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Old 11-05-2017, 01:18 AM
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Lightbulb Question re: gearing and moving up tire size

Hey guys.
So I got 30"s on my jimmy now with 3.42s...
I have been planning for the rough country 2.5", and a small body lift to fit 33's.
I did a search and found alot of feedback on the 3.73's being perfect with 33" tires. Will I be hating myself if I dont regear before sizing up? I dont tow alot and like getting good mileage but id rather not have to bag on my little 4.3 just to get to highway speed. As a student Im trying to get all my priorities in order before acting on them...just wondering if this should be one of them. And if id notice a difference with the current tire size.
And If i do regear... do I just need to grab the carrier or the pinion as well? Assuming used is okay
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Old 11-05-2017, 06:55 AM
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1. Pinion and Ring Gear are a matched set. You have to swap out both when changing ratio's.

2. If it was me I would not change the ratio until your other mods are done. Especially if it is a daily driver and you need the gas mileage. What happens if you do the gear change but it takes you forever to bag it or the project gets stalled due to money, time or personal issues?
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Old 11-05-2017, 07:29 AM
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Don't forget the front differential. If you swap the rear out for a 3:73, the front will need to be changed to 3:73 as well.
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Old 11-05-2017, 08:01 AM
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cheaper to find a new rear axle and front diff geared the same and then just swap the whole thing. I have 32 inch with 3.73`s and get at best 16-17 mpg highway. 13 city
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Old 11-05-2017, 01:09 PM
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Quote:
Originally Posted by mr.vls View Post
2. If it was me I would not change the ratio until your other mods are done. Especially if it is a daily driver and you need the gas mileage. What happens if you do the gear change but it takes you forever to bag it or the project gets stalled due to money, time or personal issues?

i agree. if youre going to do the lift and tires anyways drive it around and see how you like it. i have 33s and 3.73s on my 93 and its pretty slow.

not unbearable undrivable slow but you definitely aint winning any races against any other s10s but if you are just gonna drive it around normally it should be fine. mine is a offroad truck so once i pop it into 4low it has all the power i need
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Old 11-05-2017, 08:52 PM
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thanks for the feedback. drive ratio is one thing i have not dabbled in at all.
I might just leave it... I have a brother in law who is a gm mechanic and he thinks its sort of a waste, same with the lift. But he says that about everything after wasting so much on vehicles himself.
I will likely save it for later then
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Old 11-06-2017, 12:21 PM
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NewGuy is right with just swapping out the rear axle and front diff if you want to change to 3.73 gear ratio. It will cost you way less to pick up a used set from a u-pull place than trying to have the diffs re-geared and is something you can do easily with normal tools. I did it on my Blazer when I went to bigger tires. Personally I couldn't stand the 3.42 gears with 31" tires.
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Old 11-11-2017, 01:20 PM
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Quote:
Originally Posted by El_Beautor View Post
NewGuy is right with just swapping out the rear axle and front diff if you want to change to 3.73 gear ratio. It will cost you way less to pick up a used set from a u-pull place than trying to have the diffs re-geared and is something you can do easily with normal tools. I did it on my Blazer when I went to bigger tires. Personally I couldn't stand the 3.42 gears with 31" tires.
How does she go now with 3.73 and 31s?? and fuel economy?
I also forgot to mention I have the g80. I know it still works and would like to keep it. Im assuming this changes things?
Thanks for all your help so far everyone
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Old 11-11-2017, 05:55 PM
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I have 3.73 and 32 inch tires, I also have a cam, headers etc, and acomputer flash. Goes pretty well LOL
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Old 11-11-2017, 08:37 PM
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If you are going to 33in tires, i would go to 4.11 gears. Going from 3.42 to 3.73 you will not notice too much of a difference because you are adding 5 inches of tire under it from the factory size.
Also if you plan to take it offroad, put a good clutch or gear type posi unit in it and get rid of that garbage G80. You will break the G80 if you beat on it too much.

On the other hand, you can just do the lift and tires and drive it. My friend years ago did this with his pickup and was happy with it. He had a 6in suspension lift and a slight body lift to clear 33s nicely. But he had the stock gears and stock G80. It was not fast by any means but was drive able and comfortable.

Last edited by ChuckNTruck; 11-11-2017 at 08:52 PM.
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