'Bout to change the upper control bushings in an '86 runner, research has shown that I'm in for an undertaking. Just wanted some advice from from you guys to see if I'm looking in the wrong area. I've got vibration at 65-70 mph that comes and goes, sometimes it'll cruise smooth and straight other times enough shaking to make racket up front(and it doesn't seem to affect the steering wheel as much as you think it would). I've been searching for the vibration for awhile replacing all balljoints and tierod ends, idler and pitman arms, repacked front wheel bearings (after being cleaned and inspected thoroughly), and a new set of tires. Still the same. When I got an alignment with the tires the tire guy pointed out that my drivers side upper control arm bushings were dry rotted and getting compressed, and couldn't be aligned (free inspection of all the new front end parts anyways). Asked him if the bushings could be the culprit of the shaking. He said that it could help, but they wanted almost $500 to do it. so I imagine they would tell me anything to get the job. do you guys have any experience or idea's about what this might be? Anything else to check? Or if those bushing are coming out, do you have any advice that pertains to my pulling my frontend apart further than the upper balljoints.

Vibrations at speed tends to be a balance issue. Is the vibration felt through the steering wheel, or through the seat? If it is in the seat, your rear driveline u-joints could be going bad, or the driveline could be out of balanced. Have you had the wheels looked at?, you could have a bent rim. Did they rebalance the tires?, or rotate them to see if the vibrations moved?, you could have a bad tire.

don't think the control arm bushings would cause vibrations, they would tend to cause a clunking noise when taking off and comming to a stop, poor tire wear, a bit of wandering on the highway, and as you know alignment issue.

I just had a new set put on about 4 months ago and it had the same shake to it before and after. It seems definately be coming from the front yet only shakes the steering wheel a little. for got to mention before I noticed while crossing some reflectors on the freeway that were closely spaced the frontend seemed very loose and made the same kind of shaking just more intensified. Yet everything is tight and I still get times were it still cruises smoothly at the same speeds.

No more suggestions? nobody else has had this problem before? I guess I need to write a book then. I balanced the old set of tires and the new set before they went on. there aren't anymore trouble spots where the front suspension can loosen up? as I said I don't think that it's in the steering as the steering wheel dosen't shake/rattle as much as the front end does. any help would be appreciated.

Check your idler arm, bushings won't cause a vibration and certain speeds, that's a tire balance issue. If the idler arm is worn and the tires are out of balance, you'll get that loose feeling in the steering wheel.

I would also look into your tires/rims/ujoints (and idler arm) as well. Since your vibration is only intermittant, than I would consider suspension/steering last when diagnosing the problem. Make sure your steering doesn't have excessive play in it (sure you already did that though).

How big tires are you running? I have 33x12.5's and sometimes I'll just get small vibrations because of the bad highways in RI. You're SURE all 4 are balanced? U joints are snug and unworn? Is the vibration only limited to front end? Any other driving noise elsewhere?

linky

I did this writeup prolly back when I was in highschool but its on repacing the bushings with poly which I do recomend. I've done it on 2 trucks now and its very nice. If you want to PM me I'd be willing to install polys for quite a bit less than the shop.

I don't think that would be your vibration, but without seeing it I wouldn't know. Where are you in Phoenix?

The rear end seems to be pretty tight. The only other noise that I get driving is climbing over small rocks and the curb in front of my house, I get a creaking from the front but the truck has over 250,000 on it now but the front is tight, no play in the steering wheel. I did notice that the stabilizer/sway bar whatever it's called seems to be loose, I can slide it side to side about 1/2" to 1" is this normal? the bushings dont have any cracks in them. Ive got stock tires on it, and the rims are fine. would the u-joints cause the front end to shimmy back and forth badly, with minimal vibration through the steering wheel?

Removing the control arm bushings is not a fun job. It involves lots of heat. cutting, and hammering. That may be why a shop charges big bucks to replace them. My bushings were rusted to the control arms and did not want to come out. I recently removed mine on my T100 and then had a shop try to press new ones in only to bend the upper control arm slightly. The shop needs several specialized spacers to properly press in the bushings. I wound up buying new upper control arms with the bushings already installed. Check out the post "going back to stock" in the T100 forum for some pics.

The rear u-joints starting to go, you would tend to feel the vibrations comming through the seat, not the steering wheel.

Since you have already replaced the upper/lowerr ball joints, pitman/idler arms, and tie rod ends there isn't anything left in the steering linkage, except the steering stabilizer. A worn stabil. wont cause a vibration, only a drift while driving down the highway. You could replace it, should run you under $30 for a new one.

With the upper bushings being worn you are going to have to change them(lower ones too while you are at it), in order to get good tire wear/milegae warranty out of them. I still don't think this is the problem, but you never know.

I would say it is in the tire/rims, try moving the front to the back and see if the problem goes away. If it does you will know it is either a rim or tire.

How many or large weights were used to balance the tire? A lot of times tire guys will just keep adding weight where the machine tells them top get the tire balanced at 50mph, when all they have to do is move the tire on the rim to offset the out of balance. You could also have a bent rim(s), which would cause a vibration, most tire shops wpont catch this unless it is really bent.