throbbing sensation under 2500 rpm

[jharkin]

after my rear axle was converted to a 3.27, it was running fine till a few days ago when i started to notice throbbing sensation in the steering wheel whenever i am in 4th or 3rd at 2000rpm, or slower. but it doesn't seem to be lugging. it decreases quite a bit when i take it out of gear, and it disappears almost completely above 2300 rpm in 4th.  I'm wondering if maybe the drive train is out of balance?  or wheel bearings, although front were replaced last year, and rear were done with the axle change.   I'll be contacting my mechanic about it but in the meantime does anyone have any ideas?

[ja17]

Hello,

Make sure no driveshaft bolts are coming loose. Check your wheel lug bolts while your at it.

[jharkin]

thanks for the tips; i checked the lug nuts and they are okay but i noticed the axle end caps are missing on the "new" axle. aren't they needed to keep the axle grease in the shaft?

[jeffc280sl]

Check the slip nut on the drive shaft.  I know of a similar vibration on a 3.27 conversion caused by a loose slip nut.  It was sort of forgotten about during assembly.

[hands_aus]

maybe incorrectly fitted flex coupling bolts.

Happened to my car and one came out in the driveway at home.

[jharkin]

all bolts and slip nut were checked and in good order. replaced the transmission mount and bushings in the steering coupling. problem disappeared.