4.56 or 4.88 for 37s on JL rubi ?

Jmw015

Jmw015

New member
Ok so I’ve done what everyone else on the planet with a JL has. I’ve thrown a set of 37’s on with a couple inches of lift. It worked out great with minor reshaping of the rear inner fender liners.
I’ve heard all this talk about the auto transmission being so great that there is no need to regear a rubicon. When I made the decision to jump on the JL bandwagon I also made the decision to get one with a man pedal. I have to say, the six speed is sweet but freaking sucks with 37s and stock gears. Off road is ok, but I’d like to use 6th gear from time to time on the road!
Definitely going to do a gear swap soon. My concern is with the 4.88 ratio, would I basically be eliminating 1st gear on road? Would highway speeds produce too high rpm? Is there a big difference between 4.56 and 4.88?
My Jeep is not much heavier than stock other than the tires. I do have factory steel bumpers. AEV pintlers. Will add a winch soon and better sliders.
Any input would be greatly appreciated! Here are a few most recent pics IMG_0332.JPGIMG_0321.jpgIMG_0326.jpg
 
Jmw015 said:
I’ve heard the 5.13’s aren’t as strong as the 4.88’s. There are so many opinions out there it’s hard to know who to listen to. What’s the advantage of 5.13 over 4.88 or 4.56?
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Advantage is power. You need to hear it the same as you do a JK. I’ve been running 5.13’s for 5 years on my JK. You’ll be searching with 4.88’s still on steep grades I still downshift from 6 to 5th.


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Yep. Go with the 8 inch penis. No girl has ever said I wished I had gone a little smaller. Do it once, do it right. Especially if you carry tools and camping gear, etc.
 
If you shine a 6" penis (or wheels) and shave your hair, it'll will look bigger.

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I would go 4:88 for the extra strength on the ring and pinion. If it’s the same situation as the jk. I went with that on my 2012 and it was a solid set up.


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I have a manual trans and 5.13s on 37s (its a JK) and couldnt be happier. SO glad I listened to these guys and went with the 5.13s over the 4.88s everyone ELSE said I should run...

:twocents:
 
DWiggles said:
I have a manual trans and 5.13s on 37s (its a JK) and couldnt be happier. SO glad I listened to these guys and went with the 5.13s over the 4.88s everyone ELSE said I should run...

:twocents:
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What RPM's are you running at 75 mph? Just curious.
 
I have an automatic, so not sure if overdrive ratios make this a good comparison, but running 4.10s with 35s and a 3.8l, it always felt under powered. I recently regeared to 5.13s and it woke up the engine. I was very pleased with the 5.13s. Now that I’m running 38s, I’m glad I didn’t go with 4.88s. I’d recommend 5.13s.


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OP- the guys responding to this thread are in JKs and you’re a asking about a JL. Unless the transmissions are the same, this may be apples to oranges.


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Jmw015 said:
Ok so I’ve done what everyone else on the planet with a JL has. I’ve thrown a set of 37’s on with a couple inches of lift. It worked out great with minor reshaping of the rear inner fender liners.
I’ve heard all this talk about the auto transmission being so great that there is no need to regear a rubicon. When I made the decision to jump on the JL bandwagon I also made the decision to get one with a man pedal. I have to say, the six speed is sweet but freaking sucks with 37s and stock gears. Off road is ok, but I’d like to use 6th gear from time to time on the road!
Definitely going to do a gear swap soon. My concern is with the 4.88 ratio, would I basically be eliminating 1st gear on road? Would highway speeds produce too high rpm? Is there a big difference between 4.56 and 4.88?
My Jeep is not much heavier than stock other than the tires. I do have factory steel bumpers. AEV pintlers. Will add a winch soon and better sliders.
Any input would be greatly appreciated! Here are a few most recent pics
Click to expand...

Unfortunately, the 6-speeds is nowhere near as nice as the 8-speed auto and yes, I would recommend a regear. As far as what ratio to go with goes, there is NOTHING wrong with 5.13's in an Advantek 44 and as mentioned, the problem would be when you get up to 5.38 as your pinion would be too small at that point. That being said, if MPG is an issue for you, you WILL be running on the high side of RPM's at highway speeds with 5.13's and you WILL burn more gas. If MPG is not a concern, it will give you more power off the line and crawl better too.
 
Thanks for the input everyone! As I expected, mixed reviews. Crawling is great even with the 4.10’s. Mpg is probably slightly more important to me than most Jeep owners. 4.88 May be the route I go when the time comes. Thanks again!
 
Jmw015 said:
Thanks for the input everyone! As I expected, mixed reviews. Crawling is great even with the 4.10’s. Mpg is probably slightly more important to me than most Jeep owners. 4.88 May be the route I go when the time comes. Thanks again!
Click to expand...

If you spend a lot of time on the highway doing speeds of 70-75 mph and mpg is a concern, 4.88 is definitely what I would recommend. With 5.13's, you'll be pushing about 400 rpm more across the board and you will see a fuel economy penalty from it.
 
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