3.73’s vs 3.42’s 5 speed man.

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Red89

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On my 89’ with the 350tbi I have a 5 speed with 3.42’s 32” tires
My 95 z71 with 4l60E had 3.73’s
Pushing 33’s dynopro ATMs
I couldn’t imagine a better set up on my 95 as far as power “get up an go” an mpg combo…

My 89’ the overdrive 5th gear is just there… 4th is really all it needs maybe I’m geared to high? This manual is new to me, I’m use to 4.10’s with Dana 44’s rubicon 5speed which set the standard I’m after on acceleration an pulling (with a straight 6)


Anyone has a 5 speed with 3.73’s ?
What size tire are you running ?
I’m wondering if I would be ok making the switch or would I be to low geared?
I’m tossing the idea back an forth an researching as much as I can.

Thoughts on 3.73’s with the 5 speed for 33’s ?
 

GoToGuy

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Just curious, how do you determine it is is geared to " high " . That's not a big difference in ratio. You have more gear selection options with manual. Higher numerically ratio, will result in higher fuel use. Does your cruise rpm cause vibration, what rpm do you cruise at , within what power range of your engine setup? Are they both four wheel drive? Remember regear a 4x4 gotta do the front also. :waytogo:
 

SNCTMPL

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3.73's work well for stock size tires. For 33" tires, I would be going with at least 4.10's. I am doing a build now with 33's and going with 4.56's, but i prefer a little lower gear, and my son will probably go with 35's for his next tires. And it's a five speed.
 

CumminsFever

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Save the money, and put it toward engine mods that make 5th gear more relevant.
The difference from 3.73 to 3.42 is not that much. I swapped my 3.73 out for a 3.42, and there just isn't a crazy amount of difference.
Then again, it's been years since I drove a 350tbi with a 5spd. Perhaps it makes more difference there.
If I were making the gearing swap, I'd opt for a bigger jump, like 4.10. This should put the 350 in it's power band at cruising speed, making 5th gear relevant to cruising. Don't forget, fuel mileage may suffer with higher engine rpm.
 

Erik the Awful

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My 89’ the overdrive 5th gear is just there… 4th is really all it needs maybe I’m geared to high? This manual is new to me, I’m use to 4.10’s with Dana 44’s rubicon 5speed which set the standard I’m after on acceleration an pulling (with a straight 6)
I had an '02 Wrangler with 32s and it couldn't accelerate in 5th. When the tires wore out I replaced them with 31s and it made all the difference in the world. You can either step down in tire size or step up in ring gear size.

Or just make more horsepower.
 

Scooterwrench

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The OD ratio of your NV3500 is .73 With 32" tires and a 3.42 gear your engine will be turning about 1574 RPM,in OD and 2156 RPM in 4th.
With a 3.73 gear it's 2351 RPM in 4th,1716 RPM in 5th. That's pretty close to perfect for decent acceleration and fuel economy. I like to run my engine speed in OD somewheres around 1800 RPM for decent OD acceleration and good fuel economy without having to downshift when I hit a small grade.
 

Red89

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Just curious, how do you determine it is is geared to " high " . That's not a big difference in ratio. You have more gear selection options with manual. Higher numerically ratio, will result in higher fuel use. Does your cruise rpm cause vibration, what rpm do you cruise at , within what power range of your engine setup? Are they both four wheel drive? Remember regear a 4x4 gotta do the front also. :waytogo:
It is a 4x4,
I don’t have a rpm gauge in my cluster, the dash lights up shift with the up arrow from 4th to fifth, but my ears say nooo!!! (My ears are seasoned to my 95 z71 with 3.73 gears an a few engine mods ) 1800 rpm’s cruises shifts out at 2200 when accelerating
An 5th gear is a dog from 50-60/65
I’m looking for the difference between 4th an 5th gear no luck yet in research.
No vibration other than when the truck tells me to shift on the dash it will bog the motor down, so I tend to let the rpm’s build till I feel it’s around 2500 going off of ear .
 

Red89

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Save the money, and put it toward engine mods that make 5th gear more relevant.
The difference from 3.73 to 3.42 is not that much. I swapped my 3.73 out for a 3.42, and there just isn't a crazy amount of difference.
Then again, it's been years since I drove a 350tbi with a 5spd. Perhaps it makes more difference there.
If I were making the gearing swap, I'd opt for a bigger jump, like 4.10. This should put the 350 in it's power band at cruising speed, making 5th gear relevant to cruising. Don't forget, fuel mileage may suffer with higher engine rpm.
I appreciate your feedback. I am acknowledging that opting to 3.73 would be waist of time at this point of my project a spend my money Towards headers, heads, an air intake …
 

GoToGuy

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The upshift light was conceived as a fuel saving idea, to get driver's to be more eco friendly . Kinda like the monkey " ring the bell get a treat".
Me, I gotta have a tach with a stick.
Maybe you have adjust your shift techniques to fit your truck.
5th is a cruise, steady state travel. Accelerating means doing the dance. I'm one of the few who still have stick of many others over the years, " nah too much work ", " why auto does it ", " makes leg my tired "
And you understand having larger than Original Equipment diameter tires gives you a lower numerical axle right? Your 3.42 with larger diameter than OE tires could become 3.33
There are charts that do the math.
The cost involving changing both axles versus correct diameter tires. Ignoring the shift light how do you tell what rpm your shifting? That's what I would want to know. Good luck!
 
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