suburban proportioning valve

[phantom309]

brakes are awful on this burb, (99 c2500) new to me last fall,
there is talk of an updated proportioning valve,. also using a 2002 master cylinder
Has anyone here done either mod?
if the truck was a 4x4 i could use later model brakes with bigger rotors and better calipers,. but i have 2 wd,.

thanks for any help

[Kennedy]

What I used to do was run a cast iron MC off say a 1984 6.2. The proportioning valve does not let the rear brakes do much of anything. I believe the way this was done was to use a prop valve from a 1 ton wrecker type vehicle that was "open" to the rear, but it's been so long now.

Maybe Ron Schoolcraft remembers?

[sctrailrider]

You should be able to use the MC & prop valve from a 1ton. The HD MC's are for rear disc and they have a bigger bore piston & a disc prop valve.

[Kennedy]

I checked and RJ did not do it to his. Howie may have done it or maybe Jim Glus. Glus was yacht4u or something like that. Admin may have a better way of narrowing the search. I'd wager that the part number was posted here at some point 15+ years ago...

Possibly 12548265

[DmaxMaverick]

Originally Posted by Kennedy

I checked and RJ did not do it to his. Howie may have done it or maybe Jim Glus. Glus was yacht4u or something like that. Admin may have a better way of narrowing the search. I'd wager that the part number was posted here at some point 15+ years ago...

Possibly 12548265

That part number shows only in this thread/post. Nowhere else.

Search (advanced: click search at the top of the page, then "advanced search") for "proportioning valve" in all open forums, with no other terms. Any added terms narrows the results too much. Set the "show results as" to threads, rather than posts to help weed through the irrelevant posts. I got hundreds of hits (posts) that date back to 2003.

[Kennedy]

I'm guessing that 2003 was a forum software change date and that much of this discussion fell prior to that. I reached out to a GM tech friend and previous owner of same era trucks hoping that he recalls the bulletin.

To me the cast iron MC made a huge difference.

[trbankii]

RockAuto shows a variety of part numbers for the '84 K20: https://www.rockauto.com/en/catalog/...+cylinder,1836

Is there something specific that one would be looking for?

[Kennedy]

12548265 proportioning valve.

18029651 shoes


This was based on vehicles with the big 13" x 3.5" rear drums, but likely works with others as well.