Hey guys, new to the JK world and doing a few mods to my 08. Putting a 4 inch lift and 35's on it and have a question about re-gearing. 08 JK Sahara Unlimited 6speed manual tranny. Mostly a daily driver, but occasionally I tow a golf cart to the beach. Obviously has mileage has to be a factor but I'm looking for a good balance between that and tow power. Anyone have any advice or is in a similar situation? Which gear should I run? Been leaning towards the 4.88's. What kind of gas mileage can I expect with that?

 

I have roughly the same deal as you, I'm planning on 4:56. - 4:56 is perfect especially as a DD (more expensive tho) - 4:88 if you want a lil more kick (less expensive).

 

I have an 08 with a manual tranny, 35's and a 4.5" lift. I put 4.88's in mine and it works well for me. My mpg went down from when I had the factory 3.21's, but it's a lot easier on the motor and I don't find my self shifting constantly. I'd highly recommend the 4.88's. At 70 mph on the hwy, my RPM's are around 2800. MPG wise, you can expect any where from 13.5 to 15 or 16. Depending on your foot and/or where you live.

 

IMO, there really isn't any "kick" with the 4.88's. Really you don't notice a major power difference till you're in 4lo. Main difference is how often you shift and that you can actually pass people if you need to. Not saying that you will fly by them...because you won't. Good ol 3.8 . Just my 2 cents

 

Having spent 20+ years as truck driver I have a little different view on gear choice than most. I have read post after post saying that you will be shifting more with a higher (numerically lower) gear but that really doesn't bother me. If it did I'd buy an automatic.

I pick my ratios by what happens in first gear as much as by what happens in OD. With the 3.8, if it's geared low enough to stop the downshifting on the highway then it is probably low enough that you'll cruise round town one gear higher and effectively increase in town shifting to offset what is gained on the Xway. There's nothing wrong with that, I just feel that I have my cake and eat it too when I can use OD on flat Xways and drop a gear when I pass a car or tow something. I will concede this...if you are dropping two gears on the Xway for whatever reason then I strongly recommend a gear swap.

Of course all of this goes out the window when off road performance and crawl ratios are in question but the discussions always seem to revolve around street usage as a priority. I gear for street first and dirt second since the roads are paved all the way to work.


Jer