Transmission ratio question?

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Transmission ratio question?

Postby Emerica1975 » Fri Nov 19, 2021 10:02 am

Did Harley make only one gear set for these transmissions or is it possible to get a different setup. It seems like the first gear is really low and the third is really high and not much in between. I’m guessing that’s all there is. But I thought I’d ask. Thanks!!
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Re: Transmission ratio question?

Postby Mutt » Fri Nov 19, 2021 10:17 am

Yes, there are different gear sets, What year and model motor do ya have? What are the current gears inside of it?
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Re: Transmission ratio question?

Postby Emerica1975 » Fri Nov 19, 2021 3:21 pm

I just bought a1956 st engine and I’m waiting on delivery hopefully middle of next week. Im baseing my knowledge off of a 1949 125s model I use to have. It had a really low 1st gear a really tall 3rd gear and 2nd just didn’t seem to be much of a middle. Will I have to open the cases on the engine Im getting to tell what the gearing is?
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Re: Transmission ratio question?

Postby pumpguy » Fri Nov 19, 2021 3:53 pm

Yes, you have to figure the ratios from the number of teeth on each of the pair of gears inside the cases.

With just 3 speeds available, there isn't much you can do and any changes to the internal ratios will be a compromise somewhere.
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Re: Transmission ratio question?

Postby Mutt » Fri Nov 19, 2021 5:24 pm

Emerica1975 wrote:I just bought a1956 st engine and I’m waiting on delivery hopefully middle of next week. Im baseing my knowledge off of a 1949 125s model I use to have. It had a really low 1st gear a really tall 3rd gear and 2nd just didn’t seem to be much of a middle. Will I have to open the cases on the engine Im getting to tell what the gearing is?


You should have the standard guts in the transmission on the 56
15/32 low
21/25 second
and 26/19 high gear

This is stock & is the best currently available, unless ya happen to find a set of -59R close ratio second gears and a pair of either -59R close ratio or -62R extra close ratio third gears. The close second and extra close 3rd is what Harley should have used in all of their motors. Very little drop between any of the gears
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Re: Transmission ratio question?

Postby Emerica1975 » Fri Nov 19, 2021 11:22 pm

Thanks for the reply’s and the info. I’m pretty excited to start putting this bike together and I really do appreciate the help and info from you guys and this group. I’m in Montana and haven’t found many people around here that like the lightweight bikes.
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