If possible looking for Speedo/Tachometer pics of JTDiesel auto w/ 37's and 4.56 gears @ 55,65 mph

[MaxStrategery]

Thank you and this why I was asking for a picture of real world. According to the Grimm jeeper calculator it should be at 1996 rpm which isn't much difference but still isn't as accurate as real world. 4.56's it is.

Weird. At 80 with 37's and 373 Im at 1900 almost exactly. Grimmjeeper calculator says I should be at 1816 rpm's. Again real world and calculators not exactly synced but close, so +/- 100 rpm's sounds about right. Gear shop telling me approx 200 rpm difference between 410 and 456, yeah 200 rpm isn't going to matter that much but easily staying in 8th gear into the wind for hundreds of miles in Wyoming matters. Thanks again for the help.

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[MaxStrategery]

Interesting you experienced "no" difference. As soon as I drove off the tire shop lot, my off the line torque was noticeably diminished, and through first gear was very sluggish and required significantly more throttle to get into the power band.

 

[TheSolarWizard]

Here's the rpm at 80 mph on 37s with 4.10.

what is this gauge?

 

[MaxStrategery]

Interesting you experienced "no" difference. As soon as I drove off the tire shop lot, my off the line torque was noticeably diminished, and through first gear was very sluggish and required significantly more throttle to get into the power band.

Yes there are plenty of threads on this subject and none are very objective, they are opinions and all are going in different directions on same tire wheel gear setups, so not a lot of actionable information in those threads.

 

[MaxStrategery]

Something else to think about. Not all 37's are the same height. Have 37" KO's that measures way short vs a Super Swamper at 37. You're talking close to 1.5" difference in height.

That likely explains the 50-100 pm variances

 

[MaxStrategery]

Someone post a pic of a speedo showing 55 MPH/1,600 RPM and 65 MPH/1,900 RPM so we can make OP happy.

It doesn't have to be a diesel since they have the same trans ratios as a gas model. OP won't know if its a diesel or not and it doesn't matter.

The picture thing… that makes little sense to me… they also don’t get to tell you they won’t do 4.10’s, you are the dog and they are the tail. They could not recommend it, but does your dollar not spend or do they just have too much?

Anyways, now that 4.30’s are no longer going to be made by Nitro… 4.56 is the next greatest thing.

Here’s a thread that might help you OP, it’s been going for a while now:

https://www.jeepgladiatorforum.com/forum/threads/gearing-for-gladiator-ecodiesel.67159/page-6

Try PMing some folks in there with 4.56’s, I bet a few reply with the pics you want.

I sit at 75mph at like 1,600 RPMs and it’s the greatest thing ever with stock gears and 37’s.. for whatever that may be worth to you’d here’s a pic.

That helps, I'm at 1800 @ 75 with 37's stock gears. So there is no precision at all with the almighty calculators that much is proven and slight tire variances in diameter don't explain 200 rpm variance so Im going with the person who placed the electrical wires against the heat shielding and against the exhaust pipes that are now shorting out the the wires might be the same person who setup the speedometers.

 

[MaxStrategery]

Someone post a pic of a speedo showing 55 MPH/1,600 RPM and 65 MPH/1,900 RPM so we can make OP happy.

It doesn't have to be a diesel since they have the same trans ratios as a gas model. OP won't know if its a diesel or not and it doesn't matter.

Thank you for your insightful, relevant and truly inspiring comment

 

[TheSolarWizard]

imo 3.73 on the gladiator is perfect rpm wise for the stock sport size tires because for the few thousand miles I ran it that way, it was fantastic pickup wise and at 70 mph it got 30 mpg on flat highway. IIRC that was a Dunlap that was 31" tall. the easiest way to figure out what gear to pick based on this equation 31" / 3.73 = new tire size"/ X gearing and solve for X. the advantage the diesel has that the gasser does not is not needing to go over that stated formula rpm just to make enough power to get it out of its own way.

I've been in a bunch of diesel wranglers and gladiators now.
based on what ive seen and felt, I like 4.10s for 37s, 4.56 for 38-40s and 4.88 for 42s
these are all in non towing scenarios. if you intend to tow regularly, I'd suggest bumping it up one. if you're not gonna do that but plan on running 80+ for long periods of time, I might consider lowering it one. if you're gonna tune it don't worry about bumping it for towing.

that's just my $.02 but based on record inflation, it's officially worth $0.03, so you're welcome

 

[MaxStrategery]

imo 3.73 on the gladiator is perfect rpm wise for the stock sport size tires because for the few thousand miles I ran it that way, it was fantastic pickup wise and at 70 mph it got 30 mpg on flat highway. IIRC that was a Dunlap that was 31" tall. the easiest way to figure out what gear to pick based on this equation 31" / 3.73 = new tire size"/ X gearing and solve for X. the advantage the diesel has that the gasser does not is not needing to go over that stated formula rpm just to make enough power to get it out of its own way.

I've been in a bunch of diesel wranglers and gladiators now.
based on what ive seen and felt, I like 4.10s for 37s, 4.56 for 38-40s and 4.88 for 42s
these are all in non towing scenarios. if you intend to tow regularly, I'd suggest bumping it up one. if you're not gonna do that but plan on running 80+ for long periods of time, I might consider lowering it one. if you're gonna tune it don't worry about bumping it for towing.

that's just my $.02 but based on record inflation, it's officially worth $0.03, so you're welcome

Here is my plan, 4.56's going in tomorrow, if they don't pan out my gas 3.6 w/ 4.10's need a regear and will just swap them out if need be. Appreciate your input it is hard to get consensus on this one mod.

 

[MaxStrategery]

Here is my plan, 4.56's going in tomorrow, if they don't pan out my gas 3.6 w/ 4.10's needs a regear and will just swap them out if need be. Appreciate your input it is hard to get consensus on this one mod.

 

[TheSolarWizard]

Here is my plan, 4.56's going in tomorrow, if they don't pan out my gas 3.6 w/ 4.10's need a regear and will just swap them out if need be. Appreciate your input it is hard to get consensus on this one mod.

I think that's because we all live in different places and do different things with our jeeps.

I doubt you will be dissatisfied with 4.56. the only thing ive observed with the over geared diesels ( at least over geared in my observation) is that you end up getting 3rd gear before you make it through an intersection and the transmission can get a little confused by that behavior. it can also sometimes refused to downshift as far as you might like to pass on the freeway but again that's more of a perspective thing. I recommend you turn on your headlights and disconnect both batteries when you do the gears so you force the trans to relearn

 

[MaxStrategery]

4.10's for 37's, 4.56 for 39's

Tire Size Change Gear Ratio Calculator | Interco Tire

#math

The calculator are wrong, all of them

 

[MaxStrategery]

I think that's because we all live in different places and do different things with our jeeps.

I doubt you will be dissatisfied with 4.56. the only thing ive observed with the over geared diesels ( at least over geared in my observation) is that you end up getting 3rd gear before you make it through an intersection and the transmission can get a little confused by that behavior. it can also sometimes refused to downshift as far as you might like to pass on the freeway but again that's more of a perspective thing. I recommend you turn on your headlights and disconnect both batteries when you do the gears so you force the trans to relearn

The battery thing. Will do!

 

[MaxStrategery]

That helps, I'm at 1800 @ 75 with 37's stock gears. So there is no precision at all with the almighty calculators that much is proven and slight tire variances in diameter don't explain 200 rpm variance so Im going with the person who placed the electrical wires against the heat shielding and against the exhaust pipes that are now shorting out the the wires might be the same person who setup the speedometers.

Also, Nitro no longer offering 4.56 gears they now only have 4.63 and up

 

[Wheelin98TJ]

The calculator are wrong, all of them

The results are wrong when you input wrong data. Junk in, junk out.

It’s math. It’s never wrong.

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