Re-gearing questions

[Lexi]

So my front cv joint is toast. I was going to just replace the front driveline and hold off on the rear, well that changed.

Then I was looking at new gears and they are not as nearly as expensive as the driveline. My adhd/impulsive brain is screaming just get those too.

For those that regeared their own jeep (installed themselves) I need some input. I currently have stock 3.21 gearing. I want to go to minimum 4.11 possibly 4.56. Did you have to install a new differential case as well or am I just over thinking it?

I have a jku 2010 automatic 3.8L 33s on a 2.5in lift

 

[JeepJeezy]

You don't need a new diff case. The difference between gears is the amount of "teeth" involved.

 

[Lexi]

Thank you.

 

[Dirty Dog]

For those that regeared their own jeep (installed themselves) I need some input.

Swapping differential gears sounds like an easy job. It's really not. It requires some specialized tools, and a fair bit of mechanical experience. Most people will have the common tools, like wrenches and sockets. But do you have things like a dial indicator and dial caliper? Lock wire? Hydraulic press? Gear paint, and an understanding of how to read it?

I currently have stock 3.21 gearing. I want to go to minimum 4.11 possibly 4.56.

At 80 MPH, on 33's (have you measured? Advertised 33 doesn't really mean 33"...) with the 3.21 gears, you should be turning about 1900 RPM. With 4.11 gears, that will increase to about 2400 RPM. With 4.56 gears, it will jump to about 2700. That's something to be considered.

Did you have to install a new differential case as well or am I just over thinking it?

You really cannot change the differential housing. The pumpkin and the axle tubes are welded together. If you removed the tubes without making them unusable, you'd have to weld them to the new pumpkin. Most differential housings are cast iron. Have you ever welded cast iron? Few hobbyists would tackle such a job.

You have some off-road parts on there. If you're off-roading it, are you going to stick with the factory open differentials? If you're going to add lockers, the time to do it is when you change the gears. Otherwise all the work setting up the new gears will have to start over.

Did you recalibrate your speedometer after the 33's? You will definitely need to recalibrate (again) after a gear swap. Going from 3.21 to 4.56 means that at an indicated speed of 80MPH you will actually being going about 55 or so.

I'm not trying to discourage you from swapping gears, or from doing the job yourself. I do suspect that not knowing that the differential housing can't really be changed indicates you might be getting in over your head.

I have a jku 2010 automatic 3.8L 33s on a 2.5in lift

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Nice looking Jeep. I'd duck it.