Help me STOP

[Burbinite]

I have a '72 GMC 4x4 suburban with stock brakes. Disc front, drum rear, power brakes. (this is my first 67-72...anything) It sits on 33x12.5x15s. I have to use a lot of strength to stop this truck quickly. When I pull a trailer without brakes it's a both feet on the brake pedal, push as hard as I can, with a quick prayer to get the thing to stop in a decent distance. Even with an empty trailer. (I'm not putting it back on the road until this is fixed)

Here's my question(s): is this normal? Is it really this hard for the stock brakes to stop this truck? Is it the oversized tires? If the answer is "no" I will replace brake components with stock replacements and hope that fixes the problem. If the answer is "yes" I will put an upgraded brake kit (baer or wilwood) that will stop this thing quickly and safely.

Any advise is greatly appreciated.

[Hart_Rod]

Could be your booster. Bigger tires = greater rotational mass therefore more stopping power needed. If your pulling a trailer you should install a trailer brake module.

Rob

[Burbinite]

How do I test my booster? or is there a way to boost my booster?

[lngbed71]

Take it to a brake shop, they can hook up your booster to a vaccum machine and determine if it's good or not. My bet it isn't if you have to stand on the pedal with both feet. Another way to test it is to check pressure differences on the pedal with the motor running, and again with the motor shut off. Tough pedal with the motor running = not good. My .02

[Brewski*]

Is your truck a 1/2 ton or 3/4 ton. If it is a half ton I heard of lots of 4x4rs swapping the booster out for one from a 3/4 ton and they say it stops the trucks awesome.

[Burbinite]

It's a 1/2 ton. Thanks Brewski, I will look into that.
Does anybody know if the booster from a 73+ 3/4 ton will fit my truck? Those are easier to find...

[Sublvr72]

you can swap a 73+ booster but you need to swap the whole pedal assembly. I dont think the 67-72 will be a direct bolt up.

[newin72]

you might have already done this, but sometimes we over look the simple stuff.

1. check brakefluid level?
2. test brake booster
3. adjust rear drums
4. get a 3/4 ton booster
5. ECE drumbrake upgrade kit: EVERYTHING you need to upgrade your rear drum brakes and increase braking power by 28%. new pad, drums, springs, slave cylinders, dust cover, EVERYTHING.

[4x4Poet]

The 33s would in no way overwehlm the brakes. Their weight over stock tires and rims might make any inadequacies in your brake system more noticeable, but not because the 33s are too much tire for the brakes, just heavier. And if the 33s are on aluminum rims, the weight difference would be negligible.

If, after you diagnose the brake problem, you choose to rebuild the brakes, Praise Dyno Brakes makes awesome upgraded components that are stock sized so you won't have to make any modifications and, in an emergency, you can use stock stuff available anywhere for replacements. PDBs pads and shoes are easier on rotors and drums, so you'll save in the long run. PDB uses kevlar in their composite so they can use less metal with no squeak like carbon fiber pads. For bling bling, PDB also offers nodular iron rotors and drums that are much tougher than oem cast iron. All fairly expensive, but worth it, IMO

[fde2blk]

did you rebuild the motor? bigger cam? stop good on freeway? if so may be low vacuume i added a vac storage tank from something w/pop up headlights