Highway RPMs too high?

[Joseph]

Finally got my Jeep back after about a month after the accident. I actually was driving my old car (2002 BMW) that I sold to my parents for the time being and got smashed from the side by a guy who rolled through a stop on Sunday! That's getting hit twice in less than a month. Had to get the Jeep back before the guy could do all the frame painting. At least neither were my fault haha

But anyway, my 4.0 TJ 3 speed Dana 44 rear was running about 3100 RPM on the highway at about 70mph today. I don't remember it being that high unless I was doing about 80mph. Maybe I don't remember. I have 30" tires if that helps. With the new tube fenders I'm hoping to run 33s stock height until I can afford a lift.

Could there be a chance my torque converter isn't locking up? I thought I was having the same problem yesterday too, so I came to a complete stop then hit about 60 on a backroad. I could hear it lock up. Now, when I got on the highway today, without coming to a complete stop, I don't think I heard it lock up, but I wasn't really paying too much attention. No CEL.

Heres how she sits now guys

 

[jjvw]

I wouldn't call that a problem. What axle gears do you have?

33s would decrease the rpms a bit, but be aware that tube fenders don't add any clearance over the stock fenders. And 33s require bump stop extension to keep them out of the sheet metal. This will prevent damage, but will also decrease the suspension up travel until you can add to the ride height.

 

[Joseph]

I wouldn't call that a problem. What axle gears do you have?

33s would decrease the rpms a bit, but be aware that tube fenders don't add any clearance over the stock fenders. And 33s require bump stop extension to keep them out of the sheet metal. This will prevent damage, but will also decrease the suspension up travel until you can add to the ride height.

Where can I find out what gears I have? The build sheet? Or is there a tag on the axle? I only had the Jeep for a few months before the accident so it's hard for me to recall how everything felt and sounded, especially after driving a quiet smooth BMW for a month. My exhaust leak definitely got worse after the accident, and I can hear that it's a lot more raspy in the rear. Maybe that's why I am worrying about the high RPM, more noise than before.

 

[jjvw]

Where can I find out what gears I have? The build sheet? Or is there a tag on the axle?

There is most likely a tag on the diff covers. I would guess yours are 3.73.

 

[Brianj5600]

I like this video for checking ratio.

 

[Jerry Bransford]

The ECM would generate a Check Engine light and a diagnostic trouble code if your torque converter wasn't locking up. Your 32RH transmission doesn't have an Overdrive so it's going to have considerably higher rpms than your BMW or any normal car will have.

 

[Joseph]

The ECM would generate a Check Engine light and a diagnostic trouble code if your torque converter wasn't locking up. Your 32RH transmission doesn't have an Overdrive so it's going to have considerably higher rpms than your BMW or any normal car will have.

Yeah no doubt. I thought it was locking up but sometimes not. It felt abnormally high to me as I searched up what people were saying they got at highway speeds, most said around 2700 at 70mph, but again, my tires are considerably smaller than most (for now).