Swapping up to the 4.10s

[OldButStillJeeping]

I'm

I stand corrected, on looking at the website that chart does indicate it is based on 65 mph, but still our trans are completely diff. So if I am out of overdrive of 8th gear and in 7th which should be close to the 1:1 I am still only doing about 1900 at 65mph. One still needs to know more information and one chart is not good for all vehicles.

Respectfully, you all are missing the point AND the information in the chart. Speed DOESN'T MATTER. ENGINE TYPE DOESN'T MATTER. MANUAL OR AUTOMATIC DOESN'T MATTER.

The RPMs and engine and gear selection or any of that isn't the point. The point of the chart is to find a final drive ratio that matches a stock vehicle using the tire size and ring and pinion in the vehicle. Forget about what the RPM is in the chart, except that it is the benchmark of stock gearing. IT is just a number to match, not real RPM.

If your Jeep in stock configuration came with 31's and 3.73, check the chart and find the numerical factor. Which is listed as RPM. The numerical factor is not your actual RPM! They call it RPMs but it is just a figure for you to match. If it says 2600 with 31's and 3.73, then see what your desired 37 inch tire rates with the same 2600. It might be 4.56 or 4.88. You want to match the fictitious RPM btwn stock and your desired tire size.

My goodness JeeperS and 4 wheelers and rock crawlers, etc have been using this chart with any and all engines and transmissions for decades. You diesel JT guys are hung up on diesel RPM... It isn't about that. It's about changing tire size and finding out which ring and pinion gear ratio (FINAL DRIVE RATIO) you need to match what came as stock.

I know that you all aren't engineers but it is basic math. Yeah, you have diesel, I get it, You are special. I have a gas JT but I have had several diesels in my life... They all use the same chart!

I have owned a few Ford Super Duty diesels and I used that chart. I had a BMW 328D (diesel) and i didn't put bigger tires on it, so I didn't use that chart. But it still would have worked. For my Jeep Tjs and YJ and Dodge Ram, all gassers, I used that chart. Every seasoned off roader uses that chart.

You have a diesel JT. So get over it, that chart is what you need.

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[Wheelin98TJ]

I'm


Respectfully, you all are missing the point AND the information in the chart. Speed DOESN'T MATTER. ENGINE TYPE DOESN'T MATTER. MANUAL OR AUTOMATIC DOESN'T MATTER.

The RPMs and engine and gear selection or any of that isn't the point. The point of the chart is to find a final drive ratio that matches a stock vehicle using the tire size and ring and pinion in the vehicle. Forget about what the RPM is in the chart, except that it is the benchmark of stock gearing. IT is just a number to match, not real RPM.

If your Jeep in stock configuration came with 31's and 3.73, check the chart and find the numerical factor. Which is listed as RPM. The numerical factor is not your actual RPM! They call it RPMs but it is just a figure for you to match. If it says 2600 with 31's and 3.73, then see what your desired 37 inch tire rates with the same 2600. It might be 4.56 or 4.88. You want to match the fictitious RPM btwn stock and your desired tire size.

My goodness JeeperS and 4 wheelers and rock crawlers, etc have been using this chart with any and all engines and transmissions for decades. You diesel JT guys are hung up on diesel RPM... It isn't about that. It's about changing tire size and finding out which ring and pinion gear ratio (FINAL DRIVE RATIO) you need to match what came as stock.

I know that you all aren't engineers but it is basic math. Yeah, you have diesel, I get it, You are special. I have a gas JT but I have had several diesels in my life... They all use the same chart!

I have owned a few Ford Super Duty diesels and I used that chart. I had a BMW 328D (diesel) and i didn't put bigger tires on it, so I didn't use that chart. But it still would have worked. For my Jeep Tjs and YJ and Dodge Ram, all gassers, I used that chart. Every seasoned off roader uses that chart.

You have a diesel JT. So get over it, that chart is what you need.

OP doesn’t need that chart. He already figured he needs 4.22 gears to be equivalent to stock.

You can use formulas to calculate desired gear ratio or RPM with any setup. I’d rather do that than use a chart that has fixed parameters.

 

['22JTRD]

OP doesn’t need that chart. He already figured he needs 4.22 gears to be equivalent to stock.

You can use formulas to calculate desired gear ratio or RPM with any setup. I’d rather do that than use a chart that has fixed parameters.

Another really helpful thing you can do is search this forum and read posts from others who have already put 4.10s on their EcoDiesels running 38s and are really happy with the results and not so happy with the results they experienced with 4.56s and 38s...

I put more weight on others actual experience than on what a generic chart says, but I am kind of weird like that.

 

['22JTRD]

As a side note,
My '85 4Runner came stock with 32" tires and a 4.10 Ratio

I upped the tires to 36" TSL Swampers and 5.29 gears

I did before and after rpm test at 60 mph on the same stretch of road and found only a 50 rpm increase.

That anemic 22RE with barely enough torque and horsepower to carry itself would still pull 5th gear to the point of me not wanting to go any faster floating around on true 36s.

 

[rharr]

Some of you fell off of the the idiot tree and hit every branch in the way down.

There are no fixed parameters except what you insert. You just don't understand.

Someday you will understand. The light will go on and you'll say, "Oh, now I get it."

Tell the OP to find 4.22 gears. Good luck.

You JT diesel guys are quite a group of unique.

Have fun.

You are a silly old man, go find the door to the gasser section and stop confusing ppl.

 

[OldButStillJeeping]

You are a silly old man, go find the door to the gasser section and stop confusing ppl.

True. You guys are obviously easily confused.

Be well. Jeep on.

Eric

 

[Wheelin98TJ]

Some of you fell off of the the idiot tree and hit every branch in the way down.

There are no fixed parameters except what you insert. You just don't understand.

Someday you will understand. The light will go on and you'll say, "Oh, now I get it."

Tell the OP to find 4.22 gears. Good luck.

You JT diesel guys are quite a group of unique.

Have fun.

When you understand what builds that dumbass chart, you don’t need it.

 

[OldButStillJeeping]

When you understand what builds that dumbass chart, you don’t need it.

Lol.

 

[Rusty PW]

I'm


Respectfully, you all are missing the point AND the information in the chart. Speed DOESN'T MATTER. ENGINE TYPE DOESN'T MATTER. MANUAL OR AUTOMATIC DOESN'T MATTER.

The RPMs and engine and gear selection or any of that isn't the point. The point of the chart is to find a final drive ratio that matches a stock vehicle using the tire size and ring and pinion in the vehicle. Forget about what the RPM is in the chart, except that it is the benchmark of stock gearing. IT is just a number to match, not real RPM.

If your Jeep in stock configuration came with 31's and 3.73, check the chart and find the numerical factor. Which is listed as RPM. The numerical factor is not your actual RPM! They call it RPMs but it is just a figure for you to match. If it says 2600 with 31's and 3.73, then see what your desired 37 inch tire rates with the same 2600. It might be 4.56 or 4.88. You want to match the fictitious RPM btwn stock and your desired tire size.

My goodness JeeperS and 4 wheelers and rock crawlers, etc have been using this chart with any and all engines and transmissions for decades. You diesel JT guys are hung up on diesel RPM... It isn't about that. It's about changing tire size and finding out which ring and pinion gear ratio (FINAL DRIVE RATIO) you need to match what came as stock.

I know that you all aren't engineers but it is basic math. Yeah, you have diesel, I get it, You are special. I have a gas JT but I have had several diesels in my life... They all use the same chart!

I have owned a few Ford Super Duty diesels and I used that chart. I had a BMW 328D (diesel) and i didn't put bigger tires on it, so I didn't use that chart. But it still would have worked. For my Jeep Tjs and YJ and Dodge Ram, all gassers, I used that chart. Every seasoned off roader uses that chart.

You have a diesel JT. So get over it, that chart is what you need.

I use the same chart. It's easy to use IF you understand it.

 

['22JTRD]

Here's the Interco Calculator

https://www.intercotire.com/tire_si... calc can be used,to keep your original gears.

 

['22JTRD]

 

[Rusty PW]

That's the numbers I put into it just now. LOL

 

['22JTRD]

That's the numbers I put into it just now. LOL

4.10 if you don't tow & 4.56 if you're heavy is how I see it sorted out.

4.10 a fraction better mpgs at Highway speeds and suitable for everything else.

4.56 a fraction worse at highway speeds and a fraction more grunt under load.

Pick your poison, we're still driving bricks

 

[Rusty PW]

4.10 if you don't tow & 4.56 if you're heavy is how I see it sorted out.

4.10 a fraction better mpgs at Highway speeds and suitable for everything else.

4.56 a fraction worse at highway speeds and a fraction more grunt under load.

Pick your poison, we're still driving bricks

On a few other threads floating around. 4.30 was deemed the sweet spot for 37's. But no one makes them.

 

[UTDieselRubi]

4.10 if you don't tow & 4.56 if you're heavy is how I see it sorted out.

4.10 a fraction better mpgs at Highway speeds and suitable for everything else.

4.56 a fraction worse at highway speeds and a fraction more grunt under load.

Pick your poison, we're still driving bricks

Curious, how do you figure 4.10s will get better MPG than 4.56s? I'm currently trying to decide which as well and while we obviously can't be too nit picky about mpg when we bought a jeep, I'd still like the find the "best" mpg ratio. The thing I found while living in Utahs mountainous areas is that my stock 33s Avg. Me about 22 to 23ish, my 37s put me at around 20, and a set of second hand sport 31s for daily driving put me at 25ish. So, if I was chasing the 25ish the 31s gave, your calculator says I need closer to 4.56 when entering 31s as the old tire. Wouldn't that be mostly true across the board? I wonder why others don't like 4.56s when that's what I would say is closer to a diesel sport ratio, while 4.10s are like a diesel Rubicon ratio (sort of).

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