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guitarguy2186 06-28-2012 08:56 AM

Gear Ratio
 
Just got my super lift in the mail today and a set of 35 x12.5x17 tires . My jeep is only the V6. Will I need to change the gear ratio? Also does anyone know if this is going to be putting too much strain on the transmission and axles with that big of tires?
Thanks guys

guitarguy2186 06-29-2012 11:58 AM

Re: Gear Ratio
 
anyone?

kennzz05 06-29-2012 04:23 PM

Re: Gear Ratio
 
im sure it will. be patient someone should be able to help you
ive got a real shitty internet connection there are gear ratio calcu8lators avail online im trying to load some but its taking forever try searching gear ratio calculators, ill keep looking

kennzz05 06-29-2012 04:41 PM

Re: Gear Ratio
 
http://www.csgnetwork.com/gearratcalc.html

kennzz05 06-29-2012 05:01 PM

Re: Gear Ratio
 
well after doing some more research i think you are going to have problems, did u do any research before you laid all this money out??apparantly the lowest ratio available is 3.73 for grand cherokees and the guy i read that did this was on 33 in tires. i think you are going to end up with the performance of an old volkswagon beetle thats only fireing on 2 cylinders

kennzz05 06-29-2012 05:10 PM

Re: Gear Ratio
 
on > General Commander Discussion > Successfully swapped 3.73 gears into 05 WK with 3.7 L
PDA
: Successfully swapped 3.73 gears into 05 WK with 3.7 L

07JeepXK
04-06-2012, 07:36 PM
I just wanted to stop in and say I just did a successful gear swap from 3.07's to 3.73's on a QT I 2005 Grand Cherokee WK to include programming. Drives great and no codes. The WK is sitting on 33's with 4 inch BDS lift.
p@55w0rd
04-06-2012, 08:15 PM
Please elaborate! What difs do you have? Who is the manufacturer of the gears? OEM or aftermarket? If they were aftermarket what other ratios do they carry?
07JeepXK
04-06-2012, 08:32 PM
Please elaborate! What difs do you have? Who is the manufacturer of the gears? OEM or aftermarket? If they were aftermarket what other ratios do they carry?

The install wasn't on my Jeep. I have an 07 XK with 4.7 liter stock with 3.73's. The install was done on my friends 2005 Jeep Grand Cherokee WK 3.7 Liter QT I stock with 3.07 gears. The rear now has Motive Gear 3.73's. For the front we got the entire front diff out of an 05 WK 4.7 L that had 3.73 gears stock. So for the front we only had to swap out the front diffs. Install went smooth.

3.73's are the highest numerical gear you can go with as no one makes 4.10's or 4.56's for our front diffs. If 4.10's or 4.56's were on the market they would be in my XK as we speak.
xjtrailrider
04-06-2012, 08:45 PM
I would almost be willing to bet that if someone sent a WK/XK front diff to Randy's Ring & Pinion he could find a R&P that would fit it.

I say this because I just don't see a manufacturer like AAM setting up a whole new CAD for just a ring and pinion. My thought process is that they are using an established gear set for something else and are not releasing that info. Most likely they purchase the gear sets and give them a AAM part number.

The rear Chryco 8.25 is easy to go deep with, Nitro, YUKON and others offer as low as 4.88

I dont think we would be lucky enough to go that low with the front diff but just getting to 4.10 would be great.

Then we could start snapping axle/drive shafts:icon_biggrin:
07JeepXK
04-06-2012, 09:07 PM
I don't think 4.10's would be worth the swap unless you never plan on going bigger then a 265/70. I'd like to run some 34's with 4.56's!
cmdr jim
04-06-2012, 09:12 PM
I just wanted to stop in and say I just did a successful gear swap from 3.07's to 3.73's on a QT I 2005 Grand Cherokee WK to include programming. Drives great and no codes. The WK is sitting on 33's with 4 inch BDS lift.

When you say programming, please explain the programming. An aftermarket programmer or Jeep dealer programming?
xjtrailrider
04-06-2012, 09:28 PM
I don't think 4.10's would be worth the swap unless you never plan on going bigger then a 265/70. I'd like to run some 34's with 4.56's!

I agree, but with the HEMI, it would be a nice gear to run.

I'm running 4.88's on my XJ and 35's. Its just right on the highway and off road although a T-case with a deeper crawl ratio than the NP231 can deliver would be awesome.
07JeepXK
04-06-2012, 09:29 PM
Aftermarket...The jeep dealer is worthless, they can only program gear ratios that came stock for that specific engine/drivetrain. Your hanging out on the wrong forum bro
cmdr jim
04-06-2012, 09:31 PM
Aftermarket...The jeep dealer is worthless. Your hanging out on the wrong forum bro Which programmer, Hypertech? and which forum? Point me in the right direction.
07JeepXK
04-06-2012, 09:34 PM
Yes...and xk-forum.com. just check out my recent posts.
cmdr jim
04-06-2012, 09:38 PM
Yes...and xk-forum.com. just check out my recent posts.
Cool, and thanks bro!
07JeepXK
04-06-2012, 09:39 PM
Or www.theultimatejeep.com
It was renamed. I forgot to mention that.
07JeepXK
04-06-2012, 09:41 PM
Not a problem. What your trying to do now I already accomplished months ago. Sorry I'm not on this forum much anymore.
xjtrailrider
04-06-2012, 09:42 PM
07JeepXK, do you set up your own diffs? I do my own but won't for other folks, I'm too damn picky! I'll spend a day just on one diff getting that magical gear pattern just right:mah:

I have a tool box full of specialty tools and set-up bearings just for diffs. Mostly DANA's of all sizes, 9" Fords and my favorite axle, the Chryco 8.25
07JeepXK
04-06-2012, 10:02 PM
07JeepXK, do you set up your own diffs? I do my own but won't for other folks, I'm too damn picky! I'll spend a day just on one diff getting that magical gear pattern just right:mah:

I have a tool box full of specialty tools and set-up bearings just for diffs. Mostly DANA's of all sizes, 9" Fords and my favorite axle, the Chryco 8.25

I've personally never really messed with any other axles prior to this recent gear swap. The Chrlsler 8.25 in the rear of a QT I Jeep XK or WK is very easy to set up. All it takes is the right tools and lots of research and advise from people that know these axles like the back of their hand.
07JeepXK
04-06-2012, 10:11 PM
Here is the 05 3.7 Liter WK that just received the 3.73 gears. Front differential came out of a 05 4.7 Liter WK.


http://i208.photobucket.com/albums/b...507001208a.jpg


http://i208.photobucket.com/albums/b...1/IMAG0239.jpg


http://i208.photobucket.com/albums/b...1/IMAG0241.jpg
xjtrailrider
04-06-2012, 10:30 PM
I've personally never really messed with any other axles prior to this recent gear swap. The Chrlsler 8.25 in the rear of a QT I Jeep XK or WK is very easy to set up. All it takes is the right tools and lots of research and advise from people that know these axles like the back of their hand.

Yep, I've been setting up diffs for 25 years as a hobby for myself. Got all the tools and know-how just too picky to really make money at it.


http://i208.photobucket.com/albums/b...1/IMAG0241.jpg

Looks like a good candidate for a ARB Locker
BADOS
04-07-2012, 09:06 AM
Did you think of the odometer?
07JeepXK
04-07-2012, 09:21 AM
Did you think of the odometer?

What about the odometer? The programmer fixed the computer telling it the proper gear ratio so that it doesnt send the tranny into safe mode (limp home mode). Also the programmer corrects the speedo for tire size and we got it dead on yesterday. It mirrors the speed on GPS. So since both the gear ratios and tire size is fixed the odometer will be dead on.
cmdr jim
04-09-2012, 06:34 AM
07JeepXK, I had a thought last night, if some of these guys aren't comfortable replacing ring and pinions, could they do a complete rear differential swap with a 3.73 from a junk XK or WK? I know that's more money, but maybe not if they were going to have a shop do the gear install.
07JeepXK
04-09-2012, 08:27 AM
07JeepXK, I had a thought last night, if some of these guys aren't comfortable replacing ring and pinions, could they do a complete rear differential swap with a 3.73 from a junk XK or WK? I know that's more money, but maybe not if they were going to have a shop do the gear install.

Yes, they could get the complete rear axle from the junkyard and just swap it in. Not only that but you can get the front differential out of the same vehicle while your at it. Just make sure that the pinion flanges are identical to the curent flanges on your XK/WK. They changed throughout the years. My 2007 4.7 Liter XK has a different flange than the 05 4.7 Liter WK front differential we just installed in my buddys WK.
cmdr jim
04-09-2012, 09:09 AM
Yes, they could get the complete rear axle from the junkyard and just swap it in. Not only that but you can get the front differential out of the same vehicle while your at it. Just make sure that the pinion flanges are identical to the curent flanges on your XK/WK. They changed throughout the years. My 2007 4.7 Liter XK has a different flange than the 05 4.7 Liter WK front differential we just installed in my buddys WK.

Do you know what they changed? Bolt pattern?
07JeepXK
04-09-2012, 12:12 PM
Do you know what they changed? Bolt pattern?

Yeah, they changed the entire pinion flange on the front differential where the front drive shaft bolts up. Also his drive shaft looks different then mine on the end that bolts to the front differential due to the differences in the pinion flange. I wish I had pictures of the differences but didnt think about it at the time. So my drive shaft wouldnt work on his vehicle and his front differential is even out of a 4.7 liter like mine. Just different years. It does look like you could just swap out the flanges if you had to.
cmdr jim
04-14-2012, 07:10 AM
I am completely surprised by the lack luster response to this news. I guess there are a lot of owners here that say they want to be able to swap out gears, but when it comes down to actually doing it the numbers fall short. And we wonder why aftermarket suppliers are slow to non responsive to our requests for more products.
psycho787
04-16-2012, 12:08 PM
HELL YEA!!! There is now hope for my QTI. So the required components to this build would be a front and rear differential from a 4.7L QTII XK/WK and the aftermarket programmer, correct?
cmdr jim
05-04-2012, 06:36 AM
I will have available in a couple weeks a used set of 3.55 front ring and pinion gears with about 35,000 miles on them and a new set of Mopar 3.55 rear ring and pinion gears for sale, if anyone is interested, I can give you a good price on these. The Front new is $855 from a dealer and about $600 shipped from an online Mopar parts store. The rear would go for $462 or $350 shipped. I could do $300 for the set, that includes shipping.

guitarguy2186 06-29-2012 09:03 PM

Re: Gear Ratio
 
kennzz05, cant tell ya how much i appreciate you doing all that research, Im not very familiar with all the lifting requirements this is relatively new to me and im learning as I go. I need to read all this stuff. Hopefully Ill be able to make it work.

guitarguy2186 06-29-2012 09:13 PM

Re: Gear Ratio
 
ok so now after reading this im thinking im going to have to find a front and rear differential =\. would you happen to know which after market programmer they are referring to?

kennzz05 06-29-2012 09:18 PM

Re: Gear Ratio
 
no i dont sorry, but i just sent a msg to a guy on here that does run 35s with the 5.7 hemi and 3.73 gears ill try and repost his reply, its not looking promiseing for you though,
Originally Posted by kennzz05here is my msg to him and his reply:
hi i was just reading youre thread and saw that you had been running 35" tires. theres a guy on here that was asking about running 35s on a 3.7 litre i did some research and saw that the lowest gearset made for the wk is 3.73 i honestly dont know squat about gearing but it seems to me this guy with a six cylinder and even if he gets 3.73s is still going to come up way short on power. wondering what youre feelings are about that? what ratio are you running? hows the power? ok i presume.
i dsaw a person with an xj that had 35s and his ratio was in the mid 4s and i think the 4 litle has more torque. anyways appreciate any input. Oh and thanks for turning me on the the dullys D2s i got an amber set as fogs on my semi truck they rock. and look great with my led headlights........ken





Well I have 3.73 axel gears and the 5.7L Hemi. The combo works ok for pushing 35s but it is not an optimal combination. I would never put 35s on the 3.7L! That would really suck! There is a noticeable difference in power and drivability between my 295s and 35s. Even though the 295s weigh more than the 35s, the 35s are just that much more difficult to turn with the stock gearing. I have made a few performance mods to have more power too, and I still wish I had more. My gas mileage is pretty bad so I can't even imagine how terrible it would be with a smaller engine struggling to turn those tires constantly. I have 35s on my XJ too. Except I am running 4.56 gears and a modified 4.0L. And you are right! Those I6 engines might not be as powerful on paper, but they sure are torquey little guys!

I'm glad you are loving those D2s! They are a little pricey, but they work really well!

-Nathan
__________________

kennzz05 06-29-2012 09:37 PM

Re: Gear Ratio
 
the guys screenname is omlett you can find his build thread page perhaps he can steer you in the right direction. but honestly if you go ahead as planned i think youre going to cause damage,excessive wear and generally be miserable. if you bought the tires new id consider returning them. before they hit the street and will than be considered used

guitarguy2186 06-30-2012 09:57 AM

Re: Gear Ratio
 
I think your right, Ive bugged omlett throughout my build for various things, hes probably tired of me haha. I can still return the tires though so thats good news. What about 33's? do you think that will work better?

kennzz05 07-01-2012 06:08 AM

Re: Gear Ratio
 
well your certainly moving in the right direction, if i were you i would start another thread titled "regearing required to run 33s with 3.7L ?" that way hopefully some people that have 33s will chime in. good luck


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