Anyone have a source for big t8f/8mm freewheel sprockets?

Discussion in 'Hubs, Gearboxes, Sprockets and Chains' started by dchevygod, Mar 14, 2017.

  1. dchevygod

    dchevygod Member

    Joined:
    May 23, 2014
    Messages:
    54
    Likes Received:
    0
    Well I haven't ridden since im waiting on a new 24t. Got the derailleur and chain waiting on the 74t from china and my new 24t from SBP.
     
  2. dchevygod

    dchevygod Member

    Joined:
    May 23, 2014
    Messages:
    54
    Likes Received:
    0
    I hope the new derailleur will have tighter springs than the old one and if so that will help tremendously. If i destroy anything else i am getting the origin8 chain keeper. I ordered 2 sbp 24t sprockets "since I've gone thru 2 already! The first one was before i beefed up the freewheel mech from a single to a double and it was chain drop that caught and twisted the sprocket significantly. So now ill have a spare on hand" and the freewheel tool I'll need to remove the 54t and mod/install the 74t, but that one is from china so ill get it in April sometime lol! If you have a spare 72 tooth for a freewheel id be interested.
     
  3. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

    Joined:
    Aug 2, 2008
    Messages:
    2,364
    Likes Received:
    39
    I have a Shimano Alivio derailleur. It's worked very well on my mb for years.

    Did you shift into 1st gear and take as much slack out of the chain, when you replaced the chain?

    Sorry, I don't have any spare 72t sprockets.
     
  4. dchevygod

    dchevygod Member

    Joined:
    May 23, 2014
    Messages:
    54
    Likes Received:
    0
    I just destroyed an Alivio that came on the 8spd Motobecane 400ht. As I recall I srunk the 8spd sram chain 6 links total. The stock Alivio was replaced with a 9spd Alivio of newer construction. It will have new sram chain, a new 24t from SBP and a 74t from Aliexpress. The freewheel spacers could be upgraded to steel and i wish i could find a 10t pinion for the 5:1, but i trust your #'s on the gearing calculations so I'll stick with that for now. And after I get it dialed in ill let it known to all how good or bad it works. If the need for more chain control becomes apparent ill get said device and test it out harder than anyone has before!
     
  5. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

    Joined:
    Aug 2, 2008
    Messages:
    2,364
    Likes Received:
    39
    Ok. Good luck, chevygod.
     
  6. dchevygod

    dchevygod Member

    Joined:
    May 23, 2014
    Messages:
    54
    Likes Received:
    0
    Thank you for your insight I really appreciate it!
    This thing is an addiction. I have a 49cc 2 stroke scooter. "It's an 04 Kymco People 50" this MB is more fun pound for pound, I can and have pullled the front wheel up on moto 2.0 but I don't think it's probable on the scooter without some serious mods. Id like to build a custom 8 spd cassette with the perfect gear spacing for our application. Start with a 38t or bigger! And figure the appropriate spacing for our 460's to keep em in the powerband all the way to an 11t 8th gear.
     
    #26 dchevygod, Mar 19, 2017
    Last edited: Mar 19, 2017
  7. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

    Joined:
    Aug 2, 2008
    Messages:
    2,364
    Likes Received:
    39
    I like the fact that the 11t-34t 8-speed cassettes, chains and derailleurs are very affordable.

    I LOVE shifting, but I'm not finicky about close-ratio gearing. I firmly believe in a super-low first gear, to use in climbing really steep berms. I usually skip every other gear. My 1st gear is 51:1(equivalent to a 123-tooth rear wheel sprocket. Eighth speed is 16.5:1(equivalent to a 40-tooth wheel sprocket).

    From my experience, the derailleur has to be adjusted accurately, or the chain will jump between gears. If the chain jumps off first gear towards the spokes, you're in for a broken chain and spokes.:-||

    Let me know how your chain guide works out.
     
  8. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

    Joined:
    Aug 2, 2008
    Messages:
    2,364
    Likes Received:
    39
    Well, my new Jump Stop seems to be working well.....no chain jumping yet. I just finished tuning my carb, as the engine and bike had sat in my closet for at least 3 years.
    The 72t/10t/24t/34t first gear works very well climbing a dirt berm and tuning the carb.

    Chevygod, I found this 72t T8F sprocket at:

    http://thatsdax.com/ENGINE_KIT_PARTS_PAGE_2.html

    Maybe Dax can supply you one with the correct holes drilled.
     
    #28 5-7HEAVEN, Mar 25, 2017
    Last edited: Mar 25, 2017
  9. dchevygod

    dchevygod Member

    Joined:
    May 23, 2014
    Messages:
    54
    Likes Received:
    0
    Very cool that your bringing the bike back into the light. Its dark and lonely in the closet lol. So you just have the sbp jump stop? My front derailleur acts the same way but if I shrink the width it will capture the chain and prevent any jump in either direction. I was gonna pull the bb apart today and install the new 24t. I'll try to get some good pics and explain better.
     
  10. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

    Joined:
    Aug 2, 2008
    Messages:
    2,364
    Likes Received:
    39
    I won't need that 11-40t. My 72t/24t/34t combination is perfect for my needs. First gear(ala 123tooth single sprocket) climbs steep berms and is great for low-end carb tuning. My 8th gear is 16.5(ala 40t single sprocket), but I like 6th gear(ala 54t single sprocket) for flat ground.

    I rode about 5 miles yesterday, ranging from crawling on sidewalks to motoring on slight inclined roads. Like on previous rides years ago, I like cruising at 32mph.

    With your present setup and the Sunrace 11-40t, only your first gear drops from 34.77:1(ala 84-tooth single sprocket) to 40.91(ala 99-tooth single sprocket). 8th gear is still 11.25(ala 27-tooth single sprocket).

    Replacing your 54t with the 74t gives you 52.42:1(ala 126t single sprocket). Eight gear of 16.96:1(ala 41 tooth single sprocket). Now THAT'S usable.

    I'd suggest you replace your 54t with the 74t, and run it.

    Getting back to your chain-jumping. Are your motor mounts solid? That might be the cause of the dropped chains.

    For my new project, I just got this AWESOME universal motor mount a few minutes ago. I'd been searching for this for years:
    http://scooterpartsrus.com/X1_X2_engine.htm


    or this one might work for you:
    https://www.monsterscooterparts.com/enmofor33.html
     
    #31 5-7HEAVEN, Mar 27, 2017
    Last edited: Mar 27, 2017
  11. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

    Joined:
    Aug 2, 2008
    Messages:
    2,364
    Likes Received:
    39
     
  12. dchevygod

    dchevygod Member

    Joined:
    May 23, 2014
    Messages:
    54
    Likes Received:
    0
    Yeah the mount is a frickin rock. Ultra beefed up 4t mount plate, welded in stiffening strap for the thin top plate and added an upper brace using a turn buckle some chain and a single pull from the 5:1 mounting bolt. I had some serious engine chain sag under power and added the upper support soon after the build was rolling. This isn't the issue. When the mount moved a lot the engine chain would fall not the pedal chain. It was after i fixed the mount i started having pedal chain issues.

    I put on the front derailleur and it helped. Though i think i had compromised my 2nd 24t before installing the derailleur "free jump stop". So now i've put on my 3rd 24t sbp sprocket and need the bike running so its still 11:54 for now.

    I also decided after the 1st sprocket ate it to run double freewheels. My sbp freewheel adaptor is stripped! boo! Oh well it was reinstalled with a shmear of loc-tite red and its really just a carrier bearing any way. It would be nice to make a properly spaced carrier spider but this works for now.
     
  13. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

    Joined:
    Aug 2, 2008
    Messages:
    2,364
    Likes Received:
    39
    What's a carrier spider?

    Can you post pictures of the shift kit on your bike, including freewheels, sprockets and freewheel adaptor?

    In my present shift kit, the 24t chainring sprocket is connected to the 72t via five M5 bolts about 25mm (1") long. It works very well; the bolts have never shown any signs of twisting or damage. However, in your case as well as my project's shift kit, the distance between my 72t and the 24t chainring might cause twisting for 50mm long bolts.

    Why take that chance?

    Is that why you're using two freewheels? I'm thinking about doing that too, because of the distance between the sprockets. Seventy-five mm (3") is just too long. The freewheels I bought from SBP have two sets of five-bolt holes w/same diameter. That way, it'll be set up like two-section driveshafts, ala 1958-up Chevy.

    I won't be using any set screws or locktite on the inside freewheel carrier. The carrier HAS to spin freely and independent of the bottom bracket shaft. I might even sandpaper the carrier's inside diameter, for less friction on the BB shaft. The carrier's new purpose is simply to provide mid-stream support.
     
    #34 5-7HEAVEN, Mar 27, 2017
    Last edited: Mar 27, 2017
  14. dchevygod

    dchevygod Member

    Joined:
    May 23, 2014
    Messages:
    54
    Likes Received:
    0
    [​IMG]
    This was before cleaning and changing around spacers, sprockets and freewheels
    [​IMG]

    [​IMG]
    After moving things around cleaning an replacing a bent and broken sprocket
    [​IMG]
    This is the 74t that needs matched to this pattern
    [​IMG]
    And this is the left side view.

    Hey man tell it to me straight did I do good winging it?
     
  15. dchevygod

    dchevygod Member

    Joined:
    May 23, 2014
    Messages:
    54
    Likes Received:
    0
    A carrier spider if one existed would just be a carrier bearing inside of the 5 hole spider adaptor sbp sells. So I could get support for my long spacers without the extra freewheel I currently have. Yes the 2nd freewheel is because it twisted the bolts and spacers bad! The 1st 24t has 5 kinks in it to prove it. I would like proper steel spacers for either setup but
    1 " aluminum was what was available along with washers to take up the slack.
     
  16. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

    Joined:
    Aug 2, 2008
    Messages:
    2,364
    Likes Received:
    39
    Lol, you did good winging it.dance1

    http://sickbikeparts.com/chainring-adapter/

    This is the "carrier bushing" you might need.

    I might need two (My bottom bracket is 2" longer than yours).The adaptors are cheaper than a moderately-priced freewheel. They also don't need to be maintained, lubed or replaced.

    I might sandpaper the adaptors' ID's for less friction. No set screws or woodruff keys needed. They'll be "floating" on the shaft.
     
    #37 5-7HEAVEN, Mar 29, 2017
    Last edited: Mar 29, 2017
  17. dchevygod

    dchevygod Member

    Joined:
    May 23, 2014
    Messages:
    54
    Likes Received:
    0
    Well hello!... I just found this 72t #35 sprocket on Staton inc.
    72t 5 hole sprocket for #35 chain

    It would mean a chain size change, and that opens another can of worms by having to modify the 6 spline shaft to accept a #35 pinion sprocket also at staton. If i can get a 9t pinion to fit on the 5:1 and up size the 24t to a 30-32. I know this let me get closer to my pedal cadence id like. But ill need to change most everything :[ I really don't think its worth it.

    Like 5-7 suggests I'll run the t8f 74:11, 24:34-24:11 8 spd. If the motor reduction change doesn't fit my pedal cadence closer to what I like im going to try #35 sprockets and chain. This is my main transportation aside from my Kymco people 50 that is in need of a CDI. So ease of use and reliability are key. My work commute is short so I'll find the problems on my leisure rides. .wee.
     
  18. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

    Joined:
    Aug 2, 2008
    Messages:
    2,364
    Likes Received:
    39
    Things to consider, besides expense, if changing from T8F to #35 chains and sprockets:

    Your 74t T8F sprocket is 7.48" diameter; the 72t #35 sprocket is 8.75"OD.

    Is there such a thing as a 9T #35 drive sprocket to fit the pocket bike (PB)transmission pinion shaft? If so, where can I find it? Or can I have one made or modified to fit?

    Being that the PB tranny is relatively cheap, am I willing to weld a 9T drive sprocket onto the PB pinion shaft? scratg
     
  19. dchevygod

    dchevygod Member

    Joined:
    May 23, 2014
    Messages:
    54
    Likes Received:
    0
    I was gonna lathe the output shaft down so This would fit.

    Or this one could work as Well.
     

Share This Page