# R4F gear ratio's for gear sets 1 & 2

i emailed Jim @ R4F, for the gear ratio’s for the 2016 to present GEM car speed kit 1 35 - 38 mph, and the speed kit 2 38 - 42 mph. he say’s the gear ratio’s are for speed kit 1 19:1, and speed kit 2 is 25:1 (aprox) does this sound Kosher ?

I think you might have the ratios swapped?

No it does not…

do you really think it’s right even if (they were) swapped ? and i don’t have them swapped, thats the way
he gave them. i don’t know what the stock gear ratio is, GEM hasn’t answered yet. sometimes they answer w/a question.

First, I am not very familiar with late model stuff (use my opinion very lightly)

That being said, just doing the math-
Guessing a tire height at 23 and a ratio of 25:1, a motor needs to be turning 14k rpm to hit target speed of 38 max. I know those AC motors like to sing, but that’s a pretty high note!!!

Realizing the ratio was swapped, I use the same rpm for example:
Changing to a 19:1 ratio, that same 14k will get you to 50mph. (So the faster set is the lower numbered ratio)

Knocking that down to target speed of 42 the RPM will be about 11,500. Still crazy high.

Either talk to someone else or clarify what that number was that he was quoting.

17:1
12:1 and 8:1 are what’s available. From memory.
10:1 from Rodney’s quiet kit.

Assuming 6000 RPM and 24 diameter tires.

TRIM 17to 1 = 25 MPH

TRIM 12.3 to 1 = 34/35 MPH

TRIM 9.3 TO 1 = 44/45 MPH Not recommended. No acceleration. No range.

SCHAFER/RODNEY 10.35 TO 1 39/40 MPH quieter, no other modifications required.

Can build SHAFER/RODNEY IN 10.35 For Stock carts and flat terrain. 12.44 For Hilly terrain and modified applications.

Mike Newhouse and Gabrial Debre have 10.35s Mike helped in development of the unit. Gabrial has not installed his yet.

thank you for your input/reply. Jim from R4F answered me about the gear ratio’s he gave me. he said to ignore the quoted ratio’s, just to order the gear set for desired speed. he said gear set 2 is not for hilly (areas) then i told him that i ordered the 6.5kW motor option (for pulling and for hills) and he said it would work for both gear sets. i also upgraded from the standard wheel/tire which is 155/80/r13 to the 165/ ?/r14. i am trying to find the aspect ratio for that tire from GEM cause they don’t give it ! that would give me the tire height. thanks Rodney

He didn’t tell you that your range on a 48 volt cart with the 9.3 is going to suck. You will need to up grade to one of Daves 24 cell lithium setups.

no, he’s like GEM, don’t offer any info. 9.3 ratio is the gear set 1? i also ordered the distance gel, says to get 30 to 55 miles. gem has lithium batts 8.9kW for \$9K, and 12.4kW for \$11.8K. i’m pushing \$23K right now. my wife isn’t going to let me go any further. how much range do you think i will get ?

got an answer from GEM Company. tire size is 165/70/r14. MY2020 & MY2021 gear ratio is 17:05:1 also they said “was not possible to change” i asked them to explain why ?

Hmm
I average (1) 12.3 upgrades per month. Note: when you change something your warranty goes out the window.

Rodney

actually that wouldn’t bother me. there are a lot of people who want a 35MPH.

Go with @Old_Houseboater .
I would not trust someone who keeps the tech info to themselves. It shows “for profit” motive only.
Rodney works like me. Help first, then make enough money to keep helping others.