Cant Stop, wont stop.

[BBBURB]

Hi all, I am restoring a 1989 GMC R2500 Suburban 3/4 Ton

I changed the Front Disk Brake pads and Rotors with new ones, repacked the bearings with fresh grease. The brakes work great, they stop straight and fairly hard. I drive around on them all the time. But i cant lock up the front brakes! For normal driving everything works perfect but in a emergency I cant stop! Its just doesn't have the power. In an emergency i need to be able to lock the brakes up! I did flush the lines about 5 times, there was some serious goop in there. But after about the 5th flush it was flowing like a river. What could be the issue? Do i need to change out the caliper? I drive this thing pretty darn fast and need to stop! Please school me! What do I check?

Thanks!

 

[Blue Ox]

There's a reason they make anti-lock brakes.

I don't know if your brakes are actually working correctly or not, but wanting to lock them to stop faster is a completely wrong idea.

 

[Rickf]

Did this problem occur before you worked on the brakes? Does the truck have a vacuum booster or hydra-boost? Are the rears locking up? Is the proportioning valve working properly?

 

[BBBURB]

Did this problem occur before you worked on the brakes? Does the truck have a vacuum booster or hydra-boost? Are the rears locking up? Is the proportioning valve working properly?

When i got the truck it was not running and the brake lines were so clogged full of sludge the fronts worked but not well and the rears did not work at all. I used a vacuum to drain the whole system while my wife kept the reservoir full for me so as not to get any air in the lines. Once i saw clear pouring out all the fittings i tightening up the fitting while still under vacuum. The brakes are working good now but it feels like they are only working to 75% - 80% of their potential force.

I dont know if they are vacuum or hydra, I have replaced almost all the vacuum lines to everything including the reservoir.

You must be registered for see images attach

 

[HotRodPC]

It is not common for front disk brakes to lock up at all. Normally the rear will lock up. Now they will on snow, ice or rain slick roads. This is why when Anti Lock brakes came out they were first just Rear Anti Lock brakes. Later All wheel Anti Lock brakes were added for bad weather conditions. When tires are locked up into a skid, you have not control over the vehicle. The purpose of the wheels to not to lock up, if for you to be able to steer and control the vehicle around an obstacle in hopes to avoid it.

Reason the front don't usually lock up is, #1 Disk Brakes, #2 the weight over the engine over the front wheels makes it hard to lock them up. On the rears, it's generally much light weight and they will lock up much quicker than the front.

 

[BBBURB]

There's a reason they make anti-lock brakes.

I don't know if your brakes are actually working correctly or not, but wanting to lock them to stop faster is a completely wrong idea.

I ride Hayabusas and currently own 5 other motorcycles. I like to get up to about 130mph in the 1/8 mile just to stretch her legs and then stop quickly. I would never want to own anit-lock brakes though. just MHO. I prefer to be in control of my brakes and not a computer. Iva raced motorcycles at over 100mph in the pouring rain with no anti-lock brakes. (motorcycle races dont stop due to rain like NASCAR). I dont even think i would ride a motorcycle i couldnt lock up both brakes on. Most of my bikes came standard with Brembos on them.

That being said yes i do need to be able to lock them because at speeds over 100mph i need to bring the vehicle right to the edge of locking them. If i cant reach that edge then i cant dance. Maybe this vehicles brake system is not capable of that? (Thats what i was worried about).

But it should be able to lock them up at 10mph no?

I dont understand how they would make a 9,000lb vehicle that cant lock itself up. (Mind Boggled)

 

[Blue Ox]

1. That pic is vacuum boosted brakes. Hydroboost will help with braking force.
2. What HRPC said. Most vehicles I've driven it's hard to lock the fronts unless you blast them. Just hard force on the pedal rarely does it. My Suburban was a K10 and the original brakes were sketchy. Even with hydroboost their capacity to slow a 6000 lb vehicle was limited and they wore out in a hurry. I converted it to the same C6P brakes as my pickup and had stopping power aplenty, but still didn't seem to want to lock the fronts unless it was a smash-on panic stop. If your 2500 has the 11" drums your brakes will fall somewhere between the two.
3. I'm not a big fan of electronics either, but I see you understand the point I was making. Here's another: If you're driving a 6000 lb. truck over 100 MPH and want to push the brakes and suspension to that level you might consider getting a Porsche instead.

 

[BBBURB]

1. That pic is vacuum boosted brakes. Hydroboost will help with braking force.
2. What HRPC said. Most vehicles I've driven it's hard to lock the fronts unless you blast them. Just hard force on the pedal rarely does it. My Suburban was a K10 and the original brakes were sketchy. Even with hydroboost their capacity to slow a 6000 lb vehicle was limited and they wore out in a hurry. I converted it to the same C6P brakes as my pickup and had stopping power aplenty, but still didn't seem to want to lock the fronts unless it was a smash-on panic stop. If your 2500 has the 11" drums your brakes will fall somewhere between the two.
3. I'm not a big fan of electronics either, but I see you understand the point I was making. Here's another: If you're driving a 6000 lb. truck over 100 MPH and want to push the brakes and suspension to that level you might consider getting a Porsche instead.

Thank you Blue Ox. That is very informative.

I used to be a design/proto Engineer for a Porsche GT3 Race Shop in San Clemente. I drove GT3's every day. Its just not my thing. I like to be able to drive my car to the grocery store without getting mobbed by kids.

Thanks for your help all. Im going to look into Willwood brakes.

 

[TubeTruck]

I agree BBBURB, I like to have the ability to lock the brakes up also. Anti-locks were designed for people who can't control a car in a skid (IMO). The only way I've ever been able to lock up all 4 was when I put 1 tons in my 1/2 ton, the brakes being bigger than the vehicle. My current burb is lucky it slows down with it's 1/2 ton brakes and hydraboost. Can't wait to put 1 tons in this thing. Let us know what you decide to put in. I'm interested.

 

[Arkansas_V8]

Thank you Blue Ox. That is very informative.

I used to be a design/proto Engineer for a Porsche GT3 Race Shop in San Clemente. I drove GT3's every day. Its just not my thing. I like to be able to drive my car to the grocery store without getting mobbed by kids.

Thanks for your help all. Im going to look into Willwood brakes.

This is gonna come out making me an *******. But I dont mean anything by it.

How could you design for a Porsche and not know the difference between braking systems?

 

[82sbshortbed]

I've never heard people advocating for their brakes to lock up. Lol

I've driven bikes and cars over 130 before and never once hoped if I had to hit the brakes I wanted them to lock up. That's stupid imo because you lose steering and control but, whatever makes you happy.

 

[Arkansas_V8]

I have had many cars without ABS. A few that liked to lock up. They lock up 10x easier in the wet. I dont want a bunch of idiots that think they need to lock the brakes slamming into me.

My Suburban on cold mornings at first start will lock the fronts with ease. Have you had a 6,000lb Suburban lock the brakes up? It is a stupid ass idea.

 

[shiftpro]

I like lock-em-up brake strength as well. Not that would... but an experienced driver would appreciate the power. Juice brakes all the way for me. Nothing gets hippies off the road than hearing 6 tires skidding at them... oops well I guess I just admitted I like to lock em up at times. But THAT's
understandable!

 

[Blue Ox]

Anti-locks were designed for people who can't control a car in a skid (IMO).

No kidding.

Remember, the vast motoring public sees a car as nothing more than practical transportation. Why do you think the Toyota Corolla was the best selling car in America for so many years? Because the most boring, bland, soulless, should have an ice dispenser in the door because it's nothing more than an appliance, drives like a shopping cart, steaming POS is viewed as a great choice by most people.

Now these same people, the majority of whom believe they are above-average drivers (think about that for a minute) only understand that if you want the car to go faster you push this pedal, if you want it to go slower you push that pedal, and have no idea what to make of any other pedal. So much so that they had to put the parking brake on a hand lever because if these people saw a third pedal way up on the kick panel they wouldn't buy the car because they can't drive stick, get into a situation where Isaac Newton takes over, their reaction is to press harder on the stop pedal, because it's the pedal that makes the car stop. More "stop" is better, right?

So yes, those people are why the .gov mandated antilock brakes on new cars.



I need a nap.

 

[shiftpro]

My first anti-lock experience scared the crap outta me, I let go of the brakes and steered out of the situation I was braking for, as my left foot instinctively was hunting for the E brake. That was years ago in an Astro Van and I was skidding down my icy back alley. Good van btw but I disconnected the anti-lock by pulling a fuse. Overall braking was highly improved, and worked like juice brakes should.