Topic: Gearing Opinions

[stan98tj]

Ok i keep reading posts about the benefits of regearing, many of you have done so with your own rigs. in a few months i plan on upgrading to 32s id like to get some opinions on which gear settings to set for my TJ. i have a 98 auto. drivetrain is still stock. it's now and will continue to be my daily driver. im not well versed in this aspect AT ALL so feel free to explain. id like to still be able to hit 65-70 on the highway without pushing the engine too much, basically staying comfortable at speed and not to lose too much off the line (she's slow enough ) and of course im looking for benefits when off the beaten path.
thanks

[Jeffy]

This is the easiest way to show you what gearing will do.

http://www.jeeptech.com/javaAps/gta.html

Input your info and it will spit out a chart that will show you your MPH at what RPM.

1     2.74:1
2    1.54:1
3    1.00:1
R    2.20:1
Transfer Case  2.72:1
Stock Axle 3.73:1

[stan98tj]

This is the easiest way to show you what gearing will do.

http://www.jeeptech.com/javaAps/gta.html

Input your info and it will spit out a chart that will show you your MPH at what RPM.

1     2.74:1
2    1.54:1
3    1.00:1
R    2.20:1
Transfer Case  2.72:1
Stock Axle 3.73:1

if i enter your info provided (leaving 4th-5th blank or zeros) it suggests a 3.73:1 ring and pinion. chart seems to get to 70 or above in third so thats good. but what i dont know is actually how this gearing will ride..is it slow? is it better on the trail-use the torque available efficiently? i read the info about the table where he mentions the need to get back to or close to OEM when running larger tires...if the table calculates that then it would be safe to say that 3.73:1 s an aftermarket gear setting that will get me closest to stock for running larger tires...anyone know if this is a good setting?

[stan98tj]

i read your regearing thread jeffy...4:56 is the optimal gearing for 32 on an auto according to that thread...

[Jeffy]

if i enter your info provided (leaving 4th-5th blank or zeros) it suggests a 3.73:1 ring and pinion. chart seems to get to 70 or above in third so thats good. but what i dont know is actually how this gearing will ride..is it slow? is it better on the trail-use the torque available efficiently? i read the info about the table where he mentions the need to get back to or close to OEM when running larger tires...if the table calculates that then it would be safe to say that 3.73:1 s an aftermarket gear setting that will get me closest to stock for running larger tires...anyone know if this is a good setting?

The gearing chart would give you the ratio for if everything stayed the same except for tires and gearing.  This does not account for any additional weight you may have added as well as aerodynamics.  Generally speaking it's good to go one gear set lower then you need to to account for weight and some aerodynamics.

With that said I think 4.56's and 32's will be fine.  Although you could probably go to 4.88's and 33's as well. Just double check the RPM's and if you know your own powerband then you can get a good estimate of how it will feel.  On takeoffs you will feel lower then whatever gears you get since there is torque multiplication from the torque converter.  I think it's about 2:1 until the TC gets up to speed.  Since you don't have a OD, you will be stuck in 1:1 or what would be 4th on a manual.  Set you RPM and cruise speed and choose the appropriate gears.

[stan98tj]

The gearing chart would give you the ratio for if everything stayed the same except for tires and gearing.  This does not account for any additional weight you may have added as well as aerodynamics.  Generally speaking it's good to go one gear set lower then you need to to account for weight and some aerodynamics.

With that said I think 4.56's and 32's will be fine.  Although you could probably go to 4.88's and 33's as well. Just double check the RPM's and if you know your own powerband then you can get a good estimate of how it will feel.  On takeoffs you will feel lower then whatever gears you get since there is torque multiplication from the torque converter.  I think it's about 2:1 until the TC gets up to speed.  Since you don't have a OD, you will be stuck in 1:1 or what would be 4th on a manual.  Set you RPM and cruise speed and choose the appropriate gears.

thanks jeffy.

[stan98tj]

one more thing..4.56 will turn 32s well enough, but w/o undue strain on the engine correct? by this i mean, the engine would handle it better then if i added the 32s and didnt regear. my end goal would be to accomodate for larger tires and have the engine feel as though there werent any of the added weight, thereby not consuming more or straining more...if of course, this is at all possible.

[sharpxmen]

one more thing..4.56 will turn 32s well enough, but w/o undue strain on the engine correct? by this i mean, the engine would handle it better then if i added the 32s and didnt regear. my end goal would be to accomodate for larger tires and have the engine feel as though there werent any of the added weight, thereby not consuming more or straining more...if of course, this is at all possible.

I'm not sure if i got the question right but if you're asking if the larger tires will reduce the wear on the engine b/c the rpm will be lower then it is somewhat untrue - it will have less rpm at cruise on the hwy given that you stay around 60mph, otherwise you'll need to downshift in 4th. Also, the less resulting torque at the periphery of the tire will require that you open the throttle more, so that would result in more strain on the engine, so not really a gain there and same for mpg (again, this is in case i got your question right).

[stan98tj]

I'm not sure if i got the question right but if you're asking if the larger tires will reduce the wear on the engine b/c the rpm will be lower then it is somewhat untrue - it will have less rpm at cruise on the hwy given that you stay around 60mph, otherwise you'll need to downshift in 4th. Also, the less resulting torque at the periphery of the tire will require that you open the throttle more, so that would result in more strain on the engine, so not really a gain there and same for mpg (again, this is in case i got your question right).

i was asking if i regear to 4.56 if it will reduce the strain on the engine with the added 32s as opposed to not regearing and puttin on the 32s. if i upgrade, im looking for the best possible gearing that overall doesnt put a strain on the engine..so i dont consume more etc.

[aw12345]

Stan the question is a good one and the answer is different for everybody.
My advice would be since it's a 3 speed auto, just put the tires on first, see how it drives and if you feel the engine lugs then consider regearing, if you have 4.10's to begin with you might be happy just the way it is. 32's aren't terribly big tires, I personally would try it with the stock gearing first, since a 3 speed auto does not have an overdrive it might be ok, if not you can still regear

By the way Happy newyear, good health a job and lots of Jeeping to all

[dwtaylorpdx]

My 94 has 32's and 4.56 gears. I dropped from 33's and am much happier.

I also gained back 5mpg by going from the 33z12 tires to 32x9 tires.

Dave

[Jeffy]

Stan the question is a good one and the answer is different for everybody.
My advice would be since it's a 3 speed auto, just put the tires on first, see how it drives and if you feel the engine lugs then consider regearing, if you have 4.10's to begin with you might be happy just the way it is. 32's aren't terribly big tires, I personally would try it with the stock gearing first, since a 3 speed auto does not have an overdrive it might be ok, if not you can still regear

By the way Happy newyear, good health a job and lots of Jeeping to all

His auto has 3.73:1 gears not 4.10/4.11's.  It will feel really underpowered.  At minimum, I'd swap axles with a manual 2.5L YJ to get 4.10/4.11's.  For 32's it should be OK-ish.  I drove for 5 years with stock 4.10/4.11's and 32x11.5R15's.  I think it was better then my 4.56's and 35's. 

[aw12345]

You got to remember he has no overdrive at all. I had 31's and 4.56 gears and hated it. stayed like that for 2 days and stuck 33's on it. Was revving to high for my taste and it hurt gas milage. There is no harm in trying to run what he has and go from there.
It's kinda a pain that you cannot get 4.30 gears those would be about ideal for his setup. With an overdrive transmission 4.56 and 32" tires isn't to bad still a bit short in the gearing, liked those gears better with 35's

[sma97tj]

i  went from stock 410s on 27inch tires to 410 on 35s and it was a turd so i put 488s in my 8.8 and dana 30  and i wish i had some a little deeper 513s maybe but here in west virginia its all mountains and hills  regearing helps alot my jeep is a 2.5 five speed 97 tj it is close to stock now  with the 35s and 488s

[Torch_Ind]

i  went from stock 410s on 27inch tires to 410 on 35s and it was a turd so i put 488s in my 8.8 and dana 30  and i wish i had some a little deeper 513s maybe but here in west virginia its all mountains and hills  regearing helps alot my jeep is a 2.5 five speed 97 tj it is close to stock now  with the 35s and 488s

I second the 5:13s and also running 4.88's and it made a huge improvement but could always use more right 5:13's!!!!