Wrong Key Slot

Discussion in '4-Stroke Engines' started by jimraysr, Jul 9, 2008.

  1. jimraysr

    jimraysr Member

    I have two GruBee gear boxes. Bought them from two dealers on each end of the country.

    The clutch key way is (4.35mm) wrong in both.

    The bell housing bushing has about the same slot (4.6mm) as the Honda GXH50 (4.7mm).

    Key supplied, 4.55mm

    Has anyone else had this problem? and if so how did you solve it?

    As the bell bushing uses the same key as the clutch, it would be best if they had the same slot.

    Suggestions appreciated.



  2. stude13

    stude13 Active Member

    hi jim; any small engine shop could help, also tool rentals and motorcycle. mitch
  3. MasterLink

    MasterLink Member

    ace hardware sells keys look in in the lawn mower section then sand them down a bit to fit on a small angle sidewalk file there very soft
  4. acronn

    acronn New Member

    Same problem

    Hello, this may be the same problem? I was getting some clutch chattering and couldn't get this part off. That keystock doesn't seem to be the same size at all. But that piece is in there tight, that's my problem right now, I can't get that clutch piece off of the crankshaft, and that key is in tight.

    Attached Files:

  5. MasterLink

    MasterLink Member

    that key looks messed up to me you might have to beat it off some how try not to bend the crank but you sure need a new key
  6. jimraysr

    jimraysr Member

    That really looks like a mess. Obviously not a GeuBee gear box. That is quite a hub on the clutch. It would be good to be able to use a gear puller, but hard to pull on the hub and not on the clutsh plates. Good Luck, Jim
  7. acronn

    acronn New Member

    Managed to get it off

    I managed to work off the part that was stuck so tightly, first I tried pulling it off the keystock with vicegrips once everything else didn't work, then I put another pair of vice grips 90 degrees from the other so I could tap on the keystock that way to pull it off, that didn't work, then I cut a groove in the keystock and pried with leverage, that may have moved it just a bit, then I used a large square tool (the handle to a large punch) and tapped on that, and that piece moved, along with the keystock. Once pulled off, I noticed that when I reversed it, it fit all the way home, so it must have a slight taper. Now I have to figure out how to install that very stout clutch spring and I'm back in business.. I think.. so far, so good.
  8. Irish John

    Irish John Guest

    The keyway in the shaft should be 3/16" or 4.76mm but the shaft keyway channel on my 2 HS motors and my Honda is 4.5mm. I bought a length of 4.5mm key but it is actually 4.7mm on my vernier caliper. I have noticed that there is variance between the keyway in the clutch and that in the engine shaft. The clutch is 4.42mm at one and 4.6mm at the other. Some of the existing keys were hammered in at the factory and it's very hard to get them off and that may account for the difference.
    The bell housing bushing is 4.58mm on the Grubee and there isn't a keyed bushing on the Hoot - just a keyed clutch. The shaft diameters are the exact same on all three engines.
    My solution will be to file the keys down, in different places by different amounts, to fit both keyways so the clutch can slide off again without the need to use 100mm size gear pullers. I'm not so fussy if the bell housing is a bit looser than the other two but I'll endeavour to get them all tight because a loose key is asking for failure and contrary to what I wrote on wednesday on another thread, the key, although tempered steel is not as hard as the shaft and is therefor sacraficial. Must go and find that thread and eat some humble pie!
    Last edited by a moderator: Aug 1, 2008
  9. jimraysr

    jimraysr Member

    I got a clutch wt. the proper slot from the dealer who sold me the kit. Took a while, but he came through. Thought if I ever needed to use the clutch with the narrow slot I would file out the clutch to fit the key. I bought a lose transmission from a dealer 2000 mile from the first and the clutch in that one was narrow also.

    No doubt about it, importer, dealer or customer, the China kits is a pig in a polk. I have replaced all the bolts and modified other things to fit a modern frame. The kit was just a starting point.

    Thanks for your information and history.
  10. Irish John

    Irish John Guest

    Jim, if it's not a Grubee GB then what is it? A Hoot? and if so, how can you tell from the photo?
    The keyways in my Hoot clutch & Grubee clutch are not exactly the same. In fact on the Hoot the HS engine shaft key is 3/16" but the keyway on the clutch is smaller and the keyway on the gear wheel is different again. This is really sub-standard engineering at its very best. A pig's ear of a job and not good enough by a very long shot. Take a look at the Hoot clutch in the pictures and you'll see the key from both sides of the clutch. To get it out I'll probably haveto drill it out. I will use new keys and file the keyways I reckon. It looks like it was forced into the slot with some sort of very heavy & powerful hammer.
    This sort of engineering is a disgrace and no doubt some Sinophile will probably tell me I'm expecting too much too soon from a developing country etc.

    Attached Files:

  11. jimraysr

    jimraysr Member

    Irish, I wasn't the one that posted about the key jammed in the clutch. Both of my gear boxes are GruBee with the decals in the gear cover.

    I now have four clutches. Two have the proper keyway, but all are of the same construction. One does have three tapped holes, one in each clutch section. Don't know what they were for?

    Looks to me like several shops produce the same item, so may have different manufacturing methods.

    When one of my companies started to manufacture large valves in China, we saw knockoffs of our design in SE Asia within two years.

    GruBee may have a US patent on the box, but that won't stop China from making as many as they want.

    BTW, I can see the return spring (one spring around all three shoes) on each of my clutches on the side that goes to the engine. It doesn't seem like you can see the spring on the Hoot?

    Last edited by a moderator: Dec 15, 2015