Soft Brake Issues

Have a K3500 1998, brakes have not been the best on this truck. Have changed out the master cyl and purged the antilock. Still if I had to stop short because of traffic ...it will not happen. This truck has a hydro boost on it . 6.5 turbo diesel. Kinda at a lost of why it is very poor brakes. Mike

There are many other components in the system.

What else have you replaced / checked / etc?

Calipers
Slave cylinders
Rotors / drums
Frictions
Hoses
Hardlines
Combination valve
Fluid (type and condition)


Hydroboost relies on the PS pump. Any pump noise? Any changes noticed in the steering boost?


ABS functions normally?
ABS bleed using a scan tool?

Most of the time, soft brakes on these trucks are because the rear drums are out of adjustment. Get your rear drums in top shape first, and then bleed the crap out of the lines until the fluid is clear with no bubbles.

Erik the Awful said:

Most of the time, soft brakes on these trucks are because the rear drums are out of adjustment. Get your rear drums in top shape first, and then bleed the crap out of the lines until the fluid is clear with no bubbles.

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Rear drums were cause of soft brakes on my 93. The drums can wear enough that even if you adjust the shoes they can still be soft. Replacing rear drums fixed my soft brakes. Of course, I found this out after replacing MC, checking brake booster, replacing all soft lines, replumbing to removed disfunctional ABS, and bleeding 20 times……

1998_K1500_Sub said:

There are many other components in the system.

What else have you replaced / checked / etc?

Calipers
Slave cylinders
Rotors / drums
Frictions
Hoses
Hardlines
Combination valve
Fluid (type and condition)


Hydroboost relies on the PS pump. Any pump noise? Any changes noticed in the steering boost?


ABS functions normally?
ABS bleed using a scan tool?

Click to expand...

No problems with the power steering pump, If the brake lines were the issue it would give me a hard pedal, this is just the opposite, if I push long on the petal, the pedal will almost go to the floor. Seems that it is weeping, almost like a bad master cyl, that is why I changed it. and I tested the master again by putting in plugs and hitting the petal, hardly no travel in the pedal at all. All of the hard lines in the front have been changed from the proportional valve to the front calipers. This truck has shoes on the back. no leaks noticed on the back of the brakes. rear brakes have been adjusted again. yes brakes were purged using a scan tool for the anti locks. No codes on the antilocks.

Sabinoerc said:

Rear drums were cause of soft brakes on my 93. The drums can wear enough that even if you adjust the shoes they can still be soft. Replacing rear drums fixed my soft brakes. Of course, I found this out after replacing MC, checking brake booster, replacing all soft lines, replumbing to removed disfunctional ABS, and bleeding 20 times……

Click to expand...

I will go pull the rear and check out what might be going on. Thanks

Helvie said:

No problems with the power steering pump, If the brake lines were the issue it would give me a hard pedal, this is just the opposite

Click to expand...

I had a very mild leak in the rear brake line a few years ago. Brakes worked “ok”, no noticeable fluid loss, but during an inspection I noticed wetness on the brake line. It’s something to look for.

After replacing the line, and rear hose w/ braided stainless, the brakes were much improved. The replacement hose no doubt contributed to the improvement, but fixing the leak was a factor undoubtedly.

I had leaking brake cylinders and no sign of external leak. It was when I pulled the rubber boots back I realised the mess they were in.

Went out yesterday and checked out the adjustment on the rear shoes. They were good, one way I can tell if they are out of adjustment is applying the emergency brake, it only went down 3 to 4 inches. I will next pull the rear drums and see if the Cylinders has movement to push out the shoes. If not I will look at the rubber lines going to them and the cylinders . The cylinders and hoses are 1998. It might be the issue because when I am pulling my 33' trailer I noticed that I can smell the front pads burning when I am trying to stop and the trailer brakes having kicked in yet. because of the delay from my box. Which is hard to set with this problem. Mike

I'm having similar issues. I had to tow a car on a dolly a few days ago and noticed my front brakes were getting real hot and my rear didn't seem to be doing much. Like you, my parking brake seems to be functioning well.
I was doing a search and this thread came up. I'm wondering if you found the problem with your truck.