01-21-2018, 03:22 AM
(This post was last modified: 01-21-2018, 03:33 AM by doug tenney.)
Brian, if you haven't already, check out Azusa Engineering's catalog. They've been around since 1960 and are crucially important to this hobby. Pretty much all kart shops are Azusa dealers.
There is one format of sprocket that everyone uses for vintage rear-engine karts: 4-9/16" hub, with 6 bolts on 5-1/4" bolt circle, with #35 chain. Get aluminum split sprockets, so that you can change them if you whack one going off the edge of the track a bit, or want to change the ratio.
For your application, I'd start with roughly a 6.5:1 ratio. So, if you have 10 teeth on your clutch sprocket, go with 65 or so teeth on your axle sprockets. If you have a 9T clutch, 9 X 6.5 = 58T or 59T.
If the driver is over 180 lbs or so, and/or the track is tight, you could go to a 7.0:1 ratio.
Azusa's "Mark IV Vari-Hub" #1872 sprocket hub will work well and look at home on your kart. I don't think it's the exact hub that was available in 1960 but only experts will be able to tell. In fact, a lot of folks skip right over the Vari-Hub and go right to a machined sprocket hub. Not vintage, they run more true and are easier to align with the clutch. http://www.out2win.com/catalog/sprkthub.html.
[In general, be careful about how precise you adhere to being "period correct." Karts matured a lot between 1960 and say, 1963... a lot of the very early stuff was prone to premature wear and outright breakage when driven hard.]
Along those lines, for chain, skip right to #35 "space chain," either EK or RLV brand. Not period correct, but trust me, the chains from 1960 were constantly flying off, kinking up and stretching. (Somewhere on Azusa's website there's a great write-up on the evolution of kart chain.)
Enjoy!
You asked what it came with originally. In those infancy years, a lot of karts didn't even have clutches. So, direct-drive with 8:1 (9T/72T) seems to have been fairly common. (In the absence of any clutch slippage, I suppose you needed a super low ratio to get moving.)
I never drove a kart with direct-drive, but I would guess that it's a hassle.
There is one format of sprocket that everyone uses for vintage rear-engine karts: 4-9/16" hub, with 6 bolts on 5-1/4" bolt circle, with #35 chain. Get aluminum split sprockets, so that you can change them if you whack one going off the edge of the track a bit, or want to change the ratio.
For your application, I'd start with roughly a 6.5:1 ratio. So, if you have 10 teeth on your clutch sprocket, go with 65 or so teeth on your axle sprockets. If you have a 9T clutch, 9 X 6.5 = 58T or 59T.
If the driver is over 180 lbs or so, and/or the track is tight, you could go to a 7.0:1 ratio.
Azusa's "Mark IV Vari-Hub" #1872 sprocket hub will work well and look at home on your kart. I don't think it's the exact hub that was available in 1960 but only experts will be able to tell. In fact, a lot of folks skip right over the Vari-Hub and go right to a machined sprocket hub. Not vintage, they run more true and are easier to align with the clutch. http://www.out2win.com/catalog/sprkthub.html.
[In general, be careful about how precise you adhere to being "period correct." Karts matured a lot between 1960 and say, 1963... a lot of the very early stuff was prone to premature wear and outright breakage when driven hard.]
Along those lines, for chain, skip right to #35 "space chain," either EK or RLV brand. Not period correct, but trust me, the chains from 1960 were constantly flying off, kinking up and stretching. (Somewhere on Azusa's website there's a great write-up on the evolution of kart chain.)
Enjoy!
You asked what it came with originally. In those infancy years, a lot of karts didn't even have clutches. So, direct-drive with 8:1 (9T/72T) seems to have been fairly common. (In the absence of any clutch slippage, I suppose you needed a super low ratio to get moving.)
I never drove a kart with direct-drive, but I would guess that it's a hassle.