Driveline vibration - TCase?

[Andres]

I'm finishing up a conversion - taking the ISB305 motor, 48RE transmission, and NV271D Tcase out of a 2003 2500CTD and putting it in my '93 Hummer H1.



All that stuff is done and it starts and runs, but I'm having driveline vibration.

I noticed that when I bought the salvaged '03 ram, the rear driveshaft's yoke was cracked at the ujoint to the rear diff. So even though there wasn't any apparent rear end damage to the body, the roll may have somehow impacted the the tcase or transmission.



I've driven the truck off just the front driveshaft (with rear driveshaft removed) and done the reverse - just off the rear driveshaft. I've also pulled the hummer halfshafts to narrow it down.



Putting a screwdriver to the ear and listening to the transmission pan, it seems smooth, and the tcase sounds noticeably rougher. But the virbration does seem to get worse once it hits overdrive, so that could just be a resonant frequency or a damaged transmission.



Pulling the driveshafts and halfshafts eliminates the Diff as being the problem.



The driveshafts are new, balanced, and the angles aren't extreme. Any suggestions? Oh, and whee to buy a new/refurbed tcase and/or transmission?



I do have an '06 ram with a 271D, I thought of "borrowing" that for a test.

What a pain!



The good news is that the Hummer does have the power to spin 42" IROK's.



Thanks in Advance

 

[ezcurra]

Make sure your angles are correct and matched.



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[Applegator]

John: Have you checked the tires? If you have a lot of weights on them maybe a rebalance is needed. Also, could be a bent or defective wheel. I have seen tires and wheels that won't balance no matter how many weights you put on them. They might be close but not perfect. Fred

 

[ezcurra]

You could try dropping the rear driveshaft and driving in front wheel drive. That would rule out rear U-joint alignment issues, or driveshaft problems.

 

[BJMarshall]

I haven't had this happen on a 48re, but have fixed several 46's and 47's where the big ball bearing in the OD unit was failing and causing a vibration that got much more noticeable in OD. It is a pretty easy and inexpensive fix if you catch it early. It would definitely be worth checking if you are pulling the transfer case off. Check for movement in the transmission output shaft at the end of the OD unit. The input to the transfer case supports the shaft even when the bearing is failing so it can take a long time for it to do real damage.