Vibration in 4wd front end after brake job?

[JJorgensen52]

I just did a full brake job on my truck - new drums, wheel cylinders, rubber lines - and added a power booster (had to redo most of the hard lines in the process). Bled the system out, lubed the starwheels and replaced springs, etc as needed (shoes were new about 6k ago and were fine). Truck stops GREAT now.

Problem is, I have a front end vibration between 30 and 40mph. It was really bad at first, has diminished a bit. It is not consistent - doesn't happen every time I pass that speed range, and goes away when braking.

Had to remove the hubs to do the front wheel cylinders, have double checked the adjustment and the bearings are tightened to spec with no slop.

Anyone have any ideas as to what this could be? Symptom is new since the brake work. The only thing I can think of (having eliminated the bearings) is that maybe I have an out of balance tire that was on the rear and got mounted up front? Could one of the drums have a non flat mounting surface?

For reference info:
1969 K10, front Dana 44 w/ drums and closed knuckles. 15x8 steelies with 31x10.5 BFGoodrich All Terrain TA/KOs. Tires, shocks new within 6k. Driveshafts are both new, pro balanced. NV4500 / NP241 that has probably 800 miles on the swap and no prior issues.

[vectorit]

Did you have the drums turned?
You could have a shoe that is dragging and chattering.
Do you have self adjusters up front?
I ran into all kinds of bugs after I did mine, though I didn't have vibration just a dragging shoe which got hot.
Did you use cleaner on the shoes specifically intended for brake pads/shoes?
I didn't turn my drums, though I went to Lowe's and got a emery wheel for my drill and lightly scored the surface of the drums to avoid a glazing issue.

Just a couple thoughts.

[cdowns]

did you clean and grease the wheel bearings?

[JJorgensen52]

Originally Posted by vectorit

Did you have the drums turned?
You could have a shoe that is dragging and chattering.
Do you have self adjusters up front?
I ran into all kinds of bugs after I did mine, though I didn't have vibration just a dragging shoe which got hot.
Did you use cleaner on the shoes specifically intended for brake pads/shoes?
I didn't turn my drums, though I went to Lowe's and got a emery wheel for my drill and lightly scored the surface of the drums to avoid a glazing issue.

Just a couple thoughts.

Drums were new replacements, did not have them turned. Everything was cleaned with brake cleaner prior to assembly.

Fronts do have self adjusters, disassembled after 60 miles and the adjusters are working as intended

Originally Posted by cdowns

did you clean and grease the wheel bearings?

I did not clean and grease them, only because I did it about 5k miles ago, so I just gave them a quick once-over (had the hubs apart) and adjusted to spec. Haven't noticed any heat on the hubs, or bearing noises

[cdowns]

do you think it's easier to have to change spiindles than spend the effort and do the job correctly and use new grease?

[JJorgensen52]

Originally Posted by cdowns

do you think it's easier to have to change spiindles than spend the effort and do the job correctly and use new grease?

Nope, changing spindles would be no fun - same time, I see no reason to remove the bearings, clean out all that still clean high-temp bearing grease I put in there, and replace it... I did check them, everything was still clean and lubed as it should be.

[vectorit]

I am wondering now if you have a drum that could be really out of balance?
Were your old one completely trashed? If not, clean them up and throw em back on to see of the vibration goes away.

Such a PITA... I went through this too.

[Ironhorse]

I would agree with vectorit, check the new drums as suggested. I always make it a point to turn new drums and rotors from the parts house. Just don't trust the quality assurance on new rotating parts like that now days. Just a thought.

[JJorgensen52]

Originally Posted by vectorit

I am wondering now if you have a drum that could be really out of balance?
Were your old one completely trashed? If not, clean them up and throw em back on to see of the vibration goes away.

Such a PITA... I went through this too.

Old fronts fell apart from 40 years of road salt...

I'm thinking I'll swap drums side to side up front and see if it changes