need more out of 4th gear

[IOPort51]

your power /torque curve peek around 25-2700 RPMs that is where you will find your best power and fuel efficiency.

you should consider the fact that the 36" tires make your speedometer reading WAY off! You could already be doing 70 when it reads 60. Do the math with the actual wheel diameter and/or have a friend with a stock vehicle follow you and tell you how fast you are really going.

The alternative to changing R&Ps ( very expensive) is to run smaller tires.
not the first choice, I am sure but if you are using this as a daily driver it could be your best bet.

 

[lefty]

I noticed the speedometer difference the first time driving it. When it read 35 MPH I was actually doing 50 and using GPS, speedometer apps on my phone and having my wife follow me or vise versa I found that the speed difference fluctuated between 10 to fifteen MPH depending on what speed I was traveling. The higher the speed the higher the difference. I drive it to work which is about two miles both ways and run around town sometimes but other than that its just for fun and I like the looks and feel of the big tires but want to make the drive train stronger to support them. Thanks for all the feedback and help from y'all I appreciate it.

 

[BusaDave9]

I found that the speed difference fluctuated between 10 to fifteen MPH depending on what speed I was traveling. The higher the speed the higher the difference.

Your speedometer is off by about 66%

The PO installed tires that are 66% bigger than original tires. That makes your jeep go faster even when the engine speed is slow. When the engine is going at 66% lower rpm it doesn't have much power. By putting in 4.56 or 4.88 gears your engine RPM will go back up to what the factory intended at highway speeds (more power). You will also find out the speedometer will be more accurate too.

 

[lefty]

sounds like the gear swap is the next thing to do to the jeep. will do it soon and let you guys know how i make out. thanks for the help