Belt Drive Meditations

Discussion in 'General Questions' started by Sheik Yerbouti, Mar 8, 2008.

  1. As most of you know, my next project is based on a 4 stroke design. After seeing that ocscully quit his belt drive project, I decided to kind of pick off where he left off. I found the source for the centrifugal clutch:

    Scroll down to centrifugal pulley clutches. If I got a v belt, I could get a clutch assembly that wouldn't require a shim, it would just bolt right on. I would then need to run it to a jackshaft to get the reduction right. This is where I hit a bump. I can't find any v belt jackshafts anywhere. I would then need to put a pulley on the wheel, which I'm not sure how to connect either. I have 1/3 of the equation and need your help. The bike I'm using is a single speed Schwinn Corvette. If any fabrication needed to be done, I have access to MIG welders, grinders, etc.

    Would I need to widen the rear stays? Where can I get a jackshaft? V belt or timing belt?

    Any help is appreciated.



  2. ocscully

    ocscully Member

    You are right I did lose interest in continueing my project back between Thanksgiving and Christmas and put the parts up for sale but am currently back to work on it as no one was interested in buying the various parts I already had.

    Your questions about jackshaft kits. Most of the kits I have seen seem to come from the various Kart suppliers, and they are pretty much just the shaft and the bearings and the bearing holders. The V-belt or Timing belt pulleys would be purchased seperately. If you can't find what you are looking for with Kart suppliers you might want to check suppliers like Grainger or McMaster Carr. Timing belt pulleys and belts are another matter entirely, and are harder to find in the sizes needed to accomplish the reductions we need for our bike projects. Max-Torque has a couple of clutches with HTD Timing belt pullys attached for their final drive output and could perhaps be mated up to a GEBE Rear drive ring/sheve, thus avoiding the need for a jackshaft. The folks at Max-Torque seem to have a relationship with a company called Pfeifer Industries that manufactures the various driver and driven pulleys for timing belt systems but their web site does not provide pricing or availability information. The parts for the drive I have shown mocked-up for the GiantStone project, are based on parts from a company out of Arizona called VIZA Motors. They make go-ped type scooters and other misc. motorized toys. They even have the parts for building a jackshaft. As you continue to do your research on these various parts for Timing belt drive systems you will find that there are many different standards for these belts and pulleys. And all the pieces you intend to buy need to match up. A V-belt system will be much easier to put together and cause fewer clearence problems than a Timing -belt system.

    As you have already found out there is no "one-stop shopping" source for all the various parts you need for putting together a drive system like this. And when you do find the parts there is a really good chance that you are going to have to modify them some what or build/fabracate special adapters to make them all work together. The other big draw back to attempting a drivetrain like this is the cost. Based on the research I've done over the past several months the total outlay for the various parts will run more than $300.00 and should not exceed $400.00. And that assumes I'm doing all the custom fabracation myself.

    Last edited: Mar 9, 2008
  3. I would strive to do a V-Belt system, mostly due to clearance issues and ease of assembly.

    Assuming I bought the heeter centrifugal clutch, which would mate to the Honda with relative ease. I would then have to run it to a jackshaft which I could squeeze under my motor mount (I have clearance), and run it to my drive wheel sheeve. I found a source for for Whizzer Sheeves and the hardware to mount them. If I used that, would it require any reduction from the clutch, or would I still need a jackshaft. Actually...I think Whizzer's used timing belts, which I don't think I have the clearance for...

    So, basically, I can't use a v-belt unless I use a jackshaft or if I can find a sheeve that's the right size for the rear wheel and find a way to fasten it to the rim. I was thinking of finding a narrow 20 inch wheel and find a way to make it accept a v belt or something. That's probably impossible though.

    So, here are my options.

    1. Centrifugal V Belt clutch to jackshaft to pully on wheel.
    2. Centrifugal Timing Belt clutch to Whizzer rear sheave (would this ratio work?). I would have to widen my rear stays in order to make this work, but it's possible.
    3. Centrifugal V belt to some sort of homebrew large sheave (20 inches or so). I wouldn't have to widen my stays because the belt is narrow enough.

    Your estimate of 300 to 400 dollars, did that include the engine or was that just the drivetrain?
  4. loquin

    loquin Active Member

    Possibly Northern Hydraulics or TSC (Tractor Supply Company) also.
  5. ocscully

    ocscully Member

    First, the Whizzer drivetrain uses V-belts. There is a smaller primary reduction to the jackshaft then a longer belt from a second small pulley on the jackshaft to the rear sheave. Actually the pully on the jackshaft is a stepped double pulley with the clutch built into it. The smallest clutch with a v-belt drive I have seen to date has a 3in. dia pulley. I think the Sheave for a Whizzer is maybee 18in. dia. thats only a 6 to 1 reduction. I think you need something in the neighbor hood of 17 or 18 to 1 total reduction. So Yes I do think you will need to use a jackshaft.

    The dollars I mentioned in the previous post do not include the motor. The quote is for the clutch, jackshaft & its bearings & holders, 3 toothed pulleys and the various adapters to mount them and 2 timing belts.

    I think that the easiest and probably least expensive system for you would be to purchase a sheave from GEBE ($40.00). Then contact the folks at Max Torque or better yet Peifer Industries to see what the smallest timing belt drive pulley they can put on one of their clutch bells, I think you need something in the neighbor hood of a 12 or 13 tooth driver. If they can't do one that small then buy one of the drivers from GEBE ($25.00) as well and then attach it to the clutch of your choice. Then all you would need is a longer belt that you can get from McMaster Carr for approx. $28.00 - $35.00. This system would give you the reduction you need with out having to use a jackshaft, and should not have clearence issues assuming you have the required room for the rear sheave.

    Last edited: Mar 9, 2008

    These plans use an extra wheel for the rear sheave, but I'd have to bend my stays. The plans aren't incredibly specific, but they just use a rear wheel padded with rubber in order to keep it from slipping. It also tells you to cut the chain stays and use a heavy piece of "tin" to repair it, using bolts. Seems sketchy.

    I can't swing 300 dollars for the entire assembly, though. I'd need to do it cheaper. If it's not possible then I'd have to give it up.
  7. Great edit, oscully! I'll see what I can do.
  8. So, my only question regarding this setup is whether the gears/drivers from Golden Eagle will just attach themselves to any centrifugal clutch? Could I get one with a sprocket and take off the sprocket? Or do I need one with a timing belt driver and replace it with the correct size?
  9. ocscully

    ocscully Member


    I just spent some time looking over the various parts I recommended to you over on the GEBE web site, and feel that yes you would be able to braze or weld one of the GEBE drivers to a clutch bell. But first I would contact GEBE and ask for the specifics on their parts. What you want to know is the Pitch of their HTD (High Torque Design) drivers and belt. Its either 5mm or 8mm but you need to know exactly which it is. You also need to know the bore or what size shaft do they fit? You also might ask them what the belt width is in mm . Then I'd contact the folks at Max Torque and find out what the smallest driver they have available that matches the pitch of the GEBE. With luck they may already have what you need if they don't then tell them what you hope to accomplish and see if they can offer some help with getting the driver from GEBE attached to one of their clutches. My guess is that they will probably steer you to the folks at Pfiefer Industries for any custom work.
    Or maybe Max Torque will sell you a clutch with a bell with no output driver and you can attach one your self. Based on the engine you are planning to use my guess now is that you will want either the 13t or 14t depending upon your riding terrain. Here is the link to the GEBE Parts page

  10. I'm writing the email right now and will report back with my findings. What aspect of my terrain should I concern myself with when choosing a 13 or 14 tooth driver?

    Thanks for your continued help. You've been more than generous.
  11. ocscully

    ocscully Member

    The smaller the driver that you use the greater your reduction and there for the lower final gear you will have, meaning better hill climbing lower top speed. The bigger driver will add top end but you will have to pedal more to get the bike going and to climb hills. The GEBE Site indicates a 10% change for each tooth added or subtracted. Read the information on the drivers at the link above, its all explained there. Ask GEBE for a recommendation based on the motor you plan to use.

  12. Okay, ocscully, here's the information I was able to gather from Golden Eagle.

    "Hi Jon,
    Thanks for the details, don't know that we'd ever be on the same page, but I hear where you're coming from:)!! Eagles are bicycle Assist units, you intend to build that motorcycle, yourself - please, just wear your helmet (thanks).

    Yes, the 4n1 key is included with order of the ring

    The gears are 5/16" - 24 thread pattern, to fit drive shaft of our clutch housing/bell assembly.

    I've heard the Honda 50 is available in either a wet or dry clutch, (supposedly one fits, the other doesn't) several customers have purchased kits, intending to mount the 50, but cannot recall further calls or orders - leads me to believe it didn't work out so well.

    Bolt hole pattern on our 76/78mm clutch housing is:
    1) measure bolt holes - diagonally, left top to bottom right=3 7/8 "
    2) measure bolt holes - top left to top right=2 3/4"
    3) measure from outside edge of clutch shoe, straight across drum to opposite, outside edge of clutch shoe.=3"

    There are parts houses where you can buy gears of different bore and timing belts of different pitch and length and, sorry, I don't have the specifics, nor am I at liberty to disclose.

    Best of luck on your 'labor of love' and you're sure in the right place (at MBc) to get help working thru the rough spots.

    Best Regards,

    I'm still in the process of dissecting it all.
  13. ocscully

    ocscully Member


    Basically they are telling you that they have no intention of helping you determine weather or not their parts will work with what you are trying to do. So we may have to rely on members of mbc to get the information. I sent an e-mail to the folks at Max Torque earlier today asking about their HTD Clutches and got a very helpful reply from the owner of the company. Their instock 5mm pitch HTD clutch is a 23t which is to large for what you are trying to accomplish. As I said before you need either a 13 or 14. The owner of Max Torque's son is the owner of Pfeifer Industries and the smallest 5mm driver they offer is 14t I believe. I'm going to try and contact the folks at Max Torque tomorrow by phone and talk with them about a clutch for my project. Judging from the e-mail I recieved from them today they have experience customizing clutches specifically for the Honda GXH50. I'll forward the e-mail to you if you wish and also ask them if they could build a clutch for you with a driver supplied from GEBE. If you decide to continue to persue this type of drive train you may just have to make the decision to jump in and solve the problems as the show up. But I'm sure that in can be made to work. Despite the secracy GEBE is showing about their parts there isn't any thing out of the norm for them. Still I think the main hurdle for you is going to be price. Its been my experience when you start on a project like this where you are mixing and trying to match various parts it can get expensive very quickly, and alway in the back of your mind is I can just get a build kit from for $200.00 and be done with it. But if you get alot of satisfaction out of putting together something out of the ordinary, then the price becomes less of hurdle.

  14. I could just build a kit from bicycle-engines, but where's the fun in that? I'm going to email Pfeifer tomorrow regarding a clutch and some pricing info.
  15. ocscully

    ocscully Member

    The man you want to contact is, I'll be calling him tomorrow as well.

    I just did a search on the GEBE belt and sure enough the information is right here on mbc. The GEBE belt is a 5mm pitch, 9mm wide, and 1635mm length.

    The GEBE rear drive ring has a dia. at the belt surface of 133cm. and an approx. number of teeth/grooves of 266? approx./estimated due to the way the GEBE ring is made with sections of teeth/grooves every 90 degrees around the dia. and sections where there are no teeth/grooves.

    Based on the info. GEBE sent you I'm assuming the drivers they sell have a bore of 5/16 in.

    I just did some quick math and the 13 will give you 20.4:1 reduction, the 14t will give you 19:1 and a 15t would give you 17.7:1

    The 133cm measure ment above was taken from another post on this board and does not seem to be accuarte. That means the ring is 50 some inches in dia.

    Last edited: Mar 13, 2008
  16. Great. Any info I can gather will be posted in this thread. Thanks again, ocscully.
  17. I haven't gotten any recent emails. Any luck, ocscully?
  18. ocscully

    ocscully Member

    I had a good conversation with Jim Donavan the owner of Max Torque on Friday, and we talked about a HTD Clutch for the system for my project. We talked briefly about wat the smallest driver he could attach to one of his clutches and still work with the 5/8in. dia of the Honda Engine and he said he would get back to me with an e-mail with the answer as well as the name of who at Pfeifer Industries I should contact about some other parts I'm considering. But so far I've not heard anything from him either? I have done some checking at the Pfeifer Industries web site and in their tech section they list the various dia. of the drivers and pulleys they sell and I'm beginning to think that You won't be able to get a small enough driver on the clutch to go direct to the GEBE Drive Ring? So that puts you back into the world of a Jackshaft to get the reduction you will need. The jackshaft opes up many possabilities, but also added expense. One idea would be to locate the jackshaft such that you could use all GEBE parts including their belt. Or bite the expense bullet and build a system like I'm envisioning for my project.

    If I don't hear back from Jim buy tomorrow at lunch I'll call him again to see if he has any updates for me.

  19. Hm, that's what I was afraid of. Well, I'm not going to give up until I know for sure. I might make a phone call tomorrow as well. I appreciate the update.
  20. Well, I just got an email from Jim as well. He said his smallest inhouse clutch was 17 tooth. I inquired about the possibility of slaving one of the GEBE gears to his clutch, it's my last hope on the belt drive front at this point.

    We'll see what happens.