4.10 Gears

tjkj2002 · **Posted:** Wed Feb 20, 2008 12:28 pm

ohv_kj wrote:

if your staying w/ a 31 then stay w/ your 3.73's the gas milage will change...also if your on street tires or at's...i have precsion(not sure if that's spelled correct) 4:10's gears w/ a tire size of 265/75/16 MT's...after i swaped out gears my gas is horrible...now to the good side...yes take off will be better and low end torke...4 low will be a little slower as well...and you can keep the same carrier...it would be a good time to install lockers so you are only taking apart the diffs once...if off roading w/ mt's then yes...street queen, no...it is not worth the gas milage money...

HMMM........I gained mpg's when I switched from 3.73's to 4.10's(about 3-5mpg's),and yes I had the same 265/75's on(MT/R's),I know SkyJump136 gained mpg's going from 3.73's to 4.10's and he is running 245/75's(MT/R's on MOAB rims).I get better mpg's then USAFCOP,I'm a little heavier also,he has 245/75's(MT/R's on MOAB rims) with 3.73's and I have 4.10's with 265/75's(know running Trxus MT's on steel rims),both of ours are '02's with the 45RFE tanny and 231 t-case.

tommudd · **Posted:** Wed Feb 20, 2008 12:28 pm

cant see where it got worse with a gear change at all, would not work that way. The size tires you have are killing your mileage not the gear ratio. with the tires you are running you should be at 4.56s (of course we cant get those for the front) but thats where your gas mileage went. Read up a little on what gear ratios/ tire sizes go together

ohv_kj · **Posted:** Wed Feb 20, 2008 12:38 pm

yeah i did and that's one reason why i am only at 4:10's but i looked at a chart and i'm in the middle for gas and power...i was just saying that it might not work well if you don't need that low end...the lower gearing you go the worst your gas gets at higher speeds do to the rpm's if his is off roading then yes...not if he's driving up and down the high way to go to work every day...economical? not really

ohv_kj · **Posted:** Wed Feb 20, 2008 12:45 pm

also we have a 14 gal tank? i can go 200 miles on one tank...i remeber when i had 245/70/16 AT's and w 3.73's i could go about 250-300 miles...high way driving that is any way it'e not about me...i could care less about gas milage...i was stating what i have witness...oh i do have a roof rack w/ lights so that is also a factor...

tjkj2002 · **Posted:** Wed Feb 20, 2008 12:46 pm

ohv_kj wrote:

yeah i did and that's one reason why i am only at 4:10's but i looked at a chart and i'm in the middle for gas and power...i was just saying that it might not work well if you don't need that low end...the lower gearing you go the worst your gas gets at higher speeds do to the rpm's if his is off roading then yes...not if he's driving up and down the high way to go to work every day...economical? not really

That's where we have been gaining the most MPG's is on the highway after the 4.10 swap.

medic9402 · **Posted:** Wed Feb 20, 2008 1:08 pm

tjkj2002, did you put 4.10's in both the front and rear? I have never opened a pumpkin in my life, how hard a job is it??

Thanks!

ohv_kj · **Posted:** Wed Feb 20, 2008 1:09 pm

tjkj2002 wrote:

ohv_kj wrote:

yeah i did and that's one reason why i am only at 4:10's but i looked at a chart and i'm in the middle for gas and power...i was just saying that it might not work well if you don't need that low end...the lower gearing you go the worst your gas gets at higher speeds do to the rpm's if his is off roading then yes...not if he's driving up and down the high way to go to work every day...economical? not really

That's where we have been gaining the most MPG's is on the highway after the 4.10 swap.

look i'm not getting in a pissing contest w/ you...i agree aboout 4:10's are better...i have seen it w/ my own eyes...i am filling up every 3-4thday...w/ 3.73s the same set up...i could go 5-6 days...if your doing better, then good for you...we live in very oppisit parts and thier are many diff. factors...plus he was asking mostly what kind of gears to get... :roll:

tommudd · **Posted:** Wed Feb 20, 2008 1:11 pm

ohv_kj wrote:

yeah i did and that's one reason why i am only at 4:10's but i looked at a chart and i'm in the middle for gas and power...i was just saying that it might not work well if you don't need that low end...the lower gearing you go the worst your gas gets at higher speeds do to the rpm's if his is off roading then yes...not if he's driving up and down the high way to go to work every day...economical? not really

If you stayed with a say 29/30 inch tire and went to 4.10s then yes highway speeds/ mileage would suffer but with going to 31/32s then 4.10s are just bring the rpms back into the sweet spot for mileage and power not making it worse

ohv_kj · **Posted:** Wed Feb 20, 2008 1:16 pm

tommudd wrote:

ohv_kj wrote:

yeah i did and that's one reason why i am only at 4:10's but i looked at a chart and i'm in the middle for gas and power...i was just saying that it might not work well if you don't need that low end...the lower gearing you go the worst your gas gets at higher speeds do to the rpm's if his is off roading then yes...not if he's driving up and down the high way to go to work every day...economical? not really

If you stayed with a say 29/30 inch tire and went to 4.10s then yes highway speeds/ mileage would suffer but with going to 31/32s then 4.10s are just bring the rpms back into the sweet spot for mileage and power not making it worse

can you say that there is a point when tire size, not talking about mine... will stop that from happening? and yes you want to do both front and rear...also are your speedo's cailbrated...mine is not...this is what i mean about factors

tjkj2002 · **Posted:** Wed Feb 20, 2008 1:18 pm

medic9402 wrote:

tjkj2002, did you put 4.10's in both the front and rear? I have never opened a pumpkin in my life, how hard a job is it??

Thanks!

Yep,you need matching F/R gears in a 4wd or major damage will result,If you've never taken a diff cover off I'd leave it to the pros.

Quote:

look i'm not getting in a pissing contest w/ you...i agree aboout 4:10's are better...i have seen it w/ my own eyes...i am filling up every 3-4thday...w/ 3.73s the same set up...i could go 5-6 days...if your doing better, then good for you...we live in very oppisit parts and thier are many diff. factors...plus he was asking mostly what kind of gears to get...

Either am I,I live in CO and it ain't flat and I'm getting about 13mpg's average(mostly city) and when I still had 3.73's(and 265/75's) I was in Tacoma WA(flat,sea level) and averaged 9mpg's,switched to 4.10's and it jumped to 16mpg's,then I added about 1000lbs of armor/tools and now I'm at 13mpg's here in CO at 6000ft(can get 17-19mpg's on the highway if I keep it at the speed limit).I also has alot on how you drive also,fluids used,and gas used.Could also be that your gears wheren't set-up right and causing your declined mpg's,or the fact that your speedo/odometer is also off which can give false mpg readings.

DoverKJ · **Posted:** Wed Feb 20, 2008 5:42 pm

Quote:

also we have a 14 gal tank?

I believe we have an 18 gal gas tank. I routinely fill up with 15.5-16 gals when I hit the gas station. I get about 220 or so miles per tank, right around 14 mpg. I am thinking of regearing to 4.10s soon, but after some other mods are complete and I finish up my project XJ and m416.

tjkj2002 · **Posted:** Wed Feb 20, 2008 6:07 pm

DoverKJ wrote:

Quote:

also we have a 14 gal tank?

I believe we have an 18 gal gas tank. I routinely fill up with 15.5-16 gals when I hit the gas station. I get about 220 or so miles per tank, right around 14 mpg. I am thinking of regearing to 4.10s soon, but after some other mods are complete and I finish up my project XJ and m416.

There are 3 different size gas tanks used in the KJ's,18.5,19.5,and 20.5 gallon sizes.I know '02 and '03's have the 18.5gallon(might be wrong on the '03's),'04 and '05 get the 19.5gallon tanks,and '06's+ and CRD's get the 20.5gallon tanks,I could be off on some of the years but '02's had only one tank choice and that is 18.5gallons.

kolesy · **Posted:** Wed Feb 20, 2008 6:27 pm

I know my '05 sport has a 20.5 gallon tank, FYI

Mike

tjkj2002 · **Posted:** Wed Feb 20, 2008 6:33 pm

kolesy wrote:

I know my '05 sport has a 20.5 gallon tank, FYI

Mike

Okay it must be that the '03 and '04's get the 19.5gallon tank and it's the '05+ that get the 20.5gallon tank.Like I said I may have been off on some of the years but I do know that '02's came with a 18.5gallon tank.Thanks for clearing that up.

Cobalt-60 · **Posted:** Wed Feb 20, 2008 7:40 pm

tjkj2002 wrote:

Okay it must be that the '03 and '04's get the 19.5gallon tank and it's the '05+ that get the 20.5gallon tank.Like I said I may have been off on some of the years but I do know that '02's came with a 18.5gallon tank.Thanks for clearing that up.

Yup, the '04 has the 19.5 gal tank. The confusion may be because about 4 gal of that is 'reserve' (or at least on mine it is). My fuel warning light comes on when there is about 4 gal left in the tank. If I fill it up then, I invariably end up putting 15.5 gal (and about $45) in the tank to top it off. The 'reserve' gives you about 60 miles (at 15 mpg) to find a gas station.

I have always wondered if '60 miles' was an industry 'reserve' standard because both my '98 Corolla and my '07 Jetta had/have about 2 gal available after the fuel warning light comes on and both got about 30 mpg.

Hood297 · **Posted:** Thu Feb 21, 2008 12:20 am

my owners manual reads 18.5

C co Crusader 2/127 · **Posted:** Thu Feb 21, 2008 1:16 am

tjkj2002 wrote:

KJ04 wrote:

KY Liberty wrote:

The other option is the front diff from a 4 cylinder if you can actually find one. Wasn't too hard for me since I was the first to go that route, but people treat them like they're made of gold now.

Were there any stampings on the housing to identify 4:10 gears?

One of the diff cover bolts should have a metal tag with the gear ratio stamped on them.

Quote:

jsc7002
4.10 Gears
Has anyone tried the 4.10 gear combo from Rusty's? Is it any good? if not where can I get some good ones? thats my next mod is to switch to 4.10s, will I need a new carrier if I go from the stock 3.73 to 4.10?

thanks

Don't get any gears from Rusty's.Like Bugnout said,get the D30A gears from ReiferRacing,also can get the rears also,don't forget the master install kits.

Any gear sets from Precision gears,Motive gears,Dana/Spicer,Richmond,USA Alloy,or Strange gears is good----DON'T get Genuine gears,they whine really bad.

so igot another question for ya. I already got the 4.10 for the rear but not the front yet(dont worry their not in) and was wondering if the arb lockers im getting will still work with the 4.10's?

C co Crusader 2/127 · **Posted:** Thu Feb 21, 2008 1:16 am

tjkj2002 wrote:

KJ04 wrote:

KY Liberty wrote:

The other option is the front diff from a 4 cylinder if you can actually find one. Wasn't too hard for me since I was the first to go that route, but people treat them like they're made of gold now.

Were there any stampings on the housing to identify 4:10 gears?

One of the diff cover bolts should have a metal tag with the gear ratio stamped on them.

Quote:

jsc7002
4.10 Gears
Has anyone tried the 4.10 gear combo from Rusty's? Is it any good? if not where can I get some good ones? thats my next mod is to switch to 4.10s, will I need a new carrier if I go from the stock 3.73 to 4.10?

thanks

Don't get any gears from Rusty's.Like Bugnout said,get the D30A gears from ReiferRacing,also can get the rears also,don't forget the master install kits.

Any gear sets from Precision gears,Motive gears,Dana/Spicer,Richmond,USA Alloy,or Strange gears is good----DON'T get Genuine gears,they whine really bad.

so igot another question for ya. I already got the 4.10 for the rear but not the front yet(dont worry their not in) and was wondering if the arb lockers im getting will still work with the 4.10's?

Dje Ryu · **Posted:** Thu Feb 21, 2008 2:00 am

from what I've read/heard, yes, they will.

ohv_kj · **Posted:** Thu Feb 21, 2008 10:55 am

tjkj2002 wrote:

kolesy wrote:

I know my '05 sport has a 20.5 gallon tank, FYI

Mike

Okay it must be that the '03 and '04's get the 19.5gallon tank and it's the '05+ that get the 20.5gallon tank.Like I said I may have been off on some of the years but I do know that '02's came with a 18.5gallon tank.Thanks for clearing that up.

i have only been able to put at least 14 gals in...

4.10 Gears

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