94 F250, manual transfer case, 3sp auto, manual hubs on D60. With transfer case engaged and lockouts engaged, there is a vibration that shakes the body and steering wheel. It is most noticeable at 20 mph and seems to go away over 30-40 mph. Almost feels like running over rumble strips. It vibrates when accelerating and decelerating. All pinions are tight and drive shafts/u-joints are good. Shift transfer to 2 wh dr and vib stops. Not detectable in low range or at least not as much. I also have to stop and back up in order to get transfer to go back into 2 wh dr. It will not shift from 4 to 2 by shifting lever while on the go, even if I get off and on the gas. Transfer does sound a little rattly, oil appears to be clean. Any ideas?

 

Are your u-joints in the front shaft good? This sounds like when my sisters dakota shot the little ***** out of her front shaft joint(piece of crap design anyway). It shook violently until you were going fast, then it just was an annoying whir.

Another possiblity is a bad front output bearing in the tcase. Can you move the yoke on the case at all?

 

it could be a bent drive shaft or out of balance front drive shaft....because if the hubs are unlocked the drive shaft wont turn = no vibration, lock the hubs or put it in 4wd and the shaft turns = vibration...

just an idea.

 

After your D60 conversion, had you ever encountered this problem? I suspect that the fron drveshaft could have been installed out of phase, and if the u-joints are not aligned, the balance will be off. Joints can still be good, but the bottom and top joint will reach a diffierent speed at different times, and this eccentric will create a mad vibration.
Your shifting problem, has me baffled, and perhaps this case is not enjoying all of the 4wd playtime. You still have the BW case in there right? These chain driven cases might develop a rattle after the chain starts to stretch. Honest my limited experience with these cases is simply limited to removal and disposal. I opt for the 205 case, even in the late trucks. Have made many 205 conversions.
If this is just a newly developed situation, and the thing worked fine before, then I might be just as confused as anyone. I know that you have plenty of experience and that nothing terribbly obvious has been overlooked, so I thought i would subscribe to the thread so I can learn as we go along.

 

Front axle shafts have new u-joints, had front dr sh redone yesterday by competent machine shop, it also has new u/j. No bent shafts. I previously had a guy shorten it so it would fit my D60 swap, said he did it on a lathe. I checked it on the truck with a dial indicator and it was off center by .0070 or about a 1/16" at the front yoke where he welded it, yoke wasn't even welded on straight, don't know how he got that far off by using a lathe, I jacked the truck up and you could see the thing wobble with it in gear. Had a guy at an auto repair shop look at it up on an alignement rack, blocked axles up and spun everything in gear with engine running, everything was running true but could still feel some vibration. He was thinking transfer case, the front yoke is tight. I may get a used case and see if it makes any difference.

Thanks for the replies.

 

Just a thought, check the u-joints again, I've had u-joints that felt good, looked good and had no perceivable slop in them, but I couldn't put enough load on them to have it show. one only vibrated at 45 MPH, I checked everything to no avail, then just drove it till it got horrible then the ujoint was toast. Hope that might help.

Does it vibrate when the hubs are locked in and the transfer is in 2wd?

Are you positive the gear ratios match? (just a thought) since you prolly swapped that 60 in

Sorry, I typed that in before I read the last two posts

 

I was plowing snow today and was watching the speedo a little closer and the vibe occurs between 15 and 25 mph, with 20 being the worst. It feels more like a shudder instead of a solid vibe and doesn't match the speed of a bad drive shaft, the vibe is slower. The hubs have to be locked and the tc in 4, any other combo doesn't produce any vibe.

 

Is the t-case tight? Not any chances that the trans mount or anything like that is bad is it?
The t-case always tries to rotate under load, and it doubles this load when it is engaged into 4wd.
Any differences in 4-lo, or 4-hi?

 

Ok, got a new spin on things. Did some more testing in a smooth long parking lot this morning. First off, the transfer case and adapter were loose and leaking oil when I bought the truck (about 4-5 months ago) and I had the bolts tightened but of course they still leaked but got me by for a few months. I then had a shop put new gaskets on recently and everything is ok. Something different on the vibe, it changes when I shift the auto transsmision from 2nd to 1st, it's not as bad in 1st. Drive and 2nd feel the same. A better idea of what this vibe feels like, imagine having straight cleated tires like a farm tractor and going 15-20 mph.

I can shift it into 4wh at any speed and there is no gear grinding or binding so I'm sure the front and rear gear ratios are the same.

Also, there is a slight vibe or shutter that last about 2 seconds when I take off from a stop sign. It has been like that since I bought it. Transmission does not slip any.

 

Glad you posted back. I have been thinking about this since my last post. I am working on a ZF-5 to 205 conversion behind a 460.
Anyway, I was wondering if perhaps one of the u-joints was too tigh and perhaps the bearing has turned into a bushing. This resistance in the joint could very easily cause you vibration. I was also wondering if both slip joints were free moving and not binding?
Sticking splines can do some pretty crazy things.

 

I checked the joints and all were good and moving freely. Whatever this is starts in at ~15 mph and gets worse at 20 then goes away above that in 4wd, doesn't matter if I'm speeding up, slowing down or going steady, vibe is always the same.

 

This is speed related and not RPM related? What happens if you downsift, or hold the gear a little longer?
Running out of ammo here.
Ill try to keep thinking here. Has to be something simple.

 

It is speed related. It is there in reverse but not nearly as bad. I think I will get someone to ride with me and try to get this vibe localized. It's going to be in the single digits here next couple days though, may have to wait till next week. I appreciate you hanging in there with me!

 

I am curious to see what it was. Also wish we were a little closer, I would love to check out your ride now that the SAS is done, and try to help figure this out.
You know, rear axles with LS units chatter under acceleration when there is no friction modifier in there. Could your problems be something similar to this?
You dont have any LS units in this truck do you?
Just got me thinging a little, but my Power Lok equiped trucks have a bit of a chatter, but nothing like a vibration like you are describing.
This should be interesting......

 

No LS.....................