|08-22-2012 10:14 PM|
|hooner||Speaking of the six speed LJ, does anyone have one that is running 33s and know what gearing they have? I recently bought a used LJ rubicon with 33s and would like to compare rpm's at speed to try and determine if I have the stock 4.11s or possible 4.56s. Thanks|
|08-21-2012 02:47 PM|
4.10s for 33s, 4.56s for 35s work pretty good with the NSG370.
some do 4.56s/33s, 4.88s/35s though.
|08-21-2012 02:46 PM|
I have read countless posts about regearing with the 4.0 and the 5 speed but i cant seem to find anything about the 4.0 and the 6 speed. What i would really love to find is a gearing chart designed for the 4.0 with the 6 speed manual (ex LJ wrangler)...anybody help me out here? I would be most likely running 33's initially but stepping up to 35's.
|12-26-2009 04:03 AM|
Also, the gear charts are very misleading. They are more accurate for a 5-speed than they are for an auto though, as the auto will need even lower gearing (numerically higher). Like Jerry said though, larger tires have more weight. The charts take into consideration the diameter of the tires, but they don't consider width, contact patch, weight, rolling resistance, etc. A decent way to determine your gear ratio is to use the following equation:
New tire size divided by old tire size times old gear ratio = new gear ratio. If you are in between gear ratio sizes, ALWAYS round up (not down) to the numerically higher gear size and then jump up one more size (possibly two depending on your engine power, weight of accessories, if you live in the mountains, etc.).
My XJ with an AW4 auto came stock with 3.55 gears. I initially re-geared to 4.56 for 35's, but the vehicle was constantly shifting and searching for gears on even moderate inclines. I have a set of 4.88's that I plan to install very soon. I would have gone with 5.13's, but they are not available for the Dana-30. I drive this vehicle on the freeway at 80 all the time, and the 4.56's are way to tall. 35/ 29 x 3.55 = 4.28. Rounding up takes you to 4.56 (which was too tall on my vehicle), and jumping one size gets to 4.88's, which should will be better, but 5.13's would give much better power and still give near stock fuel economy, even at highway speeds. Too bad they're not available for the Dana-30...
My YJ with an AX-15 5-speed came stock with 3.07 gears. I just installed a set of 4.56 gears to run 35's (mainly because I had a set sitting in the shop along with lockers, so I used them to save money). This will be much better than on the XJ because of the lower gearing of the 5-speed (second gear in the AX-15 is almost identical to the first gear of the AW-4), not to mention the better control you have over the shift points with the manual trans. Now my YJ at 65 MPH in 4th gear runs 2395 RPM's (1 to 1 ratio and 65 MPH is the standard for the gear chart I am using(Tire Gear Ratio Charts). The chart says that in order to get that same 2395 RPM's with 31-inch tires, I would need 3.42 gears. If that is correct, then why does Jeep use 4.11's on the Rubicon models? 35/29 x 3.07 = 3.71 (consider that the same as 3.73). Round up to 4.11 and jump one size gets you to 4.27. In my case, I went to 4.56's, which should be fine due to the extra width, weight and resistance of the 35x12.5x15's, and I am very confident that the highway fuel economy will still be great.
My LJ Rubicon with the 42RLE auto trans came stock with 4.11's and 31-inch tires. It is now on 35's and I will be installing 5.13's to make it right. This is my daily driver (and I put a lot of miles on it) and I could buy any size gears I want for it. I am buying 5.13's because this will get it back to stock ( I don't want to go too crazy since it is my daily driver, but my mileage is suffering with the big tires and relatively tall gearing). 35/31 x 4.11 = 4.64. Round up to 4.88 and then jump up one size and you are at 5.13.
In your case, 33/29 x 3.07 = 3.49. Round up to 3.55 and jump one size and you are at 3.73. This is a great example of the charts not being accurate, nor is this formula 100%. Personally, I would use either 4.11's or 4.56's. Jeep uses 4.11's for 31's on their TJ Rubicons (and 32's on their JK Rubicons). I installed a set of 4.11's on a friend's YJ with 31's and he loves it. He drives it well above normal freeway speeds and has no problems with fuel efficiency. Your 33's will be 2-inches wider than his 31's and therefore have a greater contact patch and greater rolling resistance (more rubber on the ground); so like Jerry recommended, 4.56's should give you great power and your fuel economy will be fine.
|12-24-2009 09:42 PM|
For 33" tires and the 5-speed, you want 4.56. 4.10 would give you the same rpms as how the Jeep was delivered with 30" tires and 3.73 gearing but with bigger tires and a lift, you actually need the slightly higher rpms of 4.56 to truly restore the power lost by installing larger tires.
The bigger tires and suspension lift mean slightly higher rpms are required at the same speeds to maintain factory performance. The bigger tires are heavier, are harder to turn, have more rolling resistance, and have more leverage against the engine. The bigger tires also combine with your suspension lift to raise the Jeep higher into the windstream for more wind resistance which is just one more thing to require slightly higher than factory rpms to compensate for.
In other words, don't fear slightly higher rpms as some seem to be afraid of. 4.10 gearing with 33" tires and the 5-speed will just have you downshifting to 4th gear more for even slight grades on the highway, giving you higher rpms than even 4.56 would in 5th gear would.
Don't fear the gear, most beginners under-gear their Jeeps because they think their Jeeps should have car-like engine rpms which is not realistic for a Jeep with big tires and the aerodynamics of a barn door.
Cost-wise, $1100-1200 is pretty typical for most areas. Don't try to save a few $$$ by buying the gears on your own, have the installing shop provide all parts or you could be in for a round of finger-pointing between the shop and where you bought the parts from if anything goes wrong during or after the installation. Having the installer provide all parts will make handling any labor or parts warranty issues a snap.
|12-24-2009 09:08 PM|
|nmdriver||Well, if you never plan on going above 33's, do not tow and what would probably put you closest to stock would be 4.10's. I run 33's with my I6 but I regeard to 4.56. A tad low on the highway but my rig is not on the highway too often. IMO 4.88 is too log and 3.73 too high.|
|12-24-2009 08:41 PM|
|terrible2||yea I know, im right there with you, but theres not much you can do unless you buy a beater car or Vespa|
|12-24-2009 06:53 PM|
|WTAggie||What worries me about doing that is, I don't know wat kind of abuse the axle has been through. My jeeps my DD and it's hard to fix and repair all the time.|
|12-24-2009 01:46 PM|
|terrible2||With 33" tires youll want 4.56 or for more power 4.88, but youll get low gas mileage. If youre in Texas, check out jeepforum.com for people selling already geared axles, or check out this forums for sale ads. Check craigslists all around you. You should be able to find already geared axles with probably lockers for $700. ive seen it a couple of times. Dont regear, just swap axles.|
|12-24-2009 10:58 AM|
|WTAggie||It is the 6 Cylinder also|
|12-23-2009 12:23 PM|
Jeepohana, you on oahujeepers.com? you know theres a couple of people on there who could probably do it for cheaper.
And yea $1000+ is about average. Though if youre planning a road trip to missouri I know a guy who would do it for alot cheaper
|12-23-2009 05:18 AM|
another vote for 4.10-4.56
Figure 1000-1500 ish for gear install depending on where you live.
|12-22-2009 11:12 PM|
4.10 is good for a good mileage and feels like stock
4.56 is a bit more powerful, but with higher RPMs at highway speeds and the milege is worso.
|12-22-2009 11:09 PM|
|jeepohana80||My 2005 came with 3.73 gears. I regeared to 4.88 w/my 4 cylinder. If you have the 4.0L, I would either recommend 3.73 or 4.11 (standard on the Rubicons). If you have the 4 cylinder, I would recommend 4.56 gears. My regearing costs $400 for parts and another $900 for labor (labor is a pain in the wallet in Hawaii...not too many places to take your rig).|
|12-22-2009 10:21 PM|
I have a 2003 Wrangler X. 5 Speed with 3.07 gears and 33in tires. What do i need to regear to, to bring me back to stock? How much will it cost me?