2nd Gen Non-Engine/Transmission Part on the frame?????

[AMatsonIII]

Replaced part of the rear brake line today. There is a part that is tied in with the brake line. It is attached to the Frame and there is a rod down to the axle. I am not sure what this is. It all needs to be replaced. There is excessive rust and almost rot on and the small line and the rubber hose to the axle for the brakes. What does it do and what is it called.



thanks

ALex

 

[B.G. Smith]

The thing you describe is called "The Height Sensing Proportioning Valve". It restricts some of the brake pressure to the rear brakes when truck is not loaded. It is not serviceable and must be replaced as a unit. bg

 

[AMatsonIII]

Thanks for the info. Should i bypass it as a TSB says or buy a new one?

 

[B.G. Smith]

I couldn't find the TSB under your year truck but did find it under older tucks. As I understand the TSB, it is for trucks that are 75% loaded most of the time. Surely someone on the forums who has had this problem will chime in. bg

 

[SRath]

Here's the rub: If you tow heavy alot, you really should look into installing a set of AirLift, or Firestone, or RideRite airbags to keep the truck level. They work very well. If you doubt that, check the rear suspension on almost any modern semi tractor.



Your truck will steer and stop much better when level. You could also then buy softer rear springs for a much nicer ride, though you certainly don't have to. The air suspension will handle the loads.



However, doing this (keeping the truck level under all load conditions) will negate the function of the braking ride-height sensor and make the truck think it is empty and provide insufficient rear braking. So the solution is to bypass and eliminate the doggone thing. It is just an adjustable proportioning valve.



It would seem to be a rather un-needed feature on trucks with antilock rear brakes, anyway. On those without rear antilocks, like my old K30 which also had the height sensor, an underhood adjustable proportioning valve with a knob I can tune works much better for balancing front-to-rear braking under various loads.

 

[NoSeeUm]

I have been wondering about this for the longest time. I haul a slide in camper and am using air bags.



How did you bypass yours?



Jim

 

[SWC]

What years were the proportioning valve used? I have been under my 01. 5 with the disk brakes and have not found it.

I have no complaints about the brakes on my truck. I had 91 chev 3500 that I could lock up the front wheels if it I was loaded heavy and had to panic stop. I had a couple of pucker factor incidents with that rig!!!

Stan

 

[Joe Mc]

Guys I had same rusted line between tank and frame rail. I took the remove the tank, remove rusty line and bend up a new one approach. During this method I also noticed the small line from the proportioning valve was rusty as well and bent up one for it while I was in the bending mode.



I replaced the hose & block from the pro valve to the housing and the lines from the block to the brake plates as well.



IMHO if the proportioning valve isn't leaking it's fine . . . why spend the cost of a few tank fulls of fuel on something that's otherwize fine. I did mine last spring and all is fine.