Are 33's bad for 3.07 gears?
- Thread starter PWest08
- Start date
Chris
Since doing a re-gear is for most a one time and done, this is not something most can do themselves and is not a cheap mod.
I am not sure if somewhere on the forum there is a chart that would show something like this type of chart.
A 4.0 w/ 3.07' would give you a similar feeling as running 29" tire's with 5:13' or 30" on 4:88's. I sure this does not make any sense at all.
Anyway something a jeep owner could buy cheap or borrow a set of certain tire size that could simulate the feeling of what the power would feel like on different tires sizes. Not saying that they would need a set of 30's, 31's, 32's etc. but even if they had the orig. tires and a second tire size it could give them the feeling of the power difference. Not the height or drive ability just the feel for power.
Tell me if I F'd in the head for even thinking this
Something like a chart of tire size and gearing equivalents?
Jumping on to this thread since I have a similar setup as the OP. 3.07 gears, 1998 4.0 6cy sport, AX-15 trans, 2.5" lift only I'm on 32" tires. While I'm happy with 32's, I'd like regear once and only once so hoping to future proof my regear as best possible. I don't plan on going up to 35's or anything like that. 33 is probably the most I'll ever do in the future considering the lift I currently have. I'm not planning on boulder crawling...my driving style is highway to the on the beach or campgrounds. Nothing too aggressive.
I did the grimreaper calculations and came up with the following (5th gear RPM @ 70mph):
32":
4.10 gears = 2381rpm
4.56 gears = 2648 rpm
33":
4.10 gears = 2309 rpm
4.56 gears = 2568 rpm
While I totally understand the lack of power/performance of the 3.07 (since I experience it every time I drive my jeep) I'm trying to understand the difference in performance of the new gear choices. I've read several posts stating that the the target rpm (or sweet spot) is around 2300-2500 prm @ 65mph. Is there much of a real world difference from 4.10 to 4.56 and if so would someone please explain? What is it that makes one axle ration ideal over the other? And I guess what I"m getting at is what is ideal gear ration for me?
Follow up to all of this (once I determine the gear ratio) - is where do I go from there? Once I find an actual shop to do the work, what's next in order to get the correct parts? I've read several posts about revolution gears as a preferred choice. Is there an all in one kit that I order from them and bring to a shop? What is needed to take that next step from deciding on gears to actually getting them on my jeep?
Step one is to measure your actual tire size. 33 or 32 is not correct and is too large of a number.
Find the height of the hub center from the ground and double that number. You can place a tape measure next to the axle tube. Where it touches is the hub center.
I like 3k rpm at 75mph because it's an easy number and it works well on my daily driver that actually does 75mph quite well. With my 33s (but not really) and 5 speed the gearing is 4.88.
For 32s and the 5 speed, I would lean heavily towards 4.56.
Find the height of the hub center from the ground and double that number. You can place a tape measure next to the axle tube. Where it touches is the hub center.
I like 3k rpm at 75mph because it's an easy number and it works well on my daily driver that actually does 75mph quite well. With my 33s (but not really) and 5 speed the gearing is 4.88.
For 32s and the 5 speed, I would lean heavily towards 4.56.
I have 33" tires, 4.0 manual 2004 TJ I recently had re-geared to 4.56. I find I'm taking off in 2nd on flat ground as opposed to 1st as the shift point from 1st to 2nd comes so quick. Have you noticed this as well?
It depends on where you like to shift. Mine is geared lower. I still take off on 1st, but often wind it out above 3k before going to 2nd.
Chris
Since doing a re-gear is for most a one time and done, this is not something most can do themselves and is not a cheap mod.
I am not sure if somewhere on the forum there is a chart that would show something like this type of chart.
A 4.0 w/ 3.07' would give you a similar feeling as running 29" tire's with 5:13' or 30" on 4:88's. I sure this does not make any sense at all.
Anyway something a jeep owner could buy cheap or borrow a set of certain tire size that could simulate the feeling of what the power would feel like on different tires sizes. Not saying that they would need a set of 30's, 31's, 32's etc. but even if they had the orig. tires and a second tire size it could give them the feeling of the power difference. Not the height or drive ability just the feel for power.
Tell me if I F'd in the head for even thinking this
Not at all. I've been thinking the same. I stayed with 33" tires because my TJ came with them but would like to know how 31" would roll.
Did you check and rechecked those calculations?
I have 6 speed and on 31.7" with 4.56.
60 mph is roughly 2500 rpm, 70 mph is in 2950 rpm region.... Seems odd that our final gears have so much difference.
Ideal is a personal preference.
If you are mostly on the highways, go with 4.10 .... if more power is needed, transfer case is there for a reason.
4.10 vs 4.56 is the same debate as 3.73 vs 4.10 - literally splitting hairs here, to each is their own.
Manufacturer preference is manufacturer preference. Johnny pulled trigger and went with ABC, noting went bad, so now he is swears that ABC is the way of life.
Go visit some of the oil manufacturers websites, after 10 min on it you will swear that oil maker has discovered a magic potion that will make your engine last 27000000 miles and add extra 100 horses.
There is plenty of material on this matter around here to read, i have at least 10 book marks on my home computer. It is your responsibility to do the homework on this, get familiar, weight things out and make your own choice. If you expect simple A or B answers to be fed to you with a spoon, there is a great chance for regrets or fuckups later.
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Airjunky
TJ Enthusiast
I have 31s, 4.0, 5 sp, in a 2002 with 4.56s. I can start in 1st but have to shift into 2nd pretty quickly. Or I can start in 2nd. It definitely lugs the engine if I'm truly at a stop or facing up hill. But if I'm rolling even a little bit, or facing downhill, a 2nd gear start is all good.
If I do a first gear start and wait to shift when the engine is at 3k RPM, I find getting into 2nd without grinding hard to do. If I shift earlier, or wait for the RPMs to come down more, its easier to get into 2nd without grinding at all.
You don't lose any power with 3:07 and 33-'s..you can lose what you don't have.
The guy above will confirm this post when the 4:56 gears go in.
I , like many others, have owned a couple of jeeps that already had oversize tires and stock gears when I got them ..and I had no idea how bad it was until I regeared.
Why? Our minds adjust to what we feel , experience ,etc.
Plumbers post above it right.... Once you feel the correct power and torque you understand. A 4.0 isn't anything to write home about, power wise, and it sure doesn't need anything to hinder it
The guy above will confirm this post when the 4:56 gears go in.
I , like many others, have owned a couple of jeeps that already had oversize tires and stock gears when I got them ..and I had no idea how bad it was until I regeared.
Why? Our minds adjust to what we feel , experience ,etc.
Plumbers post above it right.... Once you feel the correct power and torque you understand. A 4.0 isn't anything to write home about, power wise, and it sure doesn't need anything to hinder it
The only time I use first is when I come to a complete stop or are starting from a dead stop.
xxdabroxx
TJ Addict
I almost always start in second gear unless loaded with gear or on an incline.
Whether on 32’s or 33’s I would never go less than 456. The powerband on TJ’s is not 2300-2500, but 2500-2700.
Whether you rock crawl or not is irrelevant. You will enjoy your rig much more when properly regeared whether you are on or offroad.
Certainly is. As I said, I'm mainly in 4th gear with upshifts to 5th on flat freeway conditions.
We only received TJ's with 3.07's so for every new owner modifying that's where the starting point is.
Will sort mine out in coming months.
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I have this setup except with a manual and on 31s (going to 33s next round) and it really is a blast on forest roads--feels like a 4WD race car. There are tons of forrest roads around here in the Oregon Cascades--literally everywhere and way more than there are rocky trails. I have to drive an hour or two for any of that stuff many of you love and life is busy. I've been planning for upgraded axles, ox lockers, and a regear to 4.56 or 4.88 but now I'm torn because the fun with the current setup is so accessible and plentiful. I'm starting to think I need a second Jeep
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When did 1st gear become a F'ing highway gear? You are SUPPOSED to shift out of it quickly. It is there to start forward motion. Not cruise around town in.
If you think you aren't loosing power running 3.07's then you don't know what power is.
If you want to lug and dog the engine because it's too much work to shift into 2nd once you are rolling then just get an auto trans.
Why you would think having a 5 speed but never being able to shift into 5th gear is a sign of propper gearing is daft! The reason for more gears is so you can keep the engine in its ideal rpm range. Not to have extra gears to show your friends.
Get a speedo app on your phone. Find out how far off you are. From there you can find the gear ratio that the factory designed the drivetrain to function at best.
Don't mean for this to be a rant, but apparently it is.
If you think you aren't loosing power running 3.07's then you don't know what power is.
If you want to lug and dog the engine because it's too much work to shift into 2nd once you are rolling then just get an auto trans.
Why you would think having a 5 speed but never being able to shift into 5th gear is a sign of propper gearing is daft! The reason for more gears is so you can keep the engine in its ideal rpm range. Not to have extra gears to show your friends.
Get a speedo app on your phone. Find out how far off you are. From there you can find the gear ratio that the factory designed the drivetrain to function at best.
Don't mean for this to be a rant, but apparently it is.