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Gear question

3K views 39 replies 14 participants last post by  Rdlynch2 
#1 ·
I'm looking at the 2012 Jeeps. I was told the only way to get the 4.10 gears would be to get a Rubicon. Seeing how I don't have the cash to do so would the 3.73 gears be sufficient to run 35's and still get the job done? I've seen the "Gears" thread under the FAQ but didn't know how it would apply to the 2012's! Thanks :tea:
 
#4 ·
He knows this - read the initial post. The gear ratio chart is for the 3.8L, not the 3.6.

To answer your question, OP - It will probably be a similar scenario - you could live with it, I'd imagine, but the 3.73s will not be ideal. You do have the manual transmission on your side, so you're not worst case scenario.
 
#3 ·
Define what you mean by "get the job done"...

Drive around town and on light dirt trails? Yes.... It wont' be optimal, but you could do it.

Heavy wheeling? I would not bank on it. More importantly, the 4.10's on the Rubi come with a stronger front axle which would help with the larger/heavier wheel.
 
#8 ·
Hey, I own a 2012 with 35s but you didn't provide any needed information!

1. Are you an automatic or a manual?

2. 2-Doors or 4-Doors?

3. How much additional weight will you add? Bumpers? Skid plates? Winch? Hi-Lift Jack? All of this can be -ALOT- of weight added to the vehicle.

4. Are you doing mostly local driving or highway driving?

5. Where are you located, is it very flat at low altitude or are you encountering steep grades all the time at high altitude? Or some combo of the above.

I have a 2012 Rubicon, 6-Spd manual, 4.10 gears, lots of armor, and 35s. I will give you my opinion when you provide the requested information.
 
#9 ·
To answer your questions.

1. Looking at Manual but would like to know more about Auto?
2. 4-doors
3. Wouldn't change bumpers for at least 4-5yrs would like to add skid plates
4. Tennessee in particular East and Middle Tn. So would have some decent climbs. Plus I'd be pulling a trailer a few times a year.
 
#10 ·
To answer your questions.

1. Looking at Manual but would like to know more about Auto?
2. 4-doors
3. Wouldn't change bumpers for at least 4-5yrs would like to add skid plates
4. Tennessee in particular East and Middle Tn. So would have some decent climbs. Plus I'd be pulling a trailer a few times a year.
I think that based on your conditions that your setup would be liveable. Would it be great? No, but still liveable. On the flatter highway driving, you should still be just fine in 6th gear even while pulling a trailer. However, on any inclines you'll find 6th gear to be weak and will probably need downshifting to 5th gear. With a trailer you'll absolutely be using 5th gear at highway speeds while on the inclines. The reason for 6th gear being weak is that for the 2012 year, they changed the 6th gear ratio to a higher ratio for better fuel economy. But that makes 6th gear less powerful, very annoying to me. Only the 6th gear was changed for 2012 manual transmissions.

I would think that you can get by with that setup. You will notice it's not the most powerful vehicle with 35s and 3.73s, but probably still doable. However you will probably want to regear further down the road to probably 4.56 to get more power. But you wouldn't need to right away. 4.10s would be better if you plan on not regearing. I have heard the automatics are better than they used to be, but I'm sure that a manual will still handle the larger tires better.
 
#12 ·
I think you're going to regret those 3.73s every time you put a trailer behind your rig at best. And forget 6th gear completely with 35s.

Lucky for you, regearing is waaayyy cheaper than a rubi. You will have to hold off until a tuner is available for the 2012, but after that you can regear for less than 1500 bucks and put that engine in it's powerband.
 
#13 ·
I think you're going to regret those 3.73s every time you put a trailer behind your rig at best. And forget 6th gear completely with 35s.

Lucky for you, regearing is waaayyy cheaper than a rubi. You will have to hold off until a tuner is available for the 2012, but after that you can regear for less than 1500 bucks and put that engine in it's powerband.
I think his 6th gear and 35s will be alright, just not with a trailer. This is based on my '12, 35s, and 4.10s. His 3.73s will not be as good as my 4.10s, but I am accounting for this in my reccomendation to him.

Also, the regearing computer problem only affects automatics, the OP wants a manual so there's no need to wait for a tuner. Also, the AEV procal already works for tire size and TPMS, I know first hand.
 
#14 ·
It's a good thing that none of this is subjective. Watching people throw their opinions around as facts can get tiring. It's a good thing that isn't happening here.

OP. Go study the gear chart. Buy your Jeep. You can't afford the Rubi, so we know what you're buying and so do you. Go buy it, drive it, and decide if you want to risk it being more of a dog than it is. If you think it's fine, then do it, if not,don't buy tires or re-gear.
 
#15 ·
Inaccurate would imply there was a fact I missed. We are talking opinion here.

You're going to lose power and mpgs running that setup with 35s. THAT is a fact. If you want some of both back, regear. Since you are looking at a manual, you can use the chart in the FAQ to show you what will work well and what won't.
 
#16 ·
Inaccurate would imply there was a fact I missed. We are talking opinion here.

You're going to lose power and mpgs running that setup with 35s. THAT is a fact. If you want some of both back, regear. Since you are looking at a manual, you can use the chart in the FAQ to show you what will work well and what won't.
I take back my statement, I was a bit harsh throwing out "inaccurate" like that. :cheers2: I apologize.

However, owning a 2012 Manual with 35s, I can tell you that chart is not accurate anymore for sure. I went from a manual 2-Dr with 4.88s to a manual 4-Dr with 4.10s, both using literally the exact same modifications and the 2012 handles BETTER than the '07 with 4.88s in local driving. And my highway experience has been pretty good, not solid yet on it's comparison. The only thing I don't like is that they changed 6th gear's ratio like mentioned above. And I live in low altitude, but VERY hilly conditions. Steep grades in both local and highway driving here constantly.
 
#18 ·
It is the same transmission, but they changed the 6th gear ratio. However, more torque and HP means that the "color coded" driving evaluations on the chart are not accurate. My new engine 4.10s are close to old engine 4.88s., can't solidify my opinion on it yet. I am waiting to see the engine fully broken in before I post a review, because if the engine's computer opens up even more power after it is broken in, then I might rate it better than the old 4.88s.

2012 Transmission Ratios

Manual
1st 4.46
2nd 2.61
3rd 1.72
4th 1.25
5th 1.00
6th 0.797
R 4.06

'07 - '11 Transmission Ratios

Manual
1st 4.46
2nd 2.61
3rd 1.72
4th 1.24
5th 1.00
6th 0.84
R 4.06
 
#24 ·
Ha, ha, ha! I got a quote from them the other day on a Rubicon just for the heck of it and got $34,000 roughly. Not too bad of a deal, but only if its in stock! :( So, not sure what I'm going to do. I've looked around and there's nothing in the area I'd throw my money at. So, I'm looking outside the area!
 
#25 ·
I am actually kinda bothered by this now...hmm...

How can an engine whose torque curve is far superior in the lower RPMs, have the exact same torque at the wheels as the old 3.8L.

Common sense says that the same transmission, the same driveline in almost every way except the new engine should show an equal change.

The low RPM torque SHOULD NOT be showing the same between the 3.8L and 3.6L, it just doens't make sense.

I'd like to see the dyno myself.
 
#34 ·
I thought the guy running the dyno said the same parasitic drive train loss ratio... Meaning: a 2012 260 hp engine gives 183 hp at the wheels. Where a 2007-11 202 hp engine gives about 148 hp at the wheels.

However, I was thinking the 2007-11 202 hp engine gives about 155 hp at the wheels?
 
#36 · (Edited)
I'm looking at suspension tires and rims and bumpers for my 2012 Sahara Unlimited. 5 speed Auto.

I am going to DD it and set it up for light to moderate trails, over landing and the beach.

I don't want to go with 35" Tire at least for now, thinking of going with 33" AT's.

Can someone help with gear selection or has anyone found a chart for JK 2012 gear setups? 3.73's stock.
 
#37 ·
I'm looking at suspension tires and rims and bumpers for my 2012 Sahara Unlimited. 5 speed Auto.

I am going to DD it and set it up for light to moderate trails, over landing and the beach.

I don't want to go with 35" Tire at least for now, thinking of going with 33" AT's.

Can someone help with gear selection or has anyone for a chart found JK 2012 gear setups? 3.73's stock.
If you buy a 2012 with and automatic and re-gear it.....The Jeep will go into "limp" mode and you will need to have the computer flashed. It is no big deal Nemesis Industries will do it for about 25 dollars or you can buy a $200 AEV procal. Just one more part to remember.
 
#40 ·
jstrubberg said:
I think you're going to regret those 3.73s every time you put a trailer behind your rig at best. And forget 6th gear completely with 35s.

Lucky for you, regearing is waaayyy cheaper than a rubi. You will have to hold off until a tuner is available for the 2012, but after that you can regear for less than 1500 bucks and put that engine in it's powerband.
I dont get why people continually say, "say goodbye to 6th gear on 35s with 3.73 gears/6 speed. I have that ratio, and use 6th gear everytime I am on the highway. Is it a vehicle to vehicle thing? If you dont tow, or live in a super hilly area, 3.73s are fine in a 6 speed. Could it be better ? Sure. But what cant be better?
 
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