Hi All

Seeing as the EB has over 385000 kms on it I though it might be wise to install some new universal joints. Luckily I have a spare car which I pulled the driveshaft out of and I commenced removing the front uni. While I was at it, one of the weights fell off the driveshaft.

So I called a driveshaft place and the said it would need to be rebalanced and that I couldn't just have the weight reattached. He also said that even by changing the uni joints, the driveshaft should be rebalanced anyway. They quoted $110 plus tax to balance the assembly.

What I need to know is,

If you change the uni joints do you really need to get the drive shaft rebalanced?

Is it feasible to just have the weight tacked back on?

All thoughts and comments are welcome.

Regards
BenJ

Its not necessary to rebalance a driveshaft after replacing UJ's but its desired. But remember to refit slip yoke and flange yoke in the same position it was removed. Also dont forget to mark the position of the driveshaft before removing it from the driveline to ensure its refitted in the original position (copy the yellow dots on both ends of driveshaft onto the diff flange and onto the output shaft on the trans). The balance weight cannot be simply respotted onto the shaft as the spotting dimples have already been burnt so i would strongly advise having the driveshaft rebalanced. Make sure the place that balances the shaft that they mark the final imbalance on both ends of the shaft (the same process as originally balanced with the yellow dots)

jools
Should I get mine rebalanced as I have changed to an alloy shaft that was not on my car. Could this be the cause of a vibration up to 80kph but nothing over this?

If its only up to 80km/h its not likely to be driveshaft with imbalance. I would be looking at other things like wheel balancing, warped rotors with sticking calipers and extension housing bush. Normally if there is a driveline vibration it comes in at about 70-80km/h and gets worse after that (a deep hum that carries through cabin). The only time there may be a vibration under that speed is when a UJ is severely worn and or a bent damaged shaft but would be almost undrivable over 80k's.

Hey Joolz

Thanks for the reply.

I am about to swap the diff from my parts car (EB11 Fairmont) to my EB11 GL (in Sig). The diff ratios are the same but the fairy has done about 120k less than the GL. I get a grumbling through the seat of the pants when there is no load on the diff, ie I am not accelerating or slowing down and a nice whine at around 80kph. I thought I would replace the UJ's at the same time for good measure as they must have suffered some wear in the last 385k.

I will go ahead and swap the diff using the current drive shaft and see if any of my symptoms disappear. I will put the new UJ's in and get the spare shaft balanced when funds permit.

Regards
BenJ

If your getting a substantial vibration from the rear on deceleration i can be sure that the rear UJ is on its way out. What happens is the diff tilts further forward on deceleration causing more of a pinion angle therfore the UJ is working harder and if worn it will cause more of a vibration than if the pinion angle was straighter.

Sooo, is there a way to correct the pinion angle in a lowered EB?

I did change my diff on the weekend to the diff from my fairmont. Luckily they both had a 3.27 ratio. The wine at 80kph has dissapeared and the driveline is noticably less clunky. The UJ's in the current drive shaft don't appear to have any play in them that I can tell.

I think however I will have the spare tailshaft fitted with the new UJ;s and have it balanced in the near future as a maintenance measure.

Regards
BenJ