How important is it to balance the driveshaft? When I swapped my diff I noticed the driveshaft didnt have any of the balance washers mentioned in the manual. Since I know the driveshaft was replaced by the previous owner, I'm thinking he just left them out. The whole thing came to mind since I'm noticing a slight vibration from the rear of the car, that depends on speed. All wheels are balanced and aligned, and the tires are new, so I dont know what else it could be.

 

bump

 

it is VERY important that it is balanced correctly if not it gonna beat itself and the joint up to the point where they are gonna fail on you

have it balanced!

 

Thanks, thats what I was wondering. Is it something an average garage can do, or go to the dealer for it?

 

Most citys have a drive shaft shop that specializes in fabricating, rebuilding & balancing drive shafts.
Boston should have 1 or 2.
Check the yellow pages.

 

On all the RX-7s I have worked on, I have never seen balance weights on the driveshaft bolts. So odds are that you just don't have them. There should, however, be balance weights welded onto the shaft.

Any local driveline shop can dynamically balance the shaft for you, but any vibrations are probably due to dead U-joints and not an unbalanced shaft.