How hard is it to swap my 3.08 gears to 3.73 gears?

[Ewhitaker0020]

Instead of saying just for fun here, I should have said just for diagnostic purposes.If you can borrow some lowered mini truck wheels and tires this will give you the feel of the gear change.Your trucks gonna look stupid with 195-60-14s on it but if it is still is a slug then you need to evaluate.Why does it feel like a tired sluggish truck? I just used that tire size as n example, but maybe truck is tired and some engine work needs to happen. I fully agree 3.73 is a 50hp kick in the nuts but if the engines tired.Thats where I'd start. Junkyard wheels and tires are stupid cheap around here and you only need 2 if you run in 2 high to feel the difference. A gear change feels awesome on a healthy motor.
In 2 months I don't want to see the post.I put 4.56 gears in my truck and it's still doggy.Whats wrong with it?

When I say tired I just mean the trucks very sluggish. The engine runs great. A little low on the oil pressure at idle 12-14 psi and 30-40 while driving. But overall the engine runs very reliably and I just put an Edelbrock carb and intake on it.

I plan on putting a 350 in it eventually and I still want the 4.11 gears for when I do that. So I don't think it'll be a waste either way.

 

[HotRodPC]

Ultimately the truck is for cruising and driving to work occasionally just for fun (1-2 hour drive each way)

But I want to be able to tow a trailer with it as well occasionally. I tow a 16 foot trailer with a 700 pound mower and the truck will take forever to build speed. I can floor the pedal and barely gain speed the way it sits. I think my wife's 4 cylinder kia Sorento would do just as good if not better.

I do not want to go huge on tires. I don't want to lift the truck and I can't remember if 33's will fit without rubbing or not. If they'll fit fine without rubbing then I would want to go with them. If not then I would probably go with 31's.

I used a chart somebody provided and to get in the green power band I would need 31's and 4.11 gears. If I went with 33's then I would need 4.27 gears, which I'm not even sure is a thing on Chevy trucks of that age.

And towing frequently? I'd be going 4.10's even with 31 tires. That's if you're swapping gears. If you found a set of used 3.73 good working axles for $300-$400 then I'd pick those up and swap them in.

 

[Ewhitaker0020]

And towing frequently? I'd be going 4.10's even with 31 tires. That's if you're swapping gears. If you found a set of used 3.73 good working axles for $300-$400 then I'd pick those up and swap them in.

Just for the money right now I would probably just swap gears. Not frequently. I do tow a 16 ft trailer with a mower, but only about 15 miles round trip. I haul 100-1500 pounds of gravel occasionally. But I do want the ability to tow something if I needed to.

Mostly it's just a cruising around truck that has no power

 

[Rusty Nail]

Oh hell yeah. I always yield and err to the side of higher RPM.
But only because it's better. The closer you can operate the engine to it's maximum torque peak, the better off you'll be.

https://www.dictionary.com/browse/volumetric-efficiency

It's got power but it has no gear.
Needs gear.

 

[RoryH19]

And towing frequently? I'd be going 4.10's even with 31 tires. That's if you're swapping gears. If you found a set of used 3.73 good working axles for $300-$400 then I'd pick those up and swap them in.

That's what I did for my 82 K5. Came with a 305, 31" tires and 3.08 gears from the factory.
I found a set of 3.73 axles and 4 factory aluminum with tires from an 83 k5 for $200.

 

[Rusty Nail]

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[Craig 85]

I actually kinda want to swap 3/4 ton axles into my truck anyways. If I found a 3/4 ton truck is there any way for me to know what gearing it has?

I wouldn't mind swapping my wheels. It'll be about time for me to get new tires then anyways, so the wheels won't be too much more.

I did an axle swap on my last truck. I had 3.08's and went to 3/4 ton 4.10's with 33's. With a TH-350 I was pulling 2800-3000 RPM at 65-70. 33's on a 8" wide wheel may fit. I've always run 10" wheels and had to lift and trim with 33's.

For me it was cheaper to do the axle swap than swap out gears in my stock axles. I was planning for new tires and wheels anyways. Also, I had a 1 legger rear originally. I used a 14 bolt SF since I wasn't going to beat on the truck, but I had to shorten the rear drive shaft. The rear axles need 3/4 ton rear spring plates and U-bolts. There is a hybrid U-joint to fit the 3/4 ton rear to the 1/2 ton drive shaft. I also changed out the master cylinder for a 3/4 ton one.

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[Ricko1966]

Just for the money right now I would probably just swap gears. Not frequently. I do tow a 16 ft trailer with a mower, but only about 15 miles round trip. I haul 100-1500 pounds of gravel occasionally. But I do want the ability to tow something if I needed to.


Mostly it's just a cruising around truck that has no power

I just want to see him pull a 16ft trailer with a mower.My mower won't do it.

 

[HotRodPC]

That's what I did for my 82 K5. Came with a 305, 31" tires and 3.08 gears from the factory.
I found a set of 3.73 axles and 4 factory aluminum with tires from an 83 k5 for $200.

That's a score !!! You can find a set of matching 1/2 ton axles around from time to time for $300 but they're gone if you're not on it quick.

 

[RoryH19]

And towing frequently? I'd be going 4.10's even with 31 tires. That's if you're swapping gears. If you found a set of used 3.73 good working axles for $300-$400 then I'd pick those up and swap them in.

That's what I did for my 82 K5. Came with a 305, 31" tires and 3.08 gears from the factory.
I found a set of 3.73 axles and 4 factory aluminum with tires from an 83 k5 for $200.

That's a score !!! You can find a set of matching 1/2 ton axles around from time to time for $300 but they're gone if you're not on it quick.

Right, one of the best deals I've had on square parts. Had to drive from DFW to Houston but it was worth it.

 

[Ewhitaker0020]

Oh hell yeah. I always yield and err to the side of higher RPM.
But only because it's better. The closer you can operate the engine to it's maximum torque peak, the better off you'll be.

https://www.dictionary.com/browse/volumetric-efficiency

It's got power but it has no gear.
Needs gear.

So you're saying that you would err with a higher gear ratio just to make sure you have the torque even at the expense of higher rpm?

 

[Ewhitaker0020]

That's what I did for my 82 K5. Came with a 305, 31" tires and 3.08 gears from the factory.
I found a set of 3.73 axles and 4 factory aluminum with tires from an 83 k5 for $200.

How did you like the the 305 with the 3.73 gears? Did you notice a big jump in power?

 

[Ewhitaker0020]

I did an axle swap on my last truck. I had 3.08's and went to 3/4 ton 4.10's with 33's. With a TH-350 I was pulling 2800-3000 RPM at 65-70. 33's on a 8" wide wheel may fit. I've always run 10" wheels and had to lift and trim with 33's.

For me it was cheaper to do the axle swap than swap out gears in my stock axles. I was planning for new tires and wheels anyways. Also, I had a 1 legger rear originally. I used a 14 bolt SF since I wasn't going to beat on the truck, but I had to shorten the rear drive shaft. The rear axles need 3/4 ton rear spring plates and U-bolts. There is a hybrid U-joint to fit the 3/4 ton rear to the 1/2 ton drive shaft. I also changed out the master cylinder for a 3/4 ton one.

You must be registered for see images attach

How well did you like the 4.10's? I'll probably be going with 31's just so I don't have to worry about any fitment issues.

 

[Rusty Nail]

Yessir. Without hesitation.
4.10 is not enough either. lolo

Need more speed /lower E.T. / run a smaller diameter tire.
Need more mph /top end / run a taller tire.

But listen to Craig , im a jackass. He's way more "moderate" than I am, just ask @Tom Sawyer
If i had the choice, 4.56 is the git r dun gear for damn near everything but Iike to drag race.

Ive said that before. 4.56 or bust.

If you gotta go 4.88 youre trying too hard.

 

[RoryH19]

How did you like the the 305 with the 3.73 gears? Did you notice a big jump in power?

They were not installed at the same time. I have an Escalade LS 6.0 and 4L65E in there now. No comparison to a 305.
If you go 8 lug, you should be able to find 4.10 from the factory. I believe 3.73 was the largest from factory in 6 lug, 1/2 ton form.