Ford Explorer Vibrations and Aftershake


Contributed by drbob and others

The shake is a definite problem with 91-94 Explorers. Ford has a service bulletin out for the problem (TSB 96416 Feb.96). The solution is two new front engine mounts (with different tuning) plus a third shock absorber that is connected between the rear axle and the frame.

A lot of folks are reporting mixed results with Ford's "cure". Even the Dealers will tell you about the mixed results. Keep in mind that their TSB and the "cure" are targeted at a problem called "aftershake". This is a completely separate problem from the 48-65 mph front-end shake, although the front-end shake will 'excite' the lateral shake problem, Cure the front first, and then attack the rear if it is still a problem.


For the aftershake:

Many are reporting improvements with different brands of tires. Since the lateral shake is a function of a resonance in the rear suspension excited by something in the front, the tires play a major role in the problem. If you find that the problem appears or seems to suddenly get worse with your new Goodyear's, you are not alone. Balancing will help slightly, but you may be doomed to 50,000 mile of abuse until you replace the tires again.

Best reports are coming from users who've chosen the Michelin LTX series tires. The AT is a more aggressive tread, while the M&S is a smoother ride. For some reason, the sidewall and tread stiffness of these seems to work the best.

Kirlinla has supplied good technical data to support the use of Bilstein shocks as the only reasonable replacement choice, especially if you are having other problems.

For the 48-65mph front-end shake:

On the early style cars (91 to 94) the front suspension is extremely sensitive to wear of the radius arm bushings, and also to alignment. Often, less experienced front-end places will overlook this area when trying to diagnose the shake. Tire and shock replacement have little or no effect on this problem, although the problem will soon destroy the front tires and shocks.

I have had the best luck taking my car to a local frame shop that specializes in heavy-duty work like this. The technician zeroed in on the problem in less than 10 minutes. Total cost of repairs and parts, including new alignment bushings, was in the mid $200's from memory. I have the exact number in the car's log book... The guy at the local tire and alignment place was clueless.

Anyway, this work, followed by tire and shock replacement at 75k miles cured the problem. Others have reported this as early as 25k, with the average at about 45k, so I feel a bit lucky.


Contributed by Garth G.

We had a wheel/suspension vibration problem first noticed 6 months after vehical purchased new. Vibration usually started at one speed ~ 55mph and got worse with time. I did the simple things first: Tires, tire balancing, front end alignment, shocks, bushings ( got many ideas from your web page and Dr. Bob's excellent maintance pages). Could make problem better, but it kept coming back.

Finally went to Thompson's frame and alignment in Sherman Tx. Mr. Thompson Jr. laid hands on the machine and precisely determined that I had a out of round aluminium wheel, He said that any change that added soft rubber would dampen out the problem until that part ( tires, shocks, bushings) wore out enough to not be able to compensate for the out of round and then the vibration would start again and steadly get worse. He would not take money for his service.

I checked wheels for out of round with a dial indicator. Indicator ball movement was adjusted to be on a line from center of spindle to lip of wheel. Be carefull to lift the dial indicator arm out of way of lead balancing wieghts while wheel is slowly being rotated during measuring process. 3 wheels had less than .015" out of round and one had over .035" out of round. Spec Wheels in Forney, Tx said .015" was Ford max. for that type wheel. They stuck it on their machine and trued it up enough to permanently remove vibration. Cost was $50. They said that out of round problems were common due to the stud hole machining process used on Aluminium wheels.


 

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Updated November 24, 2000

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