4G T-Belt Transmission (Honda)

Discussion in '4-Stroke Engines' started by Irish John, Jul 21, 2010.

  1. Irish John

    Irish John Guest

    I have a few queries regarding the 4G Honda gearbox:
    1. I notice the clutch bell has a bushing and not the bearing as per the HuaSheng model. Does this mean the bushing will wear out very quickly like on the older Gruibee GBs and will require a new bell housing and bushing every 2 - 4 thousand kilometers?
    2. Does the 11T freewheel break under increased torque through the shaft?
    3. Is this GB geared to work with a 48T rear sprocket? If not what size is the best sprocket and will it cruise at 30 mph like the older GBs?
    4. Can it take a 1 piece wide crank or must it have the 3 piece crank with the short crank arms?

  2. cruiser66

    cruiser66 Guest

    Hi Irish John,

    I have recently been researching the newer upgrades to the Hoots myself. I found this very informative site on 4G transmissions. I think Terry Blow can give you all the answers you are looking for.


  3. Irish John

    Irish John Guest

    Thanks Cruiser I've written to him to ask.
  4. Whizzerd

    Whizzerd Member

    Hi Irish John, you sir, were right on with your assessment of the G4. The gear ratio's wrong. Expensive lesson but I've purchased an EZM to replace mine. I should have heeded your first Review!
  5. Irish John

    Irish John Guest

    Hi Whizzerd, are you talking about my assessment of the Mark2 4G or the Mark1 about which I was certainly not polite and which I found to be a totally useless gearbox. The Mark2 has been re-engineered and I have no direct experience of it but the advantage in the reduction in the size of the large pulley wheel which was very necessary will be lost to some extent by reducing the drive sprocket from 11 tooth to 10 tooth.
    In this thread I am just trying to find out if anyone can tell me whether the 4G for Honda has a bell housing & bushing because if so those have all been problematic on the many old style Mark2 gearboxes I have built and they only last about 2500 kms before they become too loose to work effectively. This is what I'm trying to find out.
    These things are important only because I have a lot of customers out there who were supplied with old style Grubee kits for which there are now no spares and they absolutely have to have the bell housing & bearing replaced about every 2500 - 3500 kms and the drive sprockets at about 4000 kms.
    The Australian Grubee importer doesn't care about trivia like old models and the need for spare parts when he's busy flogging the new belt drive kits.
    I had hopes that someone would produce a trouble-free gearbox by now but it seems to be still in the pipeline.
  6. cruiser66

    cruiser66 Guest

    Hi again Irish John,

    The Honda unit uses the oilite bearing which initially has to be soaked in oil for several hours before using. The Huasheng box uses the Huasheng supplied clutch and bearing. Honda did not come with this, so 4G made up the bushing thing which will need periodic maintainance.

    I also do not like the freewheel mechanism as it is another weak point in the design.

  7. Whizzerd

    Whizzerd Member

    Yes John, my unit is the Mk. 1. Just a few months after I purchased it upgrade kits were made available through Grubee. The new version is still a 5:1 ratio gearbox if I'm not mistaken. Talking to other mb'ers at the Motorbike Show last week confirmed my experience w/ the G4. Quentin's EZM equipped bike with several thousand miles rides like a Champ! That's why I purchased one.
  8. Irish John

    Irish John Guest

    The standard grubee gearbox bushing do not require periodic maintenance so much as periodic replacement and the period is relatively short and the availability of replacement bushings and bell housings is zero for the old gearboxes.
    I have looked up Oilite bearings and super oilite and super 16 oilite and they look like good stuff. I wonder how long they last given that I have now established that the old Grubee gearbox shaft bushings need replacement between 2500 and 4500 kilometers. After that distance nasty things can happen because the lateral movement of the bell housing can damage the shaft and shaft key and potentially the teeth on the middle gear wheel.
    Running a wet gearbox might help but then you have clutch slipping problems.
    It's really no big deal because the replacement bushing and bell housing is only $25 or $30 but in Australia the dealer has stopped supplying spares for old gearboxes.
    I like the sound of the new 4G Hs kit but I'm not that keen on having to have the HuaSheng that it goes with. Once you have got used to Honda its hard to go back to HS and the difference is very noticeable.
    So I guess I'm wanting to know how long the bearings on a 4G Honda gearbox last?
  9. Irish John

    Irish John Guest

    On the old Mark 2 Gearboxes I am trying an experiment by putting several bushings and bell housings in a deep oil bath of fairly heavy gear oil after heating them to a high temperature with a Mapgas torch. I'm leaving them in the bath for 3 days to see if the oil impregnates the bushing and housing and thus prolongs their working life. I'll report back in a couple of months when I'll know if it works. I see my queries re the Mark 3 Grubee gearbox have gone unanswered on the other thread I started.
    Mustn't be a popular gearbox methinks.
    Last edited by a moderator: Jul 24, 2010
  10. domino

    domino New Member

    John, How the the three day oil soak on the bushings go? I have a Honda tran and just checked my bushing by putting a torch to it. The bushing was full of oil. I did drop it back in a cup of oil to soak over night. I'll be putting the bike back together tomorrow. Hope the bushings last more than a few hundred miles
  11. chrisnbush

    chrisnbush Member

    Hey, in case anyone still hits on this - I recently got the Dax "super titan" and am really happy with it - running with the Grubee 4g, the one with the 11 tooth freewheel. I suspect that it matches up more closely with the torque of the Honda. Don't know what Duane did to it - or HuaSheng but it is noticeably more powerful (now to see how it holds up (!), I have 530 mile on it now).

    I bought the new motor after I blew up my original standard HuaSheng, also from DAX racing a bicyclist (and losing). At that point, I had 744 miles on the 11 tooth freewheel, so now I have 1274 miles on the freewheel. Still looking good (knock on wood, my head maybe) what I have been doing is feeding it Triflow oil (the liquid, not spray) via an insuling needle my friend gave me, which I epoxied to the delivery straw that comes with the Triflow product. I just squeeze it drop by drop into both cracks in the freewheel, left and right side of bike. Waiting for bikeengines to get more freewheels so I can get a spare, probably going to have one welded just for a sure thing. Here's hoping

  12. Irish John

    Irish John Guest

    Chrisnbush, the best thing to do with the 11T freewheel is to completely dismantle it and rebuild it adding thick grease to the inside. You need to keep the grease off the threads because they need to be clean so you can put red locktite threadloc on them. When it is reassembled and installed you need to leave it for about 2 days to set. That way thefreewheel will hold together until the teeth wear out ar 4000 -5000 kms.
    Like with a lot of Chinese components you need to totally rebuild it if you want it to function properly. Freewheel1.jpg






  13. chrisnbush

    chrisnbush Member

    Thanks Irish John, that is a big help (particularly the thread direction on taking it apart, and the grease - looks like some kind of spanner wrench would be appropriate here ?).

    I will pack it with grease. I read about the loctite, I had the bolt spin off a couple of times when I first got the 4g, put a big split washer on it and haven't had a problem since then. The problem I have had with loctite is that if I don't get the metal completely clean of any oil they spray on, I guess as a rust preventative, it doesn't hold well. So, even if I think the metal is clean enough, I don't trust it. But I probably walk more than you do...

    Hey, there is a product called Tufoil - it is suspension of PTFE (teflon) particles. Slippery stuff - I swear by it in my cars, e.g. got 160+ miles on my little Tracker 1.4 liter motor, and it was still running strong (and not burning oil) when I sold it. They make a treatment size for small motors, I have it running right now in the HuaSheng. Posting it here in case you have had any experience with it, anyways I want to see how many miles i can get on this motor

  14. Irish John

    Irish John Guest

    Yeah Chris, you need to undo the freewheel with a small centre punch. There is probably a special tool for the job but I haven't seen one. When you do it up again make sure it is tight as can be. I don't get the threads totally oil free but the threadloc seems to hold really well. If your 4G gearbox puts too much torque through the shaft then you might have freewheel problems. I gave up on the 4G just after it came out and I tried one to see what it was like. I was very critical about the 4G very early on in a thread I posted and attracted lots of nasty abuse from MB members but I was proved absolutely correct over time. The newer 4G with the smaller pulley wheel is still geared all wrong. The older Mark 2 GB is a better GB but they stopped supplying it because they knew it was better than the new one. I wish Don Grube would stop experimenting and just find a disused aerdrome near his home in China where he could actually ride his inventions to see if they do or do not work.
  15. ibdennyak

    ibdennyak Guest

    John, I also appreciate the tutorial. I am putting a lot of torque through one, and am concerned about longevity. Already had a few problems with it freezing in winter.

    Rhetorical question.....wouldn't it be possible to add a few more ratchets and machine the center to beef it up?
  16. Irish John

    Irish John Guest

    It was because they found out that the 11T freewheel couldn't cope with the increased torque that they changed the 4G Mark 2 to a 10T rigid sprocket. The 10T rigid is too small and Grubee knew that but what the heck they are plentiful because the 2-strokes use them so why go and get one specially made.
    To justify this piece of logic Don Grube said ' well the old GB was making the bikes go too fast and that is dangerous etc. as if he really cared.
    The very old 11T freewheels were actually more robust than the later ones but they must have been the victim of quality fade.
    I reckon it would be easier to source an 11T freewheel that could be adapted than to include more ratchets (pretty impossible) or machine the centre to beef it up (don't really understand quite how).
    What I think a person of moderate integrity would do is to get the 11T freewheel made of better material and certainly better assembled before throwing all that stuff together in kit form.
    Last edited by a moderator: Apr 8, 2011
  17. ibdennyak

    ibdennyak Guest

    Yeah, that's kind of what I was getting at John. I don't mean modifying an existing one, I meant having one manufactured with 4 or 6 of the little pawls. I tend to overbuild stuff, and I guess *planned obsolescence* doesn't quite fit in my scheme of things.

    Guess that just makes me an olefart, and out of touch. :confused:
  18. Irish John

    Irish John Guest

    I'm the same as you.
    Our day will come!!