97 Explorer Limited vibration at speed

bknuth · 03-13-2007, 06:09 PM

97 Limited with 91K miles. 4X4 - babied and Never off road. Wifes vehicle for past 6 years.
I have been chasing down a vibration problem - at highway speeds 60 - 75 you can feel it in the seats through the chassis and a little in the steering wheel. A rumbling vibration.

Initially I thought it was wheel balance - rebalanced - no effect. Tried different tire makes - no difference. Wheels bent? NO - true and stright. Rotors are near new. Alignment is straight. Had new ball joints installed - no difference. Replaced shocks - no effect.

Next replaced 2 rear and 1 front U-joint's and had drive shaft straightend and balanced by a reputable shop in Raleigh, NC - problem seems worse.

I put the truck on 4 jack stands and run up to 65 - and the vibration buzzes the front end starting at 55 or so and gets violent - felt throughout the entire vehicle- moreso noticable than when on the highway at speed.

What could be causing this? Front half axles? Transfer case?
ANy ideas? I am hesitant to pay a dealer at this point - but I would like a smoother ride to work and hate to think I am destroying something and this truck has a lot of miles left in it.....

Anyone have this experience?

THanks for your advice,

BK

KU40 · 03-14-2007, 07:22 AM

maybe check engine and tranny mounts?

bcmikie · 03-14-2007, 07:30 PM

i have the same problem, cv joints or front wheel bearings? maybe

jeffgriffin85 · 04-07-2007, 10:06 PM

is this a 4x4 or an all wheel drive explorer. if an all wheel drive explorer it could be the transfer case.

Bigmike2008 · 06-23-2007, 06:42 PM

bk,
i am having the same problems with my 97. i was wondering if u have found out the source of the problem yet?
thanks,
mike

townsdp · 07-23-2007, 05:34 PM

Do it without the car moving at all? If not, try flywheel, torque convertor, or maybe inside the tires. I have seen mud or water in tires do it. Take tires off and do the run on stands again. If still does it, run up to speed in drive and then put in neutral. If goes away immediately or faster than it takes the tires to reduce rotating while still at speed, its the torque convertor. Otherwise inspect the flywheel. Hope this helps

bknuth · 05-28-2008, 06:47 AM

Sorry I have not responded - been riding my motorcycle all winter but now its getting too hot so back to the Explorer -

My explorer is a 4X4 model with the switch on the dash (not AWD).

I took to a Ford dealer for diagnostic analysis with their special plug in vibration equipement and went for a ride with the technician - indication was a 100 Hertz vibration at speed (low rumble) and after $100 they said it most likely is the halfshafts on the front diff. The dealer also sold me a "harmonic attentuator" ( a big donut shaped weight) that bolts to the back of the transfer case for an additional $100. No difference to the ride but I am now missing my $200 - I could have bought a better subwoofer for the stereo system and generated my own rumble which may have cancelled out the vehicles rumbling vibration....

I have since replaced the front drive shafts and still have the rumbling vibration at speed. Its driving me crazy.

I next put the vehicle on jack stands again and with the front and rear driveshafts removed run up to 55-75 highway speeds with nothing but the trans and transfer case connected and experience the same low rumbling vibration in the seats - and it rattles the center console and the dashboard buzzes - so I know I am not imaging it.

All I can think is that it is something to do with the transfer case. I noticed a very slight clunk and movement when I push sideways on the rear output shaft (with driveshaft connected for leverage) - which indicates, I believe, rear transfer case bearing seat clearance is probably out of spec(the actual aluminum case half) and wearing (worn) out - I do not think it is the rear bearing side play. Perhaps this came from the driveshaft being out of balance for 90K miles?
Could the chains in the transfer case be stretched and ocsillating at that speed? Is it the flex plate or something in the transmission?

For lack of a method to obtain further diagnosis I've been considering rebuilding the transfer case - parts run about $300+ and maybe get a local machine shop to machine in a steel insert for the rear case half - another $100 probably. Other option find a used one - which are hard to find under $400.

Anyone have any insight or ideas?

ZBlackBeast · 06-06-2008, 07:11 AM

Sounds like thats the only road you can go down... just make sure its your t-case. Try doing it with you case off and see if its the tranny...