5:1 Transmission FWD Project

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lowracer

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Oct 17, 2008
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Thanks guys.
Here is what I did to it today.
- switch freewheel cassette to drive 34T (was 28T)
- add plastic 'pie plate' spoke protector (just in case)
- add a few links of chain for bump in teeth
- switch rear pedaling cog from 16T to 14T
- Install rear slick tire
- add another 'L' brace to tighten up the engine mount
- switch saddles to big leather beach cruiser saddle & lower the seatpost
- switch pedals to big flat BMX style platform (from clipless)
This is one lightweight MB.
I really like the freewheel aspect. I actually had to get on the brakes on my normal test loop cause it just wanted to roll when I let off the gas & I was accustomed to lots of engine braking...
-lowracer-
 

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lowracer

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Oct 17, 2008
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Just to stay w/ the 'No Money Invested' theme, I filled the pocket bike 5:1 transmission with 10W30 motor oil I had laying around. Hopefully the oil doesnt leak since the transmission is directly above my front tire. If I see any of the oil seeping out, I'm draining the trans & going with grease...
I also found a chain tensioner made for single speed bike conversions I had for years in a box. I may use it on the non-drive side of the chain or fashion up an old skateboard wheel like I used quite often with my now retired v-belt drivetrains.
Stay tuned
-Lowracer-
 

BigBlue

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Nov 29, 2011
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Just to stay w/ the 'No Money Invested' theme, I filled the pocket bike 5:1 transmission with 10W30 motor oil I had laying around. Hopefully the oil doesnt leak since the transmission is directly above my front tire. If I see any of the oil seeping out, I'm draining the trans & going with grease...
I
Couldn't you just mill the case with 230 grit or less sandpaper on a piece of glass like they do with the 66cc HT heads to help prevent leaks? I would at least check with a piece of glass to see if they are true.

Your builds are always interesting and at the forefront of using various parts that are being used not for their intended purposes. Keep us informed of your progress.

Chris
AKA: BigBlue
 

16v4nrbrgr

Active Member
Mar 17, 2012
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Yeah, that's what I'd do to prevent leaks. Permatex Super Black sealant works pretty good too, Reinzosil is even better, and it'll hold the gnarliest synthetic diff oil in an old fretted VW transaxle. Another thing you can do is make grease pudding, mix some motor oil with bearing grease. I think gear oil is best though, I did some reading on it before putting it in my geared hub, and it cushions shock better than a grease or motor oil would on the teeth.

Dammit, you're making me want to do a rack mount build, maybe I should make my Motobike rack mount if the project stalls. Dax has a nice kit I was thinking about.
 

lowracer

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Oct 17, 2008
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16v4nrbrgr,
I went searching for grease today & came home empty handed. I did find one made by Rotary at a small engine supply shop rated a '0' grease...(I think that means its thin).
I'll do a little more research on it.
I drained half the motor oil I put in yesterday so its now about half full. I may go the 'grease pudding' route...lol
I also had about an hour this morning & added the chain tensioner.
I am using a heavy duty rubber bungee to lift up on the opposite side of the tensioner which applies pressure to the chain. I took it for a cold test loop early this morning (50 degrees) & it works well so far (brrrr). I didnt do the skateboard wheel tensioner, but may still go that route if this one jumps out of the chain roller area.
Cheers,
-Lowracer-
 

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lowracer

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Oct 17, 2008
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I bought the grease today, drained the remaining motor oil from the 5:1 transmission & filled it up with grease (Rotary '00'). It sounds about the same as always, but I feel better having the grease in there.
I also added the expansion chamber to not only route the fumes down & away from the rider (me), but it adds a bit more power & max rpm's to the little Tanaka 32cc engine.
I'm really digging the chain drive system w/freewheeling. I may begin another rear chain drive project with 'The Beast' currently without an engine. I'm thinking this one will have a homemade shift kit using 2 freewheels. Lets see if I like having gears to power thru as I leave lights & get it up to speed...
-Lowracer-
 

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lowracer

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Oct 17, 2008
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I dreamed up another idea for using a pocket bike 5:1 transmission for another of my bikes. It was a rear friction drive until it sheared the clutch drum from the shaft. I'm thinking of installing the 5:1 trans. onto the rear 'U' channel & running a chain from its 10T to the largest 32T chainring on the rear cassette. Then installing a front freewheel onto a new set of ISIS trials cranks (see pic).
It wont be a shift kit since I will have a fixed 10T:32T under engine power. I'll adjust the rear derailleur low gear screw to only shift up to the 28T 2nd gear. The pedal drivetrain will always be in motion and can shift without pedalling (like the old shimano ffs). When I pedal to help the engine I'll have 8 gears to choose from (16 if I keep 2 front chainrings but I'll probably go with just 1). Only bad part is if I need to limp home pedal-only, I'll be pedalling the 5:1 transmission unless I pull its chain off (lots of drag).
Maybe there is a way to ad another freewheel into the system?
Since its a full suspension bike, I'm not sure if I can run a chain from the rear rack directly to the crank freewheel without issues caused by suspension movement.
-lowracer-
 

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lowracer

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Oct 17, 2008
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bowljoman,
An internal 3 speed would be about perfect for an MB. Definitely no need for 8-9 speeds.
I've been happy with just one gear on both my motor side & my pedal side (I am an avid cyclist who can pedal).
While tinkering in the garage today I came up with a nifty cheap friction drive idea.
I have an old rear thread-on hub w/ freewheel. Mounting the hub in some angle aluminum and running the freewheel on the left, it would be a chain driven friction roller that freewheels when off the gas (the one-way rollers dont work, I got a few of those Dax rollers. As long as the hub shell aluminum lasts for awhile before it disintegrates, it would be an almost disposable friction drive unit...(see pic) or maybe superglue some old bicycle tire onto the center of the shell. Could also drill out some spoke holes and bolt thru some type of material to run on the tire???
Could allow the use of a large roller by changing the gearing using the freewheel & different size sprockets. A large roller would create less tire wear & could offer better wet traction?
Also I did some testing of Expansion chamber pipe vs. Stock exhaust canister on my Tanaka 32cc front chain drive bike today.
I was able to hit max 7500 rpm's on 4 test runs on the same straightaway with the stock muffler & max 7860 rpm's with the expansion chamber. Thats a difference between 34.12 mph & 35.76 mph...Not much, but worth the hanging few pounds of hardware & slight noise increase?
-Lowracer-
 

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bowljoman

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Aug 7, 2010
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Funny you should think about that! Do that same exact thing, but use thew three-speed hub for the friction drive :) Its good for thirty mph at around 3500 rpm!
 

lowracer

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Oct 17, 2008
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I put the expansion chamber back on & decided to take it for two more speed runs down my straightaway test road. This time I got real tucked in & was able to hit 8160 rpm's = 37.13 mph with the little 32cc Tanaka...I think I'm good now.
Bowljoman,
I like how you're thinking.
That is the simple way to do a multi-geared friction drive (the holy grail of friction..lol)
I may try this freebie hub 1st just to see how it performs. I'm still waiting on my Dax warranty replacement drum/shaft to arrive & is probably the reason why I've been experimenting with other methods of propulsion.
I did have an old Sachs 3 spd internal hub (SRAM bought them out) & ran it on a Greenspeed tadpole recumbent trike with great results (unmotored). Just wondering if the aluminum shell is worthy to run on a tire with any kind of longevity?
I'd love to take one of my old Kryptonic skateboard wheels & somehow get it to hold tight on the shell (possibly using the bolt thru the spoke holes idea of earlier).
-Lowracer-
 

wayne z

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Dec 5, 2010
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Great idea! the friction drive will slip a little and dissipate the torsional vibration of the single cyl engine and be way easier on the gearbox than a chain drive would.
 

lowracer

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Oct 17, 2008
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Charleston, SC
bowljoman,
If I go hub wheel friction drive, I wouldn't use the 5:1 gearbox. It wouldnt be necessary.
I did some more brainstorming on the rear 5:1 transmission idea & think I may give a homemade shift kit a try. I'll run the chain from the rear rack to the freewheel isis cranks with plenty of slack taken up by a spring loaded skateboard wheel tensioner to compensate for the 7" of rear suspension (suspension moves in an arc in relation to the bottom bracket so it may not be as bad as I originally thought).
10T on 5:1 transmission w/ Tanaka 40cc or GP460
11-34T cassette
44T & 32T chainrings
The ratios @ 8500 rpm (rounded):
34T = 28 mph @ 23.4:1 ratio
30T = 32 mph @ 20.7:1 ratio
26T = 37 mph @ 17.9:1 ratio
23T = 42 mph @ 15.8:1 ratio
21T = 46 mph @ 14.5:1 ratio
19T = 50 mph @ 13.1:1 ratio
I dont think I'd need to shift beyond this point.
Where I live is flat & I really dont need any shiftkit but I think it would be fun to change gears...If I dont proceed ith the shiftkit, I'll still do the rack to rear cassette chaindrive.
Anyone know where I can get a dual freewheel cassette? Something like adding a large 34T freewheel behind the normal shimano cassette & leave off the few small cogs for the space constraint? I think there was a video TheScooterguy has on youtube where he did that to a thread-on freewheel & had a dual freewheeling cluster...
-lowracer-
 
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lowracer

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Oct 17, 2008
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Charleston, SC
I got the chance today to take this new rig out for an extended test drive of 58 miles.
The chain drive performed flawlessly & didnt skip a beat (no pun intended). I got 58 miles on just under 50 oz of fuel (still some left in the tank) so lets say 48 oz.=155 mpg's...Not too shabby considering it was a windy day.
Some observations after todays adventure?
1- I dont like rigid (no suspension) bikes!!! (this rig beat me up unmercilessly especially at high speed & sat on a large leather rear sprung beach cruiser saddle)
2- I like chain drive (even though there is an annoying whine to the 5:1 transmission. Maybe that will go away over time...its still new)
3- I really like freewheeling when off the gas (I know my clutch is loving the freewheel)
4- I want to turn one of my two full suspension DH bikes into a rear chain freewheel drive (possibly a homegrown shift kit, or just a single ratio like this rig)
5- Needs a more power engine (the Tanaka 32cc is ok, but once spoiled by the 40cc & the mojo powerful pocket bike engines, only another 40cc or GP460 will do)
I'm putting a parts order together to turn 'The Beast' (the bike in my avatar) into a rear rack chain driven freewheeler...will keep ya posted
-Lowracer-
 

lowracer

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Oct 17, 2008
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Charleston, SC
Re: 5:1 Transmission REAR project

Today I got some work done on the new MB project.
I removed the front engine & all the hardware from the Litespeed MTB & got it installed onto othe rear of 'The Beast' (Rocky Mountain RM7). I also received the 11-34T cassette today but none of the other parts arrived yet so I'l be anxiously awaiting them.
I had a crazy idea today about running a long chain (2-3 chains put together) around the whole shebang. With some extra chain length on tensioners to compensate for rear suspension movement. Not sure if this has been done before, but it would have all 18 speeds available for pedal & engine.
see rough pic
 

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