5.13 gears and 35's

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Nikkormat
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5.13 gears and 35's

Postby Nikkormat » Thu Nov 15, 2018 12:54 am

I'm planning to go to 5.13 gears in my J10 with a TH400, QT, and 35.5" Q78 TSL's. Besides a max cruising speed of 55mph (until I swap to an ax15) what other negative affects could I experience? It'll stay open diffs until I can afford to replace the rear axle and I'll be trying to find some spare shafts.

Also thinking about setting up the gears myself... That'll be an exercise in patience!
Gabe, "reformed" Jeep hoarder.

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tedlovesjeeps71
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Re: 5.13 gears and 35's

Postby tedlovesjeeps71 » Thu Nov 15, 2018 5:50 am

You gonna highway drive it Gabe? 513 may be a bit deep. My suburban with 373s and small (like 245 60r16) runs out of go at about 70. Isn't quick off the line either. Lack of OD is a big hindrance. Even when you go with a 5speed manual you may find something like 456/488 a better compromise for 35s. I suppose if you go deep you could always step up to 37s? Maybe when those swampers finally die?

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Stuka
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Re: 5.13 gears and 35's

Postby Stuka » Thu Nov 15, 2018 6:51 am

5.13’s are way to deep for a non-OD trans. I have 4.56’s with 33’s and it’s too deep for extended Hwy driving.

With the TH400 you are looking at 3695 rpm not counting torque converter slippage at 70mph. Even with the AX-15 you will be running 2763rpm. Which is doable for short trips.

The gears will be nice off-road. But if you plan on lots of street driving consider 4.56’s. Or even 4.88’s would be better.

EDIT: Best gear calculator: http://grimmjeeper.com/gears.html
1981 J10 AMC 258 with HEI and Weber 32/36 DGEV Carb, T176, NP208, D44/M23 with 4.56 gears and Detroit Locker, 6" lift, 33x12.50 Cooper STT's, BJ's Offroad Rear Dozer Bumper.
2017 JKU Rubicon Lifted and stuff
Pevious Jeeps: 1975 Cherokee, 2008 JK, 2005 KJ, 1989 XJ

rocklaurence
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Re: 5.13 gears and 35's

Postby rocklaurence » Thu Nov 15, 2018 7:16 am

Im running 3.73:1 gears with 35" tires in two trucks. They pull/tow fine and run at 2400RPM @60mph. A OD trans would put the 3.73s and 70mph close to 2300rpm. Your ride with 5.13s would be great off road and quick around town but tasked on the highway..

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Nikkormat
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Re: 5.13 gears and 35's

Postby Nikkormat » Thu Nov 15, 2018 7:37 pm

I know 5.13's would be slow on the highway without overdrive. Cruising 55 gives me more of an excuse to stay on the back roads anyway. This thing is down right scary at highway speeds too...

I found a deal on the rear axle I want (60-2 from a j4000) earlier than I was expecting to so I'll hold off on the regear for now. Going from 3.54 to 4.10 will be good enough for now. And having a strong enough rear to add a locker will make a bigger difference off-road than gears would anyway!

I've been driving around a little Toyota pickup and am really liking it's 4.10 gears and stock tires. Its G52 is geared very similarly to the AX15 I'll have eventually, so 5.13's with my Q78's puts me within 5mph or so of the Toyota in every gear. The 5.13's and Q78's put my highway rpm lower than the Toyota in 5th gear, which should be fine with the much bigger engine.
Gabe, "reformed" Jeep hoarder.

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Nikkormat
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Re: 5.13 gears and 35's

Postby Nikkormat » Thu Nov 15, 2018 7:41 pm

5.13's and overdrive would only be 100 rpm higher on the highway at 65 than 3.54's and a th400.
Gabe, "reformed" Jeep hoarder.

fsj454
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Re: 5.13 gears and 35's

Postby fsj454 » Fri Nov 30, 2018 6:53 am

I have dana 60 4.56 locker 35s overdrive 5 speed stick . 2200 rpm at 65 mph . I never use first gear . Start of in second gear....
:fsj:


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