Power loss from 35's? & pwr mods - Page 7 - JeepForum.com
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post #91 of 103 Old 10-30-2013, 08:31 PM
aTX427
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It looks like a stock 2014 JKUR (3.6L / 32" tires / 4:10 gears) spinning 2,500 is about the same as 4.56's with 35's, which isn't a big jump. On stock tires cruising 80mph on the highway, I'm spinning about 3,000 rpm's and get a 1.5 mpg better than cruising in the low to mid 70's. Are most people with with the 3.6 and 35's going to 4.88's, which spin 200 rpm's more than the 4.56's according to the chart or go to 5.13, which seems like a lot, unless you are full time crawling or go 4.56? My JK doubles as a DD and overland rig, so I want to cruise at 80-85mph on the highway. . I have a built TJ for crawling

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post #92 of 103 Old 10-31-2013, 02:50 AM
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If u are sticking to cruising on mostly flat terrian. And not in a hilly or mountainous area...id go with the 4.88s before 5.13s on 35s.It aldepends on ur prefrence and what u wanna do. Will u tow alot? Will u be driving across kansas? Lol. Whatever gear u choose...dont forget some type of tuner to make sure ur computer is on the same page as ur new gears. I would try stay between 2300 and 26/700 rpms cruising. At 80mph u might be a little higher. I just dont feel comfy running my 3.8L over 3k rpms for an extended period of time. On 35s and 4.10s i hafta run 80-85mph just to keep it in a decent rpm range to hold O/D. any speed between 65mph and 78 mph, it wants to jump out of gear alot.

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post #93 of 103 Old 10-31-2013, 07:38 AM
aTX427
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On stock gears and tires, I'm spinning 3,000-3,200 on the highway at 80-85. It's not a mall crawler and I'm not flat landing. I DD the Jeep and use it for overlanding in the mountains, where we travel across the National forest two weeks at a time and camp whenever/wherever we want. I have a 4-linked TJ for crawling, so I don't ever intend to dual roll the JKUR. Having said that, running 35's with 4.88's will put my cruise rpm's at around 3,400-3,500 and 5.13's close to 4k on the highway, both of which seem excessive over a 12+ hour drive to the mountain's on my 3.6L. Even if /when I need 4L, the Rubicon has a 4:1 transfer case, which gives me a much higher numerically gear ratio than my 4.88 TJ on 35's. I'd like to hear from people with the 3.6 running 35's who have done a gear change.
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post #94 of 103 Old 06-07-2014, 07:10 AM
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Trying to do some research and get smart on the subject of regearing for possible future application. I am moving up to a 2.5in lift with 35in tires on a 2012 6spd manual sporting a whooping 3.21. I understand that I should expect to see lose of power and some dogging feeling. Where I guess Im confused even after reading the charts and this thread, is what exactly the difference is between the 6spd manual and auto transmission and what to expect from others personal experience. When talking to a local shop about gears he suggested 4.10 would be fine. Im a bit skeptical, and feel that 4.56 (or 4.88) would be better. Again looking for someone with experience in the 3.21 manual to higher manual gearing. Also would a procal or superchip really effect a manual of any gearing? Other than speedo correct and tire adjustment?

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post #95 of 103 Old 06-07-2014, 09:40 AM
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Quote:
Originally Posted by Cambie
Trying to do some research and get smart on the subject of regearing for possible future application. I am moving up to a 2.5in lift with 35in tires on a 2012 6spd manual sporting a whooping 3.21. I understand that I should expect to see lose of power and some dogging feeling. Where I guess Im confused even after reading the charts and this thread, is what exactly the difference is between the 6spd manual and auto transmission and what to expect from others personal experience. When talking to a local shop about gears he suggested 4.10 would be fine. Im a bit skeptical, and feel that 4.56 (or 4.88) would be better. Again looking for someone with experience in the 3.21 manual to higher manual gearing. Also would a procal or superchip really effect a manual of any gearing? Other than speedo correct and tire adjustment?
4.10 is a waste. 4.56 is great for that setup. I have a 2012 six speed on 35s with 4.10s stock, got to feeling under geared and under powered. Swapped to 4.88s which is way better, but slightly on the low side.
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post #96 of 103 Old 01-11-2015, 07:39 AM
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Sorry for bringing this back from the Dead but I've searched everywhere and can't find the concrete answer i'm looking for. I have an 08 JKU with 3.8 and 3.21 gears. I have 35's on it right now that measure a tad over 34. I also have the XRC front bumper with winch and stinger, led light bar across the windshield, full size spare, and plan to add the XRC rear bumper. I have almost regeared a few times but something came up and the money went somewhere else. I just took a job where the commute is longer and I will be traveling alot this summer with my son's baseball. I was going today to get some used 285/70 17's that measure 32" and try to get by that way for $250.

Here's where I need some help... my Jeep came with the 255/75 17's which are kinda like 32's and it got great gas mileage and drove fine on long trips. After reading on here all night and all the added weight I've put on it i'm not sure i could even get by with the 285's without needing a regear.

My questions are...will I be back close to stock feeling with the 285's since they're 32's? If i'd have to regear for the 32's then I would just regear for the 35's and if that's the case, what ratio would be best? Also, as much driving as i'll be doing, gas mileage does matter and what kind of mpg estimate might I expect to get if I did regear for the 35's.

Sorry for the length of the post but id really appreciate the advice, thanks
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post #97 of 103 Old 01-11-2015, 08:00 AM
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Automatic or stick and what jeep model isit ?


Quote:
Originally Posted by 08jkdogg View Post
Sorry for bringing this back from the Dead but I've searched everywhere and can't find the concrete answer i'm looking for. I have an 08 JKU with 3.8 and 3.21 gears. I have 35's on it right now that measure a tad over 34. I also have the XRC front bumper with winch and stinger, led light bar across the windshield, full size spare, and plan to add the XRC rear bumper. I have almost regeared a few times but something came up and the money went somewhere else. I just took a job where the commute is longer and I will be traveling alot this summer with my son's baseball. I was going today to get some used 285/70 17's that measure 32" and try to get by that way for $250.

Here's where I need some help... my Jeep came with the 255/75 17's which are kinda like 32's and it got great gas mileage and drove fine on long trips. After reading on here all night and all the added weight I've put on it i'm not sure i could even get by with the 285's without needing a regear.

My questions are...will I be back close to stock feeling with the 285's since they're 32's? If i'd have to regear for the 32's then I would just regear for the 35's and if that's the case, what ratio would be best? Also, as much driving as i'll be doing, gas mileage does matter and what kind of mpg estimate might I expect to get if I did regear for the 35's.

Sorry for the length of the post but id really appreciate the advice, thanks
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post #98 of 103 Old 01-11-2015, 08:10 AM
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Sorry, it's an 08 JKU X 6 speed
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post #99 of 103 Old 01-11-2015, 08:21 AM
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Over the years it seems that the generally acceptable regear ratio for the 3.8l/stick/unlimited/non-Rubi/daily Driver is-


Quote:
Originally Posted by 08jkdogg View Post
Sorry, it's an 08 JKU X 6 speed
4.88 gears, usually YUKON full master rebuild kits and bought thru/warrantied by--a well known shop-

Non-DD/non-Rubi is 5.13 gears

If you let the shop buy the gears you'll have a recourse in warranty--thru the shop-

Listen to breakin procedure and try to stick by the 500 mile breakin rule !

If you've never done it---don't try it yourself and try to get some comparison prices-

Be sure and gettaAEV ProCal Module to correct the speedo !

Good luck

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post #100 of 103 Old 01-11-2015, 09:08 AM
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Like everyone else said, REGEAR first. If that doesn't do it, try the Superchips FlashPaq.

And if you are a power-nut (like myself), add a RIPP supercharger. That will give you way more than enough power (and probably get you some speeding tickets and/or broken driveline parts...I've done both).

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RK 2.5" Max Travel, Rancho 9000XL shocks, 37" Nittos, 5.38's, RR skids, Warn VR8000-S.
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post #101 of 103 Old 01-11-2015, 09:49 AM
08jkdogg
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Lol, I was actually thinking about the Ripp before gears. Thanks for yalls help

Also, I already have a Hypertech on it. It made a huge difference after putting the 35's on
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post #102 of 103 Old 01-11-2015, 09:59 AM
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Didnt i hear they're running some super deal on Ripp superchargers right now?
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post #103 of 103 Old 01-11-2015, 11:19 AM
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Quote:
Originally Posted by 08jkdogg View Post
Didnt i hear they're running some super deal on Ripp superchargers right now?
Yes, but I believe the offer expired last week. https://www.jeepforum.com/forum/f96/r...-00-a-1458923/

It was for the Gen II, Stage 1 RIPP Kits. These were the non-intercooled RIPP kits. They produce about 40-50 HP less than the intercooler version (Gen II, Stage 2). You want the intercooler version (Gen II, Stage 2).

2008 2-dr Rubicon, auto,
RK 2.5" Max Travel, Rancho 9000XL shocks, 37" Nittos, 5.38's, RR skids, Warn VR8000-S.
RIPP Gen 2 Stg 2 Supercharger.
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3.73 gears , 35" tires , JK Wrangler , power loss , stock gears , wrangler

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