35 vs 37 no regear
JK Jedi
Joined: Apr 2011
Posts: 4,482
Likes: 2
From: Neenah, Wisconsin
I have 08 auto with 3.73 gears. Ran 37s on d30 for about 4 months. Also had the flash cal. It did ok around town, and sluggish on the freeway, on any incline. Took OD off and it helped slightly. Very lite wheeling. Like previously stated, it absolutely can be done and you do not have to regear right away but it will cause additional stress on the transmission and Cs. For me, the cost of repairing/replacing my tranny wasn't worth it. I downsized to 35s.
Hope this helps.
Hope this helps.
JK Enthusiast
Joined: Mar 2009
Posts: 223
Likes: 1
From: Los Angeles, CA
Have an 09 JK that I bought brand new in 2009 and the day after I bought it I put a 2.5" lift and 35's on it and drove around like that for 5 years with no regear. This past January I decided to upgrade to a 3.5" lift, 37's and a 5.13 gears and let me tell you that the regear was by far the past decision I made. It drives stock despite the lift and 37's.
Do yourself a favor an get'er done
Do yourself a favor an get'er done
JK Enthusiast
Joined: Dec 2012
Posts: 123
Likes: 0
From: Highland, CA
I have a 2013 Rubicon, originally with D44 front and rear with 4.10 gears and an auto.
I ran 35" tires with very few issues. Off road in low gear with the 4to1 was no issue either.
I also sleeved and gusseted my axle and spindles.
I recently upgraded to 37" tires and could really feel the difference. Up any inclines it would drop gears quickly and steeper grades I would go up in 3rd gear on the highway.
Within two weeks I upgraded the gears. I went with 5:13. I wouldn't recommend going that low. I do a lot of rock crawling, so it is fine. For more trail running I would recommend 4:88's. With the 4 to 1 transfer case and 5:13 gears I cannot get up to 20mph on dirt roads unless I really rev it in 5th gear.
With your 2:73 to 1 you would be okay with 5:13s, but 4:88s would give you better daily drivability.
In a D30 the larger gears are much thinner, so consider that when choosing.
In short, you will really feel the loss of power with 37" tires and 3:73 gearing. I did with 4:10s.
I ran 35" tires with very few issues. Off road in low gear with the 4to1 was no issue either.
I also sleeved and gusseted my axle and spindles.
I recently upgraded to 37" tires and could really feel the difference. Up any inclines it would drop gears quickly and steeper grades I would go up in 3rd gear on the highway.
Within two weeks I upgraded the gears. I went with 5:13. I wouldn't recommend going that low. I do a lot of rock crawling, so it is fine. For more trail running I would recommend 4:88's. With the 4 to 1 transfer case and 5:13 gears I cannot get up to 20mph on dirt roads unless I really rev it in 5th gear.
With your 2:73 to 1 you would be okay with 5:13s, but 4:88s would give you better daily drivability.
In a D30 the larger gears are much thinner, so consider that when choosing.
In short, you will really feel the loss of power with 37" tires and 3:73 gearing. I did with 4:10s.
JK Newbie
Joined: Feb 2013
Posts: 42
Likes: 0
From: Wylie, Tx
We have a 13 JKUR with D44s and 4.10s. Added lift and 35s and didnt really notice any difference other than fuel economy. Recently we have started to armor the underside and that has had a much more pronounced effect on the acceleration than expected. So now before we add anything we check how much it weighs. Recently did some cardboard recycling and got the jeep weighed. Using the manufacturers listed weight its about 750-800lbs heavier than stock now without passengers. Tires, subwoofer setup, a plywood rear deck, heavier suspension, and armor take their toll. Just ordered a rear body mounted tire carrier so we can add the full size spare. tried to go light, but its going to add another 80-100# of weight. Im thinking regear is def in our not too distant future.
JK Enthusiast
Joined: Apr 2007
Posts: 105
Likes: 0
I would not worry about the axles with factory gearing and 37's the rest of your drivetrain will be really stressed mainly the driveshafts but you are going to really overwork the transmission and will have no torque for climbing anything. If you have a 07-11 with the 3.8 I would stop at 35" tires and run 5.13 gears.
JK Super Freak
Joined: Apr 2007
Posts: 1,258
Likes: 1
From: Prosper, TX
K I know there are many threads on this but I have 33s on my jk right now with auto trans I am going to upgrade the first of the month to a bigger tires I don't want to get a regear right now but if I go to a 37 will I absolutely have to? Will it be unbearable and put too much stress on the front Dana 30?
A 3.6 with 4.10s will handle it better than a 3.8, juice trans and 3.21s.
I did the 3.8 juice trans and 37s for a while and it was livable. Finally regeared to 5.13 and it was much better. Don't have that Jeep any more but am back with the same set up and looking forward to the regear. It's livable, but definitely not optimal.