78 Westy Bus Swerving Left Under Braking

[Amskeptic]

I'm beginning to think the passenger side rear wheel cylinder is gummed up or stuck. I adjusted the rear brakes again last night and purposely adjusted the passenger side so both shoes were rubbing ever so slightly on the drum.

I drove it around town today at lunch to pick up AC parts for the wife's car and when I parked it, the driver's side drum was quite warm to the touch, while the passenger side was cold.

Thoughts?

Driver's side should not have been so warm? Test release on both rear wheels, have car jacked, put kid/wife in driver's seat, and spin wheel, ask them to hit brakes. Wheel should jerk to a stop, have them release, and wheel should free up quick.

Do both ebrake cables release fully? Any rusty stains on the vinyl sheath of the flexible ebrake conduits under the spring plates?
Remember, an overheating drum expands and loses friction, it would be the loss of friction in the left rear drum or right front disk pads if the car swerves left.
Colin

[vwlover77]

Remember, an overheating drum expands and loses friction, it would be the loss of friction in the left rear drum or right front disk pads if the car swerves left.

Now you're confusing me. It would be the loss of friction in the right rear drum that would cause a swerve to the left, since there would be more braking force on the left side in that case.

Was that a test?

[Amskeptic]

Remember, an overheating drum expands and loses friction, it would be the loss of friction in the left rear drum or right front disk pads if the car swerves left.

Now you're confusing me. It would be the loss of friction in the right rear drum that would cause a swerve to the left, since there would be more braking force on the left side in that case.

Was that a test?

Sorry, what I meant to say was that the left rear drum, being warmer than the right, means it is braking more, causing yaw to left. . .

[vwlover77]

Okay, after a long drive tonight I checked out the rear brakes again. Driver's rear was hot, but not sizzling. I could press my finger firmly against the drum for a few seconds before it would start to get too hot. Passenger side was cool to the touch.

I then jacked up the car and enlisted my daughter to help. The parking brake is not sticking on either side. Pressing the brake pedal immediately brings a spinning wheel to a stop on both sides, and both sides release immediately and fully.

Weird.

I think I'm going to start by replacing the passenger side rear wheel cylinder. A cheap way to begin.....

Or, maybe the rear lines (specifically the right rear) has swelled up internally. I should replace those too.

[Amskeptic]

Okay, after a long drive tonight I checked out the rear brakes again. Driver's rear was hot, but not sizzling. I could press my finger firmly against the drum for a few seconds before it would start to get too hot. Passenger side was cool to the touch.

I then jacked up the car and enlisted my daughter to help. The parking brake is not sticking on either side. Pressing the brake pedal immediately brings a spinning wheel to a stop on both sides, and both sides release immediately and fully.

Weird.

I think I'm going to start by replacing the passenger side rear wheel cylinder. A cheap way to begin.....

Or, maybe the rear lines (specifically the right rear) has swelled up internally. I should replace those too.

Left rear too. Heat is indicative of something. I am going to drive there myself if we don't figure this one out.
Colin

[vwlover77]

Maybe my perceptions are wrong, but I'm thinking the heat I felt on the driver's side rear drum is indicative of a brake doing its job. Both front rotor "hats" (the only part I could reach with a finger through the wheel hole) were as hot or hotter than the rear drum. The lack of heat on the passenger side rear drum is my concern, especially with the shoes adjusted to allow very slight rubbing with the brakes released, as opposed to the driver's side which back completely away from the drum when released.

[vwlover77]

I replaced the passenger side rear brake hose tonight. No difference.

[chitwnvw]

I replaced the passenger side rear brake hose tonight. No difference.

If you replace the drivers side brake hose, write it up, it's got me stumped. It is a weird one coming off that 'T'.

I'd replace the wheel cylinders. They are cheap, what the heck. Check the pistons in the front to make sure they are free and easy.

Have you bled the system. It made a huge difference on my Orange bus.

[vwlover77]

If you replace the drivers side brake hose, write it up, it's got me stumped. It is a weird one coming off that 'T'.

Will do. I've replaced the other 3, so I might as well complete the effort.

I'd replace the wheel cylinders. They are cheap, what the heck. Check the pistons in the front to make sure they are free and easy.

Rear cylinders are next on my list, and yes, I need to check those front pistons again - especially the passenger side.

Have you bled the system. It made a huge difference on my Orange bus.

I've done 3 wheels as a result of replacing the hoses. It hasn't really made any difference.

[bretski]

Don, I'm really late to this thread, sorry. However, I'll throw some copper your way.

I had an identical problem. Left swerve under braking. Lived with it for a long time, as I just couldn't figure out what the heck was wrong. As Chitown suggests, it ended up being the piston(s) on the passenger side caliper. Removal and inspection of the caliper were necessary to confirm.

Ended up replacing both calipers with rebuilts (the piston was shot), and the bus now tracks arrow straight under braking.

Good luck, amigo.

-Bret

[vwlover77]

Oy! What a debacle today' session was....

I got a new wheel cylinder and installed it on the passenger side rear. No problem.

I then replaced the one remaining old hose - on the driver's side rear. Chitown, it's easy. The hose is unlike all the others. It has a male end that threads into the tee connection. There's nothing to it.

I tried to crack open the driver's side bleeder valve and broke it off. Ugh. The parts store was already closed, so I took apart the wheel cylinder that came off the passenger side, polished up the pistons and bore, and it seemed to operate very smoothly. Got everything buttoned back up and was putting tools away waiting for one of my daughters to come home to assist with the bleeding and found the internal spring that I had forgotten to put back in the wheel cylinder. DOH!!!! Took everything apart again and reassembled with the spring!

Bottom line: Under light and moderate braking, there does seem to be less pull to the left, and the temperature of the rear drums seem about equal after a drive. But, under hard braking, it still veers left. I believe the passenger side front caliper is the next suspect. Chitown and Bretski may win the prizes here!

[chitwnvw]

Don,

Where'd you get your rear driver brake hose?

I got mine from Autozone, and while it is a different length than the other side, it does not have the male end! Good thing you gave me a heads up on that, I was looking for it when I loosened my hose and avoided opening up the system for nothing.

[vwlover77]

Chi, I got all the hoses from Bus Depot.

Here's the link to the rear driver's side.

http://www.busdepot.com/details.jsp?par ... 211611775C

[iwantmybustorun]

Did you figure it out?

My 73 is doing the same thing.

[vwlover77]

Nope. Still living with it. It's manageable but still bugs me. I still suspect the rear brake shoes. Their wear pattern would indicate they are not fully contacting the drum on either side.