So, to close out this post I should advise the solution to Miss Mullum's vibration issues.
From the advice offered there seems to be 3 areas that need to be checked or considered. The first is tailshaft balance. Luckily for Miss Mullum, this was the final answer. Next on our list to check was to check the tyres for balance/buckles, Robbie is still going to do this as they have not been checked for a long time. Last was going to be diff/tailshaft/motor angles (Fraser's solution).
The tailshaft imbalance on Miss Mullum was a tricky one. When Robbie got the car around 7 years ago it had a bad vibration around 55mph. He had the tailshaft balanced by a company in Cheltenham VIC - there was an improvement but still a definite vibration from 55+, still there at 65mph (GPS speed). So we swapped it with another newly balanced tailshaft from the same workshop. This made a slight but noticeable change. Robbie decided to get the original shaft rebalanced again but at a different workshop (Knox Driveshafts in VIC) requesting they pay particular attention at the revs for 55mph+. The engineer also replaced the front uni (although wear was very minor.....) and balanced the shaft for $220. We reinstalled the shaft and Robbie tested it to almost 70mph (on a 110 road of course
) with no signs of vibrations. So it was 3rd time lucky in this case!
With regard to the diff/tailshaft/motor angles, we measured tailshaft at 3.7 degrees and motor at 3.9 degrees (diff obviously at 0 degrees). This results in a front uni angle of 0.2 and rear of 3.7 degrees. Using a CAD package I was able to find the best compromise for wedging the diff on Miss Mulum was at 2.5 degrees which gave around 0.7 degrees at both unis so the wedging option would has some benefits. Fortunately we did not have to go down this route.
So Robbie is now happy (and so are his fellow Club members who were getting a little frustrated going on Club cruises at 50mph
)
Trevor_B
