vibration

Hi All,
Got a '97 2500, 4x4 w/Cummins. Auto tranny was dealer rebuilt and torque converter replaced six months ago.
When I hit overdrive under moderate acceleration, I get a slight vibration
and the shift lever starts jumping back and forth for a few seconds. If I ease off the accelerator, the vibration and shift-lever jumping goes away immediately.
I was thinking U-joints. Sound right to you?
Looks like I have 3 U-joints and a pillow-block bearing between the transfer case and rear differential. Can I just drop the rearmost U-joint and then remove the rear shaft from the pillow-block bearing? Do I have to remove the pillow-block bearing to remove the front shaft?
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Are you sure it's when you go into OD, or is it when the torque converter locks up? Next time, once the vibration starts, don't let off the acclerator, but tap the brake pedal with your left foot lightly. This will cause the torque converter to unlock. See if the vibration goes away.

If it's U-joints, it should be happening at a certain driveshaft speed, regardless of what gear the transmission is in. Try locking out OD, and acclerating to the same speed when the vibration normally occurs. See if it happens regardless of which gear you're in (3rd vs. OD)

You can disassemble the driveshaft at the slip joint to the rear of the center carrier bearing - it will entail removing the metal strap that holds the rubber boot on. The bearing is pressed on to the front portion of the shaft, and isn't (easily) removeable. Usually, you just unbolt the driveshaft from the rear differential, lay it on the ground, then unbolt the carrier bearing, and pull the whole driveshaft rearward so the front slip yoke disengages. Drain some fluid from the transfer case first, or it'll leak out when you remove the driveshaft.
You may find it easier to work with if you split the driveshaft into two. If you do this, be sure to mark the relationship between the two pieces (the splines may be keyed - they may not) so you can re-assemble it the same way. Don't worry about the metal strap on the dust boot - a plastic zip tie will work just as well.
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On Tue, 03 Oct 2006 20:50:29 +0000, Tom Lawrence wrote:

I'll definately check it. If the vibration goes away after tapping the brakes, does that mean the torque converter is bad?
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So the Dealer in Quincy Il just reprogrammed the computer so it wouldn't lock up until I get to 52 mph. At 51 mph it dwnshifts. It now bangs in third gear. Leave well enough alone. Just back off a little on the gas or give it more gas, the vibration will quit. So far I spent $3000 at the dealer in Quincy Il, and it still doesn't shift right and they say it can't be fixed unless I buy a NEW transmission.

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