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Discussion Starter · #1 ·
So heres the next issue... My brakes suck. They just seem weak. I bought and installed new brake rotors and pads thinking that it was an issue of the brakes sliding on the rotors and not gripping tight enough... The brakes are "better" but not as good as I want. If I stop, I can virtually push the brakes all the way to the floor and I don't get that "tires about to slide" feeling that I like. The brakes don't pulsate, and it doesn't feel like there is a huge loss in pressure, but I do notice that my foot sinks down very slightly. I have a feeling that its a sign of my brake master going, but I'm not 100% sure. I think the truck has been like this since I bought it, so its not related directly to big"er" wheels. I could wait like I did with the drive train until its 100% obvious, but then since I pull my car trailer a lot, that could be a big deal when it finally goes. Then again, maybe I am just not used to a big truck like this, and I don't know what its supposed to feel like. I do know that with my steel car trailer ~900lbs, and my car, ~2500lbs, I have to push the brakes all the way to the floor to stop "quickly" and at no point do I feel the front brakes locking up, or the ABS light coming on. Someone at the auto parts store I normally go to said it could be the brake booster, but since I can push the brakes effortlessly, it would be a surprise for that to be the issue.

As always, I appreciate any, and all responses. Thanks guys!
 

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Jack up your rear end (and put it on jacks). Put your vehicle in neutral and have someone step on your brakes and see if you can turn your rear wheels by hand. If you can your calipers are either siezing up or leaking internally. If you can't turn them, well they are obviously working. you said your foot sinks down, how far does it sink down? Will it go all the way to the floor? If it constantly sinks to the floor then it is probably your master cylinder leaking internally. They are pretty easy to replace so don't worry to much.
 

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Discussion Starter · #4 ·
It will sink to the floor. I think its just a sign that its getting worn, and it doesn't have as tight of a seal as it used to. The crazy thing about the pedal though, it doesn't have any problems returning to the upright position. Typically if a master cylinder is going, it will leak both directions. Oh well, its 90 bucks. I wonder if I am going to have to bleed the stupid brakes again? Thats one of the most messy things in the world.
 

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Your master cylinder is likely bypassing fluid if the brake goes to the floor and there are no external leaks. It happened to me with a Dodge van I had one time. The peddle always came back normally. The front brakes should come on at the same time as the back. What is happening is the fluid is bypassing and you are only getting rear wheel braking. Hope this helps.
 

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You can fill the new master cylinder and bleed it before you install it. Then just hook up the brake lines to the master cylinder snugly. Then have someone push once on the brake and bleed at the front line on the master cylinder. Then do the back one . If the master cylinder was bled right before installation you should get little or no air when bleeding.
 

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Discussion Starter · #7 ·
Sweet. Thanks bud. I'm going to put a new one on tomorrow.
 

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Discussion Starter · #9 ·
Well it made it a little better, no doubt my old one was getting worn, but....

Still not quite what I want. I don't feel like the front tires are going to lock up and that makes me not think the brakes are grabbing hard enough. I'm looking in to different options right now, and it looks like the only other thing I will be able to do is try out some braided lines. If that doesn't give me the grip I want, I'm pretty much SOL.
 

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My truck is behaving the same way as yours ('95 Suburban with 230k miles). So far I've replaced the master cylinder, both front calipers and hoses.

I'm leaning towards bad rear brake hardware (specifically the self-adjusters leaving too much clearance). Or the reman'ed master cylinder has a bad quick-take-up valve.

When I find the time I'm going to follow the steps in these two articles from "Brake & Front End" magazine:

Diagnosing Spongy Brake Pedals: Solving Before Installing

Follow a Diagnostic Process When Curing a Low Brake Pedal

Let us know what you find out on yours. I know it's a big heavy truck, but I feel these brakes should inspire more confidence!
 

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Im going to say its the rear brakes, do you have disc or drum brakes in the rear, GM has been known to undersize the drum brakes in the rear causing a soft pedal feel
 

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With everything you have tried I would think there are only two more to check out. First have the brakes bled to all wheels to make sure there is no air in the system. Then the only other thing I can think of is the ABS electro-hydraulic control unit on the left frame rail underneath the driver. If the lines were or any part of the brake system has ever been apart or enough air has gotten into the brake system the truck may have to be taken to the dealer to have the control unit cycled electronically to center the internal valve.
 

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Discussion Starter · #13 ·
Thanks for responding to my thread. I don't honestly remember if I replaced the master cylinder, I think I may have skipped it. I'll take a look this evening and get back to you. I'm also going to take a look at those links!
 

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Discussion Starter · #14 ·
Looks like I did replace the master. I vaguely remember doing it, but the master it's self was new, so I figure I did.

Anyway, any chance of any one new taking a look at this and knowing what the problem is? It's driving me mad. It is basically like the brakes are half as powerful as they should be. There is no "skipping" like typically is present when a braking system has air, they just feel weak. Since it's been a while, I've been keeping an eye on the rotors, and everything is wearing fair, so it HAS to be something between the pedal and the pads. I just know there is a problem because only like 3 times in the entire history I've owned this thing have I seen the ABS light. With the crap braking system I'm used to, I'm not sure why they ever even put the system in the vehicle because it doesn't seem like it would have the ability to lock the brakes in the first place.

The times I've seen the light are pretty much when it's raining and the road is super slick, I have my foot ALL THE WAY down to the stops of the pedal, and I'm going over railroad tracks. Short of that, there ain't no way this thing could EVER lock up the front wheels.
 

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I just started reading this thread, and it appears to me that you've tried all of the 'correct' fixes I would of recommended. Now it's time to turn your attention to better brake pads! Everything you outlined, would have led me to suggest that there is (or was) air in the brake lines. However, having solved this problem on MANY GM trucks, the last and only option I can and will suggest is... a more aggressive brake pad compound for the front brakes. I have sold and recommended 2 types of pads. The brand is made by Wellman (Hawk) and the type of pad is called the LTS (Light truck SUV) compound. I have sold several hundred sets to Nissan Titan owners, along with rotors to cure the same issue you're experiencing. There trucks are notorious for also warping rotors! The other compound is called the 'Velvet Touch' and it's designed specifically for Fleet or Heavy Duty use. Both are a Carbon Metallic formula and offer a significant improvement over ANY so called Premium pad offered either by the dealers or through the national parts stores.
If you'd like additional information, just send me a PM and I can hook up with for pricing and details.

Keith
 

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thread closed due to age, if new information is needed start a new topic please.
 
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