4.10 Gear - Carrier Suggestions? *NOOB*

[FSJRomanGladiator]

Hey FSJ fam - getting some new gearing in my 74 J10.

Wanted to get ya'll perspective on 4.10 and 4.09 combo. Well i have those and they were free. Can i run these together? if so, which should i put in the rear and which one in front? i'll end up with a trutrac Eaton Detroit carrier.

Dana Spicer 4.09
2004 Wranger OEM 4.10 -Thick Cut

My understanding, that there is a rule of thumb to be within 1% of each other. so....

It is (4.10-4.09)/4.09 = .002 or 0.2%.

COULD THIS TEAR UP MY DANA 20?

thanks like always

[will e]

I am not an expert in this area. The dana 20 is a gear driven transfer case so it might be a little more picky than a chain driven case. However, the difference in the axle ratio's is small enough I don't think it will matter in the dirt. Keeping in mind that even a jeep with the same ratios in the axles the front and rear go slightly different speeds any time you are turning.

[FSJRomanGladiator]

I am not an expert in this area. The dana 20 is a gear driven transfer case so it might be a little more picky than a chain driven case. However, the difference in the axle ratio's is small enough I don't think it will matter in the dirt. Keeping in mind that even a jeep with the same ratios in the axles the front and rear go slightly different speeds any time you are turning.

Thank you for replying. chain vs gear driven is a good point. didn't think of that. trying to learn at the moment and searching but nothing better than ya'll info!

[tgreese]

4.10s and 4.09s are routinely mixed front and rear, but typically that's only seen with different diameter ring gears. Look at the gear tooth counts and divide ring/pinion to get the exact ratios.

[FSJRomanGladiator]

I am not an expert in this area. The dana 20 is a gear driven transfer case so it might be a little more picky than a chain driven case. However, the difference in the axle ratio's is small enough I don't think it will matter in the dirt. Keeping in mind that even a jeep with the same ratios in the axles the front and rear go slightly different speeds any time you are turning.

so i think you made a valid point on the case.

That said if i already have these gears..

https://www.dennysdriveshaft.com/p12527 ... 9vv7MWgic4

should i just buy it again to match?

Which Eaton Detroit TruTrac can i use? do i need one for the front and rear?

man i am a noob. thanks guys

[FSJRomanGladiator]

4.10s and 4.09s are routinely mixed front and rear, but typically that's only seen with different diameter ring gears. Look at the gear tooth counts and divide ring/pinion to get the exact ratios.

thank you. i am moving to the safe bet. any advice on my last post?

[Stuka]

You will be fine. This was done from the factory quite often in the 60's and 70's. Ford for instance used a D44 front and a 9" rear on their 1/2 ton trucks and Bronco's, they have the same mismatch.

[will e]

Lockers are great and really help off road. What kind of off roading do you plan to do? Generally I recommend a front locker first, especially if you are doing a lot of 'crawling'. Is your transfer case a 'twin stick'? Can you engage the front and rear wheel drives separately? I think some of the dana 20's had this option.

[Stuka]

Lockers are great and really help off road. What kind of off roading do you plan to do? Generally I recommend a front locker first, especially if you are doing a lot of 'crawling'. Is your transfer case a 'twin stick'? Can you engage the front and rear wheel drives separately? I think some of the dana 20's had this option.

I am of the opposite opinion

You can't drive in the snow with a front locker (unless its selectable, or you have a death wish), and not sure where he lives.

And at least where I live, with hill climbs, a rear locker is of way more help. So, depends what he is going to be doing. Also, a rear locker can be a huge help in 2wd.

[tgreese]

I'm pretty much agreeing with Stuka. Put your LSD or locker in the rear axle first. Climbing hills is important - going uphill, the weight transfers to the rear axle, and extra traction on the front, on a steep hill, does not help you much. Traction at the rear does. And you're also working against gravity going uphill, so you need every advantage. Try driving a front wheel drive car in the snow. Any significant uphill will reduce traction a lot and your front wheels will spin. BTDT with my VW. And as mentioned, a LSD or locker on the front affects your steering, making choice of direction more difficult.

With a Dana 20, one shift rod controls each axle. A twin stick setup can make the rear axle freewheel and the front drive the Jeep. There are pills between the shift rods that prevent front only as I recall, but you can remove them. Just don't shift into low for one axle and high for the other - that would be bad.

[FSJRomanGladiator]

You will be fine. This was done from the factory quite often in the 60's and 70's. Ford for instance used a D44 front and a 9" rear on their 1/2 ton trucks and Bronco's, they have the same mismatch.

as always, thanks Stuka. I am going to go grab those gears then. 4.09 and 4.10 then. tooth count is different, still confident in the safety on these? 8.5" ring on both

[FSJRomanGladiator]

I'm pretty much agreeing with Stuka. Put your LSD or locker in the rear axle first. Climbing hills is important - going uphill, the weight transfers to the rear axle, and extra traction on the front, on a steep hill, does not help you much. Traction at the rear does. And you're also working against gravity going uphill, so you need every advantage. Try driving a front wheel drive car in the snow. Any significant uphill will reduce traction a lot and your front wheels will spin. BTDT with my VW. And as mentioned, a LSD or locker on the front affects your steering, making choice of direction more difficult.

With a Dana 20, one shift rod controls each axle. A twin stick setup can make the rear axle freewheel and the front drive the Jeep. There are pills between the shift rods that prevent front only as I recall, but you can remove them. Just don't shift into low for one axle and high for the other - that would be bad.

amazing info and thanks. so offroad not as much as DD, but will do. I live in GA so it will be that beautiful clay and hills.

regarding LSD or locker - i assume if i am putting the 4.09 in rear and 4.10 in front - i will need two new lockers or LSD? or does the factory house support them? if it supports them, i would use the front OEM and replace the rear. I like the Eaton TruTrac Detroit. thoughts?

thanks!

[FSJRomanGladiator]

Lockers are great and really help off road. What kind of off roading do you plan to do? Generally I recommend a front locker first, especially if you are doing a lot of 'crawling'. Is your transfer case a 'twin stick'? Can you engage the front and rear wheel drives separately? I think some of the dana 20's had this option.

thanks Will e!

mostly DD and GA clay. not a twin stick. i can engage the front and rear separately. i have Warn wheel lockers on front tires.

OEM carrier in front pumpkin with 3.54 gears. replacing those with 4.10 gears (from a 2004 Rubicon)

rear is welded from previous owner so i am putting in 4.09 gears there. (Spicer)

both are same size 8.5" ring. the front a rear have different tooth count.

what are your thoughts on these gears? foresee any issues with D20 case or blowing up my axles?

[will e]

What size tires will you be running? 33" tires would be about 2900 RPM at 65 MPH. 31" tires will get you close to 3100 RPM at 65mph

One of our local board members created the 'definitive' gear ratio calculator: http://www.grimmjeeper.com/gears.html

You can plug in different transmissions, transfer cases, gear ratios and tire sizes. It's pretty slick.


Back to the lockers. If you can afford selectable lockers that's usually the best way to go. Automatic lockers are nice, and less complicated too, so there is something to be said for that.

My friends point out that most of the weight during a hill climb is on the rear tires and less weight on the front tires. So it sounds logical you would want the locker on the rear. But.. With the weight on the rear tires there is less chance they will 'spin' a tire with an open carrier. With less weight on the front tires it's going to be easier to break one free and have it start spinning. Locking the front eliminates the possibility of the front from spinning and because there is more weight on the rear tires there is less chance one of them will spin too. My two cents. It's an on going discussion on internet boards and around campfires. Similar to ported vs manifold vacuum for distributor advance. Our local 4wd did a test with a few rigs that all had selectable lockers. They tried various obstacles with the front locked and then again with the rear. They came to the conclusion that front lockers are better. Hardly scientific but compelling. I agree about having a locker in the rear being most helpful if you are in 2wd.

I don't have much experience with slick mud. Here is AZ we don't have much mud to play in and when there is some the spots are usually not much bigger than the length of a rig. Running around on shelf roads and dry washes I am usually in 2wd low. I engage the front axle when I get to hill climbs or dry waterfalls.

In the mud I would 'think' you would want a front locker so that the tires would dig their own paths. If the front is 'open' and one tire starts to spin and the other one is stationary you kind of have to push the non-spinning tire through the mud. Just something to think about. Again, I am not an expert and I don't get to play in the mud much. I am sure the guys will pitch in their thoughts as well.

[Stuka]

both are same size 8.5" ring. the front a rear have different tooth count.

what are your thoughts on these gears? foresee any issues with D20 case or blowing up my axles?

What are the tooth counts for each?

Also, you may be aware of this, but the TJ gears use larger bolts as I recall, and you have to drill your carrier out a bit to fit them.

[FSJRomanGladiator]

both are same size 8.5" ring. the front a rear have different tooth count.

what are your thoughts on these gears? foresee any issues with D20 case or blowing up my axles?

What are the tooth counts for each?

Also, you may be aware of this, but the TJ gears use larger bolts as I recall, and you have to drill your carrier out a bit to fit them.

Never experienced TJ gears hands on but heard of that. i'll have to see with my 74 how this will workout. could i not just get TJ carrier for the 4.10 gears?

4.09 - 45/11 - Spicer

4.10 - 41/10 - TJ

[tgreese]

Apparently there is a 37/9 = 4.11 for the 9" Ford too. The Bronco or F100 mentioned above could be that ratio.

[FSJRomanGladiator]

I really appreciate all the info. i went back up to read some of the responses and missed some posts that need to be addressed, Also bring it back in a bit to what my concern is and learn along the way.

-I live in NE GA. So we get snow, ice, rain, and hot summers. GA clay is all over so it gets real sloppy and hardens in dry periods.
-Application will be mostly street riding. So want to treat as a DD but not helpless if i need to putz around the farm, off road to fishing creeks, hunt or play in the GA mud.
-Currently running 32's but moving closer to 35's. The 32's are way too small for my rig. End of day it will have a 5" lift ( previous owner welded 1" solid steal blocks before the shackle and mated to frame. will see this in a different post where posted a video about popping. viewtopic.php?p=184060#p184060

-I have two gears that were pretty much given to me and mainly wanted to know if they can work with each other. Of course i do not want to spend money where i do not have to. I posted the links to both gears below.

First gear can be found at this link:
https://www.dennysdriveshaft.com/p12527 ... 9vv7MWgic4
Second gear:
https://www.rockauto.com/en/moreinfo.ph ... 0552&jsn=3

Also, which lockers should I get for these. Looking for best traction (Safety) in all weather conditions but will not limit power. Right now the previous owner welded my rear 3.54 spider gears and it feels like i a towing 7K pounds. sucks.

Thanks ya'll.

*signature has other elements of my rig thus far if you need more info.

[Stuka]

Out of curiosity, are you getting the TJ gears for free? If not, there is no reason to get those over some Yukon gears intended for your axles. Lot less work.

[will e]

I am going to add a bit to what Stuka said. You posted in the subject that you are a 'noob'. Welcome to the party! I have learned that sometimes making something that is 'free' works ends up being more expensive or less reliable than getting the right parts. I am not familiar enough with the details of what you are trying to do to steer you one way or the other. I am just giving my personal experience and advice.