Lurked this fantastic site for quite some time, and usually find the answers I'm looking for without asking, pardon me if I missed this Q & A.

Just changed rotors and pads on my 02 DMax 4x4 ZF. I probably go thru brakes a bit quicker than an auto since I tend to brake more often than downshifting and engine braking, figure it's easier to change worn brakes than a clutch, yet I let my dealer change the clutch when replacing the DMF.:rolleyes:

Rear rotors / pads were worn much more compared to the front. Rear brakes tend to brake w/ ABS more often while braking, over bumps, etc.., so I realized the rear brakes are used excessively.

1) To reduce braking in the rear, is the existing dynamic proportioning system adjustable?

2) Can I implement an aftermarket adjustable proportioning valve (common aftermarket part show below) in the rear line to reduce pressure, has anyone tried this before in conjunction with this dynamic proportioning brake system, if the 1) answer is No?

http://static.summitracing.com/global/images/prod/large/ssb-a0707_w.jpg

1) No, the prop. valve is not adjustable, but it does self adjust acording to load.
2) The aftermarket valve may jack with the ABS, and could be a major safety issue. Maybe someone has tried it with good results, they will chime in if they have.

Personally, I don't modify anything having to do with the brake system.

Thanks for the reply.

I build old hot rod stuff, proportioning valves are commonly used for disc / drum swaps, but old car stuff is commonly low-tech to the modern computer controlled stuff, the aftermarket valve may not be compatible whatsoever, this is my daily driver / trailer rig, safety is very important.

Your reply triggered a thought. The valve is adjusting due to load. A quick look-see under the truck, I don't see any load level sensors on the suspension. I'm now thinking this dynamic proportioning valve had an internal level sensor.

I cranked up my torsion bars a bit up about an inch way back then, since having slightly larger tires and for appearance.

3) Now my theory is that the level sensor (if it is an internal thing) thinks the truck is lower in the rear, applying the rear brakes heavier? If so, I may be able to slightly adjust the level sensor to accomodate the new horizontal level of the truck?

GM tried the 'level' thing in the '80s; didn't work. The way this works, now, is through the use of computers. In simple terms, the ECM can reads/monitor engine load, and through a highly scientific guess-a-mation (rpm x wheel speed / sq. root of how many fish I caught last weekend = brake proportion) can calculate how much weight your pulling and adjust ft./rear proportioning accordingly.
All of the 4wheel disc GM trucks ('99 and up) that I've seen, the rear breaks go before the fronts.