Supercharger...what gear to go with

[ThotWrangler]

I have a 2010 mustang gt (automatic with shift kit and ratchet shifter) with a edelbrock supercharger about to be on 9lb pulley and thought my car had a 3.73 but did the tire/drive shaft rotation and came up with 3.31 so question is...what gear size do yall recommend? Iv done reserch seen lots if different answers but wanted to hear ya'lls opinions! Personally I'm thinking 3.73s, thanks for responding and any advice you guys!

 

[stkjock]

Moved, this is not a tech topic here.

What/how is the car used?

What rear tire do you run?

 

[07 Boss]

Gear selection should have nothing to do with having a supercharger or not. Do you want to be quick off the line? Then go with a lower gear like 4.10's or 4.30's.

 

[skwerl]

I had 3.73 gears in my Bullitt and it was a nice compromise with quick acceleration off the line as well as reasonable rpm at cruising speed on the highway.

Keep in mind that the differential gear ratio is only one part of your overall gear ratio. The transmission gearing as well as tire height also affect gearing. You can run a shorter gear and compensate for it by running a taller rear tire.

 

[ThotWrangler]

But a auto should have a lil to do with selection and I was thinking 4.10 but iv had someone tell me "you don't want 4.10s in a blower car".

 

[KatoS197]

But a auto should have a lil to do with selection and I was thinking 4.10 but iv had someone tell me "you don't want 4.10s in a blower car".

That just sounds like an opinion from someone who doesn't like short gears. Probably thinking "blower + short gears = running through 1st and 2nd rather quickly = not ideal for DD duty"

Again, it comes down to what Dave asked - how is the car being used?

 

[skwerl]

Also, do you have any plans for changing the torque converter?

Without actually telling us any info, we can only guess and offer opinions based on our own choices and preferences. But they will probably be different from your choices and preferences. You've already responded once and still haven't offered up any real info for us to help you in your choices.

This forum has a lot of members with a lot of knowledge. Enough so that we can offer a variety of options based on your particular situation and preferences. But without knowing anything about you, your car or your intended use then you might as well just choose whatever you feel like.

 

[skaarlaj]

But a auto should have a lil to do with selection and I was thinking 4.10 but iv had someone tell me "you don't want 4.10s in a blower car".

Simply saying "blower" is kinda crazy too, as I'd want lower or numerically higher rear gears in a centrifugal blower car vs the same car with a PD blower like yours.

Probably thinking "blower + short gears = running through 1st and 2nd rather quickly = not ideal for DD duty"

Then you have to wonder if these people that think they're shifting too much realize they're not driving a vehicle equipped with a sequential transmission like what is found in a motorcycle, and that you can skip through the gears when not "getting on it". I have 3.90's in my MT82 car, and there is a lot of shifting going on, but not if you start off in second, or skip from 1st to third or whatever.

For me, I'd never live with a taller gear than what I've mentioned for my particular car when it comes to getting off the line, and being easier on your entire drivetrain when accelerating.

 

[palanza7]

Well not to jack this thread but I have 3.73 with a tvs 2.3, tr6060 and 28 inch rear tires, should I consider 4.10s for the drag strip?

 

[JUSTA3V]

With a 28 inch tire. I would. That's what I run.

 

[07 Boss]

But a auto should have a lil to do with selection and I was thinking 4.10 but iv had someone tell me "you don't want 4.10s in a blower car".

That someone just doesn't know how to drive. That's the same person that says it will cause traction issues. Traction issues are tires and suspension, and properly applying power.

 

[ThotWrangler]

Cars gonna be street/track mainly street car, I dont drive it everyday usually only the weekends when I bought the car it had a shift kit in it (I have no idea what kind or anything) I know it has a tci streetfighter ratchet shifter. Also me and my mechanic wonder if the car has a stall but not 100% on that one either, haven't had to remove the tranny I'm not meaning to lack information I'm still getting the hang of this iv came from a big turbo fwd neon to a supercharged v8 so it's a bit of a different world.

But if I'm at the track or "mexico" I wanna be able to get off the line and go I'm not worried about much over a 1/8mile sometimes I run 1/4 but 75% of the time it'll be 1/8th mile

 

[skwerl]

Making the car hook is fairly straightforward, but it does involve spending a few dollars. Kelly or Dylan at BMR can guide you on the optimal setup for your car.

 

[ThotWrangler]

I agree with that BMR is great I have some of their stuff now just panhard bar, lower control arms, bunch of other things I need but one thing I'm really lacking is a tire but that will come soon

 

[Silverhorse.s197]

I had 4.30s in my car for a while .. was fun but got annoying after a while.. 1st gear was so short , i usually just started out in 2nd .. and once in 3rd . I read on the Kenne Bell site that they ran every gear made for the 8.8" and found their quickest time was with the 3.73s . So thats what i replaced my 4.30s with . Car pulls hard into 4th gear ... RPMs dropped form 2500 @ 70mph to 2100 @ 70 mph . I had bought a set of 3.55s but glad i went with the 3.73s

 

[travelers]

On the street with the Whipple 2.3 I skip shift all the time. MT82 and 3.31s but that's going to change

 

[Pentalab]

I have a 2010 mustang gt (automatic with shift kit and ratchet shifter) with a edelbrock supercharger about to be on 9lb pulley and thought my car had a 3.73 but did the tire/drive shaft rotation and came up with 3.31 so question is...what gear size do yall recommend? Iv done reserch seen lots if different answers but wanted to hear ya'lls opinions! Personally I'm thinking 3.73s, thanks for responding and any advice you guys!

I have a 2010 automatic with a small M90 blower. (390 rwhp, 460rwtq).
With the oem 3.31 rear gear and 5r55s auto tranny, + 26.97" tall tires, ( 285-40-18) for DD use, you will burn the rears off in 1st gear. And traction in 2nd, ( after an eaton tru trac /watts link, BMR lca's and lca re-locate brackets installed, along with BMR uca, etc, etc. )

Final gear ratio is just the rear end gear... multiplied by whatever gear you are in....in the auto tranny. ( then factor in rear tire height).

Turns out that 2nd gear on the 5r55S auto tranny is 14% lower than 2nd gear on the TR3060 manual. 3rd gear on the 5R55S is 16.5% lower than 3rd gear on the TR3060 manual !

IOW, you would require a 3.73 rear gear on a TR3060 in 2nd gear to equal the 5R55S 2nd gear + 3.31 rear gear.

You would require a 3.90 rear gear on a TR3060 in 3rd gear to equal the 5R55S 3rd gear + 3.31 rear gear.

Unless you are a hardcore weekend drag strip racer, I would leave the rear 3.31 gear alone.

Folks with a TR3060 + 4.10 rear gear + 29" tall tires is a different story. The 29" tall tire will effectively render the 4.10 rear gear into a 3.813 rear gear. (26.97 /29.00 ) x 4.10 = 3.813

IMO, if you have a 2010 auto..+ blower + 27-27.3" tall tires, leave the oem 3.31 rear gear intact...esp for DD /street / hwy use. You are already geared low enough in 2nd + 3rd gear. Put a 3.73 rear in there, and you will just burn the rear tires off in 1-2-3.....for dd /street use.