When I bought the lower hull for my late Tiger 1 I bought the low profile Taigen 5-1 premium gearboxes with thoughts of switching them out with the 4-1 Taigen H/L gearboxes in my Sturmtiger to give clearance for the Sturmtiger barrel to be fully raised. The final gear that goes on the driveshaft on these is held in place with a grubscrew. I guess the resistance of the metal tracks turning on carpet is too much for the grub screw because no matter how much I tighten it down and loctite it eventually frees up enough that the gear just spins on the shaft. Anyone got a solution to this. I'm thinking of roughing up the shaft to give the end of the grubscrew more chance of holding. Any other ideas for a solution to this? I've never had this issue on any gearbox before

Thinking out loud here … drill a small indentation into the shaft that is lined up with the grub screw so that the grub screw will be seated into the shaft. Does not have to be too deep - just enough for it to seat and not slip. The shaft may be too small in diameter? Just a thought. 

Cheers

Thanks Sandy. If my fix from a couple of days doesn't hold (I just gave it a 5 minute torture test and it did) that will be my next course of action. It's weird the right gearbox has no issues at all

One of the reasons the grubscrew backs off when Loctite'd is because the threads are not clean and the Loctite does not adhere. If you can, make sure and clean out the threads of both the grub screw and the threads in the gear...

Chasing threads?

Threads are fine. I think Sandy might be onto something with the shaft diameter possibly not being within tolerances by the tiniest amount and so the whole torque of the gearbox is on the grub screw. If it starts spinning on the shaft again I'll rough that section of the shaft and put a small notch in it to give the grubscrew a fighting chance. I like the gearboxes themselves. Can't wait to drive it off something at home and bend the shaft.............................   

Is the shaft thick enough to be drilled through and put a roll pin into?

Roll pin shouldn’t come out if it is matched to the correct diameter hole.

Oh for sure it's thick enough, it's the shaft to the drive sprocket. But I don't have access to a drill press so I'll stick to the small notch plan if it spins out on the shaft again

Thanks for information