I have the same problem !

It is hugely disappointing when this is the result after taking the car to a so called Volvo specialist.

In the 25 years I have owned the car, all the work has been done by my neighbour and I. On dropping the car off, I was going to mention the need to mark the tailshaft to ensure balance on completion. I decided it might be considered rude. How I regret this decision.

The car now suffers from an out of balance tailshaft. Most frustrating !

Mine is a 93 940 wagon with everything in pristine condition bar the tailshaft. It has 450000kms.

I'll read the answers to your post with great interest.

All the best to you and your family for the festive season.

Thanks for the info in this thread. I'm having the same issue at the same RPM. Now I know which direction to go.

Dear Eric the Swiss,

Hope you're well and stay so. I recall posts pointing out that driveshafts are balanced by using bolts of different lengths. Thus, if there's still slight vibration after you figure out the basic alignment, mark bolts' position at each end. Then move the bolts until the vibration "goes away'. This is time consuming and would have been avoided, had the mechanic known how to work on Volvo driveshafts.

You need to find another mechanic, who has - or is willing to get - access to an on-line Volvo "how to" manual. Or, see if you can find the Volvo service manual devoted to driveshafts. It is TP34125/1. It is only 24 pages. Even so, it will make clear how driveshafts are to be disassembled.

Hope this helps!

Stay Safe and Well!!

Yours faithfully,

Spook

FYI from year 1994 onwards the two halves of drive shafts are keyed (splined). Only one way to joint them together. The mechanic doesn't need to put any mark to put them back. Unlike earlier drive shafts.

As to why there is vibration I suspect some force had been used to separate the two-halves of drive shaft apart eg. hammering on the U-joints. Some drive shafts are difficult to be separated due to dried grease. Hammering could distort the U-joint holders/caps. If he (the mechanic) did that then you need to replace the affected drive shaft (difficult to repair).

Ask me how I know...

Amarin.

If you have the rubber donut at the transmission end you'll have to try each position the splines offer-then road test till you get it right.
If you have a regular U-joint in front the choices come down to two. Position the front U-joint so the flange attached to the transmission is vertical. Now insert the rear section so the flange attached to the diff is exactly opposite from the front (flange attached to diff is horizontal) giving just two solutions. Three U-joint driveshafts have to have the joints "in phase" -- not just in balance. - Dave

Just remove the back half off the driveshaft and make sure the universal joint are all Inline when reinstalling it. Make.sure.none of the bolts are loose. Some driveshaft are keyed to fit only for one way.

If your car has the rubber donut attached to the transmission end there's no way other than to try attaching the rear section to the front using each position of the splines till it comes right.
If you have a regular U-joint in front the choices narrow to 2. With three U-joints -- position the front so the flange attached to the transmission is vertical. Now insert the rear section with the flange attached to the diff positioned horizontal. Now there are only two solutions. With three u-joints it's not just a matter of balance but also U-joint "phase" where the front flange has to be 90 degrees from the rear most flange--as though front and rear formed one complete joint. -- Dave