M35a2 Bad vibration

[acesneights1]

Well my Deuce has a bad vibration. It starts around 28 mph and peaks about 35 mph and is much better 40-45. It feels like a bad bearing somewhere. I was thinking ring and pinion on one of the diffs but then driving it today I noticed something. When I feel the vibration, I don't feel it in the shifter of the 5 spd main transmission but I feel it perfectly in the shifter of the transfer case. Engine rpms do not affect it. In fact I got it going around 35 down hill and slipped the Tcase into neutral and it was the same and I pulled the engine stop as well and still had the vibration. I have not pulled the drain plug on the T case yet. It's not undrivable, but very noticable. When you old the t case shift it vibrates ALOT. Anyone have this issue ? This could be difficult to nail down as it is not easy to put a Deuce on jack stands and run it up to 35 mph to try and find it. in fact that would probably be suicide.
If I don't find any metal in the t case drain I was thinking about pulling the front driveshaft.

 

[Rmtaunton]

Did this happen all the sudden or gradually

 

[212sparky]

You could pull the front and rear drive shaft and run the gear train up through the speeds and see if you have it. Then add the rear drive line and drop the jack shaft between the rear boogie, then add in the rear axle then the front drive line.

Is it a tire imbalance vibration?

 

[acesneights1]

Did this happen all the sudden or gradually

I think it has pretty much been there since I got the truck. It did seem a little worse this weekend but I also drove it 80 miles to Rhode Island.

 

[acesneights1]

You could pull the front and rear drive shaft and run the gear train up through the speeds and see if you have it. Then add the rear drive line and drop the jack shaft between the rear boogie, then add in the rear axle then the front drive line.

Is it a tire imbalance vibration?

I have a cupped front tire and thought maybe. A friend also suggested possible wheel bearing since I have a bad seal in the R/R axle but it feels exactly like a bad ring nd pinion except the shifter for the T case is vibrating like mad and no vibration from the Trans.
I like your idea. I did not think of that. Pull both shafts. It is easy enough to do. Thanks.

 

[Rmtaunton]

There can be so many things , but I would check tires and u-joints first tired can smooth out at speed

 

[acesneights1]

There can be so many things , but I would check tires and u-joints first tired can smooth out at speed

U joints are all good. I checked those first at the show and we jacked up two wheels so I could spin the driveshafts to see if they were wobbling.

 

[Rmtaunton]

Usually if you get a vibration at speed then falls off it's a tire are you running 395 or 9-20

 

[Jeepsinker]

Pull the rear driveshaft, leave the front shaft and jackshaft in. Run it up that way and if it still vibrates it is either in the transfer case or the jackshaft. If you have a sprag case you will need to pull the front shaft as well.

 

[Rmtaunton]

And try to wiggle jack shaft , you will know if it's to much

 

[m-35tom]

And try to wiggle jack shaft , you will know if it's to much

because any is too much?
does it become better at 50 to 60? anything mechanical would only get worse with speed, tires anything is possible.

 

[Rmtaunton]

Mostly but everything moves a bit ,

 

[phil2968]

This was my vibration. Front spindle bushing was gone. It was not there all the time but came and went. My good friend Steve6x6x6 put in new bushings and polished my axles.

 

[gimpyrobb]

You have Polish axles?!!!!!!!!!!!!!!!!!

 

[phil2968]

Yes, very spensive eropeein' polish askels! Run good last long time commradd!

 

[acesneights1]

I'm running 9.20's
What is the jack shaft ?
I have an air shift T Case.

 

[gimpyrobb]

I'm running 9.20's
What is the jack shaft ?
I have an air shift T Case.

Phil's cousin Jack's shaft.

 

[phil2968]

Jack shaft. The driveshaft between the transmission and transfer case.
Jack Schitt, different story.

 

[rustystud]

Phil's cousin Jack's shaft.

OK gimpyrobb your avatar is totally creeping me out !!!!

 

[RAYZER]

I'm running 9.20's
What is the jack shaft ?
I have an air shift T Case.

The jack shaft is the short drive shaft between the transfer case and transmission.
Check all drive shaft flange bolts (especially the jack shaft) for proper tightness, i have seen these flange bolts loosen up to where I could turn them by hand, loose flange bolts will cause vibration.