Brakes work until i hit them hard then i loose back brakes

[NGaudet]

it is the wierdest thing i hit the brakes hard an loose the rear brakes

almost like the ABS is giving up any one see this symptom any fix for it ?

[IowaCummins]

the rear abs system is what is causing it. most guys just unhook the black box behind the glove box but this i think is the abs valve located behind the fuel tank. all it is is a cylinder that moves to cut off fluid supply to the back so it does not skid. the cylinder must be sticking. either you can replace it or do what most guys do and unplug the box and run the brake lines straight from the master cylinder to the rear bypassing the abs valve with just a short piece of brake line. that is what im thinking but im sure some of teh other will back me up or have other casues. good luck

[PToombs]

Yup, it's the ABS valve. The valve inside to the accumulater is sticking open. I usually recommend a valvectomy. Remove the valve, you can buy 2 fittings to connect the existing lines together, the part numbers are on the site someplace. Or, you can replace the line from the front and go straight to the hose coupling, which is normal brake line thread.
And because you are removing a sensor in the valve, the ABS brain will freak out and make the lights come on, so you need to unplug the brain box like IC said.

[IowaCummins]

Woo i got it right!

[NGaudet]

Woo i got it right!

So if i want to repair the issue will changing this valve correct the issue ?

is this the way it is supposed to work or is it actualy a defective valve assembly I dont mind it i just want to be ready for it no supprises etc

Thanks in advance for your Knowledge

Norm G

[dpuckett]

The system was originally designed to run without the AntiStop Valve in place. Then our Big Brother Government decided that rather than letting people learn how to drive again, they'd MANDATE rear (and later, 4-wheel) anti-lock brakes. Dodge went the easy route, putting an AntiStop Valve in the rear system, and leaving the rest alone. So, the only change you will notice with a Valvectomy is increased, DEPENDABLE rear braking.

Side effects include shorter stopping distances and increased front rotor life. You may notice the rears wanting to lock on wet/ icy surfaces (duh!!), though. Better than having the rears let go at the worst possible moment, though.

[Ace]

I don't know if anyone's actually ever engaged the RWAL on one of these things, but to me, that was scarier than losing traction.

[PToombs]

Norm, the valve failed. That's why it acts like that. You can replace it if you want. Most just bypass it and live happily ever after, myself included.

[chrislib]

FWIW I just did rear brakes on my truck, new 3in. shoes/drums/GM wheel cyls & hoses. After spending an entire sunday and 1/2 gal of brake fluid I FINALLY got all the air out of the system. The pedal height and feel are 100% better than I had before, truck stops waaay better under NORMAL braking. I think I may have the same issue as the O.P. , I decided to test the brakes on empty road to see how they react with all the new parts, under HARD/panic braking the pedal gets very soft and low but the ABS is NOT kicking in as I know how that feels (a leaky wheel cylinder WILL cause very aggressive brake action,lol). I have a strong feeling that the dump valve accumulator is allowing the brake pressure to bleed off too easily causing the weird pedal feel under heavy braking. I think a dumpvalve-ectomy is in my trucks near future, anyone have P/N`s for the necessary fittings needed to bypass the dump valve?