I noticed that the 4G Belt drive has gone down in Price. Is there any new updates on this kit or is it still considered junk? As I have read the other thread on the 4G.
For the price of $299? It does seem very attractive. Or should it be avoided?
Thanks in advance.
I was right about the 4G incidentally and it is a total lemon for all the reasons I stated but I have managed to make it work by adjusting the gear ratio.
As it is currently made the gearbox doesn't get enough speed but it does put a lot of torque through the 11T freewheel sprocket. They can't handle the increased torque and the users have all had problems with the 11T sprockets failing very quickly. The ratio can be changed by either increasing the size of the small pulley or decreasing the diameter of the second pulley. Increasing the size of the final sprocket isn't an option because the engine casing won't allow room for it. The 4G is too big anyway so it makes sense to replace the second large pulley wheel with a smaller one. Then you get a gearbox that performs really well and, unlike the Mark2 & Mark 3 Grubee GBs it is very quiet.
This is expensive to do of course but is really necessary if you want it to work at its optimum on a 26" wheel.
The old Mark2 & Mark 3 GBs are pretty good but are very noisy (although I have found about one in eight is actually very quiet but that must be luck of the draw).
Don Grube says people shouldn't go too fast and that is why the 4G is like it is but the real reason is that they were never tested properly before production and he was too proud to ask any of several MBc members who have the knowledge and would have helped him get the ratio spot on first time.
I haven't tried the EZ gearbox but I'd bet it has to work better than the 4G.
So I'd recommend a noisy Grubee Mark 3 GB or an EZ if you can afford one but the 4G is pretty good if you are prepared to get it partially rebuilt at good tooling workshop and are prepared to pay the cost for that and ride around with short cranks and legs wider apart because it is seriously wide.
The older Grubee GBs get worn bushings on the primary drive gear and that often requires replacing - sometimes after only 5000 miles but it isn't expensive - the bushings need replaced and the primary gear needs replaced as well but if you have lots of new bushings you will find one to fit a worn primary gear because the bushings vary a bit in diameter and a fatter one will fit a worn primary gear & bell housing very nicely. That is my experience from building and servicing quite a number of Grubee fourstroke kits. I like the old gearboxes and I suffer the horrible whining noise but many of my customers can't stand the GB noise. A good quiet GB certainly has a lot going for it.
Until I try the EZ I can't really talk about it but I have great expectations of it when it eventually arrives in our neck of the woods.
The film of it is very nice to watch. If you want my advice buy the EZ but I can't talk about it from experience like I can the others.
I also spent 4 years working in construction industry in China between 2000 - 2004 and quality is not something I ever managed to get unless we used Hong Kong fabricators or contractors and they cost a lot more.
