I'm putting 35's on my 09 JK Unlimited. Will I need to "re-gear" and buy a "super chip"?
Is "re-gearing" modifying my rear axle?

 

I have a 08 Rubi unlimited with auto trans and 35's. I went with 5.13'. I have an Airaid, Superchip and magna flow exhaust. Thing is still a dog, but I love it. I'm glad I didn't go 4.88 like some friends suggested. At 2500 RPM I'm running 71 mph...3000 RPM gets me to 80 mph.

Hope this helps.

Kyle

 

You don't HAVE to do either. You will have a bit more of a sluggish feel when you go with the bigger tires. The Superchip is a less-expensive option to gain some of the power back. If you really want to get back all of the power, the re-gear is a great option. And yes, re-gearing involves changing out the gears inside your differentials on both the front and rear axles.

If you want more info, check this out:

https://www.jk-forum.com/forums/show...276#post211276

 

Thanks for the reply and also for the link Merlin!!!!

 

Thanks Kyle!!! I have a 6 speed manual, I wonder what the difference would be?

 

My neighbor has 35", stock gears on an auto sahara. He's been running it that way for probably 2 years.

 

I have 35's with 3.73 and an auto, it is doable. Having said that, I MUST run with OD off. I am looking at the different chips and from what I gather, they help. But the real answer is re-gearing. Guys usually go with 4.56, 4.88 and 5.11's, that depends on how you drive your Jeep and what you expect. I will re-gear at some point in the future.

 

The transmission gearing between auto's and manuals is fairly significant. In the drive-train area of the FAQ's (linked above), you will find some rpm charts. They will show you 'exactly' what the difference will be. (generally, a 6spd will need to run tires that are about 5" taller to get the same freeway rpm's as an auto with the same axle gearing. Tranny gearing on autos sucks...)


Rear axle on a 2wd, both axles on a 4wd.

 

I drive a six speed as well, once I put my 35s on, I lost sixth gear and going uphills on highways is a struggle. I tow a single jet ski that weighs maybe 400lbs total and its like having an anchor back there. I have driven like this for about a year, its do able but not ideal. My MPGS are horrible not that I didnt know that wouldn't happen any way but I m mean like 12-15mpg. A re-gear should help with that but that would just be a bonus. Not my main concern. I just want some power back. This is my DD but I love to go off-road as much as possible.

I am planning on re-gearing very soon and have been doing a lot of research on this.......I also have a manual and plan on getting 4.88s. From everything I have read you will get the same results with 4.88s that an auto will get with 5.13s. It will actually be a little more gear than the stock setup. To get back to stock with a manual and 35s you only need to get 4.56s. But why spend all that money to get back to stock? we all know the 3.6L could use a little extra umf especially if you dont have a Rubi with the lower geared transfer case. I emailed around and the best price I could find was 600 an axle including gears. Thats from a shop in San Antonio, but I m trying to find someone who can teach me how to do it and I ll pay them for their time. The gears and overhaul kit should run you under 700 total for both axles.

Take my advice with a grain of salt, because like I said I have not had it done yet.....BUT on the other hand I have been trapped in Iraq for the past 5 months with nothing to do but read this site everyday so when I say I have done my research I mean I have done my research. Maybe someone can back me up who has had it done.

CX