severe Nose driving while braking. *brakes*

[chris015]

87 truck. disk front/drum rear. stock.

truck has severe nosedive/sensitive brakes. rears feel like they are not engaging and its sending most of the pressure to the front. Ive bled them properly (right rear,left rear,right front,left front).

Truck sat for 15 years. Has new Master,calipers,pads,drums cleaned and adjusted. At first,either the front or rear tire would lock upon braking. after bleeding a ton of nasty fluid (which probably had water) they no longer lock up. Now just hard braking.

Im guessing the proportioning/metering valve is bad. Can you still get factory valves aftermarket? I might buy a aftermarket,but i really dont want to build new lines. thanks a bunch.

[rudey737]

There are a couple of things that this could be. I'll leave diagnosing the brakes to someone that knows more than me. However, the nose diving during braking could also be caused by worn out shocks on the front of the truck. I would check those as well.

As far as building new brake lines, there's no need for that. Pre formed brake lines can be ordered from any number of places like Inline Tube, LMC Truck, and probably some vendors here on our board. I usually try to order from board vendors first and LMC last. The first to support the board, and the last because LMC is usually the most expensive option. For example, a preformed set of brake lines for my 84 C10 longbed in Stainless from Inline Tube is cheaper by $25 than it is from LMC for an original material set.

I'll also be watching this thread to find out about the proportioning/metering valve. My brake light will come on and stay on sometimes and I think the valve is the culprit. I can't seem to find the valve at any of my local parts stores, or online.

Chris

[chris015]

kinda bumping this thread.

Front shocks were done not too long ago as far as it looks.

Did some more bleeding etc. seemed to help a tiny bit but the front brake pressure is still nuts.

im still leaning towards the valve.

So,Jegs/summits got some adjustable $40 valves.

Now....I doubt il get any help. (if you do help maybe in the next world il cut your grass) but does anyone have the sizes needed for fitting for the aftermarket valve etc to make it work?

[motornut]

I'd check the valve,seen them not reset (old from sitting)
If the light comes on,the pressure isn't right in it.
could the back brakes be out of ajustment(to far off?)
how many miles on the new brakes.
I'd even check the rear shocks.
when my rear shock mount broke off, it bounced like crazy

[donut]

Rubber hoses changed? May not be a problem, but after sitting 15 years, may not be in the best shape.
Did you do a "self adjust" to the rear brakes? Back up, slam on brakes. I'll usually use a dirt driveway. This will allow the self-adjusters on the rear to properly adjust the shoes on the rear. (providing the adjusters aren't installed backwards, done that...)

I believe that most of your braking is done by the front brakes anyway. Hopefully your problem is not enough rear brake as opposed to to much front.

[Mr.Chevy4x4]

I didn't see you say anything about replacing the rear wheel cylinders. If the fluid had a lot of moisture in it, the wheel cylinders are probably frozen from sitting so long. Check them to see if they are functional. Is the brake light on?


Mike

[bnoon]

Nose dive has nothing to do with the brakes themselves. Either the front or rear shocks are shot, your front springs are weak, or both. You said the truck sat for 15 years and shock valves can go bad from sitting just like any other seal, no matter what the outside looks like, and the springs sag on these trucks pretty bad too after all of these years. You should be able to put the biggest baddest brakes on the planet on that truck and nose dive will still have nothing to do with the brakes themselves.