Vibrations (probably not 'Good Vibrations!) LT77

[BudgieV8]

Hi all - apologies for the poor title.
Just refitted my RV8 into my Capri. Its gained some vibration which may, or may not, be the gearbox.
Manual LT77 Rover with hydraulic clutch.
Symptoms;
Accelerate (not 'boot') & the vibration seems to be from the front of the car.
Decelerate (take foot off the gas) & vib seems to be at the rear.

Theories:
-When fitting the 'new' engine, we had to replace the brass spacer in the end of the crankshaft to fit the input shaft of my g'box as the one fitted in the 'new' engine was too big. Has this moved?
- Has something inside the box let go? If so, what?

Please could I ask for some suggestions before I pull the engine/box out for the 6th time in 2 years

Thanks
Paul

[SuperV8]

Hi does the vibration seem speed related?
or is it in any particular gear?
or only under load?
has the propshaft been changed? Its important to have similar angles at each uj in the prop.

tom

[BudgieV8]

Tom,
Removed 'other' engine as it had head gasket probs. No vibration issues with that engine/box/prop setup (or the previous 3). Fitted this engine with the previous box/prop setup.

Speed related
- yes. I originally thought it was a wheel balancing problem (happens around 50-60 mph), but wheels all good. Also, it is literally accelerate= front vibs, decelerate= rear vibs. strange....
Gear
- happens in 4th & 5th
Under load
- happens accelerating (front vibs) & decelerating (rear vibs)
Prop change
- same box mated to same prop, just changed engine.

[unstable load]

I think what SuperV8 means is are the crosses in the UJ's aligned correctly? In other words, if you simply slipped the shaft apart at the slip joint then did you refit it in the same configuration or a few splines out?
Misaligned UJ's will cause vibes.

[BudgieV8]

That would be a fair enough theory. However, my prop has a flate plate with 4 bolts at both ends as its a 1 piece adapted Capri item, so no splines to mis-match.

[davemgb]

Now it's been driven check the propshaft bolts are tight. If they are then try turning the connection 180 degrees in case the bolt holes are out for some reason.

Also the LT77 mount bobbins are notoriously soft, have you fitted the bolt and snubber bush underneath between them?

Dave

[Bryan]

It's worth checking the condition of the propshaft UJs - a worn front UJ can cause exacly the symptoms that you describe