Ok fellars, I usually don't bug everyone with my truck issues, but this one really has me stumped....

The truck:
1992
F150
2wd
longbed
It does have the Rear ABS.....

I have acquired a THUMP when I apply the brakes, you stomp the brakes, the rear wheels lock up (A no-no, since it is a RABS truck) and it sounds and feels like someone hit the rearend with a sledgehammer....Softly depress the pedal, it sounds like a gentle TAP.....W-T-F?

The brake pedal is very solid, not spongy feeling, the front brakes are new, and the rear brake drums were replaced yesterday....It seems to have softened the THUMP, but it is still there....

I have new rear brake shoes, and spring kits to put on the rear....Then the only thing left to replace is just the Wheel Cylinders...

So what does it sound like to you guys?

Thanks in advance-

-Wes



P.S-The mechanic that helped me put the rear shackles on adjusted the shoes to fit the new drums, and that also seemed to help.....The old P/S drum had a fleeck broken off the outer rim of the drum, it was a place roughly 2" x 1/4".......Just noted that in there to possibly help diagnose this issue....And btw, the broken area looked REALLY old....

 

I'm gonna throw this out there...
Egged out rims at the lug pattern?
Also check the drive-line for a binding at the splines.
(Does it happen at acceleration?)

Put the new brakes on the rear, and let us know. You don't need to replace the cylinders, unless they're leaking...

 

I bet it has nothing to do with the brakes, it will more probably be worn u-joints, engine or tranny mounts (check those carefully, sometimes they're broken and you won't notice unless you look very closely).

 

While the truck was on the rack, I pushed on the driveline a few times, no play....

-Wes

 

The new drums and rotors they sell these days are junk. Out of round,warped,ect. It could be a sticking wheel cyl,they are not hard to change and pretty cheap.

 

Check the transmission crossmember where it mounts to the tranny for rust and breaking out of member. Mine did the same thing.

 

I HATE REAR DRUMS with a passion!
IMHO... Return all the drum breaks parts you just bought...

Convert to rear disks and never look back! If I could have done it all over again I would have done the same. Drum breaks are a PITA!!!!!!!!!!!!!!!!!!! Ford Sterling Disc Brake Bracket, '84-'94 [Sterling] - $50.00 , Reviews

 

Mine did the same thing and it turned out that the rear parking brake cable was seizing up. I replaced it and the problem went away.

 

Thats the next project, after the gauge swap...I'll give all the drum brake parts to dad for his F-150.....God it'll feel good to have 4 wheel disc brakes.....

-Wes