Powertrain shudder

[Brownie92]

2000 DII with 114K
I have been having a shuddering/vibration comming through the drivetrain as I drive. This only does it under power (ie if it is vibrating and I shift into N it goes away) it seems to change frequency as the truck shifts. I have checked the u-joints (front and rear) and they seem tight. I suspect the transmission, mainly because about 2 mos ago I replaced the filter and as much fluid as possible. I only drained out 5 quarts so that is all I put back in. The old filter and fluid looked good, although there was a fair amount of metal on the pan magnet. This problem did not start immediatly after the service it just started about a week ago (oddly the same time the weather got cold @ 20F) I am thinking I am going to take it somewhere and have the tranny flushed and refilled. I just wanted to check with you guys first.
Any ideas are greatly appreciatied.
Mark

 

[joey]

I would bet on the front U-Joints in the driveshaft. Remember they do not have grease fittings and when the go out it will take your transmission with it.

 

[Brownie92]

That was my first guess too but when I checked them I didn't find any play. I had the rear tires off the ground and there didn't seem to be any wiggle in the rear shaft. I also checked the front. Is there any particular way to check them?

 

[joey]

If they are original change them even if they are not the issue...

 

[Brownie92]

I don't have any way of knowing if they are the original since I bought it used. Based on what you have said and the other things I have read I think I will go ahead and change them. It's cheap insurance. One other question Atlantic British wants 60.00ea. Is there any reason I can't use the 11.00 ones from autozone? Also is it the same u-joint for the front and rear?

 

[wolf]

That was my first guess too but when I checked them I didn't find any play. I had the rear tires off the ground and there didn't seem to be any wiggle in the rear shaft. I also checked the front. Is there any particular way to check them?

Ditto on Joey's advice: i.e., I have had u-joints that appear to have no play when I was examining them on the vehicle only to discover after they were removed that they had considerable play; also, when the darned things get bad enough they can actually seize so that there is no play at all but they will vibrate like mad at the right rpm and they will wear your tranny. After the seizure point - they can snap - and then things get really 'interesting.'

Wolf

 

[joey]

Not sure on the major differences, but again like you said cheap insurance... you can also go to NAPA, but make sure you buy goods ones with grease fittings.

 

[Brownie92]

Thanks guys, I really appreciate all the help. I knew I could count on you.