Well I've done 400 miles now in my mazda based kit car. Unfortunately the drivetrain has developed a noise.

I'll start by saying the noise sounds like its coming from the diff but I think that is a symptom and not the cause. The diff is solidly mounted so any noise transmitted through there is loud.

When I change 1st to 2nd while underway I hear a loud clunk. A couple of times 2nd to 3rd but mostly 1st to 2nd. It still changes with no problems other then the clunk. No noise when I stay in gear and get on and off the throttle. Nothing unusual from the clutch apart from a bit of judder that I kind of expect with a 6 puck clutch. No noise when changing 1st to 2nd while stationary. Oil level is good. Everything seemed to be ok for the first 200 miles or so.

What did I do before it was like that? Everything (well it is a kit car). So I had the engine and gearbox out to change the clutch. Changed the gearbox oil with redline. Had the gearstick out and replaced the boot and the nylon end that does the shifting and some more oil in the turret. Put a torsen diff centre in at the same time.

It sounds to me like may be 2nd gear syncro buggered and gears are just smashing into mesh. But....when I did the turret bits it was a bastard to get the stick back in (tight) so I'm hoping it could be simple issue like that. It was a cheap rebuild kit and not genuine parts.

edit: its 1.8 bp drivetrain