1988 Chevrolet Suburban V20 build

[Larry]

That is the Height Sensing Proportioning Valve. Its purpose is to make you pull your hair out after a suspension lift. Actually, the idea behind it was to regulate rear brake fluid based on load (rear suspension height). The best way to handle that on a lifted Sub is to remove it. You can take the main brake line from the frame to the HSPV unscrew it and screw it straight into the rubber brake line on your axle (the hose on the bracket near the fuel tank) then just remove the valve. That is what most people with old lifted Burbs do, including me. I gave up trying to adjust it for the lift.

The valve would not cause your pedal to be spongy. You must still have air in the lines somewhere or issues with the brake cylinders in your new axle. Any fluid leaking out of the brake drums?

 

[cop car]

No fluid leaks what so ever. Brakes fully lock up and also will hold it in 4 low going down hill. The rears may need adjusted still. But the fronts as long as they are bled would be all good. They have been like this for 4 weeks now. With like 1000 miles of driving no change.

 

[Erik N]

View attachment 175593

ok, so what is this thing? it has hydraulic lines going to it, it was attached to my old rear end by this little scissor like lever. is it a brake bias thing that's why my brake pedal goes down really low right now even though I thoroughly bled it? if so what is my fix for that?

I have the same issue, low pedal. Like 1" off the floor IIRC. Is that device adjustable?

No fluid leaks, new rear springs, stock ride height '88 V20. The system is bled.

Also, the brake warning light will regularly click on with pedal application, and click off with another. I figure there must be a floating piston somewhere in the circuit that is slightly mis-adjusted.

 

[Chevrolado]

Looking like a great rig so far! VERY nice work. I'm definitely going to be watching this one. Nice..

 

[Larry]

I have the same issue, low pedal. Like 1" off the floor IIRC. Is that device adjustable?

No fluid leaks, new rear springs, stock ride height '88 V20. The system is bled.

Also, the brake warning light will regularly click on with pedal application, and click off with another. I figure there must be a floating piston somewhere in the circuit that is slightly mis-adjusted.

As I mentioned above, a Height Sensing Proportioning Valve will not cause a spongy or low pedal. A spongy or a low pedal will be more a rear brake shoe adjustment issue, defective brake hose or simply more bleeding is needed. In your case, it almost sound like you just straight out need a new master cylinder. It would be a stretch, but you may even have an issue with the main proportioning valve not being centered (that is the valve below the radiator support on the cross-member). Does your Sub have RWAL (Rear Antilock)?

Back to the Height Sensing Proportioning Valve, yes….it is somewhat adjustable but from years of experience messing with these things, it isn’t worth messing with. They have been the source of brake performance and brake wear issues on G-vans and Suburban’s ever since they were first installed back in the late 80’s. Just take it off and screw the supply line to the HSPV straight into the main brake hose at the axle and call it a day. No parts needed other than line wrenches.

Here is some info from the GM service manual on the Height Sensing Proportioning Valve.

 

[Erik N]

Thanks, Larry. I was going to bleed the brakes again when I head out there next year. I'll change out the MC as well.

Pic of sleeping Suburban:

 

[zbros106]

1997 K2500 Suburban 4WD camper conversion

Hey guys, I know its a little late to repond to your thread, but a couple years ago I built a 3/4ton suburban 4wd with the vortec 454/4l80E/dana 60 diff. posi, 33in BFG's and rancho 9000's. I've used it for camping with room for two, it has central a/c and heating, a heavy duty roof rack, winch, a small kitchen, sink, cabnets, invertor, c/b etc. It can be a little tight, but it works well and I can go almost anywhere and can be used for pulling my toybox and as a daily driver. I live in the mountains and I use it often. My only complaint is that it needs lower gears and the gas mileage. If you guys want I could send some pictures. The interior cost me about $500 doing everything myself. Thanks, Jeff

 

[VoodooCLD]

zbros, you should start up your own thread and post pictures of it. I would like to see it.

 

[ColoradoBurban]

I'd like to see pictures and details about the interior mods, thanks!!

 

[Rovertrader]

I just acquired a '87 2500 and want to do the Blazer conversion- where is the best venue to find the needed rear clip/removable top?
Thanks, and really enjoy this thread- thanks for posting! I also have a 80k '76 K30 w/ a 513, front D60/14 bolt FF rear that just might find their way to the 'burb, although after reading through this thread, I have some measuring to do first ;-)...

 

[cop car]

if its a rear end out of a 1 ton truck you just have to cut off the spring perches and then the shock mounts. its not really that difficult. I thought it was going to be horrible but it really wasn't bad, just took some time. as for the blazer top, I was going to buy a truck or try to get the parts out of a junkyard. at the prices junkyards charge now-a-days you are better off just buying someones blazer that has no motor/trans, or buying a decent one and just chopping off the top yourself, then scrap or sell the K5

back to my truck, so the randomly dying issue was bad wires going from the coil to the distributor. the break in the wires was under some insulation I guess because when I would wiggle the wires it would kill the truck. $2 junkyard fix (after a $30 cap and buying a complete distributor for $20 from the junk yard) im just glad it is fixed

my next question is this: I need to put another radiator core support in my truck now... I eventually would like to do the 73-80, round headlight front end. I don't really want to do a full clip swap, can I stick in the 73-80 core support and it work with my radiator? that's my biggest concern, I know that most the holes for the fenders wont line up, but I can make something work. I want to see if the 73-80 hood would go on with the 73-80 core support but 81-91 fenders.. I know its a really odd request ha. I just really don't want to have to swap core supports twice..

 

[cop car]

nvm. they look completely different. so time to go to the junkyard and find a core support