Im look for better mpg and a better top speed. I have the stock 9.25 rear end with limited slip. Does anyone make a 3.42 gear or something lower that i could put in
Gears?
GreenDakota
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Im look for better mpg and a better top speed. I have the stock 9.25 rear end with limited slip. Does anyone make a 3.42 gear or something lower that i could put in
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What gears do you currently have? Are you tying to get the RPMs down in the hopes of better mileage? Sometimes going to a higher gear (lower numerically) will have a negative effect on fuel economy by making the engine lug more causing it to use more fuel.
I know my QC would probably benefit from a lower gear (higher numerically) to offset the larger than stock tire size & BL I am running. 3.55s and 265-75-16s make it lug like crazy once I get into OD and I actually get better mileage in 4th gear than in 5th, (about 1 or 2 mpg average at the sacrifice of being few rpm higher) and I don't have to downshift for every little hill on the highway.
I know my QC would probably benefit from a lower gear (higher numerically) to offset the larger than stock tire size & BL I am running. 3.55s and 265-75-16s make it lug like crazy once I get into OD and I actually get better mileage in 4th gear than in 5th, (about 1 or 2 mpg average at the sacrifice of being few rpm higher) and I don't have to downshift for every little hill on the highway.
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I think i have a 3.92 but im putting in a 408 so i dont think it will lug. Really i just want to go fast with the new engine
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Higher ratio choices are- 3.21 and 3.55. There is also a 2.76 but it requires a different carrier.
The 9-1/4 has been built since the 70s; there are lots of ratios available. 3.21 was common as were ratios in the 2s; I think places like National Drive train can get like 3.08, maybe a 3.27, 3.31, the 3.42 you asked about; these are common ratios for GM/Ford but aftermarket I believe about any ratio is available for any rear end. The difference between these ratios is too small to go thru the work to jump 1 ratio either way. Different tire diameters, can have the same effect. I have a wrangler with 3,07s that I'm thinking of switching to some 3.73s in. I went from 215/75/15s to 235s to 31/10.5/15s and my 1st gear is still good for about 15' but 5th is about useless.
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My 3.9 has the 3.21 gears and I never have an issue lugging. My old TA had 3.23's and never lugged had more problem with spinning the tires.
OK ill admit my experience with gearing is with Fbodies but the theory should be the same. The guys that went to 4.10s and 3.72's had more problem with crappy gasmilage and actually loosing first gear if they had a manual. They also all saw a reduction in MPG. Stock I was getting about 24-25 on the freeway with the cruise set. After all the normal LS1 mods I was getting closer to 20mpg. A good friend of mine was getting very similar MPG and went from 3.23's to 3.72's (gift form his GF) and his MPG dropped to about 16mpg which he still is getting.
not sure if that helps but its what i have seen.
www.f-body.org/gears/
I got a malicious software message when I tried to use the link. Someone must have hacked their site but it should be back up soon.
OK ill admit my experience with gearing is with Fbodies but the theory should be the same. The guys that went to 4.10s and 3.72's had more problem with crappy gasmilage and actually loosing first gear if they had a manual. They also all saw a reduction in MPG. Stock I was getting about 24-25 on the freeway with the cruise set. After all the normal LS1 mods I was getting closer to 20mpg. A good friend of mine was getting very similar MPG and went from 3.23's to 3.72's (gift form his GF) and his MPG dropped to about 16mpg which he still is getting.
not sure if that helps but its what i have seen.
www.f-body.org/gears/
I got a malicious software message when I tried to use the link. Someone must have hacked their site but it should be back up soon.
Then keep the gears you have or go with 4.56's.
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