Re-gearing: Are 4.10's Too Big?

[GordoSmasho]

You want your cruising rpm to be 2500-3000 on the highway. That's where the 4.0 is most efficient a t putting out power and efficiency. Soon I'll be running 4.10 and 31 auto and in my other rig I have 5.13 and 35 stick. Each put me in that range at 70 and I get the same mileage in each. ~18mpg.

 

[JAS]

4.10 and 4.56 are about the same as stock for gearing when running 31's with the AW4 .

I run 31 and 4.88 here in Michigan and love the "grunt" the Jeep has out on the trail. Highway is not bad... I have 4 inches of lift and I do not like going above 70 anyway in the Jeep. I can still do that.

 

[Milford Cubicle II]

4.10 is already over-geared for 31's. 4.56 isn't even close, much less 4.88. It's your jeep and I don't care what you do to it, but please refrain from spewing BS on the board that less experienced folks might actually believe.

Want more power? Stroke it. Want even more power? Turbo the stroker or swap in a much more high performance and/or bigger engine. Gears add ZERO power.

Flame on

 

[sixty7ss]

4.10 is already over-geared for 31's. 4.56 isn't even close, much less 4.88. It's your jeep and I don't care what you do to it, but please refrain from spewing BS on the board that less experienced folks might actually believe.

Want more power? Stroke it. Want even more power? Turbo the stroker or swap in a much more high performance and/or bigger engine. Gears add ZERO power.

Flame on

You're right. Gears don't add power. They add torque. I haven't seen anyone spewing BS. I've seen people giving me their opinion based on their experience with their gears. That's exactly what I asked for.

If 4.10's were too big for an XJ w/ 31's, why does everyone on here say their the best gears for the job? Why did the suspension/axle shop I went to say they're the right gears? Why did the guy at Yukon Gears tell me to go with 4.10's?

Everyone is entitled to their opinion. If you'd like me to respect yours, please respect those of others.

 

[X E Ryder]

Retaining stock ratios - changes...

The info I have is that most companies based stock gearing on a [.12 x tire dia = gear ratio]. That makes a good baseline, and I like these charts to see how combinations are Typically affected. I agree with most here that 4.10's would be a good choice, but if you plan to go any bigger or climb often, the 4.56's would add a nice dose of torque.

Going to go 33's and 4.56 myself, which will put me just a little lower geared than stock. If I find a 4.88 for the 8 ana qtr before I buy I might even drop another step because I rarely exceed 55 here on the mountain.

Either way, gears are one of the most important things to keep matched to tire size or you'll need Lots of extra power to make up for the loss of torque in final drive ratio. Have fun!

 

[Milford Cubicle II]

You're right. Gears don't add power. They add torque. I haven't seen anyone spewing BS. I've seen people giving me their opinion based on their experience with their gears. That's exactly what I asked for.

If 4.10's were too big for an XJ w/ 31's, why does everyone on here say their the best gears for the job? Why did the suspension/axle shop I went to say they're the right gears? Why did the guy at Yukon Gears tell me to go with 4.10's?

Everyone is entitled to their opinion. If you'd like me to respect yours, please respect those of others.

Math isn't subjective, genius :gee:

 

[GordoSmasho]

4.10 is already over-geared for 31's. 4.56 isn't even close, much less 4.88. It's your jeep and I don't care what you do to it, but please refrain from spewing BS on the board that less experienced folks might actually believe.

Want more power? Stroke it. Want even more power? Turbo the stroker or swap in a much more high performance and/or bigger engine. Gears add ZERO power.

Flame on

Boy it's a good thing this thread isn't about getting more power out of your engine.

I think this guy has all the answers. Hey everyone that has there own good experience and opinions. Sell all you stuff and do what this guy says.

 

[GordoSmasho]

If you want to know what a gear swap like stock to 4.10 gears is like. Drive around for a week on the freeway in 3rd instead of overdrive. That is approximately what it will be like with 4.10s. I think you will see better highway cruising capability and it will hardly ever downshift.

 

[Milford Cubicle II]

Better highway cruising capability? :roflmao:

For the record, the factory ratio for 31" tall tires would be right around 3.93. Obviously, 3.93's aren't readily available so you'd have to chose between 3.73 or 4.10, either of which would be fine. But to go all the way to 4.56 or 4.88 is way overkill and you'll be turning 2.6 or 2.8k RPM at 70. Of course if you don't drive on the highway, then it's a moot point.

 

[sixty7ss]

Math isn't subjective, genius :gee:

Again, we're not discussing power. This is about matching the correct gears to the motor and tires. Nobody said anything about gears making your Jeep more powerful.

I appreciate your persistence, but math is what will ultimately make you look the fool. Please, if you believe you have something of value to submit to the thread, you're welcome to do so in a polite and respectful manner. We're all here trying to help each other out.

 

[sixty7ss]

The info I have is that most companies based stock gearing on a [.12 x tire dia = gear ratio]. That makes a good baseline, and I like these charts to see how combinations are Typically affected. I agree with most here that 4.10's would be a good choice, but if you plan to go any bigger or climb often, the 4.56's would add a nice dose of torque.

Going to go 33's and 4.56 myself, which will put me just a little lower geared than stock. If I find a 4.88 for the 8 ana qtr before I buy I might even drop another step because I rarely exceed 55 here on the mountain.

Either way, gears are one of the most important things to keep matched to tire size or you'll need Lots of extra power to make up for the loss of torque in final drive ratio. Have fun!

I found several charts like this one and they're very helpful. Thank you for posting that. It appears that the stock gears (3.55) are better for highway miles. The 4.10 seems to be a great all around daily driver gear set. The 4.56's are more for the weekend warrior. For my situation and tire size, it looks like the 4.10 gear set would be perfect.

I really appreciate the comments and advice.

 

[Talyn]

Keep in mind that there was a 3.73 option on XJ towing packages.

 

[djlarroc]

I don't see any harm in going a ratio deeper. Always leaves you withe the option for bigger tires, and that extra, dare i say power... is nice for moving the bigger, heavier, aggressive tires, armor, axles, and gear.

i went the 4:10 route on my xj w/34" LTBs.. w/my armor, and gear, it was a dog. it wasnt close to what that chart suggested. i was disappointed, but not about to re-gear again.

 

[OutkastBoss]

I am really happy with my 4.56's i am on 31's right now but geared it for the 33's i plan to have in the future (no bigger than 33)..

Its a bit low for the 31's but i drive on the highway just fine I know i will miss the extra torque when i go to the 33's but it will probably drive a bit better.

from my research i might have gone to 4.88 for the 33's but i got a good deal on some built axles with the 4.56's and im glad i went that route especially since I'm a DD rig

 

[AmnDay]

Dont fear the gear! With 4.56 what you lose on the highway you more than make up for in town and the fun factor doubles, Im at 3.55 now and cant wait to find a axle (no need to put money in the D35) and go 4.88 on 33s.

 

[Milford Cubicle II]

Again, we're not discussing power. This is about matching the correct gears to the motor and tires. Nobody said anything about gears making your Jeep more powerful.

I appreciate your persistence, but math is what will ultimately make you look the fool. Please, if you believe you have something of value to submit to the thread, you're welcome to do so in a polite and respectful manner. We're all here trying to help each other out.

I'm not talking about power. The only reason I brought it up is because a LOT of people over-gear to compensate for not having enough power. So please, get off of it.

How about you go learn a few things before you sit here and tell me to contribute something of value to the thread. I am the one trying to advise people how to *actually* match gears and tires to the factory ratio. I attempted to correct JAS's pure BS about 4.10 and 4.56's being "the same" as the factory ratio but apparently some people... ah hem... are too dense to understand how incorrect that is. And here you are telling me "math is what will ultimately make you look the fool" :roflmao: how ironic.

Ultimately, it's your jeep, you can do what you want to it. And I have no problem with that. I'm trying to make it known that you better realize that your ability to handle freeway speeds will suffer greatly, not to mention all the other downsides of turning much higher RPM at freeway speeds.

 

[XJEEPER]

If your rig remains exactly like it rolled off the factory floor, then matching factory ratios on a chart would be great......BUT your goal is to regear to add bigger tires, which require more lift for clearance to take you offroad to explore more places where you'll need heavy armor to protect your rig and since you're finding yourself further from civilization, you'll need to haul more stuff to sustain yourself and do field repairs if something breaks.........:dunno:, charts don't mention any of these variables.....:wierd:.

99% of the gear charts I've seen are toilet paper......because they never factor in the added weight of HD bumpers, racks, cages, nor do they factor the increased drag created by lifting your vehicle higher than stock, adding the drag of roof racks and lights and a full size spare....often thrown on the roof rack, plus trail gear, larger capacity fuel tanks and the increased rolling resistance of larger tires, significant power loss due to increase in elevation......see where this is going?

Could it be that gear ratio charts were created by a bean counter for gear companies who don't have a clue about how folks actually use their rig?

OR, he's a really smart bean counter who DOES know that folks are going to follow his chart (which fails to factor in real-would applications) and they will need to re-gear multiple times......which allows them to sell more gears!

Diabolical!!!



You'd be wise to listen to folks who have themselves/or know of those who have regeared multiple times because they selected the wrong ratio the first time.....or added larger tires and lift 6 months after a regear and now their rig is a pig on the freeway and they are getting 10 mpg.

NoCalChris's numbers nail it for rig with an AW4 auto.

 

[Milford Cubicle II]

Apparently you guys just aren't going to understand that gearing is the wrong way to fix a problem cause by additional rolling resistance, drag, and weight. Which is why those "bean counters" don't factor it. It is the right way to fix the change in final gearing caused by adding larger diameter tires. Gearing is a band-aid or a short cut way to cope with losing performance from more weight and more rolling resistance and drag. While more power output is the correct way to compensate for those factors.

 

[XJEEPER]

True, but regearing is more cost-effective than a $2000-3000 stroker or $3500-5000 V-8 swap to net similar results, while retaining stock gear ratios.

 

[Darky]

More power will make it move better, you are correct there Milford. Just, don't let it go to your head. However, more power will just brute force its way through the transmission, forcing the transmission to work harder and generating more heat. Heat kills transmissions. Going for a deeper gear ratio moves the stress away from the transmission. Instead, the diffs now multiply the available torque further. Your transmission lasts longer, you have better control in the dirt, and you don't lose out on the highway. With 4.88s and 33s, I spin up around 2700rpm at 70, but that's right in the powerband. It cruises fine at that speed, has power in reserve, and (if mine were running properly all around) gets decent mileage.

I don't know how many times you've tried this same argument only to have people who've had multiple XJs with multiple setups tell you that the extra rpm isn't hurting their mpgs.