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4.10 vs 4.56 gears

L

Lucas Ackerman

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Hey everyone I’m a noob here I’ve searched all over this site and can’t find the help I’m looking for. I have a1991 3/4 ton Suburban, 4” spring lift, 35” tires, 14 bolt axle with 3.73 gears, 350 TBI engine. My question is I’m thinking I want to go to either 4.10 gears or 4.56 gears what would be the better option? My rig will mostly be used for hunting and mild trail riding nothing too extreme. Also I’m planning to put vortec heads on the motor in the future. Another question when I do decide to change out the gears how hard are they to do? I’m average at best when it comes to wrenchin, thanks in advance for any input and help guys.
 
What trans?

Gears need to be setup by a pro IMO. You can do it but you'll need some special tools and you'll end up spending a lot of time learning.
 
If you have the 4l80 you need 4.56. 4.10 just doesnt cut it.
I wish I went 488s in my 91 with 34" tires.
 
rpm @ 70 mph with 4l80-e in o.d / 35.0 tire

4.10 = 2066
4.56 = 2298
4.88 = 2460
5.13 = 2586

small block tend to make good power in the mid 2k rpm range .

if th400 trans or stick non o.d. real close to these .

4.10 = 2911
4.56 = 3238
4.88 = 3465
5.13 = 3642

my 1 rig in build stage i setup with 35.0 tires and 4l80-e with 5.13 gears and a 8.1 vortec BBC

and in the gear range of 4.10 / 4.56 there is carrier split . so plan on new depending what axles and gears . some offer thick cut gears to avoid this .
 
Personally I wouldn’t be going any higher than a 4.56, but a good deal on 4.88’s wouldn’t be a deal breaker. You need to keep in mind that at some point is going with steeper fears that you may need a carrier.
 
I have the 4l80 with overdrive. Yeah I was kinda thinking it may be a little out of my mechanical abilities to change out gears:D I was leaning towards just finding a set of axles with the 4:56s in them and just swap the axles but I’m having a hell of a time trying to find them here in Colorado. When I did find some the guy wanted over a thousand bucks which to me seemed high but maybe not?:dunno: What’s a ball park cost for a gearing job like you suggested Skunked?
 
Lucas Ackerman said:
I have the 4l80 with overdrive. Yeah I was kinda thinking it may be a little out of my mechanical abilities to change out gears:D I was leaning towards just finding a set of axles with the 4:56s in them and just swap the axles but I’m having a hell of a time trying to find them here in Colorado. When I did find some the guy wanted over a thousand bucks which to me seemed high but maybe not?:dunno: What’s a ball park cost for a gearing job like you suggested Skunked?
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Depends on location. When I had mine done yrs ago, labor was $250 for the rear alone, I supplied the gears.
 
find a set of military 1ton truck take out axles . 4.56 and detroit locker rear . front dana 60 bolt in . rear swap guts in your 14ff rear and run it . this so you dont have to move spring and shock mounts and reweld .

by the time you price all the parts you think you need and find later you need more then add in labor its around the same thing price point .
 
That’s not too terrible. The CUCV axles have 4:56 in them is that correct? Is there any particular brand of gears that stand out above the others?
 
Lucas Ackerman said:
That’s not too terrible. The CUCV axles have 4:56 in them is that correct? Is there any particular brand of gears that stand out above the others?
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like i just posted above if from the 1ton trucks m1008 / m1010 / m1028 / m1031 is the truck model #'s . the blazer m1009 just got 1/2 ton 10 bolts and 3.08 gears .
 
sweetk30 said:
find a set of military 1ton truck take out axles . 4.56 and detroit locker rear . front dana 60 bolt in . rear swap guts in your 14ff rear and run it . this so you dont have to move spring and shock mounts and reweld .

by the time you price all the parts you think you need and find later you need more then add in labor its around the same thing price point .
Click to expand...
So pretty much a wash between swapping axles and replacing the gears themselves
 
That is correct for pricing. But you gain the 60 front.
I would regularly charge 1500 for gear swaps on older trucks. they almost always need other things so it would creep up to 2 grand right quick.

Paying 1500 for one tons ain't bad.
 
Yeah sounds like 4:56 gears may be the best option for me. Especially since I will be driving the burb on the highway occasionally. Thanks for all your help and info guys I appreciate it. I just started this project I bought the burb about a year ago but haven’t had the time or money to get going on it. I just put the lift in last weekend and tires are on the way. Work in progress
 
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