Okay, I got the truck back ('94 XLT 4WD) after they aligned it, repacked and tightend the bearings, and balanced all wheels. I noticed a huge difference at low speeds. The truck is much more solid feeling now going over bumps.
However, I still get a nasty vibration between 60-70 mph. (speedo is off by 5 mph, reads low) Sometimes it is smooth as glass, then it will gradually start shaking. Other than this speed range, it is smooth.
I tried the nuetral thing with no change. I intend to troubleshoot wheels/tires to see if one is bad or slightly out-of-round. I also plan on doing a complete front brake job.

 

Since you have a Gen 1 X have you replaced the radius arm bushings. When these start to go all kinds of odd things begin to happen. Vibration, odd tire and brake wear. From your description it appears that your truck hits a resonant frequency and begins to shake. As duke-bearnie states you need significant energy to cause this and the wheels and tires do contain sufficient kinetic energy to cause severe vibration the fact that it goes away at speeds below and above the resonant point indicates something is no longer damping the energy sufficiently.

The radius arm bushings are cheap about $35 at the dealer and they are relatively easy to install. You need to drop the springs (maybe replace?) but the procedure in the haynes manual will get you through it in about 1-2 hours per side.

 

My bushings were replaced about 20,000 miles ago with noeprene bushings by Jo-SHmo's garage. Is it possible he did something wrong or are neoprene's a no-no?

Could the springs be sprung?

I don't have a manual, yet. Even tho the truck has been in the family since 1997!

Thanks

 

It looks like Jwirth has succssessfully Hi-jacked this thread! lol

I'm curious to see if GypsyR has made any progress with his X...

 

Please refrain from such remarks. I am simply keeping an informative and applicable thread alive.

 

my 91 Explorer has been having similar problems. when putting the trans. under a heavy load (acc. at 50-75 mph, or acc. up a hill, or between 2400-2600 rpms when the engine is warm) then truck feels like its going over the reflector lights leading up to a stop sign.

when i let off of the gas it stops.
if i floor it it stops.
if i shift it from overdrive to drive it tends not to do it.

I'm trying to sell the explorer( need a more efficient vehicle to make it from Atl. to B'ham every weekend) and would like to have the problem fixed before it's sold. I bought it 5 months ago. The previous owner said it has a new trans. less than a year old.

I am capable of most repairs/replacements. Any relatively inexpensive fixes to try?

 

After having all tires balanced again and the gear box tighened up and the wheel bearings replaced and tightened and putting 4oz. of anti-freeze in each tire to aid balancing, the truck is the smoothest its ever been. There are still times when I hit a bump at about 65-70 that initiates vibration and it will continue until I slow down. I need to check my radius arm bushings this spring.

There is a thread somewhere about the bushings that, even though they are new, a little play can form in them and you need to add washers or an additional cup.

 

I know you asked the question a few months ago but I believe you are looking for someone who has a Hunter GSP9700 balancing machine. The 9700 simulates road conditions and can isolate vibration problems. Check it out at: http://209.176.154.132/pub/features/how.cfm To find the nearest shop who has a 9700 you can locate one here: http://209.176.154.132/pub/search/findgsp9700.cfm

I have no affliation with Hunter, just a satisfied customer.

Mason

 

So did GypsyR and Jwirth get their problems solved? How? I've been struggling with the 65 MPH vibration for nearly 5 years on my 93 4WD, Mazda 5spd. Every bushing has been changed to polyurethane front and rear, U-joints replaced, tires/rim checked out all OK.

I get a hard clunk from seems like left front under extreme conditions - very hard braking (smash brake pedal as hard as possible) or extreme articulation while off roading. After I put 2 inch lift springs in the front, this clunk diminished in frequency but still happens at the extremes as mentioned. Thus I feel it might be a ball joint since the lift change the suspensions normal resting geometry.

I'm not sure a ball joint with a flat spot would cause such radical vibrations - like the liquidated kidney type vibration. But I'm also at wits ends on this one.

Thanks

 

Have you replaced your inner and outer tie rods and drag link?. All of these components if worn can cause shimmy at 65

 

Drag link was replaced once but some time ago. I didn't notice any loosness in these components but I suppose it's worth a deeper investigation.

Thanks

 

No luck really, but the vibration is now slightly more tolerable after yet another set of tires were swapped on. Radius arm bushings are good as is the steering linkage. Six months after repairing the transfer case shift motor (Thank you FTE forum) the damn thing fell off. Apparently the bolts vibrated out. I replaced it and LocTited the bolts. I noticed the front flange bolts of the driveshaft were also starting to back off. They were LocTited from the factory and in my various screwings around I had neglected to refresh the LocTite. Fixed that. Stuff trying to fall off the driveline makes me wonder if it might indeed be a driveline vibration? It sure feels like a wheel/suspension problem though. I dunno anymore.
Lately the damn transmission governor has been sticking. Unrelated to the vibration problem I believe but quite annoying. I replaced it and three days later the the new one started sticking too. The governor is obviously the problem but I'm rather at a loss at what to do about it at the moment.
I've been too busy doing, well, about anything I can come up with to work on the Explorer much. It still operates well enough as a daily driver. Just with a couple of quirks. It ain't "broke" at the moment, so I ain't fixin' it.
These persistent problems still lurk in the back of my mind and give me the occasional headache though. Sigh. They're a bit easier to ignore since the thing is my wife's and I drive a Bronco.
That Hunter machine sounds like something to look into. We''ll see. I can't seem to connect with either link right now.

 

Hey now there's an idea - give the old tired Explorer to my wife and take the new 2002 Durango from her.

Yeah those links didn't work for me either. My 93 Explorer has the Mazda 5sp trans so our drivelines are a little different anyway. I put it in nuetral there's no affect to the shake. So it's not the trans. Still could be the driveshaft since the diff still spins it when moving. I was thinking of pulling it and testing in 4WD with just front wheels driven. If that isn't it it has to be something with the twin I-beam. We'll see.

 

I have not cured the problem as some one recently asked. I think the only thing that is keeping the truck from shaking the **** out of me is the fluid in the tires. It seems to keep it somewhat dampened.

I have been so busy, I have not done much investigating. The last time I was under that beotch, I noticed that I could rotate the passenger side radius arm bushing by hand. The other side was tight. Could that be fueling the vibes?

I am so sick of this vibration thing. I can't see why one would have to fork out the time and money to have a specialized machine look at it. Oh well, it is warm weather and most of my attention is on my Harley!

P.S. I recently ran it off the road and almost rolled it over. Didn't seem to affect the vibes much, but the alignment got nocked off.

 

Interesting. Well, generally speaking, abusing a vehicle won't typically get it to perform better. You probably cut the bushing completely in half and now have the radius arm itself resting on the steel braket. This will throw off an alignment.

Certainly the radius arm bushings can cause vibrations. This is one of the big checklist items guys have been addressing this problem with. Think about it - anything that is designed to hold the tires in place that is then loose won't hold the tires in place. Ala vibration!

When I changed min I also did the twin I beam pivot bushings - all in polyurethane. This got about 1/2 the vibration out and also straightened out the back end. The left rear was about 1 inch lower than the right rear. Getting the fornt end geometry squared up again pulled the back end into place.

So radius arm bushings are a big deal. Change them. Let me know if you need the directions for this. You may be cutting frame rivets - which is an accepted Ford Mo Co practice as I found reading a TSB, much to many's dismay.