Vibration - Transmission or Torque Converter?

[Flye]

96 V6-4WD
270K, original trans, I'm original owner.

Vibration from about 28-42mph, to point of noticeable 'shaking' on steering wheel and anything on front seat, etc.

(probably still there after 42, but just 'tighter', so gives appearance it is gone)

I pulled driveshaft, and you still feel it (just not as intense) in near the exact same speed ranges on speedo (just a bit higher on speedo before it engages).

Initially said it matched the last gear change and asked if it might be the torque converter. I think i've eliminated this in general as while it does match last gear change, it is only because it is going to about 28mph+/- on last gear change. If you hold it in 1st, it doesn't vibrate, but if you run RPM up to get speedo to 28, it starts. Same in 2nd, etc. It is kicking in around 28mph. most noticable at lower RPM and then increases with RPM, and is far less noticeable above 45mph+, not because it isn't vibrating, but because they are much quicker.

fluid is 'old', but level is fine.

Again, it can't be driveshaft, rear axle, tires, alignment, etc., as the driveshaft is on floor. this is purely with motor running (no vibration if in N) and transmission engaged.

I don't want to have transmission replaced or rebuilt if it is torque converter only, but i also don't want to pull that trans to replace the T/C and find it was still the trans.

Local transmission shops have a bad rap (perhaps unfairly), but I need some feel. I'm also at 270K, so at some point, I have to make a decision on 'how long should I keep it rolling?).

I've heard planetary gears are usual spot, but I thought you lost transmission. The only other transmission vibration issue I ever had was the 'pump' had a broken (whatever) on it, but that was on a GM 200r4. This vibration feels similar (although it got worse even in higher speeds), but assumed it wasn't same.

Thanks for any direction if you've had a similar sympton and had it fixed correctly.

PS: I've done search here and looked at diagnostic section to no avail. Often the forums talk about cracked axles, driveshafts, etc. I know that cannot be it as it isn't connected to any of those and it is vibrating. Thanks again,

 

[PopRichie77]

You say drive shaft is on the floor, which shaft or both is on the floor?

 

[Flye]

main shaft from trans to rear end only.

just got it back from transmission shop. they drove it, said 'yeah it is vibrating, but don't think it is transmission'. they didn't do anything and didn't charge me anything.

 

[PopRichie77]

So it vibrates in neutral with the rear drive shaft removed and in drive? The flex plate that the torque converter bolts to maybe cracked.
When a torque converter goes bad they make internal noise and usually don't lockup. If it breaks bad enough internally to throw it off balance again it is going to make internal noises.
Jack it up again with shaft removed make sure it is blocked and safe, have someone give it some gas and feel the bell housing and see if it is vibrating, if so trans has to come out to see what is wrong.

 

[Flye]

They'd found nothing. They went back through my comments, jacked it up, now have front driveshaft disconnected. still vibrating in gear (while on jackstands). going to try to see if it is in the transfer case.

 

[PopRichie77]

Ford had a front axle disconnect for 2 years it was prone to problems and was discontinued, look here

http://www.explorerforum.com/forums/showthread.php?t=88718

 

[Flye]

Problem Solution:

Was transfer Case. No grease in it had led to partial failure, most likely finally triggered something 'breaking and then vibrating' when I put it in 4WD at last snow.

Used transfer from salvage yard cured the issue.

I try to keep things maintained as evidenced by the 270K, but that one just slipped by me. My fault, not Ford's, other than maybe it shouldn't have leaked out, but I'm taking the blame on that one.

Just an update on the problem/fix.

 

[PopRichie77]

Thanks for the update, glad you found the problem.