vibration with j30 diff

[jeepdan]

Ok, so i installed a J30 ABS diff with LSD into my 240, i had my driveshaft shortened to fit the new diff and now i have vibration at speeds greater then 25mph, also i have a humming noise that is equally linked to speeds. I think it might be the driveshaft but i was wondering if it could be anything else as well, i did take apart the j30 diff and reassembled, is it possible i might have put the spacers in the wrong place, etc? I'm in desperate need, the problems never seem to end with putting in my LSD.:help

[gabossie]

I would say that whoever shortened your driveshaft didn't balance it correctly. You should take it back to them and have it rebalanced.

[gabossie]

why did you have it shortened anyway? You don't need to last I checked.

[jeepdan]

I have a non abs 240 and a j30 abs housing is 5/8 in. longer and i didn't want to squeeze the driveshaft in there so i had it shortened.

[red240ne]

I had my J30 diff on the same car, and it did just fine without shortening.

curt

[NISTECH]

Try unbolting the driveshaft from the diff and rotate it a half turn form its current mount position on the diff and rebolt it down. See if that might counter out the vibration.

[jeepdan]

I had the driveshaft cut because in an automatic it fits but it leaves no room for play, it sits very tight against the transmission. I tried rotating, no luck, so i'll have it rebalanced and let you know.

[C-Kwik]

It's a hit and miss. Some have just used their existing driveshaft with no problems. Others have had rear transmission seal leaks. Having a driveshaft with the same amount of tolerance at the rear of the transmission will ensure reliability.