90 GMC Sierra rear brake change

[Supercharged111]

I dunno, after leaving those crappy brakes behind there's really no going back for me. If I ever own another truck with them it would be an overwhelming priority for me to get rid of them. I'm guessing that's part of where Schurkey is coming from when he's being "pushy" or "opinionated". Those of you who've never experienced it will never know what you're missing and that's a lot of what's being stressed. If you're like me whenever you finally cave and do something like that, you'll wonder why you waited so long to do it. Like the hydroboost swap, but I knew I'd feel that way after the fact even before I did it. I used my parking brake every day and those damn 10" brakes NEVER held an adjustment. What's even worse is you can't adjust them from the outside. And it seemed to me they sucked more to replace too. All around I feel there's a special place in Hel for them, whoever invented them, and the bean counters or whoever decided to put them into so many trucks. [/rant]

 

[Supercharged111]

What are Y'Alls thoughts on the RAWL delete?

10/10 do it.

 

[90gmcsierraL59]

Sweet

 

[Scooterwrench]

A good way to think of it, is as a "parking brake" and not an emergency brake. Use it when you park, as much as you remember. Even your park brake release handle is labeled "P" for park.

I did have to use it as an emergency brake once in a 66 Ford Galaxy with a single chamber MC. Seal blew and drove it off in the ditch rather than hit the car in front of me. Once I got it stopped and figured out what had happened I clamped a set of vise grips on the release handle stem and drove it the rest of the way home with the eh-eh, "parking" brake.

 

[Scooterwrench]

10/10 do it.

X2

 

[Das Hatt]

I did the ABS delete on my 92 C1500. Not as dramatic a difference in the pedal feel as I expected but it was there.

I always use my parking brake. I've always thought of it as saving some kind of wear on the transmission. Kind of like the weight of the vehicle is not resting on the transmission/engine. When I come to a stop, I engage the parking brake, let off on the brake pedal, then put it in the park. (I'm sure somebody with more mechanical knowledge than me would be able to expand on this.)

 

[Schurkey]

Stopping in reverse is what adjusts the Duo-Servo brakes that have the adjuster at the bottom, as a "floating link" between the shoes. The Leading-Trailing shoe brakes have the adjuster just under the wheel cylinder, and a solid anchor point at the bottom of the shoes.

LOOK at the mechanism that adjusts the crappy 254mm Leading-Trailing shoe drum brakes. It's like an old revolver--the lever has to be cocked before it can "fire" and turn the star wheel. How does it get cocked? Using the park brake.

Nobody with an automatic transmission uses the park brake. The adjusting mechanism as designed, is deeply flawed because it doesn't take into account human nature--the way the machine is actually used in the real world.

I had no end of problems with my RWAL and rear brakes...until I bled the RWAL properly, and scrapped the rear axle (which eventually got traded for a used dorm-fridge to my buddy who exploded the 8.5" axle under his '89 K1500) in favor of a same-gear-ratio, same width, 9.5" K2500 6-lug axle from a '92, I think.

The RWAL has since been functioning just fine for several years.

 

[Supercharged111]

Stopping in reverse is what adjusts the Duo-Servo brakes that have the adjuster at the bottom, as a "floating link" between the shoes. The Leading-Trailing shoe brakes have the adjuster just under the wheel cylinder, and a solid anchor point at the bottom of the shoes.

LOOK at the mechanism that adjusts the crappy 254mm Leading-Trailing shoe drum brakes. It's like an old revolver--the lever has to be cocked before it can "fire" and turn the star wheel. How does it get cocked? Using the park brake.

Nobody with an automatic transmission uses the park brake. The adjusting mechanism as designed, is deeply flawed because it doesn't take into account human nature--the way the machine is actually used in the real world.

I had no end of problems with my RWAL and rear brakes...until I bled the RWAL properly, and scrapped the rear axle (which eventually got traded for a used dorm-fridge to my buddy who exploded the 8.5" axle under his '89 K1500) in favor of a same-gear-ratio, same width, 9.5" K2500 6-lug axle from a '92, I think.

The RWAL has since been functioning just fine for several years.

My beef with RWAL is how it functions. It's a lot like the 3 channel stuff. It'll keep you pointed forward, but it just feels like the truck stops stopping. Personally I'm very comfortable with modulating a brake pedal to manage lockup, and it's about impossible to scare me with the rear stepping out. But then again I have a lot of wheeltime behind a race car with no ABS, so I don't panic when stuff gets weird. YMMV.

 

[Schurkey]

ABS was marketed to the American public as if it reduced stopping distance.

And...it can. If the driver is an idiot, or inexperienced in heavy braking. Which, sadly, is "most drivers". The reduction in stopping distance is based on the excessive stopping distances of poorly-trained drivers, not the stopping distances of experts familiar with at-the-limit braking in a vehicle they're familiar with, on road conditions they're familiar with.

What ABS is really about is vehicle control--making sure the vehicle can be steered when someone panics and dynamites the brake pedal, locking the front wheels, maybe all four. And if the rear wheels lock, it's nearly impossible to keep a straight line--which is why vehicles tend to be set up so that the fronts lock first, before the rears.

The RWAL particularly on pickups was intended to help compensate for the difference in traction between empty and fully-loaded. That's more than the proportioning valve can deal with.

IF (big IF) the RWAL actually functions like it's designed to, and IF the thing is bled properly...I don't think you could tell the difference in the braking action or pedal feel with it in the circuit, or removed from the plumbing 99 44/100% of the time.

A downside to the RWAL and other brake ABS controllers is that they're discontinued, and virtually no-one rebuilds 'em. Secondarily, it's friggin' criminal that they need special tools to bleed 'em. So, sure, if the thing is BROKEN, and you can't get a replacement...removing it may be a valid option. Gutting a functional ABS that just needs a proper bleeding is a poor idea.

Historically, brake systems were designed to be dead-simple, so that any monkey with two weeks of training could swap friction materials and/or wheel cylinders, maybe cut the iron--drums or rotors--put it back together, bleed it, and the vehicle was "safe". ABS is making that inherent simplicity/serviceability a thing of the past.

Stop the world, I want to get off.

 

[89RCLB]

Stop the world

You're going to need a NBS MC upgrade first...