Jackshaft DIY Jackshaft / Freewheel / Shift Kit

It is time to have some fun and put my engineering experience to good use. I am working out the details and will post my findings as i find them.

OBJECTIVE : BUILD Super Reliable Jackshaft for Shifting.

Lets see what we can discover.

Ok so far SBP has dominated the market on these shift kits.
And there price isn't bad.

I imagine i will spend more dough " My Nature "

I don't think you can build the same unit for less.

So why do it?

#1 Get a high quality jackshaft for about the same price.

#2 Have something to spend lots of time on.

#3 The satisfaction u get in building your own components "money can't buy"

#4 All the things we learn throughout the process. "Learning is cool"

I PROMISE THIS WON'T BE EASY.

I ask also for the other members to input your experience as well.

Ok good enough outline.

Lets Get Started!!!!!

Diy Jack Shaft

I agree, DIY is some of the best time I have spent. Great escape from work and the world. Mind works on the project while you sleep, so I don't rush it. It comes out so much better that way.

After it is all over, I have often looked back at it and thought: I am not that smart. )

I have a small 2 stroke I was given and a 20" wheel trike. Have been looking over at it while installing the hydraulic brakes on my Schwinn thinking about how to drive it for the wife. Chain drives a 3 speed hub transmission and it has a sprocket to the back axle. The other axle just has a nut on the end of it?

Anyway will be following your project and thinking of making my own.

Jim

Mysterious Hd Freewheel For Front Crank


The toughest part here seems to be the CRANK freewheel.
The pedals must turn the rear wheel & motor.
The motor must turn the rear wheel with the same chain as the pedals.
Thus the rear gear set is still shiftable for both the pedal drive and the motor drive.

The white freewheel that SBP sells is the easiest option.

Very Superior But it is still just a Bicycle Freewheel designed for a bicycle.

SPECS:

ENO freewheel
Thread size
1.37 x 24 tpi
Bearing
1 x 6708 - 16t
1 x 6808 - 17t-22t
Engagement
36 points

http://www.whiteind.com/singlespeedgearing/freewheels.html

Best quality freewheel u can buy assembled.
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Lets Talk Bearings

WHITE ENO BEARING AS SPECIFIED

6808-2RS Bearing, categorized as slim section, double sealed, radial, deep groove ball bearings, 6808-2RS bearings are made of Chrome Steel with chrome steel balls and steel cage, 6808-2RS bearing are closed with rubber seals to protect the bearing from dust or any possible contamination, 6808-2RS bearings are sealed and self lubricated, the 6808-2RS inner diameter is 40mm, the 6808-2RS outer diameter is 52mm and the 6808-2RS width is 7mm, the quality is set to EMQ (electric motor quality) to ensure high speeds up to 6,700 RPM, 6808-2RS bearings are lubricated with grease.

Name: 6808-2RS ball bearing
Item: Double Sealed Ball Bearings
6808-2RS Size: 40mm x 52mm x 7mm Ball Bearings
Inner Diameter (ID): 40mm
Outer Diameter (OD): 52mm
Width/Height/Bridth (W/H/B): 7mm
6808-2RS Quality: Electric motor quality
Type: Deep groove radial ball bearings
6808-2RS Material: Chrome Steel
6808-2RS Cage: Steel
Balls: Chrome Steel
6808-2RS Closures: Double sealed with rubber seals RS/RS1/2RS1
6808-2RS Lubrication: Self Lubricated (Grease) Bearing
Quantity: One Bearing 6808-2RS
Radial Clearance: C0
Equivalents: 61808-2RS1 and 6808RS Bearings
-------------------------------------------------------------------------

HOW MUCH ABUSE CAN THEY TAKE ??????

MAX LOAD KGF MAX SPEED
6708-2RS DYN:250 STATIC:225 5000 RPM
NOT BAD LETS SEE WHAT THAT MEANS IN ENGLISH.

DYNAMIC LOAD = 1808.250726498 FT LB
STATIC LOAD = 1627.425653848 FT LB

THAT IS VERY GOOD.

SO WHAT DID WE LEARN HERE????

WE NOW HAVE THE STANDARD TO WORK TO..
WE KNOW WHAT THE BEST FREEWHEEL IS CAPABLE OF!!!!

IS'T LEARNING FUN!!!

Lets Talk Bearings Part 2

After 2 days of searching for freewheel alternatives here's what i've found.
Lets take a look and see how the bearing compares.

Model No Dimension Torque N.m Weight (G)
d D W
CSK35 35x72x17 35mm 72mm 17mm 140 .3

The CSK series is a one-way (clutch) ball bearing. One way Bearing Sprag/Clutch Freewheel and also called as Backstops. The one-way bearings are used in any application that requires one direction rotation, such as mining, hydraulic, textile, printing and washing machines, conveyor systems that carry products to a higher level should not be reversed because of gravity during any power shortage.

DYNAMIC LOAD = ( 2835 FT LB )
STATIC LOAD = ( 1638 FT LB )
TORQUE = (140 Nm)

I believe i read the 48cc has a torque rating of 2.4Nm max.
So unless the gearing used creates a huge amt of torque.
I think were covered.
@ safty factor of 50 we would be 120 Nm.
Mannn that should cover us.

Sounds like it will be a lot of fun for you! Keep us posted on the progress! Satisfacation of the build will def be a cool factor!

Bearing Comparison

WHITE FREEWHEEL 6808 BEARING

MAX OVERRUN SPEED = ?????
MAX SPEED = 5000 RPM
DYNAMIC LOAD = 1808.250726498 FT LB
STATIC LOAD = 1627.425653848 FT LB
TORQUE = ????
50 MM OD
40 MM ID


CSK35 35x72x17
CSK35 One way Bearing Sprag/Clutch Freewheel Backstop

MAX OVERRUN SPEED = 3600 RPM
DYNAMIC LOAD = ( 2835 FT LB )
STATIC LOAD = ( 1638 FT LB )
TORQUE = (140 Nm)
72 MM OD
35MM ID

CSK35 35x72x17 VS WHITE FREEWHEEL
DYNAMIC LOAD = + 1027 FT LB
STATIC LOAD = + 10 FT LB

WHAT DOSE THIS LOAD STUFF MEAN????

Friction in rotary bearings: A rule of thumb
Friction in rotary bearings generates heat which can eventually destroy the bearing. With friction in mind, a common rule of thumb used for the allowable speed of ball and straight roller bearings is:

( B + D ) · n/2 < 500,000


Where B = bore diameter in millimeters
D = outside diameter in millimeters
n = speed in rpm

6808 BEARING (40 + 50) x ?????

DAMMIT: time to go do some gear ratio calculations.

We will be back after this commercial break "soon".

Pull Start Kit? / Bike Parts

The first thing I did when given the two stroke was to order a pull start for it. As I didn't really know the history or condition of the mains and conrod bearings, I wanted to be able to run it on the bench before putting together a complete build. Don't expect a long life as it has a sleeve top conrod bearing. The coil (CDI, not) is stamped 98 0r 99, so it has been around for a while but doesn't look to have much wear on it..

My preference for starting for both riding and tuneup. Just want to be able to start on a stand and adjust the carb. Also much easier to trouble shoot the ignition?

That should help in the drive train complexity as well?

BTW, it doesn't look like the centrifugal clutch kit is anything I want to invest in? The sleeve that fits on the crank looks to be a very weak link.

Someone pointed out that bike parts are really made for much higher torque loads than our engines are capable of providing. I put 280 foot pounds on the crank when I push off. (probably not really true as the crank isn't a foot long.)

While the initial torque is quite high, it quickly drops off as the total body (bike + engine + rider) is in motion. So the engine puts a constant load on all the drive train parts and we ride at a much higher speed than the bike parts are designed for I would guess.

Jim

210061741 said:

The toughest part here seems to be the CRANK freewheel.
The pedals must turn the rear wheel & motor.
The motor must turn the rear wheel with the same chain as the pedals.
Thus the rear gear set is still shiftable for both the pedal drive and the motor drive.

The white freewheel that SBP sells is the easiest option.

Very Superior But it is still just a Bicycle Freewheel designed for a bicycle.

SPECS:

ENO freewheel
Thread size
1.37 x 24 tpi
Bearing
1 x 6708 - 16t
1 x 6808 - 17t-22t
Engagement
36 points

http://www.whiteind.com/singlespeedgearing/freewheels.html

Best quality freewheel u can buy assembled.
--------------------------------------------------------------------------

Click to expand...

Sbp Gear Speed Calculations

Let's put this in terms of usable math.
Let's say that we have two gears in mesh.
Gear 1 (we'll call it the driver) is turning at speed S1 rpm and has T1 teeth.
Gear 2 (the driven gear) is turning at speed S2 and has T2 teeth.
Then our relationship above says that: ( S1 * T1 = S2 * T2 )


MOTOR REDUCTION BUILT IN
--------------------------
20 tooth gear 8000 rpm (S1)
82 tooth gear 1951.22 rpm (S2)
ratio 4.10:1

S1= 8000 RPM
T1= 20
S2= 1951.22 RPM
T2= 82

(S2= ?????)

S2 = (T1/T2) * S1 =

((20/82) * 8000) = 1951.22 rpm

----------------------------------------------------------------------------
----------------------------------------------------------------------------
MOTOR OUTPUT 10T SPROCKET
82 tooth gear 1951.22 rpm (S2)
10 tooth gear 1951.22 rpm. (S3)
ratio 0.12:1

S1= 8000 RPM
T1= 20
S2= 1951.22 RPM
T2= 82
S3= 1951.22
T3= 10
SG= 1951.22

S1 * T1 = Sg * T2
Sg = (T1/T2) * S1
8000 x 20 = 1951.22 * 82
SG= ((20/82) x 8000)

*** MAJOR CAVEAT ***
Note that everything said to this point
assumes that each of the gears in the gear train is on its own, separate shaft.
Sometimes gears are 'ganged' by keying or otherwise
and both gears turn as a unit on the same shaft.
This complicates the computation of the gear ratio, but not horribly.
Suppose gears 2 and 3 are keyed together into a single compound gear
we'll designate g (g for ganged).
Assuming S1 and S2 are in mesh, it's still true that:

S1 * T1 = Sg * T2
Sg = (T1/T2) * S1
--------------------------------------------------------------------------------
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LEFT JACKSHAFT SPROCKET 17T
--------------------------------------------------------------------------------
10 TOOTH SPROCKET 1951.22 RPM (S3)
17 TOOTH SPROCKET 1147.78 RPM (S4)

S1= 8000 RPM
T1= 20
S2= 1951.22 RPM
T2= 82
S3= 1951.22
T3= 10
SG= 1951.22
S4= 1147.78 RPM
T4= 17

S4= ((10/17) x 1951.22) = 1147.78 RPM

S4 = (T3/T4) * Sg = (T3/T4)*(T1/T2) * S1


If gears 3 and 4 are in mesh,

Sg * T3 = S4 * T4

(Remember, S3 turns at the same speed as S2 because they're physically
joined and we're calling their shared speed Sg.)

Therefore,

S4 = (T3/T4) * Sg = (T3/T4)*(T1/T2) * S1

So the end-to-end gear ratio is (T1*T3)/(T2*T4)
it *does* depend on the intermediate gears,
unlike the previous case when each gear could turn on its own separate axis.
Note that the resultant gear ratio
is just the product of the two separate gear ratios - (T1/T2)*(T3/T4).

--------------------------------------------------------------------------------
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RIGHT JACKSHAFT SPROCKET 17T
--------------------------------------------------------------------------------
17 TOOTH SPROCKET 1147.78 RPM (S4)
11 TOOTH SPROCKET 1147.78 RPM (S5)

S1= 8000 RPM
T1= 20
S2= 1951.22 RPM
T2= 82
S3= 1951.22
T3= 10
SG= 1951.22
S4= 1147.78 RPM
T4= 17
S5= 1147.78 RPM
T5= 11



--------------------------------------------------------------------------------
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FREEWHEEL CHAINRING 48T
--------------------------------------------------------------------------------
11 TOOTH SPROCKET 1147.78 RPM (S5)
48 TOOTH CHAINRING 263.03 RPM (S6)

S5= 1147.78 RPM
T5= 11
S6= 263.03 RPM
T6= 48

(S6= 263.03)

S6 = (T5/T6) * S5 =

((11/48) * 1147.78) = 263.03 rpm


--------------------------------------------------------------------------------
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FREEWHEEL CHAINRING 36T
--------------------------------------------------------------------------------
48 TOOTH CHAINRING 263.03 RPM (S6)
36 TOOTH CHAINRING 263.03 RPM (S7)


--------------------------------------------------------------------------------
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REAR SPROCKET 32T
--------------------------------------------------------------------------------
36 TOOTH CHAINRING 263.03 RPM (S7)
32 TOOTH CHAINRING 213.71 RPM (S8)

S7= 263.03 RPM
T7= 36
S8= 213.71 RPM
T8= 32

(S8= 263.03)

S8 = (T7/T8) * S7 = 213.71 RPM

((36/32) * 263.03) = 213.71 rpm

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
REAR SPROCKET 11T
--------------------------------------------------------------------------------
36 TOOTH CHAINRING 263.03 RPM (S7)
11 TOOTH SPROCKET 860.825 RPM (S9)

S7= 213.71 RPM
T7= 36
S9= 860.825
T9= 11

(S9= 860.825)

S9 = (T7/T9) * S7 = 860.825 RPM

((36/11) * 263.03) = 860.825 rpm


NOW WE KNOW THE SPEED OF EACH GEAR.
MUCH NEEDED INFO TO SELECT PROPER BEARINGS.

----------------------------------------------------------------------------------
EST MPH @ EXACT 26" DIA WHEEL.

Calculate the circumference of a circle:
C = 2 * Π * r

C = 81.68141 inches

FEET IN A MILE = 5280

5280 x 12 = 63360

63360 / 81.68141 = 775.69 ROTATIONS PER MILE

213.71 X 60 = 12822.6 ROTATIONS PER HR

12822.6 / 775.69 = 16.53 MPH 1ST GEAR @ 8000 RPM MOTOR

860.825 X 60 = 51649.5 ROTATIONS PER HR

51649.5 / 775.69 = 66.58 MPH HIGH GEAR @ 8000 RPM MOTOR

WOW THATS FAST.

ID HATE TO HAVE MY FREEWHEEL FAIL AT THAT SPEED.
YOU PEDALS WOULD BE MOVIN AT 263.03 RPM
I'VE HEARD THE STANDARD IS 100 RPM FOR A HUMAN

Pull Start

The first thing I did when given the two stroke was to order a pull start for it

Click to expand...

Thats very good.
The motor starting puts the highest shock load on the drivetrain.
I'll be buying a pull start for my 2 stroke.
Any suggestions where?

Anyway bridges fall and buildings collapse because engineers fouled up the leg work.

There is a method to my maddness in the end i will know that what is between my legs rollin down the street at 50 mph can handle the unexpected that gets tossed at it.

Rather than being tossed myself. ouch:tank: