I need some advice and recomendations.

SteelHeadz

SteelHeadz

Super Moderator
For some time now , i've been holding back on getting the axle gears for my CJ7 to correct some Fuel mileage issue and not being able to use my 4th gear exept when im going downhill. I have a Model 20 on the rear and 30 on the front, they have the stock gears. I'm running a set of 35 X14.5 15 tires, 360AMC with a little bit of Steroids, T-177 trans and a Dana 300 t.case. A while back, someone recommended 4.56 gears. I need help on what Gear Ratio i should get and where, and affordable..I'm waiting for 2 Geo Trackers to get delivered. I'm gonna drive one with a mild upgrade and convert the other as a little crawler for the ranch. as soon as i get these trackers, the CJ7 is going on the Blocks. this should give me enough time to save up for the gears and other "Stuff" i can think of. Your Help is Greatly appreciated.
 

Here is a chart. 4Lo.com :: Gear Ratio & Tire Size Chart It looks like 4.56 would be great for your tires.

I know at least for rebuild kits, Superior's shims are reasonable thicknesses like .01, .012, .016. Some kits come with shims like .0135 and other confusing thicknesses. As far as gears, I would do a little research to see which gears come with a nice warranty. Sorry, I can't help you there. I bought used gears.
 
I thought about 4.11's but i haven't heard of any recomendations on that. Looking at that chart, i guess it's an option.
 
I would say most guys automatically think 4.56s because MOST of us have a 4.0L, or a 2.5L. You, however, (depending on what year 360, and what mods you're running), are going to have either more, of WAY more torque than the rest of us. That said, I wonder what gears you're running now. If you already have 3.73's, you may want to go all the way down to 4.56's, BUT, if you have 3.31's you might only need to go to 4.11's. (is this any help at all? You probably know all of this). SO! I would say...360 with mods, probably 300 to 350ft/lbs of torque, 35 inch tires...4.11's would be a good choice. Just my opinion, hope it helps.
 

Boze said:
I would say most guys automatically think 4.56s because MOST of us have a 4.0L, or a 2.5L. You, however, (depending on what year 360, and what mods you're running), are going to have either more, of WAY more torque than the rest of us. That said, I wonder what gears you're running now. If you already have 3.73's, you may want to go all the way down to 4.56's, BUT, if you have 3.31's you might only need to go to 4.11's. (is this any help at all? You probably know all of this). SO! I would say...360 with mods, probably 300 to 350ft/lbs of torque, 35 inch tires...4.11's would be a good choice. Just my opinion, hope it helps.
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Unfortunately i have the 2.73 gears:( i'm not as lucky as some of the members here who already has 3.73's on his axles(not mentioning names, Dan9).. The 360AMC was pulled out of a 79 waggy. after getting the Block and the Heads back from the machine shop, i dropped the Edelbrock performer Cam, Lifters and spring set, intake and a 750 performer Carburator.. and No, i don't know everything. I have a lot of training and certification thru Chrysler and that includes Axles. The problem is Axles is my weakest point, i don't deal with it enough to be confident in making this descision. Hence, i'm asking for help from the experts, and thats YOU GUYS.. So far , the 2 gear ratios of choice is 4.11's and 4.56's. I would like to hear what Bounty_Hunter , Jps4jeeps and everyone else has to say and recommend. and Scott,thank you for your response..
 
I wonder why they had so many options for gearing. I'll bet not one out of one hundred people who bought these things new at the dealer even thought about what gearing they were getting. Just one of those strange things I guess. Sort of like the 351 cleavland/windsor deal. Maybe it just had to do with what plant made the diffs. Bounty_Hunter probably knows that too! :lol:
 
Boze said:
I wonder why they had so many options for gearing. I'll bet not one out of one hundred people who bought these things new at the dealer even thought about what gearing they were getting. Just one of those strange things I guess. Sort of like the 351 cleavland/windsor deal. Maybe it just had to do with what plant made the diffs. Bounty_Hunter probably knows that too! :lol:
Click to expand...
As far as the Cleveland and Windsor, One is a Short stroke and the other one is a long stroke engine. i dont remember which one is which.
 

Isn't one a two bolt main and the other four bolt as well? Wikipedia will know! It knows everything.
 
With 35 inch tires you should run 4:56 gears for for the gas mileage, They will be good for general off-roading. 4:88's will better for the Rock crawling side, but will give you problems if you do mudding since it will drop you too low in the toque band where higher RPM's are needed for mudding type of off-roading.

With a performance 360 you should think of a Dana 60 in the rear and a Dana 44 in the front for weight, but if weight is no problem a Dana 60 in the front will give you that extra security of not leaving you with a broken half shaft if you put too much skinny pedal into it.
 
Thanks Utah. so far, i've got 2 Recomendations on the 4.56's and 1 on 4.11's. still no recomendations on the best source. Anybody?
 
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Since you currently have 2:73 gears, you can only go up to a 3:54 without changing the carriers. I run 4:56 gears in a CJ5 with dana 44 front and rear with 36" tires. It does quite well on and off road. I would strongly suggest upgrading at least your rear axle to either aftermarket 1 piece axles for the amc20 with a truss or change to a different differential altogeather.
 
What Solon said, one piece definitely, Mike.

Also, a couple interesting facts about AMC 20's is that the ring and pinion are larger than a Dana 44's, and Hummer H1's use the M20's diff (is Hummer a swear word here? :hide:). The only real shortcoming, besides the two piece, is the axle tubes. That can be fixed by trussing and/or welding the tubes into the housing.

Sorry Southernky, I wasn't attacking your comment. I just like sticking up for the M20's.
 
Collin the Hen said:
What Solon said, one piece definitely, Mike.

Also, a couple interesting facts about AMC 20's is that the ring and pinion are larger than a Dana 44's, and Hummer H1's use the M20's diff (is Hummer a swear word here? :hide:). The only real shortcoming, besides the two piece, is the axle tubes. That can be fixed by trussing and/or welding the tubes into the housing.

Sorry Southernky, I wasn't attacking your comment. I just like sticking up for the M20's.
Click to expand...

Well, According to my Trusted reliable source here , and i do agree with what's said in the conversation, that the M20's are Good Axles to keep so as long as i upgrade to that one piece axles that you've mentioned. as far as trussing and welding the tubes, that's already drawn out and ready for the Plasma Cutter. I will take Pics. on that build.

SouthernKy4wd, What did you mean about changing the carriers?
 

SteelHeadz said:
SouthernKy4wd, What did you mean about changing the carriers?
Click to expand...


Ok class gather round time for gear school...
A quick lesson in gearing 101... please pay attention in the back! now class when you change gearing the thickness of the ring gear changes and at some point your carrier housing I.E. your locker , limited slip what ever carrier you have in your axle will have to be changed out for a different ring gears thickness.
On most Dana 30 carriers that come stock (3.07 or 3.56) you can run up to a 3.56 gearing before you have to change carriers to run 3.92, 4.10, 4.56 gears or higher. Also called the flip gear 3.56.
Now the flip gear is 3.92 on a Dana 44's.
On AMC 20's the the flip gear is 2.78, if your axle has this gearing or lower this is far as you can gear with this carrier, to go to 3.08 or higher will require you to change the carrier.
 
Utah_jeepster said:
Ok class gather round time for gear school...
A quick lesson in gearing 101... please pay attention in the back! now class when you change gearing the thickness of the ring gear changes and at some point your carrier housing I.E. your locker , limited slip what ever carrier you have in your axle will have to be changed out for a different ring gears thickness.
On most Dana 30 carriers that come stock (3.07 or 3.56) you can run up to a 3.56 gearing before you have to change carriers to run 3.92, 4.10, 4.56 gears or higher. Also called the flip gear 3.56.
Now the flip gear is 3.92 on a Dana 44's.
On AMC 20's the the flip gear is 2.78, if your axle has this gearing or lower this is far as you can gear with this carrier, to go to 3.08 or higher will require you to change the carrier.
Click to expand...


Thanks for turning the lights on. Crap, that's another thing i got to put in the budget.:(
 

Collin the Hen said:
What Solon said, one piece definitely, Mike.

Also, a couple interesting facts about AMC 20's is that the ring and pinion are larger than a Dana 44's, and Hummer H1's use the M20's diff (is Hummer a swear word here? :hide:). The only real shortcoming, besides the two piece, is the axle tubes. That can be fixed by trussing and/or welding the tubes into the housing.

Sorry Southernky, I wasn't attacking your comment. I just like sticking up for the M20's.
Click to expand...


No offense taken. Only problem I've had out of them is spinning the hubs.
 
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