Hey guys,

I just did a rear disc brake swap on my 2005 CCSB Sierra Z71. I went with the 13" Tahoe brakes. I used all new components, retained the parking brake, used Hawk LTS pads and Powerslot rotors.

Less than 1K on the truck since taking it down to do the brake swap, gears (3.42 to 4.10) and a Truetrac. So far I'm pretty happy with the brakes.

The only thing I'm a little worried about is the proportioning valve (abs unit). I kept the stock unit so far. I'm not really concerned about proportioning but I'm worried about having higher residual pressure in the rears than is needed for the discs.

I have usually read that drums require around 10psi of residual pressure and that discs typically only need about 2psi. A little concerned that the extra drag could cause excessive wear and/or heat buildup (at cruise, not when braking).

I think I'm past the point where I should still be smelling stuff cooking off on the rotors but the rears having been smelling pretty warm to me sometimes when getting out of the truck after freeway jaunts.

So, for guys who have done the swap what did you do about your ABS unit, did you keep the stocker or swap to the donor vehicle unit? This is the one aspect of the swap that I had a hard time finding much decent info on. Has anybody who kept their drum ABS unit noticed the rears wearing too fast or warping?

Thanks in advance!

 

The abs pump does not control fluid pressure, the master cylinder does that.

 

Yes the rears will wear faster. The cheapest solution would be to add an adjustable purporting valve.

The ABS valve body is controlled by the EBCM and that's how they compensate for pressures.

There is no way to modify these perimeters and the dealer will only Program what your vehicle was originally equipped with. If there was a similar year with the disc as an option you can try swapping that electronic module and see if notice the difference.

Because of liability no one will mess with this. I have have a friend that did the swap and we already went through this.

At least with the adjustable valve you can dial it in to your needs. We never got that far and he gave up so I don't know what effects it will have or if it will work 100%