Quad Conversion Gear ratio’s

    Hi Everyone. I was looking for some information regarding the rear differential options on the project 324 set up (plus one & DDM). I’ve seen a brief description on the websites selling them, but was curious as to what to expect. I’m interested in one of the LSD options. I’m supercharged at about 350HP. I don’t know what the better option is between the 3.27 LSD and the 3.45 LSD. Any information would be much appreciated.

    Quote from NJ SS

    Hi Everyone. I was looking for some information regarding the rear differential options on the project 324 set up (plus one & DDM). I’ve seen a brief description on the websites selling them, but was curious as to what to expect. I’m interested in one of the LSD options. I’m supercharged at about 350HP. I don’t know what the better option is between the 3.27 LSD and the 3.45 LSD. Any information would be much appreciated.

    One difference will be Miles Per Gallon but both will be smiles per mile

    I may be remembering incorrectly, but it's my understanding that the angle drive is a 3.90 ratio. The trakhamr is using a 3.72 gear.


    Rab has the 3.27, so I'd be curious to see his thoughts on it.


    I know with mine and the 3.72 gears, my RPMs are near 3k running down the highway, but highway riding is no fun, it feels good in the twisties and of course, acceleration is no issue at all, keeping the tires from spinning is another. I'm probably around 400 hp, but we've never dyno'd it, so not sure.

    Quote from wokka

    I may be remembering incorrectly, but it's my understanding that the angle drive is a 3.90 ratio. The trakhamr is using a 3.72 gear.


    Rab has the 3.27, so I'd be curious to see his thoughts on it.


    I know with mine and the 3.72 gears, my RPMs are near 3k running down the highway, but highway riding is no fun, it feels good in the twisties and of course, acceleration is no issue at all, keeping the tires from spinning is another. I'm probably around 400 hp, but we've never dyno'd it, so not sure.

    Stock final drive on a 2016-2019 is 3.67:1, I thought it was around a 3.90, but just looked it up on the Polaris website - https://slingshot.polaris.com/en-us/slingshot-s/specs/


    With more power the 3.45 or the 3.27 should work really well. One of our supercharger customers was the first guy to get the 4 wheel kit installed out there in Dallas and he is running the 3.45 and loves it.

    The lower the ratio the lower the RPM at cruising speed and the higher the top end speed. The higher the gear ratio was used to be at or close to red line at the end of the quarter mile (to be in the engines power band) Just trying to explain to the people that do not know the difference. I hope that everyone can understand this explanation.

    NJ SS HERE'S A FINAL DRIVE RATIO CHART SHOWING THE DIFFERENCE IN RPM WHEN SELECTING A TIRE SIZE AND COMPARING GEAR RATIOS, USING A I;I TANSMISSION GEAR WHICH IS YOUR 4TH GEAR IN YOUR PRE 2020 SLINGSHOTS . IT SHOWS YOU CAN EXPECT ABOUT 177 RPM DROP WHEN CRUISING IN 4TH GEAR AT 65MPH WITH THE 3;27 OVER A 3;45, SO CRUISE RPM AT 65 MPH IN FOURTH WOULD BE ABOUT 2700 RPM WITH A 3;27 BUT WOULD CLIMB TO 2870RPM WITH THE HIGHER TORQUE, HIGHER REVING 3;45 SHIFTING TO 5TH GEAR WOULD LESSEN THE SPREAD BETWEEN THE TWO TO ABOUT 150 RPM, I BELIEVE , I'LL TRY TO FIND THE GEAR RATIO CALCULATOR I CHECKED THAT ON A FEW MONTHS AGO AND POST THE LINK HERE

    Quote from FunCycle

    The lower the ratio the lower the RPM at cruising speed and the higher the top end speed. The higher the gear ratio was used to be at or close to red line at the end of the quarter mile (to be in the engines power band) Just trying to explain to the people that do not know the difference. I hope that everyone can understand this explanation.

    Got it. I guess that brings up another question now. Forgive my ignorance. With the 3.27, Can we get more top end speed or is it governed by the ECM at a certain speed? Depend on the tune?

    I think it depends on the tune, but my guess is that Bob removes that limitation if there is one.


    With the lower gear ratios, you do get a higher top end speed, it just affects acceleration, you don't get as good. With the amount of power you have, you will be fine there.


    You can ignore my above rambling, I'm going in the other direction, wanting more acceleration, sacrificing top end speed.

    I’ll give you that (bragging rights) but it’s useless on the street. It’ll just get you thrown in jail for reckless driving. Going for acceleration Is actually useful & can get you out of certain bad situations.

    Slingshots: making children out of adults since 2014

    Quote from rabtech

    I like my 3.27 but I have never driven with anything else. I can tell you that it is quite a bit taller now that stock. I am going to drive it today to work and ill see where 5th gear is once the torque converter locks in. Ill measure the rpm and speed at two different points.

    That will be interesting see. I’m leaning towards the 3.27. After reading all of this info, I feel like it may be the best match for the SC.

    Quote from Dave@DDMWorks

    Stock final drive on a 2016-2019 is 3.67:1, I thought it was around a 3.90, but just looked it up on the Polaris website - https://slingshot.polaris.com/en-us/slingshot-s/specs/


    With more power the 3.45 or the 3.27 should work really well. One of our supercharger customers was the first guy to get the 4 wheel kit installed out there in Dallas and he is running the 3.45 and loves it.

    Per the 2015-19 Transmission Section from the Polaris website -


    Bevel Drive Ratio =2.312:1

    Final Drive Ratio (Swingarm Pulley with 62 teeth / Angle Drive Drive Pulley w/39 teeth = 1.59 )
    1.590:1

    I was trying to figure out how Dave@DDMWorks got the 3.67:1 Final Drive ratio but then realized the Final Drive ratio = Bevel Drive ratio x Angle Drive ratio = 2.312 x 1.590 = 3.67608 to get the = 3.67:1, assuming my math is correct!