1992 Truck XCAB DLX - 2.4L 22RE

A few months ago replaced front pads, rotors, both front calipers, passenger side front soft line, bled at front wheels where work had been done, and repacked bearings using a bearing packer. After this, on initial test drive brakes became touchier and touchier after several applications, and began binding and smoking.

Dealer replaced master cylinder, LSPV, bled system, and cleaned and adjusted rear brakes.

Brakes are no longer binding/smoking, but now, while brakes do stop the truck, everything happens much closer to floor board than before. Complained to dealer on picking it up that this didn't feel right. They checked it again, test drove it, and assured me it was as it should be saying "these trucks are like that". After that exchange decided to cut my losses with them and took it home.

Let it sit awhile, and recently started back looking at it. Rear brakes appear ok to me - clean and dry, no sign of leakage, plenty of material on shoes. Shoes appear to be adjusted out enough, can hear slight contact rotating drums. Parking brake works, cannot move truck with it applied, 16-18 clicks.

Got a Motive power bleeder and rebled the system (DR, PR, PF, DF, LSPV) pushing a little less than a quart of new Valvoline Dot 3 and 4 fluid through, taking approx. 6oz out at each bleed point. Absolutely no sign of air at any of the bleed points, just clean new fluid came out at each.

Tried Booster checks listed in FSM. Three of the four checks, both "air tightness" checks, and one "operating" check seemed to be as they should be if I'm interpreting them correctly. On the other operating check, result seemed off to me. For this check FSM says "Depress the brake pedal and start engine. If the pedal goes down slightly, operation is normal.". On this one, when engine started, pedal went down not slightly, but several inches which seemed a lot to me. What I've found online so far talks about booster being bad if it does not go down some on this test. Have not found anything that says what it means if it goes down a lot.

Is my booster bad? Could this cause soft feeling pedal with braking happening close to floor? Most that I've seen about bad boosters mention brakes being excessively hard to push with no assist.

Only other thing I can think of is if they messed up on the pushrod adjustment leaving too much of a gap so rod/pedal moves too much before contact is made with piston.

Any ideas or suggestions? Wondering if I should just go ahead and replace booster and take opportunity to check pushrod adjustment. Thanks in advance for any advice.

 

Good post. So what do you measure the "pedal reserve distance" at this is the distance between the floor board and pedal. You'll find this detailed in your service manual.


Bracket fatigue we normally hear from the clutch but I don't thing I've ever heard of the brake pedal shifting, it's worth a look. While you are up under the dash you could poke around the rod also and maybe pull some measurements.

 

The binding and smoking that you had before was definitely pushrod adjustment. Nothing else in the system will do that

 

Bad boosters will make the brakes hard and ineffective.
You can often hear a whoosh from the booster while depr3ssing pedal.
the easiest way for me to diagnose a bad booster is if the pedal comes back slow.
all those service manual tests confuse me.

However, I dont recommend anyone doing what I do. Trounleshoot step by step or make more work for yourself.

 

So lets play detective. Brakes are binding, the shop pulls back the pushrod so they stop binding and dont want to keep adjusting it, although if they opened the manual i think theyd see a measurement for it. Its easier to pull the rod back too far than to get it just right.
thats just me thinking like sherlock holmes i guess
these trucks can and do brake as well as any other vehicle on the road. Its just a hydraulic system.

how i adjust pushrods is overextend them so youd have pressure on the mc to mount it on the booster then back it off until the rod just barely makes contact with the mc. You should be able to mount the mc without feeling resistance against it as you torque it down. Not by the book but mostly foolproof.

If qll your hardware is new, and you cant bleed anymore air the only other thing I can think of is adjustment of the rear star wheels. There is an easy procedure for this too, although again not by the book...