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4.10 or 4.56??

17K views 33 replies 18 participants last post by  Jerry Bransford 
#1 ·
I currently have 33x12.5x15 on my jeep with the stock gear ratio. I'm wanting to do a gear swap but not sure what ratio to go with. After my gear swap, I am looking to change tire size to 35x12.5x15. Can anyone shed some light on what ratio gears I need to go with. Thanks for the help
 
#15 ·
Don't even consider 4.10 for 33" tires or 4.56 for 35" tires... your rpms would be too low on the highway since neither of those combinations truly restore all the power lost caused by the bigger/heavier tires.

If you plan to go to 35" tires in the near-term future, go to 4.88. I ran 4.88 with 35" tires, 5-speed, and 4.0L and it was a perfect combination. RPMs were roughly 2700 at 70 mph which is exactly what you need to run that big and heavy of a tire. 2700 may seem like a lot but it's not, it takes more RPMs to run a Jeep on the highway after it has a suspension lift (more wind resistance) and bigger/heavier tires that are harder to turn.
 
#4 ·
I will be running 33's and 4.56's with a 4.0 5 speed.... everything I have read points me in this direction. I 'think' you would be fine with the same and 35's, though most would probably say 4.88's.

I would look at some gear charts on the web and make an educated decision... just remember.... MOST gear charts are made using a 1:1 ratio ( 5th gear is an OD ). Look at the charts closely to ensure what their chart is based on. So you may need to a little math to get your RPM correct to match your gear for an educated and well-though out direction for gears.
 
#11 ·
x2 on that. I have the exact same setup and love it. I would have been disappointed if i had chosen 4.10s. with the 4.56s my Jeep has a sh*t ton of torque, and a nice crawl ratio when in four low
 
#12 ·
Back when I had my 4.0 5speed I running 36" iroks on 4.56 gears ran great 2300 don at 70mph. Since I bumped up th the to my heavy humvee wheels/tire I built a 4.7l stroker and still running 4.56 gears. When I was messing with the gear calculatter I found 4.56 would put back to stock power for 35's. I know I got a YJ but its the same motor/trans combo.
 
#14 ·
with the 5 speed and 33's the 4.56 was pretty great. with 35's i wish i would have installed 4.88's...
then i swapped to the aw4 auto and that made a good difference for the 35s but still i think id ultimately like the 4.88 gears.

there is not a huge difference between 4.56 and 4.88. same with 4.10 and 4.56. we noticed that swapping from 4.10 to 4.56 was totally not worth it on one of our jeeps. even less of a difference between 4.56 and 4.88. this is why i am not swapping again.

one last thing, my jeep is set up for some pretty gnarly stuff off road but i drive it primarily on road. it gets used on both but not equally. it crawls very well in the slick rock and can manage nicely on the freeways and towns.
 
#21 ·
Don't buy the gearing with the plan of giving it to an install shop to install. If anything goes wrong, and that does happen, they'll blame your parts or tell you you didn't buy the right parts. Let the installling shop provide everything which means their warranty will have to cover everything.

And if you're planning on installing the new ring & pinion gears on your own, it's clear from your questions that you don't have the experience required to install those particular gears. They are finicky on how they are set up which involves lots of trial and error with shims to get them to mesh properly. Not even experienced R&P gear installers get it right every time and when it's not perfect, the new gears will be toast in short order.
 
#27 ·
dont mean to hijack or anything, but i was wondering how bad my jeep will be with 3.37s and 35s? i have an 05 so i have a 6spd if that helps any. just saving untill i can regear. and when i do would 4:56 be ok for me? or sometihng different
 
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