High Speed Vibration

[IAmTodd]

Fellow EFers I call on you once again for some help with my '94. I have a terrible vibration between the speeds of 65 and 75 mph. I've been using the truck daily and have been driving it on the highway a good bit so I'd love to get this fixed as it's hugely annoying. The vibration comes through what seems to be the body, never the steering wheel. Shifter shows no signs of movement and only normal vibrations.

Things I've done so far:

U joints new 8k miles ago. Them seem solid, attempted to measure with a micrometer and everything seems to be centered.
Tires rebalance (ProComp muds) - all was good there. Still had vibration. Rotated tires numerous time; never a vibration in the steering.
Purchased new tires on Thursday, smaller snow tires. No dice there.
I have it jacked up right now with the tires off the ground. Took it up to 75 and it was smooth sailing.

I think at this point I can rule out the driveshaft? Second set of tires with the same issue? Beyond this I don't know what else to do. I've seen the TSB out there to add the fifth shock but that just seems to mask the overall problem. I'm worrying about u joints and bearings being devoured by this vibration.

The truck is lifted 2 inches with shackles and leafs in the back. I vaguely remember this not being an issue with the 235/75 tires that I had on it before the big tires.

 

[Benjam]

Subscribing because I have the same problem in my 92, but only when the truck decides it wants to act up.

Does the TSB talk about a steering stabilizer or a 5th shock like the newer trucks have?

Benjam

 

[Javaman007]

I have a 94 EB and have the same issue between 65-75. The difference in my situation my suspension is bone stock with 235/75's. I suspect I am going to have to replace the bushings et all. As luck would have it my son in law is going through a vocational school for auto repair, all I have to do is supply the parts and they will do all the labor. If after I still have the issue I will worry more heh

 

[arco777]

The last time I had that issue, one of the rims in my set was bent. Bought a used replacement set and one of those was bent too. Just enough that the tire shop could balance it, but the balancer doesn't spin the wheels that fast...

 

[Jason94sport]

Ah the notorious 65mph shake...Some Explorers do it more then others. No definitive cause I have seen over the years.
Could be the drive-shaft. May be out of balance. Or something in the rear pumpkin or the rear axles. Running 32's does put more stress on these parts.

 

[IAmTodd]

Ah the notorious 65mph shake...Some Explorers do it more then others. No definitive cause I have seen over the years.
Could be the drive-shaft. May be out of balance. Or something in the rear pumpkin or the rear axles. Running 32's does put more stress on these parts.

I'm down to 265/75/15 right now. I was hoping a smaller passenger tire would help the issue. It hasn't sadly. From what I've searched it's a common problem and a problem that I can't live with. I'm going to call the driveline shop today and get the driveshaft balanced to see if that helps. Otherwise it's back to the tire shop to see if they can measure the runout.

 

[awood]

My 92 (R.I.P.) had it, my 94 has it too. Between the two of them, after changing U-joints, RA bushings, steering linkage, tires, ball joints, etc, I suspect it's just worn suspension parts (Bushings, springs, shackles). But it's just a guess.

 

[IAmTodd]

So I pulled the shaft with plans on going to get it balance. Drove the truck with fwd and still had the vibration..WHAT? One u joint had a flat spot in it, replaced it and there was play in the slip joint so I greased it up. Put the shaft back in and it was completely solid now. Back on the highway the shakes were there as normal.

I'm pretty close to listing this thing on Craigslist and getting a Grand Cherokee. This has gotten old.

 

[bovine]

i have this same issue with my 94 but i can feel mine in the steering wheel got a little better when replaced the radius arm bushings i'm thinking either bent rim or bad ball joints is my guess im looking for different rims since i need tires anyway.

 

[IAmTodd]

I'm giving up on it. I listed it for sale last night. Tired of working on it.

 

[IAmTodd]

Although the truck is now gone, I fixed the issue! It was the hugely worn transmission mount.