For those going with 37s, are you regearing??

gato

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With the 8-speed auto, 4.10 Rubi gears, lighter (e.g. KO2s) 37s and high cruise speeds, I see more downsides to regearing than upsides.

The gearing teeth are smaller and can handles less torque. You may void the warranty for things like the infamous locker sensor failure. Jeep is slightly noisier due to higher RPM if you are cruising at 75MPH.

At the other end of the spectrum, manual transmission, heavy 37s, Sport/Sahara, lower (60MPH) cruising speeds, a regear may be advantageous.

For me, if I trusted my axles to handle it, I'd have no problem running 39x13.5 BFGs with the Rubi 4.10 and A8. But everyone's driving style and preferences are different. So put the tires on, see how you like it before making any decisions. There is no set answer.





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Jammer

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With the 8-speed auto, 4.10 Rubi gears, lighter (e.g. KO2s) 37s and high cruise speeds, I see more downsides to regearing than upsides.

The gearing teeth are smaller and can handles less torque. You may void the warranty for things like the infamous locker sensor failure. Jeep is slightly noisier due to higher RPM if you are cruising at 75MPH.

At the other end of the spectrum, manual transmission, heavy 37s, Sport/Sahara, lower (60MPH) cruising speeds, a regear may be advantageous.

For me, if I trusted my axles to handle it, I'd have no problem running 39x13.5 BFGs with the Rubi 4.10 and A8. But everyone's driving style and preferences are different. So put the tires on, see how you like it before making any decisions. There is no set answer.
Yeah most everyone that did 40s is doing one ton axles. Yea 39s is close to to not have to do one ton axles. 38s you can probably get away without one ton axles but you're very limited on tire choices on 38s
 

JeepinJason33

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With the 8-speed auto, 4.10 Rubi gears, lighter (e.g. KO2s) 37s and high cruise speeds, I see more downsides to regearing than upsides.

The gearing teeth are smaller and can handles less torque. You may void the warranty for things like the infamous locker sensor failure. Jeep is slightly noisier due to higher RPM if you are cruising at 75MPH.

At the other end of the spectrum, manual transmission, heavy 37s, Sport/Sahara, lower (60MPH) cruising speeds, a regear may be advantageous.

For me, if I trusted my axles to handle it, I'd have no problem running 39x13.5 BFGs with the Rubi 4.10 and A8. But everyone's driving style and preferences are different. So put the tires on, see how you like it before making any decisions. There is no set answer.
Voiding the warranty depends on the dealership. That is if the mechanic even figures out there are different gears in there. The sensor did fail in my front axle immediately after the re-gear. The service department told me they did not care about the re-gear, but that I would have to pay to swap out the gears in the new axle. That would cost more than just getting the Tazer sensor fix.

At altitude, the re-gear was absolutely necessary. I did not notice any increase in noise and the RPM's are similar to before the extra weight and gears. Off-road crawling was incredible! The gearing was perfect.

It is difficult to jam a bunch of money into the 44's if you are planning on going with 60's later on. For me, 60's are in the future, but will probably wait a few years. I am already about 20k into mods on the JL and it performs very well off road.
 

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Someone told me that went the 513s that it doesn't down shift at a certain speed as good. So the way to get it at the stock is the 488s
There's a number of members here who have done a regear, but didn't reprogram for the larger tire and lower gearing. They seem to think that it's just a correct speedo that they get for the money, but don't realize that although the transmission is adaptive it still relies on being fed accurate baseline info.
 

gato

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Voiding the warranty depends on the dealership. That is if the mechanic even figures out there are different gears in there. The sensor did fail in my front axle immediately after the re-gear. The service department told me they did not care about the re-gear, but that I would have to pay to swap out the gears in the new axle. That would cost more than just getting the Tazer sensor fix.

At altitude, the re-gear was absolutely necessary.

.... I am already about 20k into mods on the JL and it performs very well off road.
Was that with the Turbo on 3.6 that you noticed the altitude degradation?

$20K of mods, ouch. You made me feel better since I'm around $8K. The issue is that the next step (D60 + 39x13 tires) is huge!
 

JeepinJason33

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Was that with the Turbo on 3.6 that you noticed the altitude degradation?

$20K of mods, ouch. You made me feel better since I'm around $8K. The issue is that the next step (D60 + 39x13 tires) is huge!
Was with the 3.6L. Originally purchased the 3.6l because I like the fact that the torque comes up with less RPM's than the 2L Turbo. I also figured I was going to supercharge it at some point, but honestly with the gear change, I don't think there will be a need for the superchager. Jumps off the line and holds 75mph in 8th gear just fine at 6,000 ft which is where I do the majority of my driving.

I sold one of my paid off Jeeps for 20k to use the proceeds for building up this one. Pretty much did everything I could dream of on this one right away. Will upgrade axles in a few years when it is time for new tires.
 

Zandcwhite

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Was with the 3.6L. Originally purchased the 3.6l because I like the fact that the torque comes up with less RPM's than the 2L Turbo. I also figured I was going to supercharge it at some point, but honestly with the gear change, I don't think there will be a need for the superchager. Jumps off the line and holds 75mph in 8th gear just fine at 6,000 ft which is where I do the majority of my driving.

I sold one of my paid off Jeeps for 20k to use the proceeds for building up this one. Pretty much did everything I could dream of on this one right away. Will upgrade axles in a few years when it is time for new tires.
Was with the 3.6L. Originally purchased the 3.6l because I like the fact that the torque comes up with less RPM's than the 2L Turbo. I also figured I was going to supercharge it at some point, but honestly with the gear change, I don't think there will be a need for the superchager. Jumps off the line and holds 75mph in 8th gear just fine at 6,000 ft which is where I do the majority of my driving.

I sold one of my paid off Jeeps for 20k to use the proceeds for building up this one. Pretty much did everything I could dream of on this one right away. Will upgrade axles in a few years when it is time for new tires.
While technically the 3.6L torque comes on at lower rpms, it gets destroyed in that department in every real world driving condition/rpm range by literally every other engine available in a JL. By 2,100 rpms the 2.0 is flying right past the 3.6L torque output. That's literally less than 1/10th of a second after leaving a stop sign or hitting the throttle on an obstacle. By 3,500 rpms the 2.0L is up by 75 ftlbs at the wheels. The only place the 3.6L beats the turbo is above 5,700 rpms, but who runs those kind of rpms in a jeep anyway? As far as power under the curve and real world driving, it's not even close.
20v36_torque-jpg.jpg
 

JeepinJason33

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While technically the 3.6L torque comes on at lower rpms, it gets destroyed in that department in every real world driving condition/rpm range by literally every other engine available in a JL. By 2,100 rpms the 2.0 is flying right past the 3.6L torque output. That's literally less than 1/10th of a second after leaving a stop sign or hitting the throttle on an obstacle. By 3,500 rpms the 2.0L is up by 75 ftlbs at the wheels. The only place the 3.6L beats the turbo is above 5,700 rpms, but who runs those kind of rpms in a jeep anyway? As far as power under the curve and real world driving, it's not even close.
20v36_torque-jpg.jpg
Thanks for the graph. It is similar to the others I have seen showing that "technically?" the 3.6 torque does come on at lower RPMs. I bought the JLUR for my version of real world driving which is trails every weekend. I did not want to hit 2,100 RPM's all the time. Running the same exact obstacles over several trips with guys running 2.0 turbo's I have seen them have to rev it up higher to get the torque to get up. In many cases, not being able to crawl up like I was. Could be several other factors, like driver ability, tires, lift, or whatever. To me, it seemed like a torque issue.

Not debating which is a better engine. I think it depends on the driver and what they are using it for. The 3.6l is the one I initially wanted due to the ability to run a supercharger if needed. Right now the supercharger options are not great as they are having problems getting the tune right. Eventually they will figure it out. However, I have been very happy with the 3.6l and don't feel like the supercharger is as needed as it was on my 4.0l TJ.
 

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