Help me decide between 3.91’s and 4.10’s

[Mr Cheekz 14]

It’s time for me to do another mod. And I’ve decided on gears. The only problem is I don’t know which ones to go with. I’m going with Motive gears but I’m deciding between 3.91’s and 4.10’s. I get a good discount on parts and labor though my job. The swap will be about $700 (that includes Motive install kit, gears and installation of everything). My car is a bolt bolt on LS3 (intake, headers tune and makes 415whp). It has stock suspension and Nitto motivo all seasons on it. It’s a daily driver and will never see a drag strip and I don’t launch the car ever. Im leaning towards 3.91’s but any input is appreciated.

[bottletalk]

why change'em then?
3.91 based on the vehicles intended use if those are the only 2 options. I'd be going more towards a 3:73 if that's how I drove her.

[acammer]

No reason not to do 4.10s. I've got a pretty good write-up on this. I'd encourage you to take a read through it.

https://gwatneyperformance.com/geari...1-manual-cars/

I'll also tell you from personal experience that 4.10s are a blast even in a bolt on car. You're getting more mechanical advantage in the lower gears, so more acceleration, and you get to bang another gear when you're accelerating onto the freeway, and you can even catch the 3-4 before triple digits (with a 6500rpm bolt on car sort of shift point). There really isn't a draw-back, you give up some cruising rpm, but it's still only 2,000rpm at 75mph - you might loose 1 mpg of highway economy, but I'm betting that's not why you bought the car. Unless you're on solid subframe and diff bushings it should still be pretty quiet as long as it's setup well.

[Oxtar41]

You guys over here talking about these steep gears and I'm sitting here with 3.54's in my twin turbo car wishing there was a longer gear option that I could put in my S60 lol

[CamaroCracka]

Biggest reason I would do 3.91 would be if I was using the factory AAM gearset which is known to be pretty quiet. If going aftermarket, 4.10 is even better if you are not constantly spinning the tires.

The vert is about 500whp with a 3.91 and it would light up the old Goodyear 305s at 50ish. Put on a new set of Pirellis (220 treadwear) and doing much better, but it will still light the tires from a launch. Hope that helps.

[acammer]

FWIW, you can't really blame a lack of traction on too much gear if you haven't paired it with enough tire. Here is 550whp on 275/40/20 Mickey Thompson ET S/S tires, 28psi, no burnout, no prep, 55*F ambient temp, with 4.63 gears. Hooks up very well. No special tricks here, stock suspension w/ subframe and diff bushings is all.

[SSJ2]

I also debated 3.91 vs 4.10 especially since the consensus seems to be 4.10 with a manual. I went with the GM 3.91 gears for reliability plus I get a pretty good deal on them. First gear is basically non existent anymore for me. Shift out of it pretty quickly, maybe not even use it if launching the car. I couldn't even imagine if I had 4.10's. Now with that being said I often wonder how much more fun and potential there would have been with 4.10 gears, but when the weather is nicer I daily it as much as I can and 4.10's would be too much for that IMO. Hope that helps.

[Mr Cheekz 14]

Originally Posted by bottletalk

why change'em then?
3.91 based on the vehicles intended use if those are the only 2 options. I'd be going more towards a 3:73 if that's how I drove her.

I’d like to change them because these cars need gears bad. And just because I don’t launch the car or take it to the strip doesn’t mean I won’t notice the added benefits of a gear change lol. I thought about 3:73s but I feel that 3.91’s or 4.10’s would be more while.

[Mr Cheekz 14]

Originally Posted by Oxtar41

You guys over here talking about these steep gears and I'm sitting here with 3.54's in my twin turbo car wishing there was a longer gear option that I could put in my S60 lol

I’d love to have that problem lol

[Mr Cheekz 14]

Thank you everyone for all of your opinions. After a bunch of research and Andrews thread about gears I think I’m going to go with 4.10’s. Thanks again

[Pkeen]

My 2cents , if it were me I would go with a cam upgrade before the gear change !

[CamaroCracka]

Originally Posted by acammer

FWIW, you can't really blame a lack of traction on too much gear if you haven't paired it with enough tire.

Totally agree, but not everyone is going to run ETs. My Pirellis are 30 series because I like it to go around corners too. The Goodyears were 10 years old with a fair amount of tread left before I trashed them. I don't get to drive enough to wear out tires on my cars, so how much traction they will have once a tire is five years old is a consideration for gearing decisions. Nonetheless, if going with anything besides the factory AAM 3.91 set, I also say go with the 4.10.

[Joe.G]

I run 3.91's and a True Trac, I am very happy with my gears but I do think that if I were do it again I would try the 4.10, I never feel like I have to much gear with my current set up, Of course Use of car and future mods need to be considered as well.

[Bow94z]

For anyone who's curious

Motive 4:10's on the left
GM/AC Delco 3:91's on the right