Jackshaft DIY Jackshaft / Freewheel / Shift Kit

Discussion in 'Transmission / Drivetrain' started by 210061741, Sep 29, 2009.

  1. 210061741

    210061741 Guest

    :idea: 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.

    :rolleyes7:OBJECTIVE : BUILD Super Reliable Jackshaft for Shifting.

    :detective: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 " :whistling:

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

    :icon_cry: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!!!!!:devilish:
     

  2. jimraysr

    jimraysr Member

    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
     
    Last edited: Sep 29, 2009
  3. 210061741

    210061741 Guest

    Mysterious Hd Freewheel For Front Crank

    :cool2:
    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.
    --------------------------------------------------------------------------
     
  4. 210061741

    210061741 Guest

    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 ??????:detective:

    MAX LOAD KGF MAX SPEED
    6708-2RS DYN:250 STATIC:225 5000 RPM
    :tt1: NOT BAD LETS SEE WHAT THAT MEANS IN ENGLISH.

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

    :tt1:THAT IS VERY GOOD.

    :confused:SO WHAT DID WE LEARN HERE????

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

    :detective:IS'T LEARNING FUN!!!
     
  5. 210061741

    210061741 Guest

    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.
     
  6. Hawaii_Ed

    Hawaii_Ed Member

    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!
     
  7. 210061741

    210061741 Guest

    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

    :detective: 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: :ack2:time to go do some gear ratio calculations.

    We will be back after this commercial break "soon":detective:.
     
    Last edited by a moderator: Dec 17, 2015
  8. jimraysr

    jimraysr Member

    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



     
  9. 210061741

    210061741 Guest

    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
    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------

    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).

    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------
    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



    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------
    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


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


    --------------------------------------------------------------------------------
    --------------------------------------------------------------------------------
    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:jester:
     

    Attached Files:

  10. 210061741

    210061741 Guest

    Pull Start

    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:
     
  11. 210061741

    210061741 Guest

    A Caution About Torque And Ht Motor Output

    Now when it comes to just about any type of racing known to mankind, besides engine output, gearing is the single most contributor to acceleration. It will make or break any car and the right gear selection can and will mean the difference between winning and losing a race.

    How important is gearing? Gearing nearly makes torque obsolete. Yes, it's that important. In a perfect environment with no limiting factors such as size and weight, the actual peak torque output of an engine would be totally meaningless because of gearing.

    How's that possible? It's simple. Gearing multiplies peak torque to the wheels to any amount desired. Increasing the ratio increases torque.

    AGAIN
    Gearing multiplies peak torque to the wheels to any amount desired. Increasing the ratio increases torque.

    Therefor never guess or assume it is safe.
    Do the math.
    Find the specs.

    Our little HT IC Motors can generate massive torque with the gearing
    configured to do so.

    :detective:Time for another short break.

    COMING NEXT TORQUE CALCULATION AT 36 T FREEWHEEL.:detective:
     
  12. 210061741

    210061741 Guest

    Torque At 36t Freewheel Sprocket

    Ok guys i'm getting tired here.
    Anyone... calculate the torque at the 36t freewheel sprocket.
    I'll give it another run tommorow.

    After all those gear calculations my brain is spent.

    Have a good night.
     
  13. 210061741

    210061741 Guest

    Torque Calculations

    UPDATED SCHEMATIC ILLISTRATING TORQUE AT EACH SPROCKET

    SOMEONE PLEASE VERIFY.

    THANK YOU

    SEE ATTACHED:whistling:
     

    Attached Files:

  14. Fabian

    Fabian Well-Known Member

    Hi 210061741

    The mathematics are correct in a sense that they do work when using the "optional 48 tooth" chainwheel which SickBikeParts sells on their website.
    When creating my schematic i falsely assumed that the standard chainwheel sprocket was 48 tooth but in fact, the standard chainwheel size with all of the kits is "44" tooth.
    In ways this could be seen as an error on my behalf.

    The jackshaft output sprocket size in the standard kit/s is 10 tooth with optional 9 and 11 tooth sprockets.
    Personally i want a 12 tooth sprocket to lower top gear rpm's but it is not produced.

    Feel free to redraw my schematic with the various sizes added for future reference.
    Better still - please recreate my schematic in a professionaly produced manner

    Kind regards

    Fabian
     
    Last edited: Sep 30, 2009
  15. 210061741

    210061741 Guest

    Gear Schematics

    :devilish:Yes I am basing this on the given gear setup.:grin5:

    The important thing is that the Torque & RPM are correct.
    The torque and rpm deterimine the load required to be handled by the bearings.

    For our Freewheel which BTW gets the highest torque in the gear train applied to it , we are comparing bearings to the white freewheel.

    To get an idea of reliability.

    So our bearing can be sized to provide the best duribility, and least possible chance for failure.

    These MAX torques will be applied "as stated before" at around starting speed. Very slow speed.

    I believe 48 cc ideles around 3600 rpm and 4500 rpm being max torque.
    Means a little rev and where there.

    However somewhere we should factor into this the torque created at the freewheel when peddaling and using the motor to start off.

    Cause like having 2 motors the crank and the motor both will transmit torque simultaneously.:sweatdrop:

    Anyone have the magick number.
    I saw an answer earlier.

    Once we are moving down the road the torque drops significantly.

    AS A RULE LOOK AT IT LIKE THIS.

    INCREASE SPEED = LOWER TORQUE
    INCREASE TORQUE = LOWER SPEED

    That is how it will work with our gear ratios.
    So by playing with those we could adjust not only speed. (normal reason)
    But to adjust torques if nessessary.

    Don't you love math!!!!

    It seems we have done alot of work but everything gets easier once your forces are figured.

    Find the max force and your system must stand up to it with a factor for safty.

    We will use these calculations later to determine the strength required by the shaft and to figure how much we stress the steel plate brackets.

    So yes we did all this work so far. :confused::confused:
    :confused::confused::confused:just to find a bearing :confused::confused:

    Yes at this point in time that appears what we have done.
    :detective:What did we learn?

    NOW WE UNDERSTAND WHAT ENGINEERING IS REALLY ABOUT. :shout:
    It is more than just picking up pcs off the shelf and putting them together.
    Everything must start somewhere so prototypes like that are nessessary.
    But once you know it will work, DO THE MATH.

    Know the limitations of the system.

    I will redraw the schematic in cad.

    I appreciate the use of the existing pic.
    Thanks for that it saved me time.

    Also once i get the whole system modeled in 3d i will run stress analysis software against it. My calculations could be off. I am surly not perfect.
    IF ANYONE ELSE OUT THERE HAS TIME TO DO THE MATH.......:whistling:
    PLEASE ALSO DOUBLE CHECK THE FIGURES.
    WE DON'T WANT TO BE WRONG HERE :ack2:

    After the complete unit is designed we will stress test it to the point of catastropic failure.

    Then we will know the weak points.

    I BET IT WILL BE THE BIKE FRAME.:tt1::tt1::tt1:
     
  16. Fabian

    Fabian Well-Known Member

    Hi 210061741

    I am keenly looking forward to this project gathering a strong head of steam and moving into the design and development stage.

    When it's modelled in cad, can it be designed as a moving user interface for input of different optional jackshaft sproket ratios and final drive (to rear cassette) ratios, so people can play with different ratios and see a moving outcome on the screen; rear wheel speed, rpm ratios, tensile stress forces on the chain drive systems and the torque loading on the freehub cassette pawls as they step down or step up torque through the package.

    I am curious as to the tensile forces are going through the various drive chains, especially when the jackshaft ratios are changed .

    Fabian
     
    Last edited: Sep 30, 2009
  17. Fabian

    Fabian Well-Known Member

    210061741

    Remember that these chinese bicycle motors only reliably rev to 4000 rpm and are on their way to self destruction at 5000 and completey shot to pieces at 6000 rpm.

    The seat of the pants feeling with my motor is maximum torque is around 2500-3000 rpm and max power is around 3500.
    Having said that, my engine uses the stock standard exhaust (i feel it boosts low rpm torque compared to the open muffer variant i used before which allowed more rpm but the motor self destructed).

    Fabian
     
  18. Fabian

    Fabian Well-Known Member

    Check out this dyno graph of a chinese motorised bicycle engine - i have no data as to it's capacity or manufacturer or final drive gear ratio.

    Unfortunately the graph only gives a torque spread vs road speed and a horsepower curve - it doesn't give an rpm curve which makes calculations difficult.

    Fabian
     

    Attached Files:

  19. 210061741

    210061741 Guest

    3d Models

    Yes we can generate 3D Models that simulate eyerything.
    We can create assosiative assemblys where if 1 component changes it is reflected in the model. This allows to make changes without redrawing the entire model.

    Pretty cool stuff.
    Cost me $20.000 for that degree.

    Getting ready to start modeling soon.

    Were gonna take this one to the max.
     
  20. 210061741

    210061741 Guest

    thanks

    Thanks for the correction of motor output / rpm.
    But that is good news.
    It means or torque calculations have a safty factor of
    8000 rpm / 4500 rpm = 1.777 safty factor.

    72.99Nm / 1.777 = 41.07 Nm actual Max Torque.

    DIVIDE THE MAX TORQUE OF THE BEARING BY 41.07 Nm actual Max Torque.
    = ACTUAL SAFTY FACTOR FOR THE BEARING.

    This means our sprag bearing is a very good selection.:grin5:

    This means as long as our bearing is mounted properly our freewheel should be able to take anything we throw at it.
     
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