Vibration, 79 FJ40 (1 Viewer)

[Btchnfj]

Ok so I simply have a bad vibration starting at 50mph, worst at 55mph, and goes away at 60mph.

Just took it to the shop to have the rear drums adjusted and wheels balanced and trued but was told my vibration is caused from a recent axle repair I made. They haven't told me anything else other than that. Going to pick it up tonight.

Back story, I removed the driver side rear axle after another shop told me a axle seal was bad after they discovered fluid in the brake drum. Come to find out nothing was wrong with the seal and that the wheel cylinder was causing the fluid in the drum. Put the axle back together with fresh oil and replaced the wheel cylinder. I failed to adjust the wheel cylinder out properly which ended up causing some braking issues that resulted in new front calibers being replaced multiple brake bleeding, the recent shop just adjusted the rear drums for me. But during the brake issue it resulted in sticky front calibers causing overheating. The overheating also caused the driver side weights on the wheel to not completely come off but become loose.

So my questions are could anything listed above cause the vibration, and if it could be coming from the axle itself what could I have missed when assembling it that could cause a vibration at high speeds, if anything.

Thanks for any help you can provide. When I get the cruiser back tonight I'm going to double check the Phase of the drive shaft and possibly rotate the tires to see if it changes.

Oh lastly, the shop said the center arm, or bell crank is bad causing eratic steering conditions, should I try to adjust before rebuild, and if so how do I adjust the center arm. thanks.

 

[1911]

If the working angles of both u-joints on the rear drive shaft are not close to equal, they will yield a vibration at a specific speed as you describe. You already mentioned making sure the yokes are in phase, but while you're down there looking at the yokes, put a magnetic "angle finder" on the pinion flange and the transfer case rear output flange and see what working angles you are running.

 

[sggoat]

Curious, but when did the vibration start? That would help to pinpoint what might be causing it.
As for the braking issue-not sure why a rear drum/cylinder problem would affect the front discs at all--they are separate systems-the only common point is the Master Cylinder(even that is split into front and rear)

 

[georgia fj40]

Center arm adjustment is pretty easy. Loosen 14mm bolt, crank down 22mm, then back it off half to a full turn. Then tighten back up 14mm. Also pump grease til it oozes out cleanish while everything is loose. The truth is told when you drive it. It should return to center by its self. May take several times to get it right. When you reinstalled your rear drums did they seat flush on rear hubs? No debris inside drums or on hub? Also may be worth your time to adjust rear wheel cylinders

 

[georgia fj40]

Wheel cylinder adjustment is done by jacking up that axle. Adjust the wheel cylinders out evenly via rear slots until you can no longer turn wheels by hand, then back off on them 1-2 turns until you hear them dragging. You should hear drums drag some and have some resistance to them.

 

[shawnfj40]

My first thought is to check your Ujoints. Its possible that any of the things yo mention an cause a vibration.

 

[Btchnfj]

So I picked it up yesterday from the shop, and as where I was under the impression that it was something I did it doesn't seem to be that. The mechanic said he is feeling a vibration during acceleration, and believes its coming from a slightly out of adjustment pinion gear in the rear diff. Now I had the Diff rebuilt years ago along with everything else. So I would believe now that the vibration I'm feeling HAS to be a tire losing weights. I started feeling the vibration after the onset of this brake issue. I believe I have it down to one tire, my front driver side, its the side that would stick the most and get the most hot, the weights aren't gone but a few have become unstuck to the wheel and kinda hang from it. As for the rear drums now. I had the shop adjust, WAY better, pedal movement is much nicer. Not sure why the rear wheel cylinders could cause sticky brakes but that what a read in a few forums here. So you gotta try the cheapest possibilities haven't checked to see if its changed anything yet since the vibration does worry me a little. But now I can feel the vibration during acceleration...it kind of a bummer. Well thanks for the suggestions.

 

[micruz60]

Rotate the tires? Isolate the one, sounds like you've done that if its the front left...
Pinion and u-joints are first look, or... wag - a broken motor mount?
Did you do as 1911 suggested above?

 

[MOTOV8R]

I think the most common speed related vibration is tire balance. Skill and equipment for balancing tires can vary quite a bit. Make sure you are getting a lug centric balance.