famous problem 60mph vibration

[PROTEUS]

I can't go further than 60mph because my standard Ex 91 4door start to vibrate, shake, i.e. a shimmy.

Obviusly, the first thing to do is a good alignment and get balanced tires, I have done two times. And the problem still remains.

The tires aren't the problem, they are new BFG 235/75R15. The shocks are Monroe sensatrac, they are new, too.

I have searched in the forum about it, but I can't find a solution. Someone said, the problem is a resonanting motor.

Now, I guess the problem is the front axle U-joints...but I don't know how to test them.


Finally, I can't find the source of the problem.


Someone has solved this really bad problem ????


Any comments would be useful.

Thanks.

 

[jasonb]

when searching for answers a while back, i found that some had out of balance drive shafts and bad u-joints also as a problem. i didn't check either of those just because i haven't had time to get around to it.
i haven't gotten rid of my shake either. i just deal with it now and don't go 65-70mph.

 

[schadler]

vibration

I dont know if this applies, but I just got Bridgestone Dueler HT's and dropped the psi from 40 to 35 after getting some wicked vibration at highway speeds. It seems to have totally solved the problem. I know the door says 26 psi, but I don't want to wear out the tire shoulders just because Ford wants to prevent rollover.

If your pressure is near the upper level of the tire's rated max, you might want to drop it and see what happens.

 

[410Fortune]

Okay this is a common problem with the TTB front end.

Check the condition of your radius arm bushings (replace)

Also the sway bar and axle pivot bushings need attention too.

ball joints on a 91 could be badly worn/frozen.

Wheel bearings, replace or re-pack, and check the condition of the spindles, look for grooves, worn flat spots..

Tire balance and pressure is the most important thing to keep on top of. Have you tried rotating the tires front to back, a bent rim can still balance out at the tire shop but cause some wicked vibrations.

 

[PROTEUS]

I have not check the radius arm. The problem is the sway bar or a bent rim (I have one bent rim, but when last time I rotated the wheels...I forgot what rim was).

I have checked the ball joints, by tring to move the wheel up and down... I didn't get any movement...so that...they are OK, aren't they?

The tire's pressure, uhmm... I'm running with 32psi, but I'm thinking in 28 or 30psi to get a most softly driving.


Thanks for your responses!!.

 

[93ebx]

I had the same problem with my 93 and went to buy a set of mud tires&rims for winter and that has totally solved my problems. The factory rims I had were crappy

 

[410Fortune]

Bent rim is most likey the problem. Problem is they can still get it to balance out close to 0 at the tire shop even if it's bent, but when that sucker is on the front of the truck you will feel it when braking or on the highway....

Well the only real way to check the ball joint is to get in there and look at it (remove the shim, etc..) but if you dont have any play then it's a good sign.

Also dont rule out the sprindle being worn, no matter what you do it will never be vibration free if one of your spindles is worn out (sometimes hard to detect/see)