Tailshaft balancing - what's the go?

[Shifta]

So I think the source of some of my grief is the tailshaft. When doing around 70-80km/h or higher there is a vibration in the rear end and it seems to be worse when in neutral. The Tailshaft was standard GK Sigma that came in the car but I'm using the mounting plate/rear yoke off a GB Galant so that it matches up to the Scorpion diff. Anyone ever had a Tailshaft balanced? I'm not quite sure what could have gone wrong when installing the new uni's.

[A112H]

Maybe one of the weights got knocked off at some stage?
I know Hardie Spicer on Churchill Rd North in Dry Creek make tail shafts as well as mod and balance them. Might be worth giving them a call

[81GL]

Also check that it has bolted up to the diff correctly. The scorp diff uses a larger diameter bolt than sigma, and I'll assume galant. As long as it is centered that shouldn't effect the balance, but would be worth checking.

[davetrees]

Something else to try ..... unbolt the tailshaft from the flange & rotate by either 90 or 180 degrees. It's important that when you take a tailshaft out that it goes back exactly as it came out (often there is a mark on the flange to assist with this, otherwise just mark with paint or a file).

In theory it should make no difference, but sometimes it does ! (this is particularly true for cars with 2-piece tailshafts, which are usually balanced as a pair).

[Shifta]

Thanks guys! I reckon I'll take it off tomorrow, have a good look and then try JRM - the closer to home the better!

[Shifta]

Apparently no one down south does it! Spoke with JRM and they send them to Dry Creek. Luckily my brother works out that way so I'll give it to him to drop off. Fingers crossed it fixes the rear end vibration

[Shifta]

Bloke at Adelaide Tailshaft just rang - reckons he can't balance the shaft as it's got cheap Uni's and he reckons they are the problem. I hope he is right - the Uni's were brand new . So now my $90 balance is going to cost $170 . Happy to pay if that fixes it.....time will tell I guess.

[damian]

closure, I need closure! ;)

fixed?

[Shifta]

Slowly making progress! The vibration is gone so I guess it was either the Tailshaft out of balance or the standard Unis or both. I put the Tailshaft back in and also installed two new adjustable shocks in the rear on their hardest setting. The back end still seems really creaky ( the slightest movement in the car causes weird noises back there?? ) but it drives more stable. The locker is so noisy though so it’s hard for diagnostics on the road. I gave it a quick road test yesterday and from a standing start it tramps a couple of times then seems to hook up nicely. I was too scared to jump on the brake though which is where the trouble came at the drags when staging. I was only running 10psi so I wonder with the extra 5psi or so whether the rears will light up smoother? So now I’m at a cross road. I think the car is ready for a quarter mile run but only if I’m nice to it. I think if I’m savage in staging and off the line I’ll be in trouble. So whether I throw more time and money at the thing in the form of heavier Springs in the rear and replacing the remaining control arm bushes ( they all look ok at this point ) I’m not too sure…….