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| Best rear end gear ratio for a truck https://slantsix.org/forum/viewtopic.php?t=47958 |
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| Author: | 83D150 [ Mon Feb 20, 2012 10:42 am ] |
| Post subject: | Best rear end gear ratio for a truck |
Ive been looking around the board for a little while but most info seemed to be for a car, but my question is what would be the best ratio for my truck in terms of power and mpg, it is a stock /6 and has 2.94s right now with 4spd manual trans. Its a good truck but has no power going up hills and not much power pulling a trailer. And is it possible I could nab a set of gears out of dakotas? I think a few of them used the 8 1/4 rear, thanks! |
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| Author: | Mroldfart2u [ Mon Feb 20, 2012 11:51 am ] |
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well a set of 3.xx would help the grunt but its will be a trade off for mileage... cant have both normally with out an overdrive trans.. i wouldn't use anything lower than a 3:50 gear set if mileage is that important to you... My 2c.... |
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| Author: | Joshie225 [ Mon Feb 20, 2012 1:03 pm ] |
| Post subject: | |
Which 4-speed? The Granny low NP435 or the A833OD? If you have an overdrive I would use 3.90s or 4.10s. There are a lot of Dakotas with 3.90 geared 8 1/4 axles. 3.55 was common too. If you have the NP435 with a 1:1 high gear I'd use 3.55s since you plan on towing. 3.21s are also out there, but that's only a 10% increase in torque multiplication over the 2.94s. |
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| Author: | raPoM [ Mon Feb 20, 2012 1:12 pm ] |
| Post subject: | |
If you have the 833 od with a stock tire size I would go with 4.11's,anything abouve a 30 in tire I would go 4.56's. |
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| Author: | hantayo13 [ Mon Feb 20, 2012 4:29 pm ] |
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I was happy with the 4.10 in my 81 with OD trans....I do have them for sale check parts for sale '81 truck parts' |
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| Author: | 83D150 [ Mon Feb 20, 2012 6:12 pm ] |
| Post subject: | |
Yeah I have the 833 with OD your thinking a 3.91 or 4.10 would be best with that then? |
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| Author: | DusterIdiot [ Mon Feb 20, 2012 6:32 pm ] |
| Post subject: | Yep... |
Quote: I have the 833 with OD your thinking a 3.91 or 4.10 would be best with that then?
Final ratios in OD would be (assuming stock tire sizes): 3.91=2.85 (so similar to a vehicle with a automatic or 3 spd with 2.94 gears-maybe a little more mileage for cruise on the flats in OD, a little less help if the truck is loaded and getting it moving from a stop). 4.10/4.11=2.99/3.00 a couple more rpm than the 3.91 at cruise, but if you have a load in the truck it will be easier to get the truck rolling. 4.56's @ OD is similar to auto with 3.31's...if you increase the tire diameter this goes back toward the other ratios above -D.Idiot |
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| Author: | 83D150 [ Mon Feb 20, 2012 6:38 pm ] |
| Post subject: | |
I think Id be leaning more towards 3.91 then, as of now I'm getting a little over 15 mpg, would this drop much with 3.91? |
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| Author: | 64 Convert [ Mon Feb 20, 2012 8:24 pm ] |
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My '73 with a 318, came from the factory with 3.55s as part of the towing package. Even with a slant six, I don't think I'd go lower than that. It tows fine, but is a bit too thirsty when running empty. |
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| Author: | Joshie225 [ Mon Feb 20, 2012 9:14 pm ] |
| Post subject: | |
Quote: I think Id be leaning more towards 3.91 then, as of now I'm getting a little over 15 mpg, would this drop much with 3.91?
It really depends on several factors. One big thing is that the power valve stay closed during cruise. If the power valve is open frequently now you may get better highway fuel economy with 3.90 gears than 2.94.
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| Author: | 83D150 [ Tue Feb 21, 2012 8:23 am ] |
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Alright well thanks for all the input I'll try and get some 3.91s I think they may help alot, whenever I drive in OD it's almost always pinned to the floor to keep a constant speed |
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| Author: | terrylittlejohn [ Tue Feb 21, 2012 8:49 am ] |
| Post subject: | |
4x4 dakota`s had 3.90`s and 2wd had 3.55`s with 15" wheels |
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| Author: | 83D150 [ Tue Feb 21, 2012 11:05 am ] |
| Post subject: | |
Quote: 4x4 dakota`s had 3.90`s and 2wd had 3.55`s with 15" wheels
Are there any dakotas without the 6 bolt wheel pattern so that I could just swap the entire axel? I that would probably be quicker than changing gears.
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| Author: | terrylittlejohn [ Tue Feb 21, 2012 12:53 pm ] |
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91 was the year the dakota went to 6lugs so before that they were 5lug with 4.5" bolt pattern. not sure of track width but i know the 96 is 9" wider than an A body 8 1/4, the 97 on new style are wider again. |
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| Author: | 83D150 [ Wed Feb 22, 2012 5:10 am ] |
| Post subject: | |
I think ill just take the time to remove the gears then, thanks again for all your help guys! |
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