Crazy man with sm420

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Crazy man with sm420

Postby ant92 » Tue Apr 06, 2021 8:02 pm

Hi guys!

I’m back after a year long hiatus working on a Jeep Cherokee project. After realizing I didn’t really want one, I bought another Rodeo. I am still infected with off road mod madness and still plan on building this one up...
That being said. I’m planning on doing the following:

-om617 swap- built as much as possible without hurting longevity.
-Sm420 swap
-205 tcase
-Special front axle setup that will let me use both ifs and sas (with mechanical or air lockers)
-Dana 44 rear (this year has the gm 10bolt)
-3.73 gears in rear with mechanical or air lockers
-33” tires
-2” body lift
-font winch bumper
-no bumper or diy bumper in rear

Does anyone have any opinions on this? I’ve been digging around online and have made most of my plans but wanted to get more input from real humans.
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Re: Crazy man with sm420

Postby geoffinbc » Thu Apr 08, 2021 7:54 pm

The only thing I see as a problem is you are going with less gears and a diesel. With the narrower rpm range of a diesel and the fact it will like to cruise under 2000RPM you will want more gears with overdrive or a very high axle ratio and possibly multiple low ranges. Or if this is a town and trail rig you will never drive on the freeway you should be ok.
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Off the road for an overhaul right now.

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Re: Crazy man with sm420

Postby ant92 » Fri Apr 09, 2021 12:31 am

The om617 is a weird diesel that’s built more like a gasser, from what my internet reading has informed me. Peak torque is at about 2500rpm, +- 100rpm. I would like to go down to 3.55 gears but I dunno of that’s possible with a dana 44. Might have to go chryco 8.25 or something like that. It’d almost be more worth my time to just swap in teralow 3.0 tcase gears, but when I did the math I could always get a better ratio with the tall crawler gear in front. Now that I just redid the math, the difference seems almost trivial... I wonder if I made a mistake.

But I know what you’re talking about as far as drivability concerns. From the math, I would hit about 70mph with 3.55 gears at 2500rpm with a transmission ratio of 1:1 with 33s. It would be a lot harder with stock tires.
Last edited by ant92 on Sat Apr 10, 2021 5:31 am, edited 1 time in total.
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Re: Crazy man with sm420

Postby mudoilngears » Fri Apr 09, 2021 10:21 am

ant92 wrote:-Special front axle setup that will let me use both ifs and sas (with mechanical or air lockers)


This sounds interesting! What is your plan exactly, mount this IFS on a beam of some sort?
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Re: Crazy man with sm420

Postby ant92 » Fri Apr 09, 2021 10:33 am

Correct. Essentially the a arms would be locked in place, but the beam (or axle tube) would be unlocked for off road use. Then when it came time to come home, I could unlock the ifs and lock the sas and drive home with a comfy ride. I could also independently select which components were locked for optimal off road performance. For example, If I need just a touch more droop, I could unlock the ifs and the sas and get more travel. Obviously I’m going to have some fender clearance issues, but I can go choppy choppy and fix that ;)
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