this might be a issue with the gearbox

Discussion in '4-Stroke Engines' started by MasterLink, Jul 6, 2008.

  1. MasterLink

    MasterLink Member

    This might be a issue with the Grubee Gearbox

    (Grubee box)

    have you guys seen this issue the ball bearings fall out i have about 5 missing in this final drive / jack shaft and there was play in the sprocket i took it apart and after closer look i see that its all held together with screwing it together the races. now there is a bolt on the back of the gear that i always check for tightness ...and its stayed tight and somehow i have lost some bearings and its made it sloppy there is a key in there that i put on the shaft but it power now is not goin to the chain .... does anyone no where the wooddrift key gos i took it out under the race but i dont see how to get it back in there well i might have to load the bearings and the key on the shaft dos'nt seem right ..but thats the only thing i can think of i put that key on the shaft then put the gear on that shaft but thats not working ....there has to be a trick iam not seeing yet any help in this matter thanks in advance


    ps as you can see in the fdive pic that brass looking washer thingy is really the back of the race and is a reverse thread and didnt stay tight on mine it can be adjusted i think the bolt dosnt keep it tight there are 2 indentions in it for a tool to tighten it
     

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    Last edited: Jul 6, 2008

  2. Proboscis

    Proboscis Guest

    I'm in a similar situation, I had my woodruff key break apart after 5KM!!!.
     
  3. MasterLink

    MasterLink Member


    what key broke on you ? the clutch or the key at final drive gear ?
     
    Last edited: Jul 6, 2008
  4. nsideus

    nsideus Guest

    I lost the first woodruff key when the bolt came out this was less than 100 miles. I got a new one from be.com aand sheared it at around 2,000 miles. I then made one from a larger key which has around 3,000 miles on it. As far as losing bearings have not had that problem. I would check and make sure the gear is ratcheting freely if it is then my call would be the woodruff key. The gear should slide on with the key without much resistance, use locktite on the bolt. Should you need to replace the gear call Josh at bicycle-engines.com 1-800-514-8435 I didn't see a ratcheting one listed in their site but I am sure Josh will help you out should be around $15. Locktite is my friend.
     
  5. MasterLink

    MasterLink Member

    well i found out why it was working free wheel both ways i put it back together wrong anyways i reversed and working now but it still is losing up i have one on the way to me seems as it has reversed threads that it should stay snug but its not then again there is a tool marks two dents a tool must fit in ok i think its good now i put it in a vice and took a nail set to tighting it
     
    Last edited: Jul 9, 2008
  6. Irish John

    Irish John Guest

    Yes the sprocket shaft has a 1/8" key (not a woodruff key but a straight key) and it shears easily. I made a replacement and installed it but I didn't know about the flange/ball race at the rear and it must have been loose. Those things are on lots of cycle freewheels and they ALWAYS need to be loctited in well and truly according to my bike specialist from True wheels Bike Shop, Mullumbimby. These ones aren't! Don Grube is sending my supplier a replacement from the US so I'm waiting over a week but I'll loctite that flange before I install it. Also I won't hammer it onto the shaft if I can use a vice to squeeze it back on over the new key but I'll probably end up using my trusty Irish spanner (5 lb rubber lump hammer).
    It's also quite hard to get the sheared key out of the shaft keyway cos it's been sheared flush and you can barely even see that there is a key in there.
    It is really useful to know that there are probably 24 bearings either side. I'll count mine but I'm scared to take it completely apart in case I can't get it together. I reckon the flange came loose and some bearings fell out. The fault is the manufacturers and I'm glad my supplier is coming good with a replacement cos it had only done 150 kms.
    I've posted good annotated pictures of the freewheel's innards on my Grubee Freewheel Sprocket Failure thread at:
    http://www.motoredbikes.com/showthread.php?t=14738
    which at least will help people know what's in there.
    To get the sprocket off I needed my little 3 jawed gear pullers that were recommended to me on this forum for removing centrifugal clutches and they are a Godsend. Aus$20 very well spent and given the deteriorating standard of engineering of these keyways (they are all different to the shaft they are supposed to match) I will be using this tool a lot. Thanks whoever recommended it to me.
    We, the consumers, need a lot more leverage over the suppliers but my supplier tells me that the problem is with the components that are made in Govt run factories where there is no quality control incentive. The Gearbox and tray I think is made in a good factory but the clutches are made in bad factories along with so much else of the kits and trying to get better quality has always been a fruitless exercise according to my supplier.
     
    Last edited by a moderator: Aug 28, 2008
  7. lookbiker

    lookbiker Guest

    i sheared off two woodruff keys within a week of each other. After that the freewheel itself busted apart. I ordered the solid gear from bicycle-engines.com and replaced the final output shaft. I haven't had a problem since. It did however take me awhile to get a chain that was strong enough and fit the pitch of the gear. I finally got the KMC K710 CHAIN. It's 1/2 x 1/8 and works perfectly. I've put at least 1000miles on it and I wouldn't trade this setup. My bike is practically bulletproof anymore. As I'm sure many members know, it takes a while to get your rig to run reliably. LocTite is your pal. And so is this setup. :)
     
  8. Irish John

    Irish John Guest

    Yes Lookbiker, it is easy to shear a 1\8" sprocket key when you are getting used to the gear engager mechanism. It's the first key to shear when you drop the engager at too high revs but it's easy to fix. I snapped one last wednesday while starting off and talking at the same time - my mind was not focussed on what I was doing and my hamstrings still hurt from the long ride home under pedal power.
    The freewheel sprocket is good if you loctite that flange on during the build. It should be loctited in the factory but it isn't. How many teeth has your fixed sprocket got because if it's a 10T sprocket it will change the whole gearing set-up. Does the bike freewheel just as well with the fixed sprocket?
     
  9. nsideus

    nsideus Guest

    Sheared my sprocket key again. This time I was in the creek bottom with a trailer full of wood. Nothing like and early morning ride up hill. The kit has over 5,000 mi and this is the 4th or 5th key sheared.
     
  10. Irish John

    Irish John Guest

    That's a sod of a thing to happen Nsideous. Why were you using a grubee kit to pull a trailer full of wood through a creek? The Staton NuVinci might do that but a frame mounted grubee couldn't handle the stress. Did the key shear when you engaged the sprocket or after it was engaged and pulling the trailer? I'd be interested to know because I've not had one snap once the gear is engaged.
    I can snap these keys anytime I want to and sometimes when I don't want to if I'm not carefull. I really have to be carefull with the heavy steel Schwinn\Honda because it's easier to snap the key on a heavy bike. It's a simple fix but it takes a lot of time and it's messy isn't it?
     
  11. HoughMade

    HoughMade Guest

    Still waiting to shear my first key....probably will happen at some point.

    Curious- is there a pattern (anyone) as to what you are doing when it shears, or is it random?
     
  12. Irish John

    Irish John Guest

    Yes HoughMade there is a pattern and it involves dropping the engager in at too high revs when stationery. My Schwinn Alloy7 Fosscati Indian Pacific had never broken a key until at 5000 kms I made this mistake while talking to someone as I set off.
    The Schwinn D7 Fosscati Billinudgel Bullet is easier to shear cos it's heavier and the Honda is a bit more powerful so the way to avoid it happening is to be careful. Carelessness and showing off are the two things I need to avoid.
     
  13. HoughMade

    HoughMade Guest

    Well, I can't drop the engager...I disconnected it. We'll see how long mine lasts.
     
  14. Ghost0

    Ghost0 Guest

    Another question for you two 4 stroke pros. Busy working on the 4 stroke shift kit so I am learning this whole 4 stroke thing. What is the purpose of the engager "clutch" if the engine has a centrifugal clutch?
     
  15. Irish John

    Irish John Guest

    It's Don Grube's idea and it's a good thing cos it enables us to start with a bit of throttle in cold weather so the bike doesn't take off like a rocket without the rider. It also enables us to rev up outside pubs and scare the Hells Angels away! Seriously it's a good idea and I like to freewheel down hills with the engager off. I also like to give a couple of revs when I go past my friend's farms to let them know it's me. The Hoot gearbox hasn't got an engager so you can't do this but that's not the worst of its problems. It's the reverse anthropomorphics of the pull to engage and releese to let out that I find difficult to get used to.
     
  16. HoughMade

    HoughMade Guest

    Yep- if I didn't have a rear wheel stand that allowed me to start the bike with the wheel in the air, life would get really interesting....and not in a good way.
     
  17. Ghost0

    Ghost0 Guest

    Well that was my only logical explanation but wanted input from the experienced. So what is your take on the keys? Are they too soft and shear or are they too hard and crack. Since I haven't installed it yet should I just replace them before I install the box?
     
  18. HoughMade

    HoughMade Guest

    The keys I've seen in pics looked soft- not cracked, deformed and sheared. Like I said, mine are fine and I think that has a lot to do with the fact that I do not use the engager.
     
  19. Ghost0

    Ghost0 Guest

    I wonder if you did away with the "clutch" lever and used a thumb shifter, would make it easier to wrap your head around the fact that it is not a "clutch" and just something to engage and disengage the drive.
     
  20. Irish John

    Irish John Guest

    The thumb shifters I've seen probably haven't enough travel to pull the engager in and out. Also the spring that pushes against the lever is pretty strong so it might keep coming out of engaged mode. The clutch lever locks in the in position to hold the engager in. I honestly think that if you're careful it is OK. I've broken 2 - one by showing off and panicing at a junction and the other by talking to someone as I took off and not thinking about what I was doing.
    Fixing the sheared key is easy if you buy a length of 1/8" x 1/8" key a hacksaw, file & a small 3 jawed gear puller. That piece of key goes first cos it's to protect the gearbox from more serious damage. The key could be a tiny bit thicker but has to be thinner than the engine shaft key which is harder to replace. If it happens far from home it's not much fun. Today I think I'm going to have to take out the final drive shaft and look at the engager slider and key because it isn't disengaging properly on a brand new gearbox. That is a nasty messy job and as is so often the case I find myself doing what should have been done in the factory which is getting a proper fit to all the components in the gearbox. This gearbox is just a bad one in several ways which means fron 4 gearboxes so far I have a 25% defective product rate.
     
    Last edited by a moderator: Oct 23, 2008
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