Grubee Gearbox- running "wet"

Discussion in 'Frame Mounted Engines' started by HoughMade, Jun 12, 2008.

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  1. HoughMade

    HoughMade Guest

    I have always used grease- a lot of it, but grease only. It works OK and I was satisfied. There was some noise, but not real bad. However, one of the “problems” with the 4 stroke is that it is so quiet, every other noise besides the engine seems loud. Also, the clutch chattered if I revved up at a relatively low speed (48 tooth sprocket). I just figured I needed to pedal up faster. Doing that, no problem.

    However, when is “good enough” ever good enough?

    I ran into a friend of mine this week, I had not seen him in a little while. He is a gearhead, so I mentioned my motorized bike project- guess what, not only does he have one, he uses the exact engine (Honda from Small Engine Warehouse) and Grubee gearbox that I do. He suggested I try what is suggested on the bicycle-engines website- a 50-50 mix of gear lube (85-140) and stop leak. I decided, why not?

    I had thought that something thicker than gear lube, but thinner than grease so it would flow may work because it would cling to gears. The key is the “stop leak”. I’m not talking about some substance just designed to swell seals, but to stuff you would add to engine oil (in the old days) to thicken it so it was too thick to leak much around worn guides. There is a product called “motor honey” that was as thick (or thicker) as honey. Sometimes it might be called “stop smoke” or something. The brand does not matter, but you want that thicker than thick stuff that says it keeps an engine from smoking.

    Well, I got it- the gear lube pours great, the stop leak pours....eventually. I mixed in a container 50%-50%. I never expected this, but the real challenge was pouring it in- not hard, just took forever. You pour it in where the in/out control arm goes into the gearbox. It pours very, very slowly and it will make a mess if you try to go too fast. Also, add no more than 5 ounces, probably less. You just want enough for the gears to dip down into. You do not want to come anywhere close to filling the thing. If you put too much in (which I did, by maybe ½ ounce) the excess will back up out of the fill hole when the gearbox is engaged, but when enough is out, it will not come out anymore.

    You may need to seal the gearbox. I used the original gasket, but I also used form-a-gasket as well. There was a little weeping at first at the seams, but it stopped.

    The results? The clutch chatter is gone. A good thing. This means the clutch is engaging more smoothly because it slips in, rather than grabbing all at once. However, I have not been able to detect any slippage once the clutch is at a speed where it should be fully engaged. I can actually leave from a standing stop without pedaling- I do not suggest making it a habit, but I wanted to try it. Rather than just bucking and the engine wanting to die (it never had died, but it lugged very low before), it just takes off smoothly, if a little slow. The website says that the clutch may slip when you first try it, but slippage will stop after some use. I did not notice that (other than the gradual slippage on engagement). The website also says to add a little more when the clutch starts to chatter.

    - Oh and noise- not gone, but markedly less. I still know its there, but I can hear the engine now.
    I will report as I add more miles.
    Last edited by a moderator: Jun 12, 2008

  2. HoughMade

    HoughMade Guest

    One other thing- if this works out, I will tap in a drain hole because I would want to change the fluid from time to time and I would not want to take the cover off every time- but I am waiting to see how it goes longer term.
  3. Happyzeds

    Happyzeds New Member

    Do you have a photo of your machine - I am keen to know how your drain tap will work once installed keep us posted - I am using lithium grease in the hoot gearbox that I have and alot of clatter has reduced but still grabbing as you say.

  4. HoughMade

    HoughMade Guest

    Here is my bike. If this keeps working well, I will just drill and tap a hole for a drain some place on the bottom of the gearbox, probably at the front because it will be lower when my bike is on the stand.

    I don't know if the Hoot will work wet or how well the cover seals, but I expect it would work about the same- but it would take someone trying it- sounds like we have a volunteer.

    Attached Files:

  5. MasterLink

    MasterLink Member

    hay man whats happing
    i been changing my grease out every few weeks and have seen lots of clutch dust when i pull the clutch out i have seen if i take my time and adj. the clutch to just engage it works smoother and fresh grease the bike is very smooth on take off i have even took a wire wheel to the clutch that only made it grab to hard so ,,,i like the ideal of the grease /oil ideal even better now u have tried it is it still silky smooth on take offs ? how many miles u went so far ? i think this will save the clutch
    thats cool u chated to yer old Buddie
  6. cruiser66

    cruiser66 Guest

    Grubee gearbox running wet

    I have the JL Hoot which I am running wet. So far I'm using 75W90 with good results, but I was thinking of going a little heavier for the summer months. The 50/50 mix sounds interesting. To fill my gearbox, I heat my gearoil in the microwave until it's thin enough to pour easily. I have had no problems with clutch engagement or slippage. Using about 5 to 6 ounces of oil. BTW, could you tell me what that chrome cylinder and tubing thing is for that is pictured in the last thumbnail? Is that how you fill the gearbox? :?: Thanks.

    Last edited by a moderator: Jun 13, 2008
  7. HoughMade

    HoughMade Guest

    The chrome cylinder is my tire pump that I fancied up to look like an oil pump on a motorcycle from the teens.

    The copper loop is just there for looks...and to hold the end of the pump- it goes nowhere. The larger copper tubing below holds the gearbox engager cable in place. The Grubee allows the gearbox to be disengaged, but stock, it requires you to hold the left handle in to keep in engaged. I reversed it so it is always engaged unless you pull the handle...I haven't touched the handle since. To reverse it, the cable now comes from the outside and the copper keeps the cable away from your leg.

    Where the engager cable connects to the engager arm, there is an opening into the gearbox and that is where the oil is poured in.

    I like the idea of heating it up to pour it in- maybe then it wouldn't take 1/2 hour.
  8. Sianelle

    Sianelle Guest

    Wow! I like your bike Mister :grin:

    Very nice styling and proportions.
  9. HoughMade

    HoughMade Guest


    I now have about 30 miles running "wet"....I ain't going back to dry.

    I was satisfied with grease as my previous posts all over this place say, but everything is better with the 50%-50% 85-140 - stop leak/smoke mix.

    It got better as time went on- less slippage at startup, but still smooth.

    I still hear the gearbox, but much less and the engine much, much more. Before, at speed, I never heard the engine, just the gearbox. It was not annoying the other way, but this is better.

    I also feel like my engine is now well broken in. It just pulls and pulls. I will not make a habit of it, but I met and possibly exceeded the 40 mph speed limit on one road, at least according to my speedo.

    I just got back from a 17.5 mile ride and it all just gets better and better!

    ...and nothing fell off.
  10. fetor56

    fetor56 Guest

  11. HoughMade

    HoughMade Guest

    I am...and I will!
  12. Irish John

    Irish John Guest

    Brillian Research HoughMade

    This post is just what we need for our Grubee GBs and the Hoot GB guys will be able to report back on the efficacy of this mixture too. I'm sold on the mixture too HoughMade but I need you to clarify a couple of points.
    Should the 50/50 mixture of Gear Lube & Stop Smoke should be premixed prior to pouring into the GB?
    The total amount of mixture is 5 fluid oz - i.e. 142 millilitres or about 70mls of each of the components?
    The microwave idea sounds good for making the mixture easy to pour.
    How viscous/liquid is the final mixture?
    Also I'm not doubting the method but 140mls seems hardly enough to allow the bottom of the gears to dip into it and spread it around the whole gearbox.
    Won't this mixture, if it is fairly fluid, go through thr holes into the centrifugal clutch and cause sticking problems?
    The lithium grase method had the big problem of throwing off the grease at the high speeds at which the gears revolve so this continuous wetting method seems to be the answer.
    Lasty I would have thought that you'd only need to top up the mixture occasionally and that the lubricant would be effective on the gear wheels for a very long time (5000 kilometres or so).
    Fetor's magnetised plug idea will work only if the mixture is fairly liquid like the engine oil where I've found his invention to be nearly as good an idea as the NuVinci hub!
  13. cruiser66

    cruiser66 Guest

    The clutch runs best with oil. It partly acts as a lubricant and allows the clutch bell to gradually reach engine speed. Once the clutch reaches a predetermined operating rpm, it locks so no slipping occurs like a lock up torque converter in a car. When the engine slows below the predetermined rpm (around 2200) the internal springs of the clutch will take over and disengage the clutch. The oil lubricates the action of the clutch so if sticking occurs, it is not because of the oil. Premixing the 50/50 and heating will facilitate filling the gearbox and ensure the proper ratio. I will be trying the mix as soon as I get the "motor honey" to mix with the gear oil. However, I have had very good results with just 75W90 oil. My JL Hoot apparently runs pretty quiet since I can hear my engine running through all of the operating speeds.:smile:

  14. Irish John

    Irish John Guest

    That's great Cruiser, it's good to be reading about the Hoot GB etc. xcan you let us know some brand names for this Stop Smoke Honey stuff. The guys in the shops around here don't seem to know much about the products they sell cos the shops aren't family businesses but big franchises and I don't trust anything they tell me.
  15. cruiser66

    cruiser66 Guest

    Grubee gearbox running wet

    Hi Irish John,

    This is the stuff I will be trying. Has been around for decades and was one of the original additives for oil burning. It is very thick like honey. I guess that's why some people call it motor honey.

  16. MasterLink

    MasterLink Member

    i think a brake bleeder screw is a good ideal to use as a drain might fit on that ridge i think the bleeder is 3/8 inch
  17. HoughMade

    HoughMade Guest

    Sounds like you got your answers, but I'll chime in anyway. Yes- premix.

    Yes, but don't be surprised if some backs out of the hole even with 5 ounces. It will stop, and the stuff is so thick it does not drip fast at all.

  18. nsideus

    nsideus Guest

    I have tried all these in the grubee gear box
    straight wheel grease - clutch sticks
    synthetic grease with a little oil ( greasoil ) - no slip seams to be quietest
    50/50 mix trans stop leak and gear oil - worked for a while then began to experience slippage
    lithium grease - works well no slippage somewhat less whine than 50/50
    the oldest and the greasiest works the best 4,500 est miles
    I will try the honey oil next
  19. Irish John

    Irish John Guest

    Thanks HoughMade I'm switching over to 50/50 today. Incidentally your quote above is also a brilliant description of the best way to tell if you have been served a perfect pint of Guinness in Dublin!
  20. HoughMade

    HoughMade Guest

    Good point!

    I took the cover off today for two reasons- I developed some more weeping and i want to seal it better and I had to see how far up the gear the oil level was- it had sat all day, so I knew it would all be in the bottom. Interesting- only 5 ounces and the oil level was a bit more than 1/3 up the largest (middle) gear. When I refill, I am going to try it with a bit less, then add more if I have to.