mounting sprocket to sprocket

[dcastillo]

Is this possible, or is this stupid?

I need more torque on my sons little gokart, cant change the motor sprocket to smaller, and dont want to add a jackshaft.

current sprocket on the rear is
http://www.surpluscenter.com/Power-...ets/72T-3-4-BORE-25P-SPROCKET-1-2742-72-F.axd
(obviously the picture is not accurate, it looks more like this)
http://thumbs4.ebaystatic.com/d/l225/m/monDw3RK7ofuV7CimfpkiCQ.jpg

Is it possible to bolt/weld this sprocket
http://www.monsterscooterparts.com/...rocket-schwinn-izip-mongoose-gt-scooters.html
to it?

My thought is to very carefully clamp them together and using calipers ensure they are centered as perfectly as possible. then either drill holes through and bolt together or just weld them together...

thoughts?

 

[itsid]

I'd say it's possible although I'd say don't!

First linngear makes B-type sprockets in #25 (up to 104teeth IIRC)
which would be a nice drop in replacement (and you can go back in a matter of minutes)

second, because that 1-3/8" thread is- If I'm not mistaking- the std thread for bicycle sprockets (threaded of course)

So a threaded hub with a 3/4" bore should be out there to accept that sprocket,
although none showed up in my quick search *shrugs*

Anyways.. personally.. a tiny little jackshaft with one 8T and another 10T sprocket will do just the same (or 12 and 15 if you want a bit more grip 16 and 20 for all the grip there is)
shouldn't be more expensive than that currie sprocket you linked to
and with just a small sprocket to tweak much easier and cheaper to dial in correctly

yes, a jackshaft is unfortunate.. but it's convenient so, I think that'd be my choice (if there's room to add one of course)

'sid

 

[mckutzy]

IF the bores are the same, just clamp together and weld. theyll align on the same shaft....

 

[chancer]

What Kart and engine is this going on?

 

[dcastillo]

What Kart and engine is this going on?

see here
http://www.diygokarts.com/vb/showthread.php?t=32914

---------- Post added 06-21-2016 at 12:03 AM ---------- Previous post was 06-20-2016 at 11:54 PM ----------

Sid, I checked linngear (cool site btw) but saw none that would drop into a 3/4 axle with keyway.
Mckutzy, bores are not the same, so it will be 'tough' , I think doable, but decent chance I snap the #25 chain

so I guess jack shaft is the plan, which is a good learning experience I guess...

would I just get two of these (weld to the frame)
http://www.bmikarts.com/Jackshaft-Bearing-Hanger-_p_1046.html
then pound two of these into them and add a lock collar to hold in place?
http://www.bmikarts.com/Flanged-High-Speed-Wheel-Bearing-34-x-1-38_p_2369.html

slide two sprockets on and done?
(is it that simple?)
-Danny

 

[chancer]

Checkout MFG supply they have That stuff and kits. Plus 6.99 flate rate "all you can order" shipping.

 

[itsid]

so I guess jack shaft is the plan, which is a good learning experience I guess...

would I just get two of these (weld to the frame)
http://www.bmikarts.com/Jackshaft-Bearing-Hanger-_p_1046.html
then pound two of these into them and add a lock collar to hold in place?
http://www.bmikarts.com/Flanged-High-Speed-Wheel-Bearing-34-x-1-38_p_2369.html

slide two sprockets on and done?
(is it that simple?)
-Danny

Almost that simple!
I'd get pillow blocks intead of weld-ons to have at least a chance to level the jackshaft afterwards ..
Anyways, make sure to check the bores of the available sprockets first!
you'll never fit a 8T on a 3/4" shaft for example...
and with the motor you currently have a short 1/2" shaft should be rigid enough (I said tiny right )
frankly, I even think you could get away with a single bearing wedged between the two sprocket collars.
which would give you an overall length of ~2"..
Yes, the bearing wouldn't like the side load too much and you
should always support a shaft with two bearings;
still I think it might work long enough in this scenario.
On the other hand.. a second bearing doesn't add too much to the overall length...
so it'd still fit nicely onto your kids kart.

But work your way out, not in..
i.e. start with sprocket bore -> shaft diameter -> bearing size -> bearing hanger(pillow block)

'sid

PS with linngear as with nearly all industrial sprockets that's only a pre bore.
needs to be broached/bored according to your shaft.
I'm sure they can do that or provide you a list of machine shops near you..

 

[dcastillo]

thanx a ton...
need to find time to flip the cart over and see how to mount this stuff.
1/2" pillow blocks seem like a good idea to me.

thanx for the info Chancer, but their kits come stock with #35 sprockets, I want to stay with #25 I already have setup...

though in a few years, for fun, I may look for a 1kw motor and drop it in there (with #35 chain setup) instead of the 250w I have now and that thing will be dangerous!!!! (-ly fun)
-Danny

 

[chancer]

I also meant they sell individual parts. You may have to use the search box on their site though.
I just hate that BMI wanted 8 shipping bucks for 2 dollar GIANT washers, that would almost fit in a 42cent envelope!

 

[Iron John]

I've piggybacked sprockets. It worked fine. Here is one - the smaller was turned down to fit inside the bigger with a slight interference fit, then pressed together and welded:





I realize that OP's existing donor sprocket is of a much larger diameter, but the point is that you can build them up to make what you already have on hand useful.

 

[dcastillo]

wow, thats pretty handy, thanks
-Danny