4.10 or 4.56 gears for 4.0L/5sp with 33s?

[Neil]

35" tires with 4.88 gears is the equivalent of running stock tires with 3.78 gears. Don't believe me? Check out http://4lo.com/calc/geartire.htm and input your tire size (35 in new and 27.1 oem) and 4.88 axle ratio. 2 inches makes quite a difference and I would probably do well with slightly lower gears (3.87 or 3.94 is tougher to come by except in IH Scouts)
I am building a house on the foothills of Mt Index (so I can be only 12 miles from Reiter trails) and my MJ is hauling in everything except the concrete (took 6500lbs in my '73 J4000 last trip)

Calculators are great but they are not always as accurate as they would lead you to believe. I have the gears and the tires so I did the math. I am 8% lower than stock. I know that that is close enough, the Highway Patrol doesn't think so, I still haven't corrected the speedometer. 4:88's are great though very close to stock. I wish that I could have gone to 5:38's. However, I was limited by the D30, it only goes down to 4:88. If I could have gone to 5:38's there would be no need for a Terra low kit. I don't really need to go that fast on the highway. I never take it on the freeway or on long trips.

As far as your thinking of lower gears. You are going the wrong way, 3:87 and 3:94 are higher. I also have not seen them available in aftermarket form. Any combination of axles involving a D30 reverse cut gear only goes as low as 4:88.

Neil

 

[carnuck]

Calculators are great but they are not always as accurate as they would lead you to believe. I have the gears and the tires so I did the math. I am 8% lower than stock. I know that that is close enough, the Highway Patrol doesn't think so, I still haven't corrected the speedometer. 4:88's are great though very close to stock. I wish that I could have gone to 5:38's. However, I was limited by the D30, it only goes down to 4:88. If I could have gone to 5:38's there would be no need for a Terra low kit. I don't really need to go that fast on the highway. I never take it on the freeway or on long trips.

As far as your thinking of lower gears. You are going the wrong way, 3:87 and 3:94 are higher. I also have not seen them available in aftermarket form. Any combination of axles involving a D30 reverse cut gear only goes as low as 4:88.

Neil

3.87 and 3.94 are lower than 3.73 (my current ratio) Stock tire is 205/75/15 which is 27.1" tall. I don't need Terra low as a NV241 OR with factory 4:1 low range will bolt right into my rig!

 

[mr4x4]

now I started out with 3.07's and and altho I was happy with the offroad performance dirving to town on the highway at 75 I was reving to a little high. I found myself driving 65 just to keep the rpm down
the drive to town is 70 miles
but around town and here its fine.

I was planning to put 35's on her anyways so I should be closer to stock
although if I started out running 1.55's or 3.73 then I could see 4.56 with 33's

 

[cterlizzi]

now I started out with 3.07's and and altho I was happy with the offroad performance dirving to town on the highway at 75 I was reving to a little high. I found myself driving 65 just to keep the rpm down
the drive to town is 70 miles
but around town and here its fine.

I was planning to put 35's on her anyways so I should be closer to stock
although if I started out running 1.55's or 3.73 then I could see 4.56 with 33's

And you're hitting on a point of mine... I'm going to be driving on the highway a lot (like 2000 miles from TX to CA and back) so I do want to be able to drive 75-85 without revving too high... Right now I'm running 235s (28.9s) with 3.07s and it's fine on the highway (actually quite peppy)... That's why I'm debating so much between the 4.10s and 4.56s...

 

[Neil]

Look... You have two choices... If you want to be at or near "stock" gear ratios, and you want to get good gas mileage... Sell your Jeep!!!! And buy a Geo Metro. If you want to own a Jeep and have a little fun... Stop worrying about mileage and staying "stock" and modify it as much as you can afford. Then drive it like you rented it!!! If you are looking at lifting or putting larger tires on your Jeep, then stock or near stock gears will not work!!! Let us not forget the aerodynamics of a Cherokee. It's a rolling brick people!!! The higher you lift that brick in the air and the more rolling resistance you put on by adding larger tires the worse this problem becomes. You either need more horsepower or lower gears to combat this. Also, as much as Jeep and the government (EPA) would like you to think that your Jeep needs to run at 1500 or 2000 rpm's on the freeway, it's not true. Your engine is still comfortable at 2500 and 3000 rpm's on the freeway. I have over 260,000 mi. on my original engine, have 4:88 gears, 35" tires and 50 miles one way to work. I drive at about 80 - 85 mph (on the flats). That puts me at about 2800 rpm (for those of you with the gear ratio calculators lastara )

Most of the people that have modified rigs and post on this board know what it means to "afford" to modify your Jeep. If you modify your Jeep and then piss and moan about the crappy mileage and poor streetability, then you obviously can't afford to modify your junk!!! You don't have to go straight to a 6" lift and 35" tires. There are many capable rigs out there on 31" tires and 2" of lift. These rigs maintain some of their fuel mileage and streetability while still being able to play weekend warrior. I and several people that have gone into the higher lifts and larger tires have decided that instead of pissing and moaning about the shortcomings of our modified rigs, we would purchase another car and use that as our daily driver, and save our junk for the trail. Still others use theirs as daily drivers. It's a choice, If you can't afford it don't do it!!! :banghead: :banghead: :banghead: :banghead: :banghead: :banghead:

Neil

 

[vegas_baja]

Speak it brother !!!

 

[cterlizzi]

Look... You have two choices... If you want to be at or near "stock" gear ratios, and you want to get good gas mileage... Sell your Jeep!!!! And buy a Geo Metro. If you want to own a Jeep and have a little fun... Stop worrying about mileage and staying "stock" and modify it as much as you can afford. Then drive it like you rented it!!! If you are looking at lifting or putting larger tires on your Jeep, then stock or near stock gears will not work!!! Let us not forget the aerodynamics of a Cherokee. It's a rolling brick people!!! The higher you lift that brick in the air and the more rolling resistance you put on by adding larger tires the worse this problem becomes. You either need more horsepower or lower gears to combat this. Also, as much as Jeep and the government (EPA) would like you to think that your Jeep needs to run at 1500 or 2000 rpm's on the freeway, it's not true. Your engine is still comfortable at 2500 and 3000 rpm's on the freeway. I have over 260,000 mi. on my original engine, have 4:88 gears, 35" tires and 50 miles one way to work. I drive at about 80 - 85 mph (on the flats). That puts me at about 2800 rpm (for those of you with the gear ratio calculators lastara )

Most of the people that have modified rigs and post on this board know what it means to "afford" to modify your Jeep. If you modify your Jeep and then piss and moan about the crappy mileage and poor streetability, then you obviously can't afford to modify your junk!!! You don't have to go straight to a 6" lift and 35" tires. There are many capable rigs out there on 31" tires and 2" of lift. These rigs maintain some of their fuel mileage and streetability while still being able to play weekend warrior. I and several people that have gone into the higher lifts and larger tires have decided that instead of pissing and moaning about the shortcomings of our modified rigs, we would purchase another car and use that as our daily driver, and save our junk for the trail. Still others use theirs as daily drivers. It's a choice, If you can't afford it don't do it!!! :banghead: :banghead: :banghead: :banghead: :banghead: :banghead:

Neil

I've been modifying cars for years and disagree with your philosophy nearly 100%. Yes, there is no way that a more trail capable Jeep will run as as quietly as "city Jeep", but there is still room to do things the right way and the wrong way... and just because this is not my daily driver it doesn't mean that the modifications cannot be done in an elegant way.

The best modifications are the ones where you have done as much as possible to the vehicle and it still feels, looks, handles, etc, as if it had been done by the factory and/or that's the way the factory should have done it in the first place.

Just my .02

 

[Neil]

I've been modifying cars for years and disagree with your philosophy nearly 100%. Yes, there is no way that a more trail capable Jeep will run as as quietly as "city Jeep", but there is still room to do things the right way and the wrong way... and just because this is not my daily driver it doesn't mean that the modifications cannot be done in an elegant way.

The best modifications are the ones where you have done as much as possible to the vehicle and it still feels, looks, handles, etc, as if it had been done by the factory and/or that's the way the factory should have done it in the first place.

Just my .02

Ok... I never said to half ass anything. Everything that I do to modify my Jeep is done to the highest standards. Whenever I build something for my junk, I always overbuild it. However, there is no way whatsoever that you or anybody else can say that you can build a Cherokee on 35" tires and 6.5" of lift that will handle exactly like a stock Jeep or have the same fuel economy as a stock vehicle. My junk handles great and drives great. I prefer to drive it over my Lexus. My wife makes me drive the Lexus because it gets twice the gas mileage. I don't think that you have a full understanding of my "philosophy". If you have any specific questions about my "philosophy" feel free to ask...

Neil

 

[ChuckD]

Ok... I never said to half ass anything.Everything that I do to modify my Jeep is done to the highest standards. Whenever I build something for my junk, I always overbuild it. However, there is no way whatsoever that you or anybody else can say that you can build a Cherokee on 35" tires and 6.5" of lift that will handle exactly like a stock Jeep or have the same fuel economy as a stock vehicle. My junk handles great and drives great. I prefer to drive it over my Lexus. My wife makes me drive the Lexus because it gets twice the gas mileage. I don't think that you have a full understanding of my "philosophy". If you have any specific questions about my "philosophy" feel free to ask...

Neil

:roflmao::roflmao::roflmao::roflmao::roflmao:

Anyway, Neil if you read his first post, you can read into it, that has to do more with money. If he sticks to 33's he'll do just fine.

 

[Neil]

:roflmao::roflmao::roflmao::roflmao::roflmao:

Anyway, Neil if you read his first post, you can read into it, that has to do more with money. If he sticks to 33's he'll do just fine.

Thanks for your support Chuck!!! That's kind of what I was trying to get across, build what you can afford. And that "affording" modifications also means the cost after you do the modifications. You may get a income tax return and be able to afford 4:88's and 35's, and then not be able to afford the gas anymore after the modification. And Chuck, standards are subjective. :laugh3:

Neil

 

[cterlizzi]

Ok... I never said to half ass anything. Everything that I do to modify my Jeep is done to the highest standards. Whenever I build something for my junk, I always overbuild it. However, there is no way whatsoever that you or anybody else can say that you can build a Cherokee on 35" tires and 6.5" of lift that will handle exactly like a stock Jeep or have the same fuel economy as a stock vehicle. My junk handles great and drives great. I prefer to drive it over my Lexus. My wife makes me drive the Lexus because it gets twice the gas mileage. I don't think that you have a full understanding of my "philosophy". If you have any specific questions about my "philosophy" feel free to ask...

Neil

Then I apologize, because that's how it came across, as "half-assing" it and, like you, I want to do things to the highest standards.

I'm actually not worried about gas mileage at all, I don't drive a Jeep for mileage. Maybe somewhere down the road the original reason for the question got lost through the threads... I plan to drive this vehicle (as I always have) to off-road events throughout the country and therefore it's about what is the best trade-off setup between highway comfort (i.e. NVH) and off-road capability.

If I planned on towing the Jeep thousands of miles versus driving it, then I would just stick 38s and a 8" lift on it and be done with it... If all I really wanted was a highway vehicle with some "looks" to it, I would probably stick 31s and a 3" old man emu lift on it and be done with it.

I'm stuck between chosing 33s and 35s as the middle of the road between those two extremes. The gear ratio has more to do with the tire size than anything else... After reading everyone's replies, I'll probably end up going with 33s and 4.56s just in case I change my mind down the road and put in 35s

 

[cterlizzi]

:roflmao::roflmao::roflmao::roflmao::roflmao:

Anyway, Neil if you read his first post, you can read into it, that has to do more with money. If he sticks to 33's he'll do just fine.

Ah, maybe that's what's confusing some people... Where I said, "it would help the budget"... no, it's not that I can't afford it, it's just that I hate to waste money and I'm always looking for the best bang for the buck whether it's a $100 or $10,000 part... And I start every project with a budget in my mind and try to stick to it... It's sort of a challenge to do the best you can with the least amount of money... although I've been known to blow through the budget the minute I see something that I really, really gotta have (sort of a left brain, right brain thing)

Heck, my wife would dearly wish that I stuck to my original budgets... Unfortunately I probably just spent more on Dinan headers and exhaust for my M5 then I'm about to spend for the entire XJ conversion... and don't get me started on the newly released SC kit for the M5, that's 25K and it'll probably cause a rift in the household if I even look at it more than once a week on the web... but it sure would be nice to have 600HP... Dang those german cars are expensive to work on...

 

[HaZakated]

I didn't read the whole thread; however, I am going to 4.56 because I know that eventually my Jeep will be a trail rig only. If I get 4.56 now with my 33"s and a lot of road driving, when I go to 35"+, I can wait a while before I go to 4.88+ gearing, and I will be ok.

 

[vegas_baja]

I didn't read the whole thread; however, I am going to 4.56 because I know that eventually my Jeep will be a trail rig only. If I get 4.56 now with my 33"s and a lot of road driving, when I go to 35"+, I can wait a while before I go to 4.88+ gearing, and I will be ok.

33" and 4.88 gears are a really good combo. I ran 5.14 with 35" on a dd prerunner for years with no problems. Do yourself a favor and read the whole thread and you'll see others that love 4.88 gears.

 

[XJ Eric]

I don't know about you guys, but the word "stroker" has had my interest ever since I got my Jeep.

I'm with you. I'm going to start looking for a HO to rebuild after my lift. A stroker would be awesome. A turbo may be an interesting way to go as well. may be a little cheaper to go that way too.

 

[Neil]

I'm with you. I'm going to start looking for a HO to rebuild after my lift. A stroker would be awesome. A turbo may be an interesting way to go as well. may be a little cheaper to go that way too.

If you plan on off roading it a lot a turbo won't do you any good. Off roading generally requires that you build power in the low RPM range. By the time a turbo spools up it's time to shift or let off the throttle. A turbo would be good to get you to the trail, but that's about it.

Neil

 

[cterlizzi]

If you plan on off roading it a lot a turbo won't do you any good. Off roading generally requires that you build power in the low RPM range. By the time a turbo spools up it's time to shift or let off the throttle. A turbo would be good to get you to the trail, but that's about it.

Neil

Agree 100%... I was thinking of a turbo myself, but that's for city and highway driving... you also have to be careful about the turbo spooling up on the trail if you get in a bit of jam and, as some often do, use the throttle to try to get you out of the mess... a sudden surge of power on the trail may do you more harm than good...