#35 driven sprocket vs #420

[Gibsonfan159]

To my understanding, a #35 driven sprocket is smaller in diameter compared to a #420 with the same amount of teeth (let's say 60t). How does this affect torque? Will the larger #420 have more torque? Will a #420 60t have the same torque as a #35 72t? I ask because I'm thinking of switching out my #420 setup to a #35 so I can use a 72t driven. But if the smaller #35 sprocket affects torque it might be a waste of time.

 

[mckutzy]

Should have just left this as one topic as this does pertain to your previous thread.....

NO. torque isnt affected...its all the same..... however the strength of #35 chain is different from the #420.....
Changing from 420 to 35 just allows a more broad range of ratio within the same space, as there are more teeth per the same given area of the larger size.
Also a more common chain size.

 

[Joe-405]

Do not buy the same size sprockets for both sizes. It will affect the whole drive ratio.

The #35 at the same tooth count is much smaller diameter than the 420 at the same tooth count.

 

[OzFab]

Ok, we're talking apples & oranges here; to best explain the situation, whether you use one or not, let's talk about centrifugal clutches for a minute:

Standard, cheap centrifugal clutches (CCs for short) for a 3/4" shaft come in two sizes, #35 & #40/41; a #35 CC has 12 teeth because that's the least amount of teeth that will fit around the engine shaft; likewise, a #40/41 CC only has 10 teeth for the same reason...

Now, to gain a 6:1 ratio, you would need a 72t #35 axle sprocket whereas, you would need a 60t #40/41 axle sprocket... which are roughly the same size...

So, changing from #420 to #35 to gain a higher tooth count rear sprocket is pointless because, in #35, you would need an axle sprocket roughly the same size as a #40/41 72t sprocket, which puts you in the 90t range...

The best advice we can offer has already been offered in this thread, get a torque converter...

 

[Randy H]

So, changing from #420 to #35 to gain a higher tooth count rear sprocket is pointless because, in #35, you would need an axle sprocket roughly the same size as a #40/41 72t sprocket, which puts you in the 90t range...

I don't understand this statement. I mean tooth count is the factor here, right? Diregarding space and strength requirements.

 

[Joe-405]

He is saying what I was saying.................

A #35 sprocket with a 72 tooth =smaller than a #420 sprocket with a 72 tooth sprocket

If that doesn't clarify then I don't know what to tell you other than waste some money and buy them and then you will see visually.

---------- Post added at 07:48 PM ---------- Previous post was at 07:47 PM ----------

So the ratio is not gonna be even remotely close when you switch chain sizes on both the same tooth count.

 

[Randy H]

I agree there will be a visual difference.

Sprocket ratios are calculated by tooth count. Rear tooth count divided by front tooth count.

60/10=6.0

Check out some charts or calculators. The pitch doesn't effect the ratio. It effects strength and size.

Respectfully
Randy H

 

[OzFab]

You're only reiterating what I said; changing the chain pitch will only change the strength & number of teeth, the size of the sprockets remains the same...

 

[Joe-405]

Wanna bet ! I put a 35 chain on my bike at a 60 tooth count and then the same count on the 420 chain and it wasn't even close at the same rpms and with my GPS I lost 15mph.

 

[bob58o]

Wanna bet ! I put a 35 chain on my bike at a 60 tooth count and then the same count on the 420 chain and it wasn't even close at the same rpms and with my GPS I lost 15mph.

Not sure what you mean "wasn't even close at same rpms"

You are saying that even with the same gear ratio, the heavier chain and bigger sprockets cost you 15mph off your top speed?
And that your RPMs never got as high as with the #35?

I know in racing, people will use lighter chain/sprockets for small gains, but that seems pretty significant. I can't imagine a 20-25% increase in RPMs by only using a smaller chain sprocket combo.

 

[Joe-405]

I'm saying the same tooth count on a #35 vs. #40/41/420 chain will NOT be the same final drive ratio. You will loose ratio cause the #35 will be a alot smaller diameter. I had to go down 10 teeth on my 420 sprocket to match the #35 overall diameter to get the same mph at the 1/8 mile mark.

---------- Post added at 11:12 AM ---------- Previous post was at 11:11 AM ----------

We might be saying the same thing I just thought you guys were saying the same tooth count on different size sprockets will be the same final ratio.

 

[Randy H]

Ratio is ratio. You can use pitch diameter, overall sprocket diameter, or tooth count to figure it. Say you have 10 tooth drive and a 60 tooth driven. The ratio is 6 to 1. It's 6 to 1 wether you have #35 chain or #40 chain right on up to infinity chain.

I can't explain your discrepancies but there is no getting around the fact that the ratio doesn't change with pitch. When you change pitch both sprockets change size (physical size). They both have to because it's a ratio.

Respectfully
Randy H

Found this obscure sight in the dang old internet

http://www.diygokarts.com/speed-calculator.html

 

[OzFab]

... Which is exactly what I said in post #4; a 10t #40/41 sprocket is the same physical size as a #35 12t sprocket & a 60t #40/41 sprocket is the same physical size as a #35 72t sprocket...

 

[Randy H]

You're only reiterating what I said; changing the chain pitch will only change the strength & number of teeth, the size of the sprockets remains the same...

I respectfully disagree. The tooth number stays the same. The strength and the sprocket physical size changes.

A #35 72t sprocket has an outside diameter of 8.8 inches. A #40 72t sprocket has an outside diameter of 11.75 inches.

Given the same tooth number drive sprocket. Say 12 teeth. The ratio is 6 to 1.

Also there is an inch difference between a #35 72t sprocket and a #40 60t sprocket. #35 8.8 inches.

 

[OzFab]

Oh for pete's sake, reread post #1, then read post #4...

A 60t #420 sprocket & a 72t #35 sprocket are roughly the same size & standard CC sprockets (#35 12t & #40/41 10t) are also the same size & both combinations will deliver the same ratio... WHICH IS EXACTLY WHAT i SAID!

I'm confused, you say

I respectfully disagree.

& then say the same thing I already said

So, how many more times would you like me to repeat it?

 

[mckutzy]

........


IBTL

 

[KartFab]

Ok we all get it, but what about real world appplication?

Has anybody seen #35 chain in large off road go karts? I have only seen it on small karts and racing karts.

420 chain has a better tensile strength and will last much longer/stretch less under the same load vs the 35 chain.

Also, with 35 chain you limit the number of teeth you can have on jackshaft or centrifugal clutch (depending on transmission).

With 420 chain, you can get a smaller tooth count jsckshaft sprocket or centrifugal clutch than the 35.

For example, on a regular run of the mill centrifugal clutch, the lowest you see is 12t for #35 chain, and 10t for #40/41/420 chain.

 

[Gibsonfan159]

Ok we all get it, but what about real world appplication?

Has anybody seen #35 chain in large off road go karts? I have only seen it on small karts and racing karts.

420 chain has a better tensile strength and will last much longer/stretch less under the same load vs the 35 chain.

Also, with 35 chain you limit the number of teeth you can have on jackshaft or centrifugal clutch (depending on transmission).

With 420 chain, you can get a smaller tooth count jsckshaft sprocket or centrifugal clutch than the 35.

For example, on a regular run of the mill centrifugal clutch, the lowest you see is 12t for #35 chain, and 10t for #40/41/420 chain.

These are some more topics that I don't understand. An off road kart needs torque, but larger driven sprockets are only in #35, which is a weaker chain. This seems stupid. Why not have 72t for a #420? I was rather surprised by the limited sizes of sprockets. I can't go any higher than 60t on my #420.

---------- Post added at 03:15 PM ---------- Previous post was at 03:10 PM ----------

A 60t #420 sprocket & a 72t #35 sprocket are roughly the same size & standard CC sprockets (#35 12t & #40/41 10t) are also the same size & both combinations will deliver the same ratio... ?

This is the answer I was looking for. Thanks. So there's no reason whatsoever to switch the chain setup.

 

[OzFab]

I was rather surprised by the limited sizes of sprockets. I can't go any higher than 60t on my #420.

The main reason for that is ground clearance:

Yard karts tend to have smaller tyres so, the axle sprocket must be smaller than the tyres...

Off road karts tend to "find" obstacles which may damage the axle sprocket...

Also, a larger sprocket will tend to flex &/or bend easier than a small sprocket...