Advice requested re regear for 315’s

[dayusmc]

Mine has been causing misfires above 6k in fourth gear. Truck is in the shop for that.

Your Banks Pedal Monster is causing misfires?

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[Russ2023]

The 3.6 is a high revving engine it's gonna want to shift later than what you're thinking it will because of that.

High revving? I’m used to some of the cars I’ve had liking to live in the higher rpm range, but I wasn’t aware that would apply to the JT as well. Interesting. Thanks

 

[Russ2023]

The 3.6 is a high revving engine it's gonna want to shift later than what you're thinking it will because of that.

Thanks. I guess I need to adjust how I view a high revving engine. I’m used to cars where when you’re in the higher rpm’s you know it w/o having to glance at the tach because they were screaming like a banshee as you’re bouncing the needle off redline. I guess I was figuring if I pushed it even half as hard I’d be hearing a boom instead.

Well again it proves true that the most important mod you can make is typically with the driver. Guess I better get after it.

 

[Russ2023]

Have you addressed this with the dealership?

Yep, twice. And both times I was able to demonstrate the rough shifting to an SA (to clarify I’m talking about it seeming to strain to upshift) but then the wrench turns it back in saying no problem found.

Probably a good time to visit a different dealership. It’s becoming increasingly frustrating to feel like you’re talking to a form of intelligent life at my dealer anyway.

 

[Gee Man]

Ok, I’m sorry for being responsible for yet another question about regearing. Trust me, I’ve been immersing myself on the subject to the point of feeling like I know less now than when I started. Even people who I was thinking of as pretty damn knowledgeable had contradictory opinions and advice.

So, my ride is a Texas Trail version. It came with the 3.73 gear ratio. I just upsized the tires to the BFG All Terrain T/A K02’s 315/70R17’s (C2).

I’m waiting on the Veepeak Bluetooth device and cable adaptor and currently I’m really only planning to modify the tire size and the gear ratio IF THE LATTER IS NECESSARY. I’m confident about the tire size needing to be recalibrated, but because of all the contracting opinions about the regearing I’m not sure what to do. I realize I could just play around with the setting until I’m satisfied, but I don’t really want to have to jack with that damn bar down there under the dash that makes access to the cables exponentially more difficult than it had to be.

The only other thing I can add is shifting in this thing is NOT impressive and it’s been that way since new. Never have the display set to where I can see the gear but it seems like it really sucks going from either 3rd to 4th or it might be 5th to 6th. I’m so used to it now I don’t really pay that much attention.

So anyway, I’d be forever thankful just to hear what you’d do. The area I’m in (bit west of Ft. Worth) is about as flat as it gets with the odd rolling hill added for good measure. I rarely have the opportunity to get off-road and it’ll never be climbing rocks. I’m leaning towards 4.10 but I know there’s a lot of people that would say stay with the 3.73. As I was saying, I realize I could just play with it and see how it drives between 3.73 and 4.10, but I’d really rather have to jack with that bar down there once. My hands are just way too big for getting in and out of that area.

‘Thanks a ton for listening. I appreciate it.

Look on line for gear ratio for tire size it will give you ratio and RPM. For 315 it recommends 4:56

 

[Gee Man]

Thanks. I guess I need to adjust how I view a high revving engine. I’m used to cars where when you’re in the higher rpm’s you know it w/o having to glance at the tach because they were screaming like a banshee as you’re bouncing the needle off redline. I guess I was figuring if I pushed it even half as hard I’d be hearing a boom instead.

Well again it proves true that the most important mod you can make is typically with the driver. Guess I better get after it.

 

[dayusmc]

Thank you for this!!!! This is exactly what I was looking for. So 37" with 4.88 are as close as you can get to 35" with 4.56.

 

[Russ2023]

Look on line for gear ratio for tire size it will give you ratio and RPM. For 315 it recommends 4:56

Excellent information, thanks.

 

[Russ2023]

Thanks!!!

 

[Wheelin98TJ]

Thank you for this!!!! This is exactly what I was looking for. So 37" with 4.88 are as close as you can get to 35" with 4.56.

Excellent information, thanks.

That is the wrong chart. It's for a 6 speed auto. RPM numbers are not correct for the 8 speed.

4.88 with 35" tires (assume 34.5" actual height) in 8th gear at 70 MPH = about 2,300 RPM.

 

[dayusmc]

That is the wrong chart. It's for a 6 speed auto. RPM numbers are not correct for the 8 speed.

4.88 with 35" tires (assume 34.5" actual height) in 8th gear at 70 MPH = about 2,300 RPM.

Thank you. But now I am really confused...
I am trying to figure out what gears would be the same for a 37" tire as a 35" tire with 4.56.

 

[Iddpaul]

Ok, I’m sorry for being responsible for yet another question about regearing. Trust me, I’ve been immersing myself on the subject to the point of feeling like I know less now than when I started. Even people who I was thinking of as pretty damn knowledgeable had contradictory opinions and advice.

So, my ride is a Texas Trail version. It came with the 3.73 gear ratio. I just upsized the tires to the BFG All Terrain T/A K02’s 315/70R17’s (C2).

I’m waiting on the Veepeak Bluetooth device and cable adaptor and currently I’m really only planning to modify the tire size and the gear ratio IF THE LATTER IS NECESSARY. I’m confident about the tire size needing to be recalibrated, but because of all the contracting opinions about the regearing I’m not sure what to do. I realize I could just play around with the setting until I’m satisfied, but I don’t really want to have to jack with that damn bar down there under the dash that makes access to the cables exponentially more difficult than it had to be.

The only other thing I can add is shifting in this thing is NOT impressive and it’s been that way since new. Never have the display set to where I can see the gear but it seems like it really sucks going from either 3rd to 4th or it might be 5th to 6th. I’m so used to it now I don’t really pay that much attention.

So anyway, I’d be forever thankful just to hear what you’d do. The area I’m in (bit west of Ft. Worth) is about as flat as it gets with the odd rolling hill added for good measure. I rarely have the opportunity to get off-road and it’ll never be climbing rocks. I’m leaning towards 4.10 but I know there’s a lot of people that would say stay with the 3.73. As I was saying, I realize I could just play with it and see how it drives between 3.73 and 4.10, but I’d really rather have to jack with that bar down there once. My hands are just way too big for getting in and out of that area.

‘Thanks a ton for listening. I appreciate it.

Hoping this may help! From my own personal experience, I've had the gearing changed on several rides to get the trans/engine/powerband back in line with my tire size and intended use. You will also need to recalibrate for the gears/tire size (Jscan or Tazer).

With the 3.6 auto 8 speed:
35's/315's - I found 4:56 gears to be perfect for my use (Highly recommended).
With 37's I changed to 4:88 gears (if I had been at high elevations or maybe rock climbing I would have gone with 5:13's for sure).

I'm now driving a JTRD with 37's and 4:56 gearing, which is perfect for my use and is one of the best improvements I've made to date.

You will read lots of comments on the forum "for doing or not doing" a gear change. Personally you will feel a marked improvement in performance/gear shifts, etc., by changing the gears, especially going from 3:73 to lower gearing like 4:56. (4:10's will be fine with 315's BUT if you go to bigger tires in the future then you'll be "under-geared" again)

Now the other issues (1) Cost and Time (Dana gear set approx. $650 front and rear, Bearing install kits approx. $480 front and rear, and then labor - somewhere around $1,200 to $1,500), (2) finding a shop that can do the work correctly, (3) possible added costs for changing out other items (driveshafts, extended brake lines, etc., etc.)

 

[JT1]

buy the extension cable (sounds like you are going to be using JSCAN) to adjust tire size.

Thank you. But now I am really confused...
I am trying to figure out what gears would be the same for a 37" tire as a 35" tire with 4.56.

4.88s on 37s is within 50RPM of 4.56s on 35s

 

[Wheelin98TJ]

Thank you. But now I am really confused...
I am trying to figure out what gears would be the same for a 37" tire as a 35" tire with 4.56.

4.88 with 37s is about the same final drive ratio as 4.56 with 35s.

 

[MaximusTX]

Here is another source of information for you. Exodus4x4 builds jeeps and has a ton of youtube videos on their builds. Here is what they recommend for regears. Have 35s with the 3.73 gears. Mine hardly gets out of 6th gear unless I am going downhill and then it will go into 7th but has never gone into 8th. I plan on going to 40s shortly and will regear at that point. I also have the Banks Pedal Monster installed but from my understanding it does not do anything for shifting it just helps match the throttle curve to the correct gear.

Exodus 4x4 Regear

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