91 front brake issues.

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T

TBetts

Joined
Jun 5, 2021
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68
Location
Ca
I've been reading all I can on every forum about braking issues and nothing seems to help. Everyone seems to point to the load proportioning valve but from what I've gathered that only affects the rear.

It seems to brake fine until I really mash them or if I'm in low and have to push hard to make it not creep forward or reverse. Regular street driving doesn't seem to be the issue as long as I give myself plenty of room to stop. The fronts will not lock up and they make a creaking noise at low speeds.

I've pulled everything off to inspect and measure. Nothing is looking bad or out of spec. Replaces the master and tried a new booster but the problem is the same.

Any help would be appreciated
 
Last edited:
Assuming you got a good bleed and all the air is out of the system? Checked the brake booster?
 
Fj80oregon said:
Assuming you got a good bleed and all the air is out of the system? Checked the brake booster?
Click to expand...
Brake booster past the tests from the FSM and I've bled the brakes 4 time, 2 south a vacuum 2 using the peddle. New fluid and master cylinder. Put a different booster on and no change.
 
Maybe a silly question, but did you bench bleed the master cylinder? And make sure that the fluid level didn't drop below the minimum level while bleeding?
 
On a 91/92 with rear drum brakes, the setting of the rear shoes plays a large role in brake performance, as well as the setting of the LSPV.
Frequent use of the handbrake when parking the truck will help keep the shoes set correctly, assuming the adjusters are working properly and the rear shoes are in good condition. Pull the drums and inspect. Wheel cylinders can be rebuilt with OEM parts or replaced.

If you lifted the truck at all, you'll want to adjust the LSPV to max height to increase rear brake pressure. This will give you a firmer pedal feel, assuming the rear shoes are working correctly.
Front calipers can be rebuilt using OEM parts or replaced. If your front calipers are 33 years old, you might consider having a look at them.

If your soft brake lines are 33 years old, replace them.

The vacuum system will have a profound effect on brakes. If you have clogged vacuum lines under the hood or if the EGR valve and EGR regulator are faulty, this can cause vacuum system issues.
 
jonheld said:
On a 91/92 with rear drum brakes, the setting of the rear shoes plays a large role in brake performance, as well as the setting of the LSPV.
Frequent use of the handbrake when parking the truck will help keep the shoes set correctly, assuming the adjusters are working properly and the rear shoes are in good condition. Pull the drums and inspect. Wheel cylinders can be rebuilt with OEM parts or replaced.

If you lifted the truck at all, you'll want to adjust the LSPV to max height to increase rear brake pressure. This will give you a firmer pedal feel, assuming the rear shoes are working correctly.
Front calipers can be rebuilt using OEM parts or replaced. If your front calipers are 33 years old, you might consider having a look at them.

If your soft brake lines are 33 years old, replace them.

The vacuum system will have a profound effect on brakes. If you have clogged vacuum lines under the hood or if the EGR valve and EGR regulator are faulty, this can cause vacuum system issues.
Click to expand...
Excellent!
 
jonheld said:
On a 91/92 with rear drum brakes, the setting of the rear shoes plays a large role in brake performance, as well as the setting of the LSPV.
Frequent use of the handbrake when parking the truck will help keep the shoes set correctly, assuming the adjusters are working properly and the rear shoes are in good condition. Pull the drums and inspect. Wheel cylinders can be rebuilt with OEM parts or replaced.

If you lifted the truck at all, you'll want to adjust the LSPV to max height to increase rear brake pressure. This will give you a firmer pedal feel, assuming the rear shoes are working correctly.
Front calipers can be rebuilt using OEM parts or replaced. If your front calipers are 33 years old, you might consider having a look at them.

If your soft brake lines are 33 years old, replace them.

The vacuum system will have a profound effect on brakes. If you have clogged vacuum lines under the hood or if the EGR valve and EGR regulator are faulty, this can cause vacuum system issues.
Click to expand...
What rebuild kit would you suggest? I'm only finding a few made by duralast and performance brakes.
 
I bet you have air in your lines....use speed bleeder valves to get all the air out in the correct order from FSM. You might have to do it a few times!
 
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