Thanks, Tanksareus.
It turned out I didn't have to use the barbell weight trick to bend an arc in my tubing. My friend that does the major fabricating for the 07 race team rolled me up an arc that matched my template perfectly. I cut it in two this morning and mocked it up.
Pics of the race car that we have been working on are on my website
www.wlbsite.com scroll down to "photos of new race car"
It turned out I didn't have to use the barbell weight trick to bend an arc in my tubing. My friend that does the major fabricating for the 07 race team rolled me up an arc that matched my template perfectly. I cut it in two this morning and mocked it up.
Pics of the race car that we have been working on are on my website
www.wlbsite.com scroll down to "photos of new race car"
Thanks firemarshal71, incogrhino, and deejaaa
The shop where the race car pic was taken belongs to the friend that bent the arc. It is a first class fabrication shop. Their main products are service equipment for the marine industry but they can make most anything. The race car belongs to another friend.
deejaaa, My son says I have the computer skills of the average 10 year old. I think he was being kind to the old man.:smile::smile:
The shop where the race car pic was taken belongs to the friend that bent the arc. It is a first class fabrication shop. Their main products are service equipment for the marine industry but they can make most anything. The race car belongs to another friend.
deejaaa, My son says I have the computer skills of the average 10 year old. I think he was being kind to the old man.:smile::smile:
Looks like I will be making the lower frame section over. I bent up the forward ends to take away the right angle where the down tubes join the lower section and now the engine will extend forward of the straight section unless I make the wheelbase 4 inches longer. Either way I have to bend a new lower frame section. The options are to let the down tubes intersect at a right angle like post 24 above or extend the wheelbase 4 inches. The thing is about 76 inches overall length now. So it's either right angle down tube intersection or 80 inch minibike. Decisions, decisions.
that makes sense. just looked like a lot of room in the photos. I think the curved down tube gives a better overall appearance and may be structurally stronger than a hard corner. you might be able to stretch the length out without bending a new section if you have other pieces for cross members that may reinforce the main tube sides. It's already a large bike, what's a few more inches :shrug::smile:
I still do not see how how you need this much room. Heck, my driven clutch is 10.5" diameter and I won't need that much room. Now if you have to have the sprocket on that side, it could make it more interesting.
Can you show us just what it is you have in mind for your driven/jackshaft? Are you thinking 2 jackshafts?
And I like the wrap around frame! :thumbsup:
Can you show us just what it is you have in mind for your driven/jackshaft? Are you thinking 2 jackshafts?
And I like the wrap around frame! :thumbsup:
Yes that is a lot of room. More than I wanted but that's the shortest I could make work with two jackshafts. The backwards facing cylinder, carb and exhaust location also forced a long layout as well as wanting to keep the seat height low since I will be using this in some fairly rough places at little more than a walking speed and may need to be able to get my feet firmly on the ground for balance.
Bending a new main lower tube is no big deal. Figured I might have to bend a few to get it right since this is a scratch build. Tubing never goes to waste here. Sections can be cut out for some other project or it might just work perfect for the next one with smaller tires and a vertical flathead engine:smile::smile::smile:
Bending a new main lower tube is no big deal. Figured I might have to bend a few to get it right since this is a scratch build. Tubing never goes to waste here. Sections can be cut out for some other project or it might just work perfect for the next one with smaller tires and a vertical flathead engine:smile::smile::smile:
Are you running the two jackshafts for more reduction like a tote gote? I was going to say run the second jack higher up like a tote until you said low seat. Hmmm. Low seat as in just above the rear tire?
Just thinking out loud here, how about two shorter jacks. First one off the driven to the first cog which would be under/just behind the cylinder, give or take, and the second just behind it going to the final drive sprocket. If it was just a 10/20 sprocket reduction under the cylinder, that would not take much room. Shafts 4" apart give or take. More reduction, farther apart, space limited.... This would also put the sprocket on the other side....
But even so, it looks like plenty of room now with two full length jacks. Must be planning on a lot of reduction....
Just thinking out loud here, how about two shorter jacks. First one off the driven to the first cog which would be under/just behind the cylinder, give or take, and the second just behind it going to the final drive sprocket. If it was just a 10/20 sprocket reduction under the cylinder, that would not take much room. Shafts 4" apart give or take. More reduction, farther apart, space limited.... This would also put the sprocket on the other side....
But even so, it looks like plenty of room now with two full length jacks. Must be planning on a lot of reduction....
Overall reduction will be 25 to l on high side of torque converter and 75 to 1 on low side. 3--5--5. I figured with the very large tires I am using that will be about the equivalent pulling power of a typical Totegote. I made cardboard cutouts of the gearing and tried all sorts of locations for the shafts. The backward facing cylinder and the location of the intake and exhaust create all sorts of issues when combined with the desire of a low seat height. My son suggested I make a simple gear reduction to change the direction of rotation so I could mount the engine with the cylinder forward. Even mocking that up didn't make it enough shorter to be worth the trouble and expense.
I don't think the extra length will create any ride issues but will mean I can't carry it sideways on the back of my Suburban.
I don't think the extra length will create any ride issues but will mean I can't carry it sideways on the back of my Suburban.
WLB, I'm sure you know what you're doing, but I just have to say that I think your proposed gearing plan is absurd. I was worried about mine being too low with an 8.5:1 but a 75?? The rear wheel is going to move like a minute hand on a stopwatch. I wish you the best of luck, your skills are awesome with the tube bending but I just had to question the overall design as a retired engineer, sorry.
Absurd.
You apparently do not understand or did not read what the intended purpose of this build is, the type of terrain it will be used on, and what I expect from it. Or take into account the effect tire diameter has on gear ratio. The rear tire diameter is 25 inches . Or the fact that ROUGH terrain with a heavy load demands a different gear ratio than pavement riding.
According to my in house engineer (my son, BS MS Mechanical Engineering, Purdue) that gearing will haul me, my gear, and a good sized dead deer out of the woods at a speed compatible with terrain.
Sorry but I just had to question your engineering evaluation.
You apparently do not understand or did not read what the intended purpose of this build is, the type of terrain it will be used on, and what I expect from it. Or take into account the effect tire diameter has on gear ratio. The rear tire diameter is 25 inches . Or the fact that ROUGH terrain with a heavy load demands a different gear ratio than pavement riding.
According to my in house engineer (my son, BS MS Mechanical Engineering, Purdue) that gearing will haul me, my gear, and a good sized dead deer out of the woods at a speed compatible with terrain.
Sorry but I just had to question your engineering evaluation.
I think I see what you are doing. I could be wrong, so let me know.
When I saw your post after mine I was trying to figure out the 25:1 and think maybe it was supposed to be 2.5:1 for the TAV. Nice midrange place to take a general number. Then rounded to 3 for the multiplication?
I would assume you are using 1" jackshafts then. If you went down to 3/4", you could use a 10T sprockets and get the reductions at 6:1. Maybe then take the second reduction down to 10/50 or 10/44 for a smaller sprocket and more room and with the final reduction at 10/60, you would have 26.4:1 with the smaller 44t not including the TAV. This would allow more room and a little better reduction.
I looked around Ebay and found several 40b44 and 40b50 sprockets but none with the right bore. There were some with 5/8" bore that could be bored out. I would bet McMasterCarr or similar would have the right ones.
One other thought. You can get flat rear sprockets for the rear axle all the way up to 112 teeth. You would have to drill the flange bolt holes, but they are out there.
Lets say you use a 40A80 sprocket at the rear axle. To get the same overall ratio(25:1 or so after the TAV), you would only need a 3:1 reduction after the TAV. 3(TAV) * 3 (10/30) *8(10/80) = 72:1 overall. Way more room for the jackshafts then.
And I like where the motor is sitting forward. Looks like the frame wraps around the TAV.
When I saw your post after mine I was trying to figure out the 25:1 and think maybe it was supposed to be 2.5:1 for the TAV. Nice midrange place to take a general number. Then rounded to 3 for the multiplication?
I would assume you are using 1" jackshafts then. If you went down to 3/4", you could use a 10T sprockets and get the reductions at 6:1. Maybe then take the second reduction down to 10/50 or 10/44 for a smaller sprocket and more room and with the final reduction at 10/60, you would have 26.4:1 with the smaller 44t not including the TAV. This would allow more room and a little better reduction.
I looked around Ebay and found several 40b44 and 40b50 sprockets but none with the right bore. There were some with 5/8" bore that could be bored out. I would bet McMasterCarr or similar would have the right ones.
One other thought. You can get flat rear sprockets for the rear axle all the way up to 112 teeth. You would have to drill the flange bolt holes, but they are out there.
Lets say you use a 40A80 sprocket at the rear axle. To get the same overall ratio(25:1 or so after the TAV), you would only need a 3:1 reduction after the TAV. 3(TAV) * 3 (10/30) *8(10/80) = 72:1 overall. Way more room for the jackshafts then.
And I like where the motor is sitting forward. Looks like the frame wraps around the TAV.
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