New ratio 4G gearbox from Grubee

I

Irish John

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The attached is a message from Don Grube. My query is given that the large pulley wheel in the old 4G was way too large and consequently the drive to the rear wheel was all wrong will this one get it right? The maths guys on this forum will surely know whether this GB will work adequately like the Mark2& Mark3 gearboxes did with an 11T chain sprocket to a 48T rear wheel sprocket on a 26" wheel? I'm worried that the reduction in size of the rear pulley wheel will be diminished by the reduction of the chain sprocket from 11T to 10T.
Don's Message:
These pics. will be posted on our grubeeinc.com web site in 4G 4 cycle section in the coming weeks; By viewing now you can have first look see at the new 2010 4G upgraded transmission with one-way brg. 80T pulley and 10T soild drive.


FYI: A conversion kit will take a 2009 model to 2010 specs. with a simple shaft and pulley change.

The new 2010 4G PL/PO form has all items listed. Please acknowledge if interested.

Cheers:
Don and Angel China GAS
1 (2).jpg

4G 20T-80T-10T-50T.jpg

#1. _4G upgrade.jpg
Don's reply to my query that the ratio being wrong again:
You can have choice of 36T, 44T, 48T or 50T rear wheel sprockets. Now do the math. with a 4 to1 trans. ratio and 10T chain drive sprocket. You worry to much. Cheers Don
My answer is I don't know but if he lent me one for 2 weeks I'd be able to tell him what rear sprocket size, if any, it works best with. I do worry I suppose because of my experiences with the first 4G which was documented elsewhere last August.
 
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I just looked at this and the figures that Don Grube has listed for the ratios are incorrect. It actually is 20 to 1 not 9 to 1. Several sprockets were mentioned.

The 36 tooth ratio is 14.4 to 1
the 44 tooth ratio is 17.6 to 1
the 48 tooth ratio is 19.2 to 1
the 50 tooth ratio is 20 to 1

Just thought I would point this out to be helpful.

Tom
 
I wonder if the cover will be smaller as well. That could help with the crank to transmission clearance.

I doubt he'll change the flimsy bracket that breaks off from vibration or the plastic cover so we'll have to wait and see but I'm certainly not interested in it until he gets the reduction ratio right which, at present, he hasn't. The gain on reducing the pulley wheel size (still looks too big) will be diminished by the decrease in the drive sprocket from 11T to 10T. Why doesn't he just post a thread and ask?
Has anyone found the G4 useable? if so how have they made it useable?
 
Hey Irish,

I have the 2009 version of the 4G belt drive, i can tell you right now that the 5:1 ratio gear box with the 5:1 ratio for the rear sprocket, for an overall reduction of 25:1 is very useful. I went on a rally this past weekend and i had no problems keeping up or passing people. and now i can acutually get up hills. I will get a speedo this weekend and i will have numbers for you later.
 
Hey Irish,

I have the 2009 version of the 4G belt drive, i can tell you right now that the 5:1 ratio gear box with the 5:1 ratio for the rear sprocket, for an overall reduction of 25:1 is very useful. I went on a rally this past weekend and i had no problems keeping up or passing people. and now i can acutually get up hills. I will get a speedo this weekend and i will have numbers for you later.
That's interesting HseLoMein but you need to supply info like G4 GB with 11T freewheel drive sprocket to 44T rear sprocket on 26" wheel for your information to become really useful. A good picture (left side) always helps as does the mileage you have covered since the install. You are the first happy customer I've read about because I can tell you that the early G4 I built was unuseable as Sean, the owner, attested elsewhere on this Forum. Your set up must be different. It never performed well because of the gearing but the increased torque pulled the 11T freewheels to bits - the 11T freewheels for the G4 are not the same bolt fitting as the 11T freewheels for the older Mark2 & Mark3 GBs incidentally.
 
another happy 4G owner

That's interesting HseLoMein but you need to supply info like G4 GB with 11T freewheel drive sprocket to 44T rear sprocket on 26" wheel for your information to become really useful. A good picture (left side) always helps as does the mileage you have covered since the install. You are the first happy customer I've read about because I can tell you that the early G4 I built was unuseable as Sean, the owner, attested elsewhere on this Forum. Your set up must be different. It never performed well because of the gearing but the increased torque pulled the 11T freewheels to bits - the 11T freewheels for the G4 are not the same bolt fitting as the 11T freewheels for the older Mark2 & Mark3 GBs incidentally.

my setup is the honda 4G drive which is thinner than the Hausheng 4G drive. I'm running a 48t rear free wheel sprocket,and it has the 11t free wheel[I know 2 free wheels] Would like to try the 44t sprocket but can;t find one. The so called flimsy brackets on my unit are actually pretty stout.I now have over 200 trouble free miles on my 4G. 30mph top speed with plenty of torque to make it up hills. Very happy with the 4G
 
my setup is the honda 4G drive which is thinner than the Hausheng 4G drive. I'm running a 48t rear free wheel sprocket,and it has the 11t free wheel[I know 2 free wheels] Would like to try the 44t sprocket but can;t find one. The so called flimsy brackets on my unit are actually pretty stout.I now have over 200 trouble free miles on my 4G. 30mph top speed with plenty of torque to make it up hills. Very happy with the 4G

That's good to hear Bill. How much thinner is the Honda 4G? A 44T sprocket is available from any 2-stroke kit vendor (at least they are here) because that is what they mostly use on 48cc & 66cc kits. Has the freewheel pulled the ratchet through the pawls yet?
Are there photos posted anywhere of your bike because I'd love to have a look?
200 miles is only 90 miles more than I include as the trial period before I hand a bike over to a customer and sign off on it but most serious defects should have become evident by this distance.
 
photos of my 4G huffy cranbrook

That's good to hear Bill. How much thinner is the Honda 4G? A 44T sprocket is available from any 2-stroke kit vendor (at least they are here) because that is what they mostly use on 48cc & 66cc kits. Has the freewheel pulled the ratchet through the pawls yet?
Are there photos posted anywhere of your bike because I'd love to have a look?
200 miles is only 90 miles more than I include as the trial period before I hand a bike over to a customer and sign off on it but most serious defects should have become evident by this distance.
I have photos of my 4G at below links
http://www.motoredbikes.com/showthread.php?t=26544

and

http://www.motoredbikes.com/showthread.php?t=26376
 
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