Magnuson SC and proper gearing

[Pznivy]

I wanted to take a minute to share my Rubicon project. I picked it up today after getting a big chunk of the parts installed. Here's the list so far:
Rock Krawler 2.5" X factor Lift
Fox 2.0 resevior shocks
Fox ATS steering stabilzer
Currie Anti-rock rear sway bar (for the Gobi rack/ARB tent)
Currie correctalink steering linkage
River Raider bumpers, fenders corner armor
Warn CTI-S winch
Method Race wheel beadlocks, custom powder coated
SPOD w/ G screen
Genesis Offroad dual battery kit
GOBI rack
Baja Designs Onyx Pro 30in and two 8in lights, S2's around the rack
Baja designs Squadron Pro lights for fromt bumper
Rockslide Eng power sliders
ARB CKMTA12 compressor w/ under seat mount
ARB drawer system w/ ARB 50 qt fridge
ARB sampson 3 tent and awning
Few iterior mods.

Is this guy serious with this list? Dude, you have been holding out on us! We need threads on all that stuff!!

Or at the very least a build thread with 10,000 pictures.

I love the stuff you picked.

[FLIPmeOVER]

Is this guy serious with this list? Dude, you have been holding out on us! We need threads on all that stuff!!

Or at the very least a build thread with 10,000 pictures.

I love the stuff you picked.

x2. Jt1911 is going to have to take the next week off work and post about all that gear. Is it a piece by piece build? or did you just go nuts with the credit card and morph a stock jeep into a monster overnight?

[JeepLab]

I have 4.88 gears and running 35's nitro trail grapplers on my 2012 jk. Spent last weekend running Moab and drove it there from home, approximately 190 miles away. On the trail the gearing was perfect as we were rock crawling Prichett canyon (serious stuff). On the highway I wish I had another gear.. Going to jump up to 37-38's especially since the supercharger is being installed in two weeks. My suggestion is to go with 37's.

FF

4.88 with 35s is a TON of gear. It was probably great in moab. But you will want to kill yourself in daily driving situations if traveling distance on highways.

Thats the whole thing with the north east. if you live here and want to really wheel, you have to be prepared to do 3 hours in the car. Knowing that you are overgeared and that 3 hours is going to be miserable with your truck spinning at 3k rpm to keep up with traffic, you will talk yourself out of wheeling all together. You need a blend of highway and offroad. Thats why the transfer case is a reason to get a rubi. You can maintain good off road gear, in 4LO but still have a livable truck on the highway.

[JeepLab]

You're correct. I spend most of my time on the highway (and mostly at or above 80 mph). My thought on going to 4.56 is because my auto trans is five speed. I would like all of my passing and acceleration at highway speed to be with a downshift to 4th gear. But to really "kick it in the guts" and push myself back in the seat I need to downshift to 3rd gear and let the motor spin up to 3,500 rpm and stand on it through 4,500 rpm and then either lift off the pedal to shift or use the auto-man to up-shift. I would hope that the lower gears would get the rpms up just enough to get have a bit more available power at the pedal in 4th gear.

So let me know if I get this right.

SC + AUTO + 35s + 4.10 gearing = highway passing in 4rd gear?

SC + AUTO + 35s + 4.56 gearing = highway passing in 3rd gear?

Now, this all brings further questioning

1. Is your speedo calibrated perfectly?

2. What is the RPM you cruise at if doing 80mph?

baumann, Ive read your posts a bunch of times now trying to get clear about how to help the OP in this thread. Since you have the auto with the mag and we dont, your experience above ours in this case because of your AUTO transmission.

I have the Mag S/C on my 2013 JKU with automatic trans. I have 35s and 4.10 gears. If I had it to do over I would get 4.56 gears.

Here is what I think about your situation, not Jt1911's.

I think are geared right. 4.10 for 35s with the SC is PERFECT gearing. If you had 4.56, you would feel overgeared. If you have never been overgeared, take it from me. It sucks. Do not feel like if you did it over again, you'd do it different. The grass is always greener on the other side of the fence. I promise, you are on the greener side of the fence. Being overgeared, turns your supercharged truck into a pig on the highway. I dont care how much horsepower you make.

If you had 4.56 with 35s on an Auto, you would be at 2700 RPM at 70 MPH! Your truck would struggle to get to 80, and would be gasping for air there at 3500 RPM. You would almost be forced to go to 37s.

Just my position. take it from a guy who geared twice.

[JeepLab]

Now back to you Jt1911,

SC + AUTO + 37s + 4.10 = good drivablilty. Would it be better with 4.56? Maybe.

My own truck BB is

SC + Manual + 37s + 4.56

Do I love it? I'll tell you this. I hated the 4.88s. Took my rocket ship and turned it into a row boat. I struggled to get to 80 MPH, really struggled. Made me sick to drive her.

Is she now at 4.56 the highway cruiser she was with 4.10? when I'd cruise at 85mph at 2300 RPM in 6th gear? No. Ive lost her awesome effortless cruising speed. even dialing back to 4.56s. I cruise at 75 now.

Everyone's perception of what is "Good" is different. Jesse (snarf) and I have very similar builds, but we go in opposite directions on certain points like gearing. He likes more gear than I do. But he is also the kind of guy who dosent mind back roads. If im not on a highway cruising at 75 at least...I'm pissed.

You dont know what gear YOU will like until you live with gearing for a time. I say, live with your 4.10s for a while. If you hate it, consider 4.56. People will tell you, "if you want 4.56, you should just go to 4.88" Thats BS.

If you have 37inch KM2s, then look at the 35 inch line of the gear chart. And pick your gearing by where you want to cruise on the highway. You have a rubi, so your transfer case will make whatever gear you have 4.10, 4.56, 4.88 , low enough to wheel with anywhere in the united states.

[UselessPickles]

But to really "kick it in the guts" and push myself back in the seat I need to downshift to 3rd gear and let the motor spin up to 3,500 rpm and stand on it through 4,500 rpm and then either lift off the pedal to shift or use the auto-man to up-shift.

Why force an up shift at 4500 rpm? This engine has 6500 of them available. Use them!

[gbaumann]

[QUOTE=JeepLab;3125]So let me know if I get this right.

SC + AUTO + 35s + 4.10 gearing = highway passing in 4rd gear?

SC + AUTO + 35s + 4.56 gearing = highway passing in 3rd gear?

Now, this all brings further questioning

1. Is your speedo calibrated perfectly?

2. What is the RPM you cruise at if doing 80mph?

baumann, Ive read your posts a bunch of times now trying to get clear about how to help the OP in this thread. Since you have the auto with the mag and we dont, your experience above ours in this case because of your AUTO transmission.[QUOTE=JeepLab;3125]

OK.

SC + AUTO + 35s + 4.10 gearing = highway passing (65 mph to 80 mph) in 3rd gear. I use auto-man to go to 3rd and that lets me get the throttle open enough to get boost up. 4th gear is problematic when passing. Even in auto-man if I pass in 4th gear the trans will downshift when accelerator is depressed beyond a certain point. It won't stay in 4th. The downshift from 4th sometimes jumps two gears to 2nd! That's not safe for me or the motor. So to stay safe I go to 3rd. Yes, I can pass in 4th but it takes much more distance and not at all uphill. Again, there is probably more power available in 4th gear but I can't access it because opening the throttle enough to close the SC bypass and get into full boost will cause an unwanted downshift. I'm thinking that 4.56s will get rpms up in 4th a bit and reduce the downshifting. A better solution would be to get access to the transmission side of the PCM and reprogram automatic trans shift-points and keep my 4.10s. But I hear that's not going to happen for a long time if ever based on how difficult it is to crack Chrysler's PCM transmission programming.e

I'll record my rpms at 80 today and report back.

[jt1911]

Hey guys, sorry for the delay with pics, work schedule has been crazy. Thanks again for continued information. One of the things I wanted to wait and see what effect there was, was throwing the GOBI rack on top. One thing that I've been thinking about was how much weight I've added to my jeep. I installed the rack just yesterday and I love it, but man that thing is a pig. I was able to drive the jeep for two days without the rack and a short road trip yesterday with it.

I thin the added weight from everything is something that has pushed my decision to go with 4.56's. Now, I do not spend a lot of time on the hwy and when I did, I wasn't hammering 80mph regularly. Most of my driving is backroads. That being said, with the terrain around here, there's a lot of up and downs and I was annoyed at how I had to push up to 4500 rpm to get a gear change. But, The SC wil be getting installed in two weeks and I'm goon wait and see how she does with 4.10's and then I'll make my mind up at that point.

So.. for pics, can anyone chime in with simple directions? never posted pics before..

[jt1911]

[jt1911]

Figured it out..I think