4.10 gear install

[Lightnin 1]

I am able to acquire a few parts from an old CJ5 military jeep. It's got 4.10's in it. Was thinking about switching out my 3.54's for them provided they are not damaged. Will I have to change the carriers in order to make this work?? Also, I got a Lock-rite in the rear. If the carrier is changed, will I still be able to use my locker?? Any insight into this is greatly appreciated.


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[Hedgehog]

Sorry dude.....4.10's won't work with your parts.

 

[Posi]

I am able to acquire a few parts from an old CJ5 military jeep. It's got 4.10's in it.

Doesn't sound like military axles to me.
If they were military the axles would be from a MB38a1 not a CJ5
The front axle would be the D25 and rear Dana 44
Both would come from the factory with 5.38s
Post some pics of the axles

 

[Lightnin 1]

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[Lightnin 1]

I was told that this jeep had 4.10's in it. It was acquired from military surplus.


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[Petescj]

Well it's not a military model. That's a CJ5 . Has a Dana 30 front and a AMC20 rear. As for the 4.10 ratio that's possible.

 

[Petescj]

Oh and to answer your original question you should be good to go to switch gears and carriers between that Cj and yours. Axles won't swap cause your CJ7 is a wide track model and the Cj-5s were all narrow track.

 

[Posi]

That's a "newer" CJ5 1980-83
Good chance it has 4:10s with the gm4
Open the diff cover and check the gears to be sure
If their 4.10 they will swap over

 

[Lightnin 1]

I already got the 1 piece axles in my 7... So all I need to do is swap carriers and gears??


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[Posi]

All you need to do is swap over the ring and pinion. New carrier and pinion bearings, pinion seal, and nut.

 

[Lightnin 1]

Ok. So the 3.54 carrier is the same as a 4.10 carrier?


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[Posi]

No, you will need the 4.10 carrier as well.

 

[Lightnin 1]

10-4. Thanks for all the info.


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[Shifter]

Carrier breaks :
AMC20 = M20 2.73 & down / 3.07 & up
Dana 30 = Dana 30 3.54 & down / 3.73 & up

Info here http://http://www.ringpinion.com/TechnicalHelp/ContentFrame.aspx?FilePath=~%2FContent%2FParts%2FCarriers%2F%2FCommon+Carrier+Breaks.inc

 

[Lightnin 1]

Oh and to answer your original question you should be good to go to switch gears and carriers between that Cj and yours. Axles won't swap cause your CJ7 is a wide track model and the Cj-5s were all narrow track.

Can you swap the wide track to a narrow track,or is that not a good idea? I'm new to the world of Jeeps.


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[Posi]

Been awhile since I worked/owned a 20, 2.73 is the break thanks for posting.
Yes, the wide to narrow track is a direct swap if you have the NT tie rod and drag link. I'm guessing you want to save money on gear setup and parts, you could use wheel spacers on the NT. I have no idea what spacers cost I've never used them.

 

[Lightnin 1]

Yes sir..... You got me figured out Posi!!! Even though I have the gears, it looks like I'm still gonna invest over $600 in rebuilding and setting up the differentials. Hate to spend that much $$ on a swap. Just unsure how going to the narrowed rear & front end will affect the handling. Got a narrow track set with 4.11's already set up. May be buying another donor jeep with a narrow track Dana 44 rear & 3.73's. Just not sure what gears I really want. Going to switch from a 4 cylinder to a AMC 304 eventually. Don't want to turn the motor hard and mess up the fuel mileage. I drive the CJ quite a lot.


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[Hedgehog]

Warning! 4.10's won't do your mileage any good at all.

 

[Lightnin 1]

Warning! 4.10's won't do your mileage any good at all.

That's what I was thinking with the V8. But I just ran across this deal for a somewhat running AMC 304 in a donor jeep. Probably better stay with the 3.54's. If I go that route.


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[Hedgehog]

If you don't go all crazy with tire size, around here 3.54's are considered to be very decent gears to run. Not to high not to low, 3.73's are also in the running. When you go much lower or higher you need to give your choice a lot of thought. For instance 4.10's make your jeeps engine scream while on the highway, but pull hard in rough terrain. Of course taller tires would calm the engine down at highway speeds. Those big tires scare me to death on a short wheel based vehicle. It's my opinion that most people use too much lift with taller tires. If you want to go taller, look at BusaDaves rig. He has much bigger tires than you think, but he also kept the vehicle as low as possible. In the other direction, against some considerable pressure, I went with 3.31's for use on Arizona's almost endless Interstate system. Relatively tall gears, but to make up for it there is 360 power under the hood. Eventually the T-15 will be replaced with a Jeep T-18A and a T-20 with terra low gears in it. In my opinion this combination will be the best of both worlds. In high range there is a compound gear for a quick and easy grab at power gearing. When in low range there would be a nice selection of low gears AND an ULTRA low gear if its needed to slow things down.