HELP - wierd vibration

[PerfRedV6]

I installed new control arms, upper and lower, and now I have a really bad vibration whenever I am on the gas. It goes away when I let off the gas or push in the clutch. It is not the motor, I can rev that in neutral and not hear anything, but like I said, whenever I am in gear and am giving it gas, the car vibrates. At higher speeds the vibration kind of surges. My only guess is the upper control arm changed my pinion angle and that is causing the vibration. Am I on the right track?? Help!

[gunner_501]

Did you remove the driveshaft? If so you may not have got it back in the right spot and it maybe causing a balance problem. I awalys marked them with a grease pencil so they went back the same way they came out. Just a thought Bro.

[PerfRedV6]

no, I did not remove the driveshaft. I didn't think it was necessary. I have replaced the upper control arms with my stock ones and have noticed no difference. My next step is to loosen the lower control arms and cycle them up and down to see if they are just not aligned right and then set the car on the tires and tighten them up. If that doesn't work, I am going to put the original ones back on.....

[PerfRedV6]

anybody have any other ideas?

[PerfRedV6]

So I loosened everything (upper and lower control arms), cycled them up and down a few times, set the car on the tires and tightened everything up and the vibration is still there.

I jacked the car up and inspected the driveshaft because I am tired of screwing with the control arms and where the driveshaft enters the transmission, it seems kind of loose. If I shake the driveshaft, I get movement (not like the u-joint is bad). I also noticed the other day a weird clunk in the shifter when I shift gears.
I only know enough about cars to get myself into trouble, so I am not sure what is going on. Any ideas?

[91GT347]

Could be a few things. I would try putting the old lowers back on. If it goes away, then its something to do with them. That way you eliminate any tranny issues ect. My guess is its a tire out of balance(or a bad tire) or something simple like that. You put on new control arms which have poly bushings Im sure. Much stiffer than stock. So your stockers rubber bushings were absorbing all the vibration before. If it were anything to do with the trans,driveshaft,ect. I think you would have felt it before. Check your tranny mount while your under there. Seems like one of my cars had a surging vibe and that fixed it. That will make it clunk on gear changes too. Especially hard ones.

[PerfRedV6]

So now the vibration is kind of intermittent. If I get on the gas a little, although not every time I get on it, it seems the vibration kind of goes away and my car seems normal, but if I ease up at all, the vibration comes back.

Also, in 4th gear, it seems bogged down and the vibration is really bad if I just give it a tiny bit of gas, like if I am coasting and just want to keep my speed steady. When I give it more than a little gas, the bogged down feeling goes away, but the vibration is still present. Everything in this post was just noticed yesterday, and has not been felt before.

91GT347, I appreciate the advice, and the biggest reason I am not pursuing the suspension aspect is that when I am not on the gas at all, or the clutch is pushed in, the vibration goes away completely. Like I said before though, I only know enough about cars to get myself in trouble, so it may still be in the suspension. I will check out the tranny mount next time the car is on jacks, which will probably be soon.

[PerfRedV6]

Well, I took it to the Ford dealer for an inspection and the tech couldn't find anything wrong (related to the vibration) so he told me he thought it was just excessive vibration through the polyurethane bushings on the new control arms.

I came home and swapped out the lower arms and the vibration is gone! I never thought it would have such a drastic effect on how much noise is transmitted to the chassis from the bushings.

Now I just have to work on the other issues he found, new exhaust.......

[PerfRedV6]

Oh yeah, 91GT347, the tranny mount looks fine? but the tranny is leaning towards the driver side? I don't know if this is bad, but the dealer tech didn't seem too concerned.

[PerfRedV6]

After taking the car on a road trip, down to NC and back, the vibration noise is apparently still there and just muffled enough by the rubber bushings that I didn't notice it before. Same exact symptoms, just not as noticeable.

Also the brakes are starting to feel squishy, and if I am stopped and I push on the brake pedal any harder, it makes kind of a crunchy/bubbly sound? Is the brake fluid going bad? Can it go bad? Nothing, recently, has been done to the brakes. Nothing that could have caused these symptoms.