How to Choose Rear End Gear Ratios

Rear end gear ratios can drastically alter how a car applying torque. Learning how to choose rear end gear ratios will get your build on the right track by maximizing all of the other parts. Whether you're building a fast 1967 GTO or a rock crawling XJ; gear ratio matters. We also discuss when to shift gears in a car and how it impacts the overall performance.

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[annasbanana]

Would love to hear more about torque converter stalls

[HotRob]

If you wanted to keep your Car/Truck pretty much stock other than gearing and you had an Ford FE 352 and all you wanted to do was wake it up a little (not for track purposes) what gear ratio would you choose for your vehicle as in not to recommend myself or anyone else, but what would/could YOU choose without having to change the torque converter or whatever else to make the difference improve noticeably?
And Thank You for your time and input.

[brentonwickham]

Great video, great information
Thanks man

[emanuelrusinga]

Whats the best gear ratio for turbo ls truck applications? Would 4.10s or 3.42 gears be better? I hear some say 3.42s are better for loading the turbo?

[am]

Love your videos man! I have a 67 Firebird convertible with a 2.56 gear and I have a 350 HO with ram air III #16 6x heads and a ram air IV cam. I am still in the break in period in the rebuild and have not gotten on it at all. What I have noticed is that there is literally no power during the lower RPMs. Mind you, I am just turning out into traffic to get up to speed and have not punched it at all. I am looking to install a posi unit and either a 3.55 or 3.73 gear so I can more off the line power. Based on your video, it seems like the 3.73 is going to be a better choice? I am only driving it around town and not on the highways.

[rifleman]

I know that there's probably a computer program for this I just don't know it. But how do you think a combination of 4.88 gears, 30 inch tires, a 4L60 transmission, and a gear vendors over/under drive would work for a 4000Lb 4wd vehicle with a built 800+ H.P. 383 stroker built on a 5.3L LS. According to my rough calculation with the grimmjeeper gear calculator it should hit about 200mph at 6000rpm.

[rickeyhahn-wiju]

You never talk about us 4 speed transmission users

[TechTokOffical]

So I'm swapping my bmw from auto to manual right now. I'm using the same rear diff for both that has a 2.91 gear ratio. Everyone in the forums is says gonna be a problem on the highway and ill be riding a like 4000rpm when crusin 80(that seems normal tho). Am I going to run into issues.

[shawneewarclub]

Good discussion but…
My 4.10 cars all went 2-3 tenths faster in the quarter than the exact same car with 3.73s
Granted 99% of the guys out there aren’t looking for max et but I’ve been street racing Pontiacs since the early 80s so all I care about is results
400 with worked 16s or 62s, worked stock intake, worked q-jet, raiv cam 1.6 rockers, recurved distributor, 10.5-1 forged pistons, balanced rotating Assy, 4 tube headers with turbo mufflers, Vega converter with long snout in a built turbo 350, 10 bolt with 4.10s 11.30s- 11.50s from spring till fall on 80s street tires with a 150 shot in my back pocket those cars were almost unbeatable on the street in the 80s and 90s
It took race cars to beat the car I hauled my kids to school with
I’ve street raced since 77 until the 90s if you had a 11.50 car you weren’t afraid to race anyone!
The truth is a 11.50 car was super dominant on any street most guys who thought they had fast cars would get bus gapped by a 11.50 car
Give me 4.10s for the win😎

[Drthmnl]

I’m currently looking for some help on what would a 3.9 do compared to a 4.1 or 4.3. It’s a LSD for a Miata not sure if it’ll help but right now I’m cruising at 80 mph @4000rpm not sure what ratio I’m running but would love some help!

[LaSierraAcresQuailFarm]

currently running 4:11 gears in my 67 pontiac lemans with a 389.. rpm is pretty high, so im looking at 3:55 gears to drop down the rpm's.. i would like to do more highway driving than going just around town.. will lowering the gear ratio to 3:55s also help with keeping the engine running cooler also? would like a good cuising speed at about 75mph while keeping the rpms as low as possible, but still have some get up and go...

[rogerhankins]

I have a 71 clone convertible with a 455 and right now it's got 256 they got to go also changing the transmission to a 4 speed I'm. old school and don't know a lot about some of this but it's a retirement project and I want to do everything myself any help I can get would be appreciated

[karlloper]

This is all fine and dandy on paper, but at the track, your results may vary. I have run 2.73, 3.50, 4.10, 3.25, 3.70, and currently back to 3.25 in my 67 Mustang. 2.73 to 3.50, woo hoo! 15.8 to 15.3 (Famoso). After that, gear changes ONLY changed what gear and at what RPM I went out the back gate. 3.5 to 4.10 did NOTHING but raise my RPM out the back gate. I went to 3.25s... yuck, back to going out the back gate in 2nd gear. I hit 6500 rpm about the 1000 ft mark. Do you shift or hold it? I split the difference between 3.25 and 4.10 to arrive at 3.70. The NA best of that car was a 340hp crate 302 with the 3.25 gear in Phx, AZ, 12.8. At my home track in Fallon, NV (4000 feet), it ran a consistent 13.1 with 3.70s. Which, by the math is ~ 12.7 in Phx. (Other engine mods support this lower ET.)

Things that lowered my ET: a converter that would let me leave at 3000 RPM, go fast parts, and NOT shifting so high! Yes! 7000 1-2 and 6500~ 6800 2-3 shifts cost me a full tenth when dropping to 6000 RPM shifts. The Z303 roller may rev to 7000, but it's done making power by 6000.

So, while the desk top dyno is cool for bench racing, actual track time is a gooder teacher.

[GARZA]

1993 chevy silverado on 6.0L with a th350 what gear ratio do you recommend ????

[ryanthorpe]

I have 08 crown vic with 3:27 lsd gears with 4 speed auto trans. What gears can i safely upgrade too i wanna little more take off?

[MrSeanthedon]

I have a 393 Windsor with 11 to 1 compression and a 600 lift cam The max RPM is 7000 I have 3.08 gears in it now thinking of putting 3.73 or 4.11 maybe 4.10 what would be the best sitting on 15 inch drag radios

[MIKELOTEMPIO]

Hey man. I have a 78 Camaro 350 small block with a th350 and I just put 4.11 in the car. Im debating on dropping down to 3.73 or even Lower. Before the gear switch I had 2.73 and could cruise to 140 mph no problem. The car now can’t even hit 90, the engine is just screaming. Any tips or certain combination I need to get this car running right!?

[phoenixstudios]

if you drive a lot on the interstate, pick 373s or 390s. everything else 410s for the street.

[titosvip]

I'm just getting into gears . I drive a 2010 jaguar xfr 5.0 gear ratio would u recommend??? I'm making about 461 thanks

[joshbrekke]

There is a very intelligent solution available now.
Winters Street Rod Performance V8 Quick Change rear end.