Hey everyone. Im gettting closer to getting my JK. When I do get it I can have the dealer install a lift kit and new 18" wheels with 35" tires and drive off the lot with my new Jeep already the way I want it. With 35" tires what front and rear gearing would I need to make it drive like it had stock wheels and tires on it? Also is this something I can install myself at my house? Im pretty good with motor swaps in Honda's and Acura's but I dont know what Im going to get in to messing with with a Jeeps front and rear end. Any help on this would be great. Thanks

 

theres a ton of threads on this but.

4.88's will make it stock.

I personally run 5.13's its quicker than stock, and will be perfect for when I upgrade to 37's.

If you've never done gear swaps, its not something i would try.

 

x2... if its an auto. Also, just a word of advice on dealers doing mods... DON'T LET THEM! I've got a lengthy story on the dealer trying to install my lift and gears. The lift, I'd give them a D+ for what they accomplished... the Gears... well, lets put it this way, the Dealer had to call me up to tell me they couldn't get my axels put back together and that they'd be towing my Jeep on a flat bed to the 4x4 shop of my choice at their expense. Needless to say the 4x4 shop put it back together and have had no issues!

BTW... Welcome to the forums!

 

I regeared to 4.88 and there it now runs at much higher rpm at any given speed. I had heard the 4.88 and 35's would return it to stock, but that is not true. I run at almost 3000 rpm at 70 mph in 6th gear where it was at 2300 before. I am not unhappy, but would have opted for 4.56 if i knew then what i know now.

 

I'm running 5.13's at 70MPH and 3000RPM w/ 35's

 

Do you have a 6 speed too?
I have the auto w/5.13's and Im only doing 2700RPM at 70MPH

 

The dealer that Im going to buy from seems to do really good work. I havent heard any complain about their work. I bet they have about 20 JK's on the lot right now and half have Skyjacker lift kits with 18" wheel and 35" tires. I have a lot of pictures of the Jeeps on their lot that I will post up later to see what opinions you all have. I may just wait and do it all myself. Not sure how hard the lift will be to do in my driveway.

Im going to do a lil test this weekend as far as stock gears go. Im going to test drive two 6 speed Sahara's. One has stock wheels and tires and the other will have after market wheels with 35" tires. Im going to drive both Jeep to 3000 RPM and write down the speed in all six gears. I know the speedometer will be off so Im not sure how close the 35"s will be to the actual speed. The main thing I want is the stock speeds at 3k so I will know if my gears are right when I do a regear. I had a 4 banger YJ and did a 4" lift with 33" tires and my top end was 60 MPH at the most. I am not going through anything like that again.

This is a great forum and everyone seems nice on here. Any input you all give will greatly be appreciated. Oh one more thing. Does anyone know the formula for calculating gear ratios in JK's?

Thanks

 

I belive the 4.56's would put you back to stock and 4.88's one above. I was told this by a ring and pinion shop he's been doing this since before my time.

 

Sorry but 4.56 will bring 33" tires back to stock, 4.88's for 35's and 5.13's for 37's. But, as Pininajeep said, I'd personally recommend 5.13's with 35's (what I have now) if you want to see a little performance gains.

 

Yes, 6 speed @ 70MPH 3000RPM