1999 8600 gvw brake questions.
 

My 1999 2500 7.4 hydro boost brakes have sucked since new.
Have done 6 sets of pads 2 sets of rotors. And yet to change rear shoes.

Done some reading here.
NBS master sounded good but not with a hydro boost truck.
More reading lead to using a 3500 wheel cylinder. Its a 1-3/16 bore vs 1-1/16 stock.
Has anyone done this.
About to do new shoes tomorrow and stainless brake hose.

Front rotors pads bearings and stainless brake hoses this afternoon.

Pedal feels okay, but want more.

Checked in the GM shop manual
 

It says in the Hydro boost section, excessive effort may be due to a pressure problem from the power steering pump.

There is a gauge that is obviously needed J5176-E (highly expensive) and a procedure of checking power steering pump pressures in different situations. However, I think this would be done if you found that brake fluid pressure were low.

The brake system pressure test is much easier to test and the gauge to do so is dirt cheap. I bought one years ago from Summit.

Oddly enough the manual never mentions the brake fluid pressure range of operation. It merely refers to the brake pedal pressure required to depress the pedal.

Unfortunately the brake pedal effort gauge is J28662. is over $450.

You could ignore all that and obtain the brake system pressure tester from some where like Summit https://www.summitracing.com/parts/ssb-a1704/overview/

In the kit it lists typical pressures. If after testing you feel it is low, then maybe go from there. I don't know what you could do to increase the pressure if all the components in your vehicle are working within design specs. But obviously if you are in the lower end of the operating range, you may be able to bring it up.

The power steering pump incidentally has a pressure relief valve in the back of it that may be sticking. Perhaps you could replace it and see what happens. I wouldn't think it is very expensive.

Good luck to you

Re: 1999 8600 gvw brake questions.
 

The pedal is mushy.
If I apply the parking brake about half way and tighten up the rear shoe adjustment. It feels normal.
And 2 different hydro boost units too.

All that being said.
At 115-k and the rear shoes are oem. It's either a application or adjustment problem.
I guess I'll swap the wheel cylinder for the 3500 ones and see what happens.
Really wish it was outboard drums like my dana- 60 in my other truck.

Re: 1999 8600 gvw brake questions.
 

If it gets better when you partially apply the parking brake, it sounds like the rear brakes aren't properly adjusted. The self adjusters on these trucks don't always work.

Re: 1999 8600 gvw brake questions.
 

Pics of what I'm working on.
The family truckster for 19 years now.

Re: 1999 8600 gvw brake questions.
 

I'd tend agree with that.
But the adjustment stays the same on both sides
Either the adjuster isnt aggressive enough or it wants more application pressure.

And the 20 year old brake hoses cant be the best.

Re: 1999 8600 gvw brake questions.
 

Partially applying the parking brake doesn’t change anything hydraulically. You ruled out a hydraulic issue.

Re: 1999 8600 gvw brake questions.
 

Maybe.
But a bigger wheel cylinder will apply them more as well. I should not have to manually adjust my brakes on weekly basis or apply the park brake.
If the wheel cylinder helps the pedal feel I will report back.

Re: 1999 8600 gvw brake questions.
 

Our friend from Amish country is correct. It's not a hydraulic issue.
You need to free up the star wheels on the adjusters and then do an initial set of the shoes via the adjuster.
You need a drum brake spoon and a flat screwdriver. You may be able to do it with a flat screwdriver.
This is a brake spoon.
Attachment 1840020

There should be slots in the face of the drum or the bottom of the backer plate with plugs. Sometimes they were not knocked out so you get to drill and file the access slots.

This is a smaller axle but American cars all work pretty much the same way.

Re: 1999 8600 gvw brake questions.
 

The adjusters were pretty tight.
Leading shoe had just got to the rivets.
Trailing shoe looks really good.
New wheel cylinders in, shoes on one side.
Ran out of daylight. I'll know tomorrow if it helps or not.
117k on rear shoes and multiple sets of front pads and rotors leads me to believe the back needs more help.

Re: 1999 8600 gvw brake questions.
 

P.s I'm wishing I'd spent the $500 on a disc kit. I really dont like drum brakes.

Re: 1999 8600 gvw brake questions.
 

Rear disc kits generally suck on these trucks. An elderado caliper has a piston too small and a parking brake that doesn’t hold. You can put bigger calipers on but you lose the parking brake.

My truck had a disc brake kit with elderado calipers when I got it. Braking was terrible. I put early 80s c20 front calipers on and braking was great. But I didn’t have a parking brake. I later switched to a 2001-2007 2500HD axle in. Then I finally had discs and a parking brake.

Then I did this to the front:

http://67-72chevytrucks.com/vboard/s...d.php?t=732837

Re: 1999 8600 gvw brake questions.
 

I'm working a 2wd though.
That's good to know about the disc kits. Although if the shoes went 117k theyll out last the life of this truck for me.

Kinda impressed how nice everything cleaned up

Re: 1999 8600 gvw brake questions.
 

This is a relevant thread since I also have a K2500 that I have do a four wheel rebuild on the braking system. I've already replaced the master cyl. and hydro-boost unit. So I'm following along on the drum rebuild.
I installed a rear disk conversion over ten, maybe fifteen years ago on my K1500. It was a Stillen kit with an internal drum emer. brake. I was fretting earlier this year because I wore down the rear pads to metal and was told by a rep at Stillen that they no longer have parts for this kit. It turns out I was in luck because the calipers used are the same ones on my '98 Firebird. I had an extra set of pads and I was able to get the rotors turned and be back in business. I never had complaints about braking on this truck with this kit. My truck stops smoothly and quickly in my experience.

Re: 1999 8600 gvw brake questions.
 

My wife drives this one usually.
I like driving my '68 or the 73 better. So she will be the judge tomorrow.

Parts so far plus front wheel bearings and seals.
And rear wheel seals.

Re: 1999 8600 gvw brake questions.
 

Have to ask, I had a '96 C-3500 SRW and it had outboard mounted drums. Your '99 has inboard?

Re: 1999 8600 gvw brake questions.
 

Yeah unfortunately it does.
Even less impressed with spindle nut retainers. A piece of square stock and a spring clip.

My '68 has outboard drums with a dana 60.

Re: 1999 8600 gvw brake questions.
 

That will work with 2wd. Just use 2wd hub bearings and forget about the cv axles.

Re: 1999 8600 gvw brake questions.
 

Those nut retainers have been used for over 50 years. They work really well.

Re: 1999 8600 gvw brake questions.
 

Did it space the wheels out any further?

Re: 1999 8600 gvw brake questions.
 

The front no. The rear was about 1/2" per side.

Re: 1999 8600 gvw brake questions.
 

Well... took a big swing at our crew cabbie in the last 2 days.
Not sure which one component or the fresh bleed and new brake fluid or brake adjustment made the biggest change but it finally has a nice pedal.
And stops like I've always thought it could.
Only took 19 years of not liking the brakes to do something about it.

Now to fix the heater core next. Stupid trucks Ha-

Re: 1999 8600 gvw brake questions.
 

The Hayes ABS motors are notorious for holding onto air.
The 2000 and 2005 service manuals say to use a pressure bleeder at 20PSI. You can build one fairly cheap or buy a Motive Products brake pressure pot for $50.

Even the expensive aluminum master cylinder cap from Motive isn't as good as the GM J tool because it doesn't have a plug in the center with an O-ring that seals the cap to the master cylinder. You can find the J-35589 GM pressure bleeder master cylinder cap on Evilbay all the time. I paid $15 for mine.

J-35589 GM quarter turn pressure bleeder master cylinder cap.
Attachment 1840658
Attachment 1840657

Re: 1999 8600 gvw brake questions.
 

Those are great for the GMT800 trucks. But these GMT400 trucks have a big square opening in the top. Its hard to get a pressure bleeder to work on these.

Attachment 1840659

Re: 1999 8600 gvw brake questions.
 

I just flushed the Impala and the 2005...
The 2000 is a T400 and I'd forgotten it still has the square reserviour. I'm looking forward to that task even less now...

Motive makes an aluminum cap for the square reserviour Master Cylinders that actually works on the older square plastic and cast iron MC. I have one and it doesn't leak on the 2000 as long as it's assembled properly. I usually dispense with the dog chain and use welding clamps. The last time I flushed the brakes out in 2015 I thought about making an easier to use cap with an o-ring on the milling machine. I may do it this time.

I have used a chunk of 1/2" thick ABS plastic cutting board from WalMart, welding clamps, brass pipe, and inner tube for a seal.