New guy here... Morgan-esque 3 wheeler

[itsid]

That's for checking, i'll fiddle with it when the new spring gets here.

Suggestions on rear drive wheel anyone? I'd like to have a size to work with as I figure out the frame.....

As far as I know the morgan has three wheels of identical size,
so you might want to do the same,

If you were to build a pedal kart I'd say:
You already have a rear wheel, just get another front wheel for the BMX and you're good.

But you don't..

For added stability I'd go for a much wider wheel but for the look of the same diameter.
Assuming the bike is a 16" BMX (I can't tell by the picture for sure)

I'd say get a wheel of the same size, but wider.. maybe a
16 X 650 X 8 (8" rim 16" wheel diameter 6.5" wide)
maybe like this:
http://www.ombwarehouse.com/16-X-650-X-8-2Ply-Turf-Saver-Carlisle.html

'sid

 

[Poboy kartman]

As far as I know the morgan has three wheels of identical size,
so you might want to do the same,

If you were to build a pedal kart I'd say:
You already have a rear wheel, just get another front wheel for the BMX and you're good.

But you don't..

For added stability I'd go for a much wider wheel but for the look of the same diameter.
Assuming the bike is a 16" BMX (I can't tell by the picture for sure)

I'd say get a wheel of the same size, but wider.. maybe a
16 X 650 X 8 (8" rim 16" wheel diameter 6.5" wide)
maybe like this:
http://www.ombwarehouse.com/16-X-650-X-8-2Ply-Turf-Saver-Carlisle.html

'sid

No- The Morgan has 19" wire spoked front wheels with 4.00 × 19 tires and a 175/55 R16 in the rear. So if those are 16" rims, then we're basically talking 4/5th scale.

So: OAL- 126" @ 4/5 =100.8"
92" wheelbase @ 4/5=73.6"
60" track@ 4/5= 48"
ect. ect....

But I'm thinking that the rear tire should be small because of the engine size. ...

 

[itsid]

No- The Morgan has 19" wire spoked front wheels with 4.00 × 19 tires and a 175/55 R16 in the rear. So if those are 16" rims, then we're basically talking 4/5th scale.

So: OAL- 126" @ 4/5 =100.8"
92" wheelbase @ 4/5=73.6"
60" track@ 4/5= 48"
ect. ect....

But I'm thinking that the rear tire should be small because of the engine size. ...

Oh okay..

the only "rear wheel" image I could find was this:


and there it looked like the same thing front and rear...

Anyways; rear wheel diameter for a 175/55 R16 is 59.89 cm (~23.5")
a 400x19 would be 71.1 cm (28") so noticeable bigger

Well, let's do some math ...
a 16" bicycle wheel is (more or less) exactly 16" in diameter inkl the tire,
and to keep the same ratio (16/28 * 23.5) we end up with a 13.5"-14" diameter rear wheel...

Ah well
13:
http://www.ombwarehouse.com/13-X-500-X-6-2Ply-Turf-Saver-Carlisle.html
14:
http://www.ombwarehouse.com/14X500X6-2PLY-TURF-TIRE-TUBELESS.html


Oh btw, it's not 4/5th scale but 4/7th (16/28 = 4/7)

'sid

 

[J_Walker]

bicycle tires, nioce! try to source some old steel hubs, and new bearings to replace those existing BMX ones. they last a "tad" bit longer in motorpowered situations.

 

[Poboy kartman]

Oh okay..

the only "rear wheel" image I could find was this:
View attachment 42443

and there it looked like the same thing front and rear...

Anyways; rear wheel diameter for a 175/55 R16 is 59.89 cm (~23.5")
a 400x19 would be 71.1 cm (28") so noticeable bigger

Well, let's do some math ...
a 16" bicycle wheel is (more or less) exactly 16" in diameter inkl the tire,
and to keep the same ratio (16/28 * 23.5) we end up with a 13.5"-14" diameter rear wheel...

Ah well
13:
http://www.ombwarehouse.com/13-X-500-X-6-2Ply-Turf-Saver-Carlisle.html
14:
http://www.ombwarehouse.com/14X500X6-2PLY-TURF-TIRE-TUBELESS.html


Oh btw, it's not 4/5th scale but 4/7th (16/28 = 4/7)

'sid

Well that's why I included the biggest little word in the English language "if"!!!

So back to the conversion: Then- OAL: 126" @4/7th =72"
Wheel base: 92" @4/7th = 52.6"
Track: 60" @ 4/7= 34.3"
Sound like doable numbers to me.

To me, scaling the rear tire is a non-issue. As you proved, seeing only 1/2 of it makes scaling by eye difficult. As long as the stance is correct, that is a detail easily overlooked IMHO.

With a bigger engine scale would trump function. But the question still remains as to what size tire and tooth count sprocket and clutch would work the best.

 

[itsid]

okay, let's assume a weight of 350 lbs (kart + driver)
and 13" wheels
with a transmission ratio of 9:1 (jackshaft set up: 12->27-10->40 )
given the 2.5HP engine (3600 rpm governed)

that'd be a
Maximum torque of 32.79 ft lbf (44.46 Nm) on the driven wheels.
Estimated acceleration: 5.58 ft/s² (1.7m/s²) reaching top speed in ~4.12 seconds.
Estimated top speed : 15.47 mph (24.9 km/h)

Numbers are calculated without friction loss or road inclination and unfortunately without knowing the torque curve for the engine...
so they will be off of course.

'sid

 

[Poboy kartman]

okay, let's assume a weight of 350 lbs (kart + driver)
and 13" wheels
with a transmission ratio of 9:1 (jackshaft set up: 12->27-10->40 )
given the 2.5HP engine (3600 rpm governed)

that'd be a
Maximum torque of 32.79 ft lbf (44.46 Nm) on the driven wheels.
Estimated acceleration: 5.58 ft/s² (1.7m/s²) reaching top speed in ~4.12 seconds.
Estimated top speed : 15.47 mph (24.9 km/h)

Numbers are calculated without friction loss or road inclination and unfortunately without knowing the torque curve for the engine...
so they will be off of course.


'sid

OK- Again Sid- NO!!!!! I truly do thank you for a reply- you're the best! BUT- here's the rub. This is a "Poboy" build- (near and dear to my heart).

The OP is trying to make something with nothing. It's something we do in the Southern U.S. and we do it better than anywhere else in the World! Well excepting maybe Puerto Rico- wait- that's Southern US!!!

Wait- Outback Australians, Alaskans, Eskimos, bush Africans-some South Americans. ....Oh He//, well...we make better crap outta nothing. ...

.......So he has no jackshaft- IIRC , his budget for the total build is TC territory. Centrifugal clutch BUDGET BUILD!!!!!!!!

So we're not working with a lot here. HENCE- My emphasis on gear/tire size, ect.... To have a chance, that must be maximized.

Like I said, tomorrow , I will have a little more working knowledge.

 

[itsid]

well the gear ratio shouldn't be below 9:1 with a 2.5 engine.
I don't know if a 90T sprocket will fit onto a 13" wheel,
that's why I mentioned a possible JS ratio


[EDIT]
So I checked with the azusa chart...
#40 chain 90T sprocket is 14.618 inches; doesn't fit onto a 13" wheel.. (jackshaft necessary)
#35 chain 108T sprocket is 13.113 inches, still doesn't fit onto a 13" wheel (again.. jackshaft necessary)

So either OP needs to fab a jackshaft, or find a clutch that has 10T for a 35 sprocket
(90T sprocket 10.964" diameter) or 8T clutch for a #40 chain (72T sprocket 11.752")

I'm not sure what's the cheapest, my best guess: jackshaft

'sid

 

[landuse]

Yeah, I would also not gear higher than 9 with an engine that small

 

[Poboy kartman]

Jeeeze-
For guys so smart, it amazes me how hard it is sometimes to get you guys to get subtle hints. Good thing ya'll are on the internet or I would be using the BFH....

 

[itsid]

Jeeeze-
For guys so smart, it amazes me how hard it is sometimes to get you guys to get subtle hints. Good thing ya'll are on the internet or I would be using the BFH....

subtle hints... on forums.. to non native speakers...
you might want to rethink that

'sid

 

[landuse]

Jeeeze-
For guys so smart, it amazes me how hard it is sometimes to get you guys to get subtle hints. Good thing ya'll are on the internet or I would be using the BFH....

subtle hints... on forums.. to non native speakers...
you might want to rethink that

'sid

Yeah....hints given through the written word are generally not picked up....

 

[sxk122]

Wow!!! Thanks for all the input.

the "esque" is I want to make something with a similar look and feel, but I'm not making a copy. I'm not going for exact scale.

I think to best maximize what I have I need to use a smaller rear wheel, more 'cart' sized. Poboy hit it on the head with my plan. The rear wheel won't be completely visible, it will be under a fairing. I fully intend to fudge on size there. I was thinking a 10" wheel that is 3-4" wide would give me the a better rotational size, will allow me to "shrink" the fairing a bit, and will be cheap as I can pick up 10" pneumatic dolly wheels for $6 or a 13" for $13.


J Walker- I had wondered how well the hubs would last, but in the interest of saving pennies, I'm going to go with these hubs to start and I'll swap them when they fail or I loose confidence in them.

Kinda bummed at this point tho, as it seems like the gearing will eat up the entire (lack of) budget. I goofed and really didn't think about the gearing too much, I didn't realize I'd need a 10" gear or a jackshaft....

 

[sxk122]

here is an back view of the morgan showing that big rear wheel, and a profile shot of another 3 wheeler. I like the general shape of the red 3 wheeler, that's where I would like to head if I can get this off the ground.....

 

[sxk122]

http://www.diygokarts.com/vb/showthread.php?t=3397


Can anyone ID that gearing? I'm wondering if I could use the largest gear from a bike (53 tooth or so) as my wife's cousins have offered any extra bike parts I need......

Never mind. #35 chain is a lot heavier duty. That won't work. Argh.

I'd post in his thread, but it's long dead, and he hasn't logged in since 2011.....

 

[firemanjim]

NEVER give up!! So things didnt work out as "not " planned... no big deal.... re-think,re-engineer.... what ever you wanna call it .... Find a CHEAP mini crotch rocket back tire/wheel in the 15" range. Gear it for 9 or 10:1 using #35.... no jack shaft... Look around scrap yards,people around here throw away a lot of great usable parts.... i bought a complete running kart for $27 ,along with a couple other things. The karts non drive rear tire looked like someone backed over it with a car. A torch,new bolt,BFH,and a welder fixed it all up....

 

[sxk122]

Thanks man. I'm not going to give up, but just a bit bummed at my gaffe. It feels like I never see deals in Dallas, lol

 

[landuse]

I'd post in his thread, but it's long dead, and he hasn't logged in since 2011.....

Please do not even think of posting in dead threads (even though we have locked that down now). If you want to get hold of anyone, please PM them...

 

[sxk122]

Please do not even think of posting in dead threads (even though we have locked that down now). If you want to get hold of anyone, please PM them...

I've been around forums long enough to not create Zombie threads..... my statement was more of an explanation as to why I wasn't asking the OP

And, as I speak....

What are the thoughts on this? 10" rear wheel......
http://dallas.craigslist.org/ndf/tag/4196010614.html

These look to be the specs.....
http://www.rcramer.com/bikes/pr200/drivetrain.shtml

 

[sxk122]

I've been around forums long enough to not create Zombie threads..... my statement was more of an explanation as to why I wasn't asking the OP

And, as I speak....

What are the thoughts on this? 10" rear wheel......
http://dallas.craigslist.org/ndf/tag/4196010614.html

These look to be the specs.....
http://www.rcramer.com/bikes/pr200/drivetrain.shtml

The gearing appears too low, but could it be multiplied with a home-made jackshaft...... couple bearings, a rod, and 2 more gears......