Here is what I have found over the years-

The OEM shoes hold better than the aftermarket shoes because they are softer (stickier).

If you glaze the shoes by driving with the brake on, or with the adjustment too tight (just once is all it takes), they will never hold well unless you remove the glaze and start over.

The differential (clutches) throw off the adjustment substantially. To get it right, you have to disconnect the half shafts so you can tell how much drag is actually being generated by ONLY the shoes. This is the only way I have been able to successfully adjust the PB on a first pass (without relying on luck) so that the shoes are not accidentally glazed on the first test drive. This is my trade secret, so don't tell anyone.

The factory procedure does not instruct you to disconnect the half shafts. But that is how I do it to avoid re-adjustment and/or shoe glazing. It's a PITA, but when I want to do something easy, I bake cookies instead of adjusting a parking brake.

I installed Stainless shoes (and all the other parts) a while back and even with the half shafts un-hooked and a perfect adjustment, the brake worked "so- so". Recently, my PB was not working very well, so I took it apart. One of my Stainless (hard, non-sticky) shoes had disintegrated.... the rivets had been installed crooked at the factory. I remember noticing this when I installed the shoes, but figured it wouldn't matter. Wrong. I removed it (a single shoe), and replaced it with a 35 year old sandblasted/used shoe. With that one GM shoe installed, the brake holds better than it did with all four SS (hard) shoes installed. When I take it all apart the next time, I'm putting all GM shoes back in.

On the issue of "holding" in general, I have never been able to get the C2/C3 parking brake to hold REALLY hard against forward motion. When I set the PB on my other cars, it will hold the engine (automatic) even if I rev it a little. I have never seen a C2/C3 PB that will hold the engine in forward. The reason is in the design. 1) small shoes, 2) the geometry of the mechanism- the way the shoes rotate when drag is applied.

"Working Perfect" for me would be to hold my 454 when I let the clutch out slowly in 1st. Or, to hold a 427 with a Turbo 400 at 1500 rpm in Drive. Other designs will do this. My 1966 Ford Ex State Police Cruiser with a BB Ford & TriPower and a heavy duty C6 would do this. I've never seen a C2/C3 that can solidly pass this test.

The first time I encountered this problem was for a NY State Inspection- they are supposed to test the parling brake. I had adjusted mine by the book (327 4 spd) but if you tested it by letting the clutch out in first gear (which is what they may do), the brake would slip. In reverse, the engine would stall. So, they flunked it. I took it home and over-tightened the PB so that it was dragging, took it back for inspection, and it passed. When I got home, I loosened it up again, but the shoes were already glazed & ruined, not to mention the steamy wheel bearings. Burnt the paint right off the rotors! From that point on, if it flunked based on the PB, I would take it somewhere else if logic has no effect on them.

 

Thanks for the tips Tom. I will be checking my shoes for glazing. I thought I was doing good when I ordered the SS p-brake kit :nonod: .

 

Hmm...and I thought my car was just weird.

Oh, well...I have a strategy of only parking facing uphill. :D

 

Very interesting topic, and thanks Tom454 for the advice on adjusting. The e-brake didn't work on my car when I bought it, and I plan on repairing it this winter.

The reason a drum brake works well in one direction, and not the other is the location of the pivots. When the slave cylinder pushes out a shoe, the friction will actually increase the pressure in one direction. In the other direction, it will decrease the pressure. This is why one shoe wears faster on most drum setups. Honda began using a system with two slave cylinders on its motorcycles in the 70's I believe. Using two slave cylinders allows you to have both shoes increase pressure.

Tom454 is also correct about the capability of the e-brake; the OEM's size e-brakes to handle full engine torque in first gear.

 

Mine actually works on my '82 - the cable that goes between the two sides was frozen - the shoes were already in decent shape. I put the new cable in and readjusted everything carefully.

I wish I had thought of Tom454's procedure with taking the halfshafts off. I could probably get it to hold even better. Next time I pull the brakes apart again, I'll probably do that.

As of now, I can rev up to about 1200 or so RPM and they still hold - it passes TX state inspection, so that's really all I'm concerned with.

Ken

 

Mine is lousy. Had the inspection guy try the let it out while in gear thing, and of course it failed. I pointed out that the engine was a lot stronger than new and he accepted it. The car needs inspecting again, guess I'll go back there...

Maybe one day, I'll get it to work... :rolleyes:

 

Just barely!!! :cry

 

I too went through the lousy emergency brake blues. The adjustment goes far beyond turning the star. It's a combination of the cable and star adjustment. If you don't adjust it properly, you will have very poor emergency brakes. Tom has some very good points and please do follow the manual to the T. The procedure is well described. I initially made the mistake of doing the brake the way I've done it on a drum-braked car. It won't work that way.