Heavy Vibration

[Joes4x4Ranger]

I've got a heavy vibration at highway speeds in my 4X4 '91 4 dr. I'm running BF Goodrich 31X10.5's on NEW alloy rims a 2" suspension lift and Duff radius arms. The vibration starts at about 65mph and gets worse the faster I go, at 70-75mph it shakes my teeth loose. I feel it in the seat as well as a slight shimmy in the steering wheel. Below 65mph this rig is smooth as silk. Here are some of the things I've checked so far.

I had the tires balanced at 2 different shops about an hour apart. I watched both times and saw no signs of out of round or "wobbly" tires. Both times no weight was needed tires were prefect.

Rotating the tires has no effect on where I feel the vibration.

I checked the steering linkage nothing loose. Ball joints are new. Front wheel bearings packed and tight.

Shocks seem to pass bounce test ( I get it rocking and let go, it comes up once and settles) and show no signs of leaking.

It's not an ignition miss at high speed, I drop the throttle and the vibration continues till my speed drops below 65mph.

U-joints are new just replaced them a couple weeks ago.

Transmission mount looks good and feels tight.

Alignment as follows: Caster L 3.75+ R 4.25+ Camber R .50+ L .50+ Toe is 1/8" IN. The caster is well within the specs printed on the sheet I got from the shop, max + caster is 5.25

I'm out of ideas, the tire shop will not replace the tires cause they balance up, show no signs of separation, and are wearing perfect. HELP!!!

 

[TennTechMan]

I was having what sounds like the exact same problem. I've got the same tires and a 2" lift (lift coils in the front, warrior shackles in the rear, and aftermarket shocks all the way around). I also have a 86 Ranger. I swapped the wheels and tires off the Ranger onto the Explorer. Vibration gone. After replacing 4 tires and a wheel, the vibration hadn't gotten any better. I took it to Firestone to get a second opinion on the balancing, and the tech said all the weights were off by at least an ounce on each wheel. The vibration is not nearly as bad now, but it's still there a little. I can drive at 70 without feeling like the truck will rattle apart.

I still intend to get my driveshaft balance checked sometime in the future to see if it will completely cure my problem. It looks like we have a couple things in common, 2" lift and BFG 31x10.50's. Is your lift in the rear by shackles? Rear end angle is changed when adding shackles. It's something else I've been meaning to check, but haven't had time.

I bought my Ex with a blown engine, and it vibrated from the first time I drove it. Has yours always had the vibration, or can you narrow down what might have caused it to start?

Let me know if you figure out what your problem is. I know how annoying it is to have to do 60mph on the interstate.

 

[Joes4x4Ranger]

My lift is rear shackles. I had 2 shops balance my tires and both said "Good to go". I still think it is a bad freaking tire, but Discount will not replace a tire that shows no visiable sign of problems. This rig has had this vibration ever since I put these tires on it, I've *****ed and *****ed to Discount but they swear the tires are fine.

I did the balancing at two different tire service centers(not Discount) and both say the tires "Look" good. The only problem is YOU CAN BALANCE A FREAKING SQUARE but it's still not going to roll.

The only other thing I can do is try to flip the cams on my TTB and reduce the + caster. Most passenger cars only run 2-3 degrees positive.

I just don't have the money to go out and buy another set of tires. I only have about 3000 miles on this set.

 

[Yomie]

i would double check the u-joints again, sounds like a driveline vibe....when did the vibe start? Was it after a whelin trip, or new tires...snyhting significan't happen before the viibe started

 

[Joes4x4Ranger]

i would double check the u-joints again, sounds like a driveline vibe....when did the vibe start? Was it after a whelin trip, or new tires...snyhting significan't happen before the viibe started

It started about 2 weeks after I put the tires on. Started with a mild "nuisance" type shake now it almost feels dangerous to drive at anything over 65mph. I can somewhat tolerate it at 70 but at 75 it feels like the rig is gonna shake apart.
What really pisses me off is the tire store will not even consider the possibility that one of those tires is bad. I guess I'll have to wait till the bad one spits the tread to convince those A-holes they sold me a bad product.
The shaking is too heavy for a drive-line related problem. Also bad u-joints usually rattle on accel or decel and at all speeds. This vibration starts at 65mph. The engine RPM at 70 is 2200-2300 in 5th gear. Under 65 no vibration at all, even at 2200-2300 RPM in 4th gear, from 65mph and up it shakes worse as speed increases. I can't find any speed over 65 where it wont shake.

 

[Yomie]

I was suffering from the same type of vibe about a week ago. I couldn't run the truck over 60 mph, sounded like the windows were gonna bust..

Came out to be a u-joint in the drive shaft, no noises no squeeks nothing

 

[Joes4x4Ranger]

I was suffering from the same type of vibe about a week ago. I couldn't run the truck over 60 mph, sounded like the windows were gonna bust..

Came out to be a u-joint in the drive shaft, no noises no squeeks nothing

I'll give em another look, but I just replaced the 2 rear, and the front at the pig due to excessive rust. I guess it's possible I dropped a needle in one of the rears. the only thing is if I did screw one up, I don't think I could have installed the clips. I can still see the index marks I made with white paint on all the yokes and shafts, they are in the right place.

Anyone think it may be a weak shock getting ready to fail, just not showing any leak yet?