diff mod ?

J

johnuk

New Member
Hello I have a 1968 2000 auto I have converted it to 2200tc with sd1 5speed. although she goes much better and quieter I feel that p6 transmision noise could possibly be improved on. I think that if the diff was moved to the left so that the prop ran in a straight line this would help trans noise. has anyone tried this or have an opinion on it. Im a mechanic and mot tester and Ive never seen any other car with a prop shaft angle like that of the p6. I have also thought of putting in the 2200/v8 rear suspension for extra insulation but it will leave that horrible prop angle maybe I should do both?

Thanks
John
 
Hello John,

The differential with pinion extension case although offset runs in the same plane as the transmission and engine, thus the likely suspect for unwanted noise may well be the universal joints in the tailshaft and / or halfshafts. Have you replaced these? The tailshaft yokes also run with an offset which is quite different to most where the yokes run in phase. If you wanted to move the diff to the left then there is also the issue of halfshaft lengths, and the requirement to make a longer one whilst also reducing the length of the other. Then there is the issue of balance.

Ron.
 
Thanks Ron, all six UJ joints have been replaced, all three shafts have been balanced, all transmission, gear box and engine mounts have been replaced. Many widely experienced mechanics have road tested and looked at this car (friends of mine), but the noise persists!

John
 
Changing the drive shaft length then balancing them would not be a problem as there is a firm fairly local that does that work for me.
 
Hello John,

Sounds like you have all the bases covered then.. :wink:

Are you running metalastic suspension bushes or poly bushes?

Can I ask,...why do you think that moving the differential into a different plane will cure the noise?

Ron.
 
Altering the driveshafts so that they are of different lengths just so that you can move the pinion to the center will mean that the rear wheels will move out different amounts for the same amount of upward movement. Rover went to great lengths to iron out vibration problems in the original design which although it's not perfect I don't think you're going to be able to improve things by doing what you suggest. I think that either your car is no worse than any other, or more likely all the people who've looked at the car have missed the problem.
 
I feel I should ask, what kind of noise? A vibration or a soft/sharp whine in certain gears (or all the time)? What's the condition of the LT77? And of course, if you're setting up a rally car you might have removed the rather useful insulation material over the gear tunnel and over the selector mechanism?
 
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