mknittle

Have you checked your low vacuum switch? it is wired in parallel with the switch on the balance valve and the parking brakeswitch. Mine came on a couple times then flickered off and on. turned out to be the parking brake switch.

bigragu

I checked that, by disconnecting the harness to the low vac switch. Brake light still came on when pedal got depressed

mknittle

Some times the littlest things can be the biggest PITA. I wonder if the balance valve has some corrosion and the piston is frozen.

bigragu

Well, took the truck for a spin today finally. My injector showed up and got that in. My goal for the drive was not so much to check on the new injectors, but to see how the brakes reacted after swapping back to the stock 7/8".

Did some hard, panic stop brakes from around 40 mph. No more lock up and skid. In fact, I had to fully open up that adjustable prop valve to even make it stop. I can't say I'm overjoyed about it, but for now, it's good. I say that because looking back at all of it, I want to suggest to anyone, who has never upgraded to 3" shoes and 1 1/8" cylinders that that modification is the best bang for your buck, braking wise, IF you have a well functioning master cylinder, brake booster, and all other components brake related are up to par. I want to say that I miss those larger cylinders, but I just couldn't make those and the hydroboost fall in love with each other. Just too much. Having said that, I probably should have went with 1" cylinders, but the very thought of opening up those drums again makes me cringe. So, for now, 7/8" cylinders, combined with 3" shoes, brings out the best in the HB. I don't skid, but I don't lock up either. Just a slow smooth stop.

Still gonna tweak on it some more. My goals are to slightly lock up, and stay forward in a straight line.

samiam4

Glad to hear you have it fixed..

yes, dump and hub assemblies are heavy. Next time I will use gen 2 drum and brake assemblies


anyone know a good gm partnumber for the hydro boost from 1995-98 ish? Maybe I can find old stock one and a new mc.

bigragu

I take back everything I said, in my last post. Well, some things. The 1 ton upgrade is still a go, but other problems have arose that I need to diagnose. Almost another dirty drawer event, LOL

bigragu

Okay, update. So, I think I figured out what's been going on wrong. I kick myself, or better yet I'm gonna have all you guys kick me, for wasting a lot of time and stupid money for troubleshooting this lock up and skid issue from the hydroboost(HB).
So, to recap on my wasted efforts:
1. Lock up and skid. Too much power at the rears. So an adjustable proportioning valve was installed to tame the rears
2. Taming down the rears made me loose to mulch brake power. So, I installed new pads for the front, and swapped in smaller wheel cylinders in hopes of balancing it out, and not having to shut off too much pressure to the rears
3. Took it for a test drive. Was at a stop, with foot on brake pedal. All of a sudden, no brakes, and truck starts to roll forward. Pushed harder on the brakes. Nothing happens. Quickly put it in Neutral, to avoid crashing into guy ahead of me. Head back home.

So, this is what I found out, what went wrong. Not going to take all the blame for this, as the vendor I bought it from should have told me. The kit I bought came with a 50/50 reservoir, and was designed for either disc/drum or disc/disc systems. It was a true bolt on system, except the port holes on that Chevy style master cylinder had the port holes reversed. Our factory MC's have a fron port of 9/16"-18 feeding the rear brakes, and a back port of 1/2"-20 feeding the rears. The Chevy master is reversed. I plumed the front port to the rear lines, and the back port to the front lines, just like the factory MC. That was the mistake.
I went on some hot rod forums, and they all said that Chevy and corvette style MC's are designed as fron port for front brakes, and rears for rears. So, last night, I swapped in new brake lines, crisscrossing them.

Took it for a test around my circle driveway, and now, the truck literally "stops on a dime" in forward and reverse. I never felt my front lock up like they do now, before I re plumbed the brake lines. It pisses me off, that the vendor never clarified that, or the instructions mentioned that. After looking at diesel HB conversion pics, I see now why others didn't have my issues, cause those MC's came with 9/16"-18 already as the front port, like our factory MC's.

Anyway, long post. I am not too proud to share my errors. Hopefully this will assist someone else. I did not want to not say anything, and discourage someone from converting over if they read my problems. I still say, this has been the best mod yet, even more so now, that I've finally got it dialed in. I'm gonna do one more round of bleeding, then I should be all good.
Oh, those 7/8" wheel cylinders? I think they will suffice.

edwinsmith

Disc brakes use fluid as the pads wear down because there is no compensating self adjustment mechanism like the rear drums have. Therefore the bigger reservoir is for the front disc and the smaller is for the rears. The rears use hardly any fluid.

After I redid my calipers I noticed a big puddle of fluid on the driveway and the rear reservoir was empty. I had to clean and re-tighten the banjo joint at the caliper.

Edwin

bigredbrick

Regarding the RWAL system. It's my understanding that this system is the "proportioning valve" to control rear wheel lock-up for different load weights. Empty bed is prone to lock-up and obviously heavy load not. I had an 84 toita pickup way back that used an arm to a valve in the rear so that with a load the arm would be pressed and apply more braking to the rear.
Anyway, mine seams to be working so I'll keep it for now. There's was a long discussion about the RWAL system long time ago.

bigragu

It's funny, but when the topic of the RWAL valve comes up, its either loved or hated. Then there's the in between folks, like myself. I kinda rode the fence on this one, cause I didn't mind the pulsating brakes, but then again I've never had a fierce panic stop to see how they would react. I ended up removing mine, for the sole reason I could not bleed it correctly, and ended up stripping out the bleeder port beyond repair. Shortly after I learned about the RWAL delete. Got lucky there.