Everyone,

I've read multiple forums and tried to fix the source of my 70+ mph vibration. The vibration starts at 70mph and doesn't go away till 85mph (not that I drive that fast, just tested), felt through the seat like you're running over rumble strips on the highway.
Doesn't matter if you're on/off throttle or in drive or neutral.


2004 Disco with 90k + miles
Rebuilt front driveshaft with centering ball and balanced by a reputible shop. No change.
Replaced rear Rotoflex. No change.
Replaced tires. No change.
Made sure tires were balanced. No change.
Replaced shocks. No change.
Engine and trans mounts look good, no cracks.
Checked for slop on xfer case flanges, no movement.
New steering stabilizer. No change.
New pads and rotors. No change.

Things I haven't checked or on the to-do list -
Replace springs
Replace engine and trans mounts
Pull front drive shaft- Can I lock the CDL, yank the front shaft and test drive?
Bent wheels. Doubt it.

Any ideas? It's my wife's car and we have our first kid on the way, trying to get this sorted ASAP without throwing a ton of money and parts at the thing. Any and all suggestions are appreciated!

 

You can pull either drive shaft and lock CDL, then test drive. I would suggest trying with one off and then the other.
Do you have stock wheels on there, i.e. you don't have a set of RR wheels or something else?

 

Sure lock your cdl and pull the shaft. Front or rear just take it easy while you have the shaft out. I had the same problem and it turned out to be drive shaft balance after a rebuild and balance. Reputable shop. But your engaging cdl and pulling a shaft at a time is where I would start.

 

Tires are only balanced up to 70mph. The quickest thing to do would be take it to a local tire shop and have them check tires for flat spot, bent rims and balance, if all looks good there then goto the drive shafts as stated by Bundu and texmbr. U-joints and balancing issues normally rear their ugly head through a much wider range of speeds. Keep us posted.

 

There was a guy on here last year or so from Mexico with a '03 that had the same vibration as you.
Turned out it was the output shaft on the t-case, it was bent.
I'm not saying thats your problem, I'm just saying its something to keep in mind.

 

If you are feeling it in the seat and not the steering wheel that would point me to the rear drive shaft. I had a similiar issue, but the rotoflex fixed it. I'd pull the rear shaft and take it for a drive. Might need ballanced??

 

I get a slight one too, but it starts around 75 or so. But, I know my tires need some help as do my shocks. If your tires and shocks are good like you say, you might want to find a local buddy with a Disco to just swap wheels real quick and take a test drive. At the very least, rule that out. Also, check for a cracked spring.
Now... being you say this happens in nuetral as well as drive and on and off the throttle I'm leaning away towards and kind of drift shaft or transmission issue... but I suppose can't rule those out. I'm thinking it is more in the suspension somewhere.
If you could, take measurements on the tires each corner for tread depth and post that. Do inside, outside and center. See if any uneven wear (even to the casual eye) might pop out.

 

Did you have a road force balance done, or just a regular one?

 

Thanks for all the input. I know I have a collapsed/broken LF spring and hope that might help. I'm running stock 18" wheels with a regular balance, I work for a chain of tire and auto shops so I can always have them checked. As far as I know the wheels aren't bent...

I'm going to pull each drive shaft and go for a test drive, I've checked to see if the rear driveshaft had any weights missing and still see the stock Rover stuff but one never knows.

Keeping my fingers crossed it's just a drive shaft!

 

That broken spring can cause all kinds of vibrations into the vehicle. I would get that fixed ASAP. You might be surprised.