Do I need to re-gear?
- Thread starter WallyWest
- Start date
1. determine the largest diameter tire you will run
2. if it is dramatically larger than what you run now, wait until you are ready for those bigger tires
3. if it is not dramatically larger than what you run now, use recommendations from this forum and/or grimmjeaper.com to determine proper ratio and get it regeared
2. if it is dramatically larger than what you run now, wait until you are ready for those bigger tires
3. if it is not dramatically larger than what you run now, use recommendations from this forum and/or grimmjeaper.com to determine proper ratio and get it regeared
Are you really comparing the old 4.0 to the 3.6 or turbo 2.0?
Apples and oranges, the JK and JL Rubicons came with the more powerful 3.6L engine. The TJ Rubicon only came with 4.10.
Thanks.
No worries, not my first internet rodeo.
And yeah, cleaning the throttle body, MAF, checking plugs/wires, all that stuff is on my list.
Hey Chris, quick question. Can you explain what it's like after getting a Jeep regeared. I've always been surprised at how bad my Jeep sucks going up hills on the highway. It's always done what I want offroad, but it's kind of wimpy.
Quicker to accelerate, faster shifting between gears, less downshifting on grades, better in low range off road, less braking both on and off road, less strain on the clutch, less lugging on the engine. Maybe some others I forgot.
What size tires are you running? And look at the axle ratio tag for your ratio, does it say 3 73 or 3 07? You'll find the tag bolted onto the differential cover at its 9 o'clock position. The ratio will be stamped onto it.
If you're misgeared and running big tires that will turn a Jeep into a dog. Regearing fixes that and it can make a more than dramatic performance improvement not to mention better mpg.
The Jeep just feels and sounds more comfortable all around. It becomes a very different vehicle to experience when it can begin to get out of its own way.
Quicker response, quicker shifting, etc. It's not going to give your vehicle more power, but it's going to keep it in the power band where it needs to be to make the right power at the right time.
He means 3:73 Canadian. That's 4:56 down here .
So after reading thru some of the replies, I still say 3.07s and 30s around town shoulr launch fine assuming there are no engine issues. The 4.0L should be easy to launch. It sounds like yours is performing like an SE. And if it is down on power, regearing won't really help.
Off roading is quite a different matter. But with 3.07s I shifted to 4LO real early and never had an issue getting over a log or boulder.
In 4HI off road, if you don't want 4LO, once you know the engine is 100% you will be better off with lower gears. Depending on how much off roading you do vs highway driving it is always a compromize between low enough gearing to climb over obstacles from a stop, and getting a nice quiet highway cruise.
No doubt, the best reason to regear is to get enough lift from a stop. Tall tires and tall gears in High Range will shorten the clutch life long term if you are in challenging off road conditions, but then Low Range will also fix the problem.
Just to clarify, I was not saying it's impossible to launch, just that it stalled easier than I expected the first few times driving it. I've already adjusted and haven't killed the engine since. Also, the hill behind my house that I have to launch on is an extreme slope. Like, I have to rev to about 3k in first gear before even thinking of shifting to 2nd, and that's not limited to my TJ. My automatic Grand Cherokee won't even get out of first on that hill until about 30 mph.
This might be slightly steeper, but not by much.
When I'm going down the street I don't even use first gear, I start in second. And usually just leave it in 2nd for engine braking because it's not that long and there's a stop sign at the bottom. Lots of fun in the snow.
Last edited:
89grand
TJ Addict
Hey Jerry, Thanks for responding. It's 3.07. I bought it with 31 inch tires on it.
3.07 is also known as the abysmal ratio since it causes the engine to run at such low rpms that it can't develop much power. If power is acceptable for you with 31" tires I don't know that I'd regear but if you ever go to a larger size tire, definitely regear.
Having had 4:10 with 33 inch tires... I would imagine 3:07 with 31's would be sluggish....I think when owners inherit a bad gear and tire combination that they get used to it and don't realize how far off the mark the performance is.
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