B6/B6D gearboxes
 

On the bench I've got a B6 and a B6D. The box in the B6D is very free and smooth, the B6 is a little tight and not quite as smooth as the B6D.
Is this normal or should both be the same and the B6 has a problem?
I'd have though that they should both spin freely and smoothly as they're both 3 gear systems rather than belts.

Thanks.

Gearbox
 

Could be a bearing or two at the end of their life?

Have you over tightened the screws in the casing?

I have both cars and both are spot on.

Something isn't right. With the case just held together by hand it's ok but as soon as I start fitting screws it tightens up. Have ordered a new gear case and a top shaft just in case.

One is a gear diff and the other is a ball diff right? They'll feel quite different one another... could that be it?

Correct, but not the diffs. Whole box is noticeably tighter on one than the other.
On closer inspection the box case looks to have some possible heat damage from the motor.

I had this... on my original B6. New gearbox case didn't fix it, so I think it was a bearing. Same problem existed between ball diff and gear diff as well, so that was the shims eliminating the issue.

I would try replacing the bearings first.

Sorry I cant be of anymore help!

New case and/or top shaft have cured it. Bearings felt smooth so they're ok.