Rebuilt S80 Gearbox Rattle


My little theory above is rubbish as the guy was running the box for nearly a year before I bought it from him.

I tried switching the upper and lower shims to move the diff upwards a touch. The diff is a little harder to turn but the knock is still there and I'm almost certain it's coming from the teeth connecting.

I'm stumped.
 
You could be right it could be a difference in the meshing between the fd and mainshaft gear, if the fd has been changed then the mainshaft needs changed at the same time

Although if the mainshaft is not meshing properly with the FD ring gear it will be very difficult to turn them together freely

Its very hard to diagnose the problem without being there to have a look at the gearbox, it could be something very simple that you have missed out. It takes you to build them a few times to become farmiliar with some of the problems that can happen when swapping transmission parts
 
Everything rotates and shifts nicely. Feels solid too, just the knocking.

Ive followed different how to's and diagrams everything is there, in the correct places and orientation. So it's beyond me now.

Like you say it needs to be looked at by someone with experience, which I will have to do later on when I have the time.

It's all back together now, just now sealed so it can be pulled apart quick enough.

Thanks for all the help though chaps, I'll get to the bottom of it eventually! :D
 
Keep us up to date, I'm interested to find out what the knocking is

One last thing, did you remember the two shims that go beneath the input shaft? They sit on top of the bearing that the input shaft slides through. Remember the lower shim is concave the top is flat.

Did you also remember the big washer with a tab on it that goes on top of the input shaft?

Other than that I'm wondering if one of your bearings is worn causing a lot of backlash between the gears
 
No worries will do. I have an ok box on the car at the moment already so it will be a while.

Yep all the shims are there, it's all there. All bearings have been checked, everything feels smooth. Random!
 
Taking the box to TGM Sport on Friday for them to look at, so should have an answer soon. More importantly I will have it on the car! :D
 
is there backlash between the crown wheel and the pinion? is there wear on the bearing surface on the pinion shaft?
 
So the outcome of this is that somehow the casing is duff.

Does anyone know if these S80 internals will fit my Y21 casing??
 
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