 Westfalia Deluxe Camper, 2.0L FI, Manual Transaxle

[shiningstar76]

Most likely solution:
I'd back the stars off a tad more until you have the slightest rub on the drum, and see how your pedal feels.

Possibly Bogus solution:
The only other thing that comes to mind is that the shoes are a tad off center. That whole system assembled has some movement to it. Remove drum and tap with hammer.
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[kreemoweet]

I suggest you follow the procedure for adjusting drum brakes in your
Bentley service manual. Nothing in there calls for tightening the adjusters
until you can't turn the wheels. You didn't mention adjusting the parking
brake mechanism, which is a separate procedure to be done after the
shoes are adjusted as above.

With new shoes and well-worn drums, you are likely to have to repeat
these adjustments several times until things settle in.
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[busdaddy]

Tightening the adjusters evenly until the wheel locks and you can't turn the adjusters any more is a good idea after brake work IMO, it fully compresses the cylinders and centers the shoes, of course back it off after to the slightest little drag sound. As Kreem says the Bentley describes it well, especially the part about fully backing off the parking brake cables before starting then adjusting them last.
If the brakes only drag through part of a rotation you have an egg shaped drum or it's not seated on the hub properly, better do some more checking.
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[Desertbusman]

[Wildthings]

A good place to start would be to pull the offending drum and make sure there is no crap between the drum and where it seats against the hub. Clean the drum and hub surface one more time. If you didn't have the drum turned, you should also take a 4 1/2" grinder and remove the ridge along the outer edge of the drum. You can not get at the ridge on the inside of the drum, but it could cause problems as well. The shoes will rapidly wear to fit against the inside ridge but will be a pain until they do.

[zerothehero]

If your drums are warped, you might be able to feel it through the pedal depending on how bad. Try lightly applying the brake on a long downhill and see if the pedal lifts and drops slightly.
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[RONIN10]

I'm confident of the adjustment procedure and the only deviation I perform from the Bentley manual is to max out the adjusters so that the wheel won't turn for the same reasons busdaddy mentioned. Well, that's not completely true. Once the initial adjustment has been made, I climb back into the van and do 4 or 5 full cycles on the brake pedal to ensure the shoes are seated correctly

I think there's a lot of credence to the egg-shaped drums theory since I did get a bit of ABS-like behavior when taking the bus out last night and performing a firm brake (not quite emergency braking, but more like when you decide to stop for that yellow light you were about to run). It doesn't show up on light braking.

The plan was always to replace the drums soon since they're near the end of their service life, but cash investment is limited so replacing the brake shoes is all that's on the agenda for the time being. Drums next paycheck perhaps. Regardless, I'll pull the drums today and conduct a more detailed measurement to verify the out-of-round condition.

On the parking brake, after getting the brake adjustment satisfactory (but before the ovalized drum conclusion), I did get under the bus and adjust the cables to pick up some of the slack that was present. I do think the ovalized drums though are interfering with determining where to set the lock nuts since I might be getting a little extra interference from the narrower section of the drum. I'll toy with it more today as well and see if I can get a satisfactory interim adjustment in place.

Thanks again.[/b]
_________________
Andrew

Oscar: 1976 Westfalia Deluxe Camper, 2.0L FI, Manual Transaxle

[RONIN10]

Sold my wife's Jetta so I was able to buy new drums. Problem solved. No uneven brake pressure and wheels rotate cleanly.

And I think I just need new parking brake cables. After installed the drums, adjusting the shoes, I went to adjust the parking brake and the driver's side line bottomed out on the threaded portion. Given the amount of ick that I had to clean off of them to get them to thread down, they may well be the original cables.

Thanks for the input everyone!
_________________
Andrew

Oscar: 1976 Westfalia Deluxe Camper, 2.0L FI, Manual Transaxle