Another Truck Issue! Advice / Knowledge appreciated - Lots of Vibration

[Stark in the Wild]

Hi All,

First a thanks as I have come here with a few questions as i continue adventuring in my super cheap ($900) truck and you all have been extremely helpful!

Now the latest issue...as I am cruising and shift into neutral the truck - 1980 Ford F250 - vibrates A LOT. When I am driving down hill and accelerate just to keep up with the flow of traffic it will do it too. Under load when accelerating heavy or going up hill it stops shaking. I have tried shaking the driveshaft and it is not loose and looks to be seated well on both sides. The Harmonic Balancer looks to be okay too. I don't see any visible leaks around the tranny seals and the clutch feels great. This started after i went on an exceptionally bumpy gravel road.

Any ideas or opinions (besides getting a new truck ) are much appreciated!

 

[nitro_rat]

You may need to actually drop the driveshaft to feel for a tight u-joint. You can just take the u-bolts off at the rear end. Move the rear joint by hand in both directions. Move the loose shaft in both directions to test the front joint. Everything should move freely with very little resistance.

If you have a two piece shaft with a carrier bearing you will have a little more work to check everything out...

 

[Halligan]

I'm leaning toward a bad U-joint or out of balance drive shaft. But definitely check your springs, shocks, and if the truck has a TTB front axle the bushings in that.

 

[rayra]

Google "Ford F250 death wobble"

probably bad ball ends on the track bar.

I do believe I've mentioned 'baselining' all the suspension, steering wear parts.

It's the cost of driving old big trucks. Got 350k+ miles on the C-10. I've owned it for 33yrs. 2nd engine, 3rd trans, suspension has been rebuilt more than once.

 

[85_Ranger4x4]

Google "Ford F250 death wobble"

probably bad ball ends on the track bar.

I do believe I've mentioned 'baselining' all the suspension, steering wear parts.

It's the cost of driving old big trucks. Got 350k+ miles on the C-10. I've owned it for 33yrs. 2nd engine, 3rd trans, suspension has been rebuilt more than once.

An '80 F-250 has a twin traction beam Dana 50 if it is 2wd or twin I beam if it is 2wd, no solid front axle/trackbar.

You might also check the engine and transmission mounts, maybe something is shifting after your rough road and is messing with the driveline angle.

I agree, check over the driveshaft really good. Also check output on the trans/t-case and pinion bearing on the rear differential for slop too. If you wanted since I think yours is 4wd you could take the rear driveshaft out and drive in 4wd (gingerly) and see if it still does it.

It isn't a bad thing to go thru the front end but since this changes with throttle/gear selections I don't think it is related to the front.