[Mike S]

I have a 98 GMC 2500 that I bought a year ago.I finally got around to fixing some things on it. My last problem is the brakes. They work fine but the pedal has a lot of travel in it. Will a bad brake booster give you a lot of play in the pedal? If I pump the brakes 3 times with the engine off the brakes are right there. While holding the brake pedal down after I pump them up and then start the truck my brake pedal will go down 4 to 5 inches. Don't know if this is normal for GMC's. My ford the brake pedal only has mabey 1 inch before brakes start to apply. This GMC has 4 to 5 inch before the brakes start to apply.

thanks

[68 green bird]

Hey, I have 96 chevy 1/2 ton that does pretty much the same thing, I have now just replaced everything except for the power booster. (Except the brake light comes on and pedal goes to the floor) hope someone here can help out .

[nh68gto]

Its a GM truck thing they all suck. Friend is a mechanic, and mostly GM stuff. From old to present they go to the floor. I drove his 03 GMC 2500HD last week and almost went through a stop sign because of it. I then get in my 05 Ram and almost go thought the windshield they are so touchy. You can replace every part on the truck and will still have a soft pedal.

I have had many GM truck and don't miss the brakes in them.

[judgethis]

Mike when you pump the pedal with the engine off you are basically having no power brakes, like old cars without boosters. When you start the vehicle you are then getting the assist of the booster. It is normal for the pedal to go down when you start the vehicle and this lets you know the booster is working.
Have you tried bleeding the brake system (power bleeding). Also make sure your rear brkes are properly adjusted. 96 to 99 gm trucks did tend to have spongy brakes though. When I worked in the dealership that was a big complaint. I think there was a bulletin about it, Ill check it out.

[rod cole]

If it has ABS it is normal. It is part of how the abs gets enough pressure to work and then bypasses the rest. It will work normal when driving just not what you are used to. Rod

[poncho-mike]

My 96 Suburban 2500 has a 454 with the JD7 brakes, so it has hydroboost. The power assist is powered off of the power steering pump. If you pump the brakes with the engine off, you are getting no power assist. If you then crank the engine, I expect the pedal will go down because you're now getting power assist. With the engine off, you're not going to be able to build much pressure. If you have any doubts about the engine providing boost, cut the truck off and try to stop without the motor running. You have to really stand on the pedal to get it to go down very far.

Do you have vacuum assist or hydroboost?

Mike

[stimpy]

tighten up the back brakes... Gms bendix self adjuster setups don't ( murphys law of mechanics #16 ) , if you have the 11-13" drums they do this all the time , I have to adjust mine every oil change or sooner if I pull the trailer , and I have all new mechanicals except the wheel cylinders , also my brakes got bettter when I put braided stainess lines on the flex line portions , I had the front left hose swelling ( you could see it when the pressure was applied )

[cuz68]

Originally Posted by poncho-mike

My 96 Suburban 2500 has a 454 with the JD7 brakes, so it has hydroboost. The power assist is powered off of the power steering pump. If you pump the brakes with the engine off, you are getting no power assist. If you then crank the engine, I expect the pedal will go down because you're now getting power assist. With the engine off, you're not going to be able to build much pressure. If you have any doubts about the engine providing boost, cut the truck off and try to stop without the motor running. You have to really stand on the pedal to get it to go down very far.

Do you have vacuum assist or hydroboost?

Mike

My 88 gmc done the same thing, I hated it runing off the power stearing, I think that was a bad ideal on GMC.

[Mike S]

I have the vacume power brakes. Well anyway, tighted up the back brakes and bleed them. No air in the brakes line. Pedal is a lot better. I can live with it now.
Thanks for the idea's

[stimpy]

the brakes are supposed to adjust up by backing up and appling the pedal ( normal backing ) , but they don't seem to do this you can also do it by appling the e-brake and releasing it several times you will here the adjuster click in the drum assy , I think the dust and corrosion is what keeps them from working properly , I used neverseize( thinned out with linseed oil ) on the adjusterscrew and it seams to work better. my kids brakes on his 1500 seam mushy to me but I have hydroboost on my 3500 , Gm brakes always felt this way compaired to Other Brands .

[Polar-Pontiac]

Originally Posted by nh68gto

Its a GM truck thing they all suck. Friend is a mechanic, and mostly GM stuff. From old to present they go to the floor. I drove his 03 GMC 2500HD last week and almost went through a stop sign because of it. I then get in my 05 Ram and almost go thought the windshield they are so touchy. You can replace every part on the truck and will still have a soft pedal.

I have had many GM truck and don't miss the brakes in them.

THat is a can of Bull-***** .My 2500hd the brakes would put you on the hood.I worked at Midas as a Brake Mech never had a problem.Maybe it's the guy with the wrench in his hand...

[68 green bird]

Originally Posted by Polar-Pontiac

THat is a can of Bull-***** .My 2500hd the brakes would put you on the hood.I worked at Midas as a Brake Mech never had a problem.Maybe it's the guy with the wrench in his hand...

Do you have any ideas how to fix are issues here ? thanks.