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Old 12-02-2015, 08:42 AM
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Is regearing worth the $$??

Trying to decide what to spend $1500 on, bumper and winch, or gears.

I have a 2008 jk rubi on 35" toyos.

Wanting to go with 5.13 gears and was quoted $1500 from the nearby 4x4 shop.

Does regearing make a $1500 difference in performance?

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Old 12-02-2015, 08:56 AM   #2
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That's a tough one. Do you do slow crawling offroad much? If not. I might go for the bumper and winch. Do you have an auto 4 speed or manual 6 speed?

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Old 12-02-2015, 09:06 AM
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That's a tough one. Do you do slow crawling offroad much? If not. I might go for the bumper and winch. Do you have an auto 4 speed or manual 6 speed?
Its an auto and it's my DD. Not super often do I do any slow crawling.
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Old 12-02-2015, 09:34 AM   #4
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For the 3.8 (which is what you have), regearing for 35's is highly advisable. Especially for the automatic. That transmission has a really tall overdrive and the 3.8 is a pretty gutless engine at low RPMs. Two things that don't mix well. The solution is to regear.

You can probably live without regearing but it is a solid investment in making the Jeep more enjoyable to drive.
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Old 12-02-2015, 09:35 AM   #5
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I have a 2011 JKU Rubicon Auto with the same 3.8L engine. On stockers and a 2.5" lift it was fine for 4 years. Offroad I had absolutely no issues and I still maintain there is no appreciable improvement with the 3.6L offroad.

Now, on-road, yes it's been disappointing going up hills and long elevation climbs on the freeway but freeway use for me was extremely limited. Well, I just put on Toyo 34" tires which are heavy and taller than many other brands' 35" tires ... so the time has come to regear. I am actually doing 5:38 gears next week.

Keep reading...many members here with a ton of upgrades on their 3.8L JK and JKUs swear the regear is their most gratifying upgrade...especially when running 35" or 37" tires.

$1,500 is actually a good price for a master kit installation.
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Old 12-02-2015, 11:16 AM
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Thanks guys, and yes the shop said they use Yukon gears and it will be the master install kit, I'm having them email me a full quote right now.
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Old 12-02-2015, 01:06 PM   #7
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yes, I just did this, passing on winch and bumpers. I have the rancho sport lift 2" and 35x12.50x18 toyo mts. Make sure you pick up a tuner to reset the gears and tires in the computer. much , much better. that terrible dead spot at 40 is almost gone. I can drive the highway at 2500rps and still have power.

1500 is a great deal , have them change the dana 30 inner axle seals while its apart.
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Old 12-02-2015, 01:07 PM   #8
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Old 12-02-2015, 02:17 PM   #9
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If moving from a stock 3.73 wheel/tire combo to larger tires and a higher gear set to match (thus matching the original effective gear ratio), what is the effect on MPG?

In other words, if a stock 3.73 with 31's was seeing 19mpg highway at 2400rpm but went to 35's and 5.38 gears would it still see 19mpg at the same 2400rpm?
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Old 12-03-2015, 01:51 PM
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yes, I just did this, passing on winch and bumpers. I have the rancho sport lift 2" and 35x12.50x18 toyo mts. Make sure you pick up a tuner to reset the gears and tires in the computer. much , much better. that terrible dead spot at 40 is almost gone. I can drive the highway at 2500rps and still have power. 1500 is a great deal , have them change the dana 30 inner axle seals while its apart.
I have a tuner, I also have Dana 44s up front?

Also one main question your rig sounds setup like mine, can you maintain 75mph on a long incline on the interstate without downshifting? That's one thing that bothers me a lot when driving with stock gears
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Old 12-03-2015, 02:43 PM   #11
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I no longer have to down shift on the highway. I'm turning 2600 at 70 to 75 mph. With a rubicon you could go deeper on the gears but I wouldn't unless you planned 37s. I like the 5.13 in case I ever have to go 33s but I doubt I ever will. I love the look of 35s measured 34".... heres a test for you , turn off the overdrive and hit the highway. That's about what it will be like. Although I had 3.75 vs 4.10 of the rubi, it's only 150 rpm diff.
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Old 12-03-2015, 10:25 PM   #12
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....I'm turning 2600 at 70 to 75 mph. With a rubicon you could go deeper on the gears but I wouldn't unless you planned 37s...
Fair statement, for a 3.8L manual with D44s, not to go deeper than 5.13.

In the case of an automatic, 5.13 will spare you a mere 120 RPM at that speed but likely have you going in and out of OD. I'd take the extra RPM of the 5.38 and stay in OD more consistently.
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Old 12-03-2015, 11:15 PM   #13
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Quote:
Originally Posted by samtuck11 View Post
Trying to decide what to spend $1500 on, bumper and winch, or gears.

I have a 2008 jk rubi on 35" toyos.

Wanting to go with 5.13 gears and was quoted $1500 from the nearby 4x4 shop.

Does regearing make a $1500 difference in performance?
Yes, a 2008 JK with 35"s should definately be re-geared. 5.13 seems right to me, although 4.88 might be ok. definitely consult with other 3.8 JK owners before picking gears would be my suggestion.

Regearing is an absolute must for you IMO.
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Old 12-04-2015, 05:16 AM   #14
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keep in mind to use the measures height of the tire , not the calculated or whats stamped on the sidewall.. My "35s" only measure 34"...

very good calculator, you can choose auto or manual, and adjust all of your gear values..

Visual RPM, Speed, and Gear Ratio Calculator


The overdrive ratio for the pre 2012 auto is .69, when you work this calculator//
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Old 12-04-2015, 07:31 AM   #15
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Originally Posted by Austintatious View Post
In other words, if a stock 3.73 with 31's was seeing 19mpg highway at 2400rpm but went to 35's and 5.38 gears would it still see 19mpg at the same 2400rpm?
No

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