I am on the verge of finishing a garage shed in order to remove engine from bike and then go after the transmission. Do I trust Robinson and what he can do to a transmission? 100%. Never heard anything but good stuff about his work. If anyone has a complaint please post and let us know.
Ah yes I remember you had a very similar issue affecting 4th gear. It will be interesting to see what is going on when you have it apart.
I'm sure Robinson do a great job. I decided against sending it to them purely as it's overseas because of the distance and import duty issues. So I was looking for a UK company to do the same. I saw BSD mentioned, they have a good reputation too I haven't spoken to them. I spoke to the company local to me who do race transmissions and they were talking the pros and cons of back cutting in general not just in relation to rocket. They were saying that when your cutting away material you're removing the hardened metal from the the case hardening and the component should be heat treated again after being worked. They said there are plenty of companies that will back cut a standard cog for me, but unless you're heat treating again, you're effectively shortening the usable life of the component, the trade off of making standard components 'race' components. The real way to make the gearbox into a race gearbox would be to replace any cog with dogs that are to be back cut with a billet version that is back cut from manufacture rather than modding the standard production component.
Their point was if I want a racing rocket gearbox, the components should be remade rather than modding a standard part to be a race part. They weren't saying it wouldn't work, but they were wondering what would be the life span of the said product.
They were essentially pondering that me wanting a race box that would last another 40k miles might be mutually exclusive if I was backcutting the standard part.
So I decided to not get back cut done. However I may still purchase the Robinson 4th gear or ask them to make a billet 4th not sure yet.