Who makes the best gears?
09-10-2013, 10:02 AM
#11
JK Enthusiast
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An 07-11 automatic needs 5.38s and a tuner to stay in OD with 35s. At lower elevations and with rigs that aren't as heavy, 5.13s will suffice with a tuner.
Problem is that they no longer make 5.38s for the Dana 30--at least to my understanding. You need a Dana 44 front axle to run 5.38s.
No other upgrade will have more impact on your performance than regearing. Even swapping an LS, Hemi, or supercharger requires regearing to operate efficiently with oversize tires.
To answer your question, 3.73 gears with an 07-11 automatic turns the same engine rpm--producing the same power--at highway speeds as it would with 5.38s and the overdrive turned off. Rumning with the OD off at highway speeds is a temporary solution that will work. It will still be weak around town and offroad.
09-10-2013, 11:12 AM
#12
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So if you have a 3.8 auto with 3.73 and 35's that actually measure 34" :
1781 rpm @ 70 (od on)
/ .69 =
2581 rpm @ 70 (od off)
And from the chart, 34" and 5.38 gears =
2569 rpm @ 70 (od on)
12 rpm difference between 3.73 with OD Off and 5.38 with OD On.
Last edited by nthinuf; 09-10-2013 at 12:45 PM.
09-17-2013, 08:55 AM
#13
JK Super Freak
An 07-11 automatic needs 5.38s and a tuner to stay in OD with 35s. At lower elevations and with rigs that aren't as heavy, 5.13s will suffice with a tuner.
Yes this is true. Kinda wish I went with 5:38's but the Pinion is SO small that the gears deflect rather easily with little effort.
Nothing that going from a D-44 to a D-60 would not cure 
Problem is that they no longer make 5.38s for the Dana 30--at least to my understanding. You need a Dana 44 front axle to run 5.38s. Yes buuuut I juuust hate the idea of teeny pinion leverage on the ring gear
No other upgrade will have more impact on your performance than regearing. Even swapping an LS, Hemi, or supercharger requires regearing to operate efficiently with oversize tires.
True true true
To answer your question, 3.73 gears with an 07-11 automatic turns the same engine rpm--producing the same power--at highway speeds as it would with 5.38s and the overdrive turned off. Rumning with the OD off at highway speeds is a temporary solution that will work. It will still be weak around town and offroad.
Kinda. Around town with my setup with 35's , 5:13's , Superchips, AFE filter and exhaust it is close if not a touch better than stock. Highway with O.D off it's fine... really I am amazed the Torque converter stays in lockup as the variable lockup command the autos have is brutal on heat. You can feel fluid shear with O.D off @ 45 mph when the computer is trying to regulate converter clutch aplucation VS throttle position. Out on the rocks it is fine. GRANTED I have a Rubicon and the 40:1 / 5:13 combo is great with 35's I do admit but still have butt clench when slipping and catching traction
Yes this is true. Kinda wish I went with 5:38's but the Pinion is SO small that the gears deflect rather easily with little effort.
Nothing that going from a D-44 to a D-60 would not cure Problem is that they no longer make 5.38s for the Dana 30--at least to my understanding. You need a Dana 44 front axle to run 5.38s. Yes buuuut I juuust hate the idea of teeny pinion leverage on the ring gear
No other upgrade will have more impact on your performance than regearing. Even swapping an LS, Hemi, or supercharger requires regearing to operate efficiently with oversize tires.
True true true
To answer your question, 3.73 gears with an 07-11 automatic turns the same engine rpm--producing the same power--at highway speeds as it would with 5.38s and the overdrive turned off. Rumning with the OD off at highway speeds is a temporary solution that will work. It will still be weak around town and offroad.
Kinda. Around town with my setup with 35's , 5:13's , Superchips, AFE filter and exhaust it is close if not a touch better than stock. Highway with O.D off it's fine... really I am amazed the Torque converter stays in lockup as the variable lockup command the autos have is brutal on heat. You can feel fluid shear with O.D off @ 45 mph when the computer is trying to regulate converter clutch aplucation VS throttle position. Out on the rocks it is fine. GRANTED I have a Rubicon and the 40:1 / 5:13 combo is great with 35's I do admit but still have butt clench when slipping and catching traction