Swapping up to the 4.10s

[caryt]

I read this again people keep bringing up tire height on the ground. What difference does that make..air pressure used will change that and that pressure will change as the tire gets hot, as well the weight of the JT ..affecting the height. My 38" trail grapplers cold are 36.25" ,,with 12k miles on them and being 7400+ LBS and the pressure I run. All that doesn't change the rolling radius. The circumference of a tire is exactly the same no matter how much air is in the tire. The APPARENT DIAMETER with differing air pressure does not change the actual CIRCUMFERENCE or LENGTH of the rubber tread.

Just a fyi but best gearing chart is: https://www.grimmjeeper.com/gears.html for those that don't know of it.

Sponsored

 

['22JTRD]

Hallelujah, finally got an appointment at my local hot rod shop to get my gear sets swapped.

Only other shop in our county that does differentials wouldn't work on the AdvanTEK 44.

Dropped the JT off at noon today, they're pulling it in Monday morning.

 

['22JTRD]

Just a fyi but best gearing chart is: https://www.grimmjeeper.com/gears.html for those that don't know of it.

IMHO, the best* gear calculator is:
37/33 = 1.12
3.73 x 1.12 = 4.17

And, measured tire size on the ground is needed to flash your ecm and calibrate speedo and shift points in the tranny.

 

[tj3089]

I think you might regret spending all that money just to go to 4.10 gears, especially if you decide to go with 38s or 39s later down the road.

Personally I went with 4.56 gears because I tow our 22ft 4800lb loaded toy hauler a few times a year. I also figured with the engine working less off-road and to get up to speed, it would bring down engine temps a bit. That turned out to not be the case when I had to pull over to do a forced regen on my trip to CO last summer. The biggest difference I have found so far with performance and steadier temps has been the stage 2 delete, which I strongly recommend sooner than later.

 

['22JTRD]

I think you might regret spending all that money just to go to 4.10 gears, especially if you decide to go with 38s or 39s later down the road.

Personally I went with 4.56 gears because I tow our 22ft 4800lb loaded toy hauler a few times a year. I also figured with the engine working less off-road and to get up to speed, it would bring down engine temps a bit. That turned out to not be the case when I had to pull over to do a forced regen on my trip to CO last summer. The biggest difference I have found so far with performance and steadier temps has been the stage 2 delete, which I strongly recommend sooner than later.

As l mentioned in the opening post,
already running "38s"
live in very flat Florida
don't tow other than across town dropping and returning the trailer for my Cobia 280 DC when it gets serviced every 100 hours ( B.O.A.T. )

Since there's no do-overs or take-backs , you have to be comfortable living a life with "No Regerts*"

Every time you leave the fuel dock after pumping 170 gallons @ $5 per kind of de-sensitizes the sting of sticker shock related to things that last longer than 1 or 2 days.

This JTRD will be flat towed behind a Thor Outlaw 29-J, carrying my Fat Boy and Yamaha TW-200 when it makes my next trip to the San Juan's, so it won't be needing any extra re-gens on the side of the road.

BTW, the current "effective ratio" is 3.30 and manageable but less than ideal under the conditions I drive in , the change from 3.73 to 4.10 returns to just under the oem power curve spec.

Just did a long session with ChatGPT / Open AI , after inputting all the oem and changed parameters , the resulting opinion is that it will be so close to oem spec the slight difference will be unnoticeable.

Even input all the chassis changes and got a Trail Rating on the JT from AI.

Honestly was impressed at the level of information I got back and the speed of it's delivery.

 

[Wheelin98TJ]

As l mentioned in the opening post,
already running "38s"
live in very flat Florida
don't tow other than across town dropping and returning the trailer for my Cobia 280 DC when it gets serviced every 100 hours ( B.O.A.T. )

Since there's no do-overs or take-backs , you have to be comfortable living a life with "No Regerts*"

Every time you leave the fuel dock after pumping 170 gallons @ $5 per kind of de-sensitizes the sting of sticker shock related to things that last longer than 1 or 2 days.

This JTRD will be flat towed behind a Thor Outlaw 29-J, carrying my Fat Boy and Yamaha TW-200 when it makes my next trip to the San Juan's, so it won't be needing any extra re-gens on the side of the road.

BTW, the current "effective ratio" is 3.30 and manageable but less than ideal under the conditions I drive in , the change from 3.73 to 4.10 returns to just under the oem power curve spec.

Just did a long session with ChatGPT / Open AI , after inputting all the oem and changed parameters , the resulting opinion is that it will be so close to oem spec the slight difference will be unnoticeable.

Even input all the chassis changes and got a Trail Rating on the JT from AI.

Honestly was impressed at the level of information I got back and the speed of it's delivery.

Can we see pics of the boat?

 

[Uparms]

35s work great w the 4.10 and 8 speed auto but are still just slightly begging for more. I agree, 4.10 a waste unless you are sure your won’t want bigger in the future. I failed to see what size you running now (or plan to).

 

['22JTRD]

Can we see pics of the boat?

 

['22JTRD]

 

[AustyPosty]

37s on stock 4.10s still get me up to 20mpg on the highway with the 3.6L. Might consider regearing after I put a 300lb camper on the back, but idk. Drives great.

 

['22JTRD]

37s on stock 4.10s still get me up to 20mpg on the highway with the 3.6L. Might consider regearing after I put a 300lb camper on the back, but idk. Drives great.

This thread is about going from 3.73/33s to 4.10/38s on a 3.0 EcoDiesel for a Florida driven JT that doesn't tow or Overland.

Nothing concerning the 3.6 gasser is relevant to the conversation

 

[tj3089]

As l mentioned in the opening post,
already running "38s"
live in very flat Florida
don't tow other than across town dropping and returning the trailer for my Cobia 280 DC when it gets serviced every 100 hours ( B.O.A.T. )

Since there's no do-overs or take-backs , you have to be comfortable living a life with "No Regerts*"

Every time you leave the fuel dock after pumping 170 gallons @ $5 per kind of de-sensitizes the sting of sticker shock related to things that last longer than 1 or 2 days.

This JTRD will be flat towed behind a Thor Outlaw 29-J, carrying my Fat Boy and Yamaha TW-200 when it makes my next trip to the San Juan's, so it won't be needing any extra re-gens on the side of the road.

BTW, the current "effective ratio" is 3.30 and manageable but less than ideal under the conditions I drive in , the change from 3.73 to 4.10 returns to just under the oem power curve spec.

Just did a long session with ChatGPT / Open AI , after inputting all the oem and changed parameters , the resulting opinion is that it will be so close to oem spec the slight difference will be unnoticeable.

Even input all the chassis changes and got a Trail Rating on the JT from AI.

Honestly was impressed at the level of information I got back and the speed of it's delivery.

It seems like you have made up your mind, so please come back and let us know how you like it since a lot of people are interested.

You keep mentioning OEM spec or power curve, but why is that the end goal and not a better setup? Your jeep is already modified and heavier than a stock JTRD, so it might not feel as peppy with the 4.10 gears.

The 4.56 gears will get up to speed faster and will most likely be more efficient in city driving.

 

[AustyPosty]

This thread is about going from 3.73/33s to 4.10/38s on a 3.0 EcoDiesel for a Florida driven JT that doesn't tow or Overland.

Nothing concerning the 3.6 gasser is relevant to the conversation

Cool beans

 

[Zachanadandy]

37s on stock 4.10s still get me up to 20mpg on the highway with the 3.6L. Might consider regearing after I put a 300lb camper on the back, but idk. Drives great.

How slow and or mostly downhill do you drive. I didn't get 20mpgs when the mojave was stock.

 

[AustyPosty]

How slow and or mostly downhill do you drive. I didn't get 20mpgs when the mojave was stock.

I see 20mpg occasionally, but as you said, does depend on how much downhill driving I'm doing. I tend to do a decent amount of downhill driving in the mountains, I don't drive that slow, usually 5 over the speed limit. However on a long highway trip such as driving through I5 I have seen 18-20mpg consistently. I would say generally I'm easy on the accelerator, I try to accelerate really smooth from stops. Overall though 20mpg is a luxury, and usually I'm hovering around 16-18 daily driving.

Sponsored