Brakes for towing

[stutaeng]

...as was mentioned, all 96-00 GMT400 C/K 3500 have hydroboost, besides the C/K 2500 BBC/Diesel. Same also applies to the Suburban C/K 2500s.

You should be able to find any of those at just about any wrecking yard that has GMT400s. You could buy a new/remanufactured hydroboost, but they usually want a core.

 

[L31MaxExpress]

I wouldn't expect it to help, as your engine isn't notorious for having low vacuum (unless you're prone to apply the brakes repeatedly while at wide-open-throttle).

That's more of a product targeting engines with low idle vacuum (e.g., long duration camshafts).

However, it reminds me: You should check the condition of the vacuum hose running from the intake to the brake booster's vacuum canister... I don't think this has been mentioned earlier. Although I don't expect it's bad, take a look for cracks or other deterioration, particularly where it's been stretched around the male fittings. If it needs replacement, you'll have to get a hose rated specifically for vacuum and not just any old automotive hose.

Too, check the vacuum check valve and rubber grommet on the booster. It should hold vacuum long after the engine's been shut-off... indeed, if you remove it from the booster (which is usually pretty difficult, as the rubber seal / grommet is usually good at its job), you should hear a "whooosh" of air rush into the vacuum canister indicating it's doing it's job of sealing the canister from outside air.

Vacuum level really doesn't matter. Hydroboost still makes more boost than the highest vacuum on vacuum boost. Like kick the ABS in at 75 mph kind of braking power on my Express.

 

[RichLo]

Like somebody else has said, as long as your current breaks are upgraded with aggressive pads/shoes, fresh rotors/drums and stainless flex lines your vacuum booster should be sufficient for what you need. And you can keep the hydroboost upgrade as a wishlist item to save up for and slowly collect parts as you find them.

 

[Ruff Idol]

So where should I start rotors and pads ? Calipers ?… etc And what do you recommend brand wise ?

IMHO, these trucks are doomed for squishy brakes with the stock setup. Do the NBS master cylinder upgrade, you will not regret it. Just need an adapter fitting for one of the lines, bend em where you want em to go and the new master is pretty much bolt-on. I did this to my '92 along with fresh rotors, pads, and drums (old hardware was like a decade old) and now the brakes are better than any vehicle I've owned so far.

This is after you've confirmed the pads, rotors, and drums are functioning properly. Here's a writeup on the process & what size adapter:

How to: NBS master cylinder swap for firm brake pedal

 

[1998_K1500_Sub]

IMHO, these trucks are doomed for squishy brakes with the stock setup. Do the NBS master cylinder upgrade, you will not regret it.

Too, confirm you're using (or will be using, as replacements) the JB7 front calipers. They have a large diameter piston (3 5/32” IIRC) and, in particular, are not the "quick take up" variety like the JB5/JB6 calipers, which means they're better suited for the NBS MC.

You likely have the JB7 calipers already on a K2500, but that's not for certain. The calipers are physically interchangeable, so fitment isn't an issue if replacing JB5/JB6s with JB7s.

Some people swear by the NBS upgrade, some swear about it. For me, it made a HUGE difference in the brake feel and performance, albeit in combination with other changes on my Suburban (JB7 front calipers - JB8 1.1875" rear cylinders on 11" drums - SS lines - bleed). The Sub weighs 3020# in front and 3160# in the rear, so the JB8 rear wheel cylinders are welcome addition to the stock 11" drums. These changes, and with "only" vacuum assist, it brakes very nicely. But I'm not pulling big trailers around, either.

 

[Supercharged111]

Like somebody else has said, as long as your current breaks are upgraded with aggressive pads/shoes, fresh rotors/drums and stainless flex lines your vacuum booster should be sufficient for what you need. And you can keep the hydroboost upgrade as a wishlist item to save up for and slowly collect parts as you find them.

Agree to disagree. I did all that, lived that way for years, and was never happy with my brakes until I added hydroboost.

 

[1998_K1500_Sub]

Agree to disagree. I did all that, lived that way for years, and was never happy with my brakes until I added hydroboost.

I had a somewhat similar experience.

I had swapped to the NBS MC, JB7 front calipers, and SS lines in front only, and the braking was much better but still not what I thought it could be. At least on panic stops I wasn't going white-knuckle and sucking air like I used-to. OMG, the OE system sucked in panic situations.

I bought (and still have, NIB) a hydroboost ACDelco assy and sat it on a shelf, intending to install it... sometime. Got the PS cooler too, used. Figured I would buy the hoses just-in-time.

Fast forward: The rear brake line started leaking (I caught it early, it was just "wet") so I replaced it, along with the rear hose (using SS line), and also the drums' slave cylinders with the JB8 1.1875" diameter ones (OE diameter was 1.000").

Whoa!!! What a difference those last couple of changes made. They, or I should say the sum total of changes, made the Suburban brake very nicely.

So I've left the hydroboost on the shelf. I'll keep it there, and in fact I ought to get off my a$$ and locate the appropriate brake pedal assy so I've got the hardparts ready, should I find the desire to pull the trigger.

 

[Frank Enstein]

A few things that are often overlooked;

Make sure the calipers float properly.
Bolt the caliper down without the pads. You should be able to slide them in and out with one finger. You may need to push FIRMLY with one finger. If they don't fix it. Use official brake lube only. It really is better.

Check the rear backing plates for wear on the raised pads where the shoes contact the backing plate.
Weld/braze/smooth them out or replace them if needed. The shoes get stuck and it leads to inconsistent braking.
I smooth the contact areas of the shoes with a wire wheel to remove any burrs. Do not remove any metal! Just smooth them out.
Put a small smear of brake lube on the backing plates so they will move smoothly next week as well.

Bleed the system well. If the brake fluid is dark it is dead. I use the Earl's Solo Bleed bleed screws. They have a check valve built in making bleeding ultra easy. They are sold by size. You need diameter, thread pitch, and overall length to get the right ones.

Braided PTFE hoses are a very good upgrade and really help with the brake feel. Be warned if you do braided brake hoses on one vehicle you will put them on everything else you own. The same goes for the solo Bleeds.

Upgraded frictions are next. Pads/Shoes have a letter code that tells how hard they pull. The first letter is for cold braking and the second is for hot breaking like when the trailer is on the back. The farther down the alphabet you go the harder they grab. The higher level of braking frictions may accelerate drum/rotor wear as well as increasing brake dust production.

Follow the friction manufacturer's bedding procedure. I does make a difference.

Please do not tow anything heavier than the truck is rated for. Even the best brakes won't give you heavier bearings, frame, or axles.

 

[1998_K1500_Sub]

Pads/Shoes have a letter code that tells how hard they pull. The first letter is for cold braking and the second is for hot breaking

Please cite some examples of this ^^^

I just checked RockAuto and looked at pads for a 1998 K1500 Suburban w/JB6, and I see lots of letters (codes?) for the "369" series of pads:

- RAYBESTOS MGD369MH
- RAYBESTOS SSD369
- RAYBESTOS MGD369CH
- WAGNER ZD369
- BENDIX SBM369
- BOSCH BE369H
- WAGNER MX369
- ACDELCO 17D369CH
- BOSCH BP369
...

Looks like alphabet soup to me. Perhaps for one vendor I can see a trend, but across all vendors the use of letters appears rather unstructured.

 

[Frank Enstein]

I don't think they come up in the part numbers but they are ink stamped? on the friction material itself. There is a thread around here somewhere. I learned it from here. the letters will be FF, HH, or EF or something like that. The closer to "Z" the more they want to toss you out onto the hood.