Jeep Wrangler Forum

Jeep Wrangler Forum (http://www.wranglerforum.com/)
-   JK General Discussion Forum (http://www.wranglerforum.com/f274/)
-   -   Gearing issues? (http://www.wranglerforum.com/f274/gearing-issues-40288.html)

BroilerBK 11-24-2009 06:34 AM

Gearing issues?
 
Newbie question...I have an 08 X unlimited totally stock (for now). Looking to upgrade tire size from 225/75/16 (blech!)to a 32 or 33 inch. Is this enough of an increase in size to cause any noticeable loss of performance without messing with gearing? I believe my X comes with 3.23 axle ratio.

I read many threads about this topic, and can't see that anybody that has done this "minor" upgrade has also needed gear upgrades...

Thanks...this is an awesome forum. I don't post often, but I read almost everything, and have learned a TON.

Much appreciated

scopop 11-24-2009 10:01 AM

have you read the active thread "new tires, poor mpg, options" The Forum gave me a bunch of good advise on gears and tires. The bottom line, when you modify one thing, it leads to another, which leads to another...

USAntigoon 11-24-2009 11:18 AM

This chart has some very good info...;)

http://farm3.static.flickr.com/2752/...5cd36c65_o.jpg

jk'n 11-24-2009 02:55 PM

^^ Great info, thanks! :punk:

I saved the image to my hard drive for future reference. :cool:

Pretty much says it all. :D

BroilerBK 11-24-2009 04:01 PM

That's awesome advice by both of you..thanks so much!

Hilldweller 11-26-2009 11:59 AM

Your Jeep either came with a 3.21 or 3.73 ----- I couldn't live with either and 33s. In fact, I have 4.56 gears and 285/75-16 tires and often long for 4.88 gearing when I'm towing in the hills.
Then again, I have an autotrans.

sefatboy 11-27-2009 09:33 AM

Great INFO USAntigoon...Thanks

scopop 11-29-2009 08:40 AM

USAntigoon, In your charts, there is a big differance between auto and manaual trans for what is proper gearing. according to the auto chart, a stock JK 4dr with auto trans, 31 255/75/17s and 3.73 gears and a tow package came from the factory under geared. Is this chart from Jeep?

USAntigoon 11-29-2009 09:12 AM

The yellow band doesn't mean "under geared" it just means "minimum allowable" gears.. @ 75 MPH.. I will agree this chart is very "conservative" but it is the best to understand the relationships and effects..

The difference between manual and automatic is related to the HP losses in the auto transmission and the shift ratio differences.....

Keep in mind that CAFE standards are a driving factor in what you can get factory installed.. Of course they will supply the minimum to make it work and to add to the CAFE totals....

Hilldweller 11-29-2009 04:17 PM

You also have to interpret Goon's charts by relating them to your needs.
A flatland-dweller might be very happy with a set of gears that a Hilldweller will cuss to eternity...

xxxxxxxxdavem 11-30-2009 08:26 AM

all i know is the 35's on the rubi w/4.10 gears here i western pa just sucks the life right out of that little 3.8 motor. got prices on gear change and cant justify $1700 right now. going to 4.88 when we have it done tho.

Hilldweller 11-30-2009 09:29 AM

Quote:

Originally Posted by davem (Post 496744)
all i know is the 35's on the rubi w/4.10 gears here i western pa just sucks the life right out of that little 3.8 motor. got prices on gear change and cant justify $1700 right now. going to 4.88 when we have it done tho.

Shop around for install prices; you should be able to do much better than that.
Unless it's some sort of lifetime warranty from a reputable shop or something...

yj-genral 11-30-2009 09:46 AM

install isnt $1700 but install and gears are $1700 but that is alittle high...

i got my gears, and master install kits for under $800 and then got a buddy of mine to install them for me (hes got all the right tools and has done plenty of installs) for about $200 but a professional shop will charge more because 1) it takes quite a bit of time and they charge alot for their time and 2) they have to stand behind their work (usually :D)

scopop 11-30-2009 11:59 AM

is it safe to assume that everyone sharing their gearing/tire stories has already reset their computers with the correct tire dia. to correct shifting and speedos?

Hilldweller 11-30-2009 12:05 PM

Quote:

Originally Posted by scopop (Post 496851)
is it safe to assume that everyone sharing their gearing/tire stories has already reset their computers with the correct tire dia. to correct shifting and speedos?

That was included with my install; I should've passed on his added expense and bought a Procal instead...

yj-genral 11-30-2009 12:32 PM

well, mine was on my YJ techinically but add another $200 for the procal and your golden :D


All times are GMT -5. The time now is 07:46 AM.