Re: RE-GEARING TO EITHER 3.73 OR 4.11 (repeat -- sorry)
 

nrs wrote:
> On Sep 21, 10:47 am, Tracie <brain...@upstate.edu> wrote:
>> I have posted this once today, but for some reason it did not post.
>> If anyone finds it, sorry for the duplicate post.
>>
>> Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or
>> the 4.11 ratio would be better for me. I currently have 31" BFG All
>> Terrain T/A KOs, but will definitely upgrade to a 33" tire of some
>> sort in the future when these wear out. I will never upgrade to
>> bigger than a 33" tire. As for off-roading, I do some light trail
>> riding and the occasional hop in the mud puddle when I find one that
>> looks fun. 80% of my driving is highway at approximately 70 miles
>> round trip at a speed of anywhere from 60-70 mph. The other 20% is
>> split between city driving (10%), and off-roading (10%). My main
>> goal
>> is to get my Jeep to drive as close as possible to the way it did
>> bone
>> stock (being able to use my 6th gear on the freeway) and to prevent
>> excessive wear and tear on my clutch and engine parts. Someone
>> please
>> help! : D
>>
>> '06 TJ (4.0L with I-6)
>> 6 speed manual
>> Dana 30 front/35 rear
>> current 3.07s
>>
>> P.S. Would I also need to upgrade my Dana 30/35 to a bigger one
>> (like
>> 44s)? I don't know if this makes any difference as far as which gear
>> ratio to go with, but where I live (upstate NY), there can be quite a
>> bit of snow from Dec. - Apr.
>
> If you want it too run like it does now the ideal gear ration would be
> 3.07*33/31 = 3.27 rounded up to what is available. 3.55 seems to be
> available. The 3.73 or 4.1 would give you better performance off road
> but your fuel economy would suffer on the road.
>

Not necessarily. Her original tires were 225s I believe. If so her
original tires should be about 29", which would be close to the same
effective ratio as 3.55s with 33" tires. Going to 4.11s would result in
approximately 15% more RPM to attain the same speed. You have to
remember that going up in RPM doesn't cause a loss in fuel economy if
the gearing was too high to begin with. Since her highway RPM is below
the torque peak RPM of the engine, it is very possible she will see the
same, or even slightly improved economy. Besides, she is having to use
only 5th gear on the highway now, so obviously she needs more gear ratio.

Chris

Re: RE-GEARING TO EITHER 3.73 OR 4.11 (repeat -- sorry)
 

nrs wrote:
> On Sep 21, 10:47 am, Tracie <brain...@upstate.edu> wrote:
>> I have posted this once today, but for some reason it did not post.
>> If anyone finds it, sorry for the duplicate post.
>>
>> Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or
>> the 4.11 ratio would be better for me. I currently have 31" BFG All
>> Terrain T/A KOs, but will definitely upgrade to a 33" tire of some
>> sort in the future when these wear out. I will never upgrade to
>> bigger than a 33" tire. As for off-roading, I do some light trail
>> riding and the occasional hop in the mud puddle when I find one that
>> looks fun. 80% of my driving is highway at approximately 70 miles
>> round trip at a speed of anywhere from 60-70 mph. The other 20% is
>> split between city driving (10%), and off-roading (10%). My main
>> goal
>> is to get my Jeep to drive as close as possible to the way it did
>> bone
>> stock (being able to use my 6th gear on the freeway) and to prevent
>> excessive wear and tear on my clutch and engine parts. Someone
>> please
>> help! : D
>>
>> '06 TJ (4.0L with I-6)
>> 6 speed manual
>> Dana 30 front/35 rear
>> current 3.07s
>>
>> P.S. Would I also need to upgrade my Dana 30/35 to a bigger one
>> (like
>> 44s)? I don't know if this makes any difference as far as which gear
>> ratio to go with, but where I live (upstate NY), there can be quite a
>> bit of snow from Dec. - Apr.
>
> If you want it too run like it does now the ideal gear ration would be
> 3.07*33/31 = 3.27 rounded up to what is available. 3.55 seems to be
> available. The 3.73 or 4.1 would give you better performance off road
> but your fuel economy would suffer on the road.
>

Not necessarily. Her original tires were 225s I believe. If so her
original tires should be about 29", which would be close to the same
effective ratio as 3.55s with 33" tires. Going to 4.11s would result in
approximately 15% more RPM to attain the same speed. You have to
remember that going up in RPM doesn't cause a loss in fuel economy if
the gearing was too high to begin with. Since her highway RPM is below
the torque peak RPM of the engine, it is very possible she will see the
same, or even slightly improved economy. Besides, she is having to use
only 5th gear on the highway now, so obviously she needs more gear ratio.

Chris

Re: RE-GEARING TO EITHER 3.73 OR 4.11 (repeat -- sorry)
 

nrs wrote:
> On Sep 21, 10:47 am, Tracie <brain...@upstate.edu> wrote:
>> I have posted this once today, but for some reason it did not post.
>> If anyone finds it, sorry for the duplicate post.
>>
>> Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or
>> the 4.11 ratio would be better for me. I currently have 31" BFG All
>> Terrain T/A KOs, but will definitely upgrade to a 33" tire of some
>> sort in the future when these wear out. I will never upgrade to
>> bigger than a 33" tire. As for off-roading, I do some light trail
>> riding and the occasional hop in the mud puddle when I find one that
>> looks fun. 80% of my driving is highway at approximately 70 miles
>> round trip at a speed of anywhere from 60-70 mph. The other 20% is
>> split between city driving (10%), and off-roading (10%). My main
>> goal
>> is to get my Jeep to drive as close as possible to the way it did
>> bone
>> stock (being able to use my 6th gear on the freeway) and to prevent
>> excessive wear and tear on my clutch and engine parts. Someone
>> please
>> help! : D
>>
>> '06 TJ (4.0L with I-6)
>> 6 speed manual
>> Dana 30 front/35 rear
>> current 3.07s
>>
>> P.S. Would I also need to upgrade my Dana 30/35 to a bigger one
>> (like
>> 44s)? I don't know if this makes any difference as far as which gear
>> ratio to go with, but where I live (upstate NY), there can be quite a
>> bit of snow from Dec. - Apr.
>
> If you want it too run like it does now the ideal gear ration would be
> 3.07*33/31 = 3.27 rounded up to what is available. 3.55 seems to be
> available. The 3.73 or 4.1 would give you better performance off road
> but your fuel economy would suffer on the road.
>

Not necessarily. Her original tires were 225s I believe. If so her
original tires should be about 29", which would be close to the same
effective ratio as 3.55s with 33" tires. Going to 4.11s would result in
approximately 15% more RPM to attain the same speed. You have to
remember that going up in RPM doesn't cause a loss in fuel economy if
the gearing was too high to begin with. Since her highway RPM is below
the torque peak RPM of the engine, it is very possible she will see the
same, or even slightly improved economy. Besides, she is having to use
only 5th gear on the highway now, so obviously she needs more gear ratio.

Chris

Re: RE-GEARING TO EITHER 3.73 OR 4.11 (repeat -- sorry)
 

On Sep 21, 1:58 pm, c <c...@me.org> wrote:
> nrs wrote:
> > On Sep 21, 10:47 am, Tracie <brain...@upstate.edu> wrote:
> >> I have posted this once today, but for some reason it did not post.
> >> If anyone finds it, sorry for the duplicate post.
>
> >> Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or
> >> the 4.11 ratio would be better for me. I currently have 31" BFG All
> >> Terrain T/A KOs, but will definitely upgrade to a 33" tire of some
> >> sort in the future when these wear out. I will never upgrade to
> >> bigger than a 33" tire. As for off-roading, I do some light trail
> >> riding and the occasional hop in the mud puddle when I find one that
> >> looks fun. 80% of my driving is highway at approximately 70 miles
> >> round trip at a speed of anywhere from 60-70 mph. The other 20% is
> >> split between city driving (10%), and off-roading (10%). My main
> >> goal
> >> is to get my Jeep to drive as close as possible to the way it did
> >> bone
> >> stock (being able to use my 6th gear on the freeway) and to prevent
> >> excessive wear and tear on my clutch and engine parts. Someone
> >> please
> >> help! : D
>
> >> '06 TJ (4.0L with I-6)
> >> 6 speed manual
> >> Dana 30 front/35 rear
> >> current 3.07s
>
> >> P.S. Would I also need to upgrade my Dana 30/35 to a bigger one
> >> (like
> >> 44s)? I don't know if this makes any difference as far as which gear
> >> ratio to go with, but where I live (upstate NY), there can be quite a
> >> bit of snow from Dec. - Apr.
>
> > If you want it too run like it does now the ideal gear ration would be
> > 3.07*33/31 = 3.27 rounded up to what is available. 3.55 seems to be
> > available. The 3.73 or 4.1 would give you better performance off road
> > but your fuel economy would suffer on the road.
>
> Not necessarily. Her original tires were 225s I believe. If so her
> original tires should be about 29", which would be close to the same
> effective ratio as 3.55s with 33" tires. Going to 4.11s would result in
> approximately 15% more RPM to attain the same speed. You have to
> remember that going up in RPM doesn't cause a loss in fuel economy if
> the gearing was too high to begin with. Since her highway RPM is below
> the torque peak RPM of the engine, it is very possible she will see the
> same, or even slightly improved economy. Besides, she is having to use
> only 5th gear on the highway now, so obviously she needs more gear ratio.
>
> Chris- Hide quoted text -
>
> - Show quoted text -

Ok, that's true. To get close to stock you would need 3.07*33/28 =
3.62. So 3.73 would probably work well. I don't know enough about
the engine to know the ideal RPM so who knows, maybe 4.1 would be
better than stock. I do know it would be better off road.

Re: RE-GEARING TO EITHER 3.73 OR 4.11 (repeat -- sorry)
 

On Sep 21, 1:58 pm, c <c...@me.org> wrote:
> nrs wrote:
> > On Sep 21, 10:47 am, Tracie <brain...@upstate.edu> wrote:
> >> I have posted this once today, but for some reason it did not post.
> >> If anyone finds it, sorry for the duplicate post.
>
> >> Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or
> >> the 4.11 ratio would be better for me. I currently have 31" BFG All
> >> Terrain T/A KOs, but will definitely upgrade to a 33" tire of some
> >> sort in the future when these wear out. I will never upgrade to
> >> bigger than a 33" tire. As for off-roading, I do some light trail
> >> riding and the occasional hop in the mud puddle when I find one that
> >> looks fun. 80% of my driving is highway at approximately 70 miles
> >> round trip at a speed of anywhere from 60-70 mph. The other 20% is
> >> split between city driving (10%), and off-roading (10%). My main
> >> goal
> >> is to get my Jeep to drive as close as possible to the way it did
> >> bone
> >> stock (being able to use my 6th gear on the freeway) and to prevent
> >> excessive wear and tear on my clutch and engine parts. Someone
> >> please
> >> help! : D
>
> >> '06 TJ (4.0L with I-6)
> >> 6 speed manual
> >> Dana 30 front/35 rear
> >> current 3.07s
>
> >> P.S. Would I also need to upgrade my Dana 30/35 to a bigger one
> >> (like
> >> 44s)? I don't know if this makes any difference as far as which gear
> >> ratio to go with, but where I live (upstate NY), there can be quite a
> >> bit of snow from Dec. - Apr.
>
> > If you want it too run like it does now the ideal gear ration would be
> > 3.07*33/31 = 3.27 rounded up to what is available. 3.55 seems to be
> > available. The 3.73 or 4.1 would give you better performance off road
> > but your fuel economy would suffer on the road.
>
> Not necessarily. Her original tires were 225s I believe. If so her
> original tires should be about 29", which would be close to the same
> effective ratio as 3.55s with 33" tires. Going to 4.11s would result in
> approximately 15% more RPM to attain the same speed. You have to
> remember that going up in RPM doesn't cause a loss in fuel economy if
> the gearing was too high to begin with. Since her highway RPM is below
> the torque peak RPM of the engine, it is very possible she will see the
> same, or even slightly improved economy. Besides, she is having to use
> only 5th gear on the highway now, so obviously she needs more gear ratio.
>
> Chris- Hide quoted text -
>
> - Show quoted text -

Ok, that's true. To get close to stock you would need 3.07*33/28 =
3.62. So 3.73 would probably work well. I don't know enough about
the engine to know the ideal RPM so who knows, maybe 4.1 would be
better than stock. I do know it would be better off road.

Re: RE-GEARING TO EITHER 3.73 OR 4.11 (repeat -- sorry)
 

On Sep 21, 1:58 pm, c <c...@me.org> wrote:
> nrs wrote:
> > On Sep 21, 10:47 am, Tracie <brain...@upstate.edu> wrote:
> >> I have posted this once today, but for some reason it did not post.
> >> If anyone finds it, sorry for the duplicate post.
>
> >> Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or
> >> the 4.11 ratio would be better for me. I currently have 31" BFG All
> >> Terrain T/A KOs, but will definitely upgrade to a 33" tire of some
> >> sort in the future when these wear out. I will never upgrade to
> >> bigger than a 33" tire. As for off-roading, I do some light trail
> >> riding and the occasional hop in the mud puddle when I find one that
> >> looks fun. 80% of my driving is highway at approximately 70 miles
> >> round trip at a speed of anywhere from 60-70 mph. The other 20% is
> >> split between city driving (10%), and off-roading (10%). My main
> >> goal
> >> is to get my Jeep to drive as close as possible to the way it did
> >> bone
> >> stock (being able to use my 6th gear on the freeway) and to prevent
> >> excessive wear and tear on my clutch and engine parts. Someone
> >> please
> >> help! : D
>
> >> '06 TJ (4.0L with I-6)
> >> 6 speed manual
> >> Dana 30 front/35 rear
> >> current 3.07s
>
> >> P.S. Would I also need to upgrade my Dana 30/35 to a bigger one
> >> (like
> >> 44s)? I don't know if this makes any difference as far as which gear
> >> ratio to go with, but where I live (upstate NY), there can be quite a
> >> bit of snow from Dec. - Apr.
>
> > If you want it too run like it does now the ideal gear ration would be
> > 3.07*33/31 = 3.27 rounded up to what is available. 3.55 seems to be
> > available. The 3.73 or 4.1 would give you better performance off road
> > but your fuel economy would suffer on the road.
>
> Not necessarily. Her original tires were 225s I believe. If so her
> original tires should be about 29", which would be close to the same
> effective ratio as 3.55s with 33" tires. Going to 4.11s would result in
> approximately 15% more RPM to attain the same speed. You have to
> remember that going up in RPM doesn't cause a loss in fuel economy if
> the gearing was too high to begin with. Since her highway RPM is below
> the torque peak RPM of the engine, it is very possible she will see the
> same, or even slightly improved economy. Besides, she is having to use
> only 5th gear on the highway now, so obviously she needs more gear ratio.
>
> Chris- Hide quoted text -
>
> - Show quoted text -

Ok, that's true. To get close to stock you would need 3.07*33/28 =
3.62. So 3.73 would probably work well. I don't know enough about
the engine to know the ideal RPM so who knows, maybe 4.1 would be
better than stock. I do know it would be better off road.

Re: RE-GEARING TO EITHER 3.73 OR 4.11 (repeat -- sorry)
 

On Sep 21, 1:58 pm, c <c...@me.org> wrote:
> nrs wrote:
> > On Sep 21, 10:47 am, Tracie <brain...@upstate.edu> wrote:
> >> I have posted this once today, but for some reason it did not post.
> >> If anyone finds it, sorry for the duplicate post.
>
> >> Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or
> >> the 4.11 ratio would be better for me. I currently have 31" BFG All
> >> Terrain T/A KOs, but will definitely upgrade to a 33" tire of some
> >> sort in the future when these wear out. I will never upgrade to
> >> bigger than a 33" tire. As for off-roading, I do some light trail
> >> riding and the occasional hop in the mud puddle when I find one that
> >> looks fun. 80% of my driving is highway at approximately 70 miles
> >> round trip at a speed of anywhere from 60-70 mph. The other 20% is
> >> split between city driving (10%), and off-roading (10%). My main
> >> goal
> >> is to get my Jeep to drive as close as possible to the way it did
> >> bone
> >> stock (being able to use my 6th gear on the freeway) and to prevent
> >> excessive wear and tear on my clutch and engine parts. Someone
> >> please
> >> help! : D
>
> >> '06 TJ (4.0L with I-6)
> >> 6 speed manual
> >> Dana 30 front/35 rear
> >> current 3.07s
>
> >> P.S. Would I also need to upgrade my Dana 30/35 to a bigger one
> >> (like
> >> 44s)? I don't know if this makes any difference as far as which gear
> >> ratio to go with, but where I live (upstate NY), there can be quite a
> >> bit of snow from Dec. - Apr.
>
> > If you want it too run like it does now the ideal gear ration would be
> > 3.07*33/31 = 3.27 rounded up to what is available. 3.55 seems to be
> > available. The 3.73 or 4.1 would give you better performance off road
> > but your fuel economy would suffer on the road.
>
> Not necessarily. Her original tires were 225s I believe. If so her
> original tires should be about 29", which would be close to the same
> effective ratio as 3.55s with 33" tires. Going to 4.11s would result in
> approximately 15% more RPM to attain the same speed. You have to
> remember that going up in RPM doesn't cause a loss in fuel economy if
> the gearing was too high to begin with. Since her highway RPM is below
> the torque peak RPM of the engine, it is very possible she will see the
> same, or even slightly improved economy. Besides, she is having to use
> only 5th gear on the highway now, so obviously she needs more gear ratio.
>
> Chris- Hide quoted text -
>
> - Show quoted text -

Ok, that's true. To get close to stock you would need 3.07*33/28 =
3.62. So 3.73 would probably work well. I don't know enough about
the engine to know the ideal RPM so who knows, maybe 4.1 would be
better than stock. I do know it would be better off road.

Re: RE-GEARING TO EITHER 3.73 OR 4.11 (repeat -- sorry)
 

nrs wrote:
> On Sep 21, 10:47 am, Tracie <brain...@upstate.edu> wrote:
>> I have posted this once today, but for some reason it did not post.
>> If anyone finds it, sorry for the duplicate post.
>>
>> Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or
>> the 4.11 ratio would be better for me. I currently have 31" BFG All
>> Terrain T/A KOs, but will definitely upgrade to a 33" tire of some
>> sort in the future when these wear out. I will never upgrade to
>> bigger than a 33" tire. As for off-roading, I do some light trail
>> riding and the occasional hop in the mud puddle when I find one that
>> looks fun. 80% of my driving is highway at approximately 70 miles
>> round trip at a speed of anywhere from 60-70 mph. The other 20% is
>> split between city driving (10%), and off-roading (10%). My main
>> goal
>> is to get my Jeep to drive as close as possible to the way it did
>> bone
>> stock (being able to use my 6th gear on the freeway) and to prevent
>> excessive wear and tear on my clutch and engine parts. Someone
>> please
>> help! : D
>>
>> '06 TJ (4.0L with I-6)
>> 6 speed manual
>> Dana 30 front/35 rear
>> current 3.07s
>>
>> P.S. Would I also need to upgrade my Dana 30/35 to a bigger one
>> (like
>> 44s)? I don't know if this makes any difference as far as which gear
>> ratio to go with, but where I live (upstate NY), there can be quite a
>> bit of snow from Dec. - Apr.
>
> If you want it too run like it does now the ideal gear ration would be
> 3.07*33/31 = 3.27 rounded up to what is available. 3.55 seems to be
> available. The 3.73 or 4.1 would give you better performance off road
> but your fuel economy would suffer on the road.
>

Unfortunately the flying bricks we drive don't react the same as cars
when it comes to low revs.

Once you get the axles 'into' the air stream by raising the body away
from them with a suspension lift, it reacts 'strongly' to wind resistance.

On a lifted Jeep, anything much below 2000 rpm at highway speed will
start the engine lugging so you need way too much gas pedal to keep up
with wind twitches or slight hills.

Everyone I know and that has posted on the newsgroups that has 'dropped'
the overdrive with large tires and tall gears gets better mileage at
highway speeds.

My CJ7 came with overdrive (5th) and 3.31 gears or 'mileage' gears.
When I lifted it 3" and put 33's on, my mileage dropped by about 8 mpg
after calibrating the odometer when I drove it the same as before using
all the gears. It just 'doesn't' like 1750 rpm at 65 mph...

As soon as I stopped using 5th so I stayed in the 2300-2400 rpm range at
65 mph, my mileage jumped way up and has stayed a consistent 23 mpg to
this day.

Now I do have a manually 'tuned' carb engine with a 'hot' spark and
timing curve that insists on 91+ octane with a super light fiberglass
body (it only takes two people to 'easily' pick up the whole body tub
'with' the seats and roll bar in it) so the thing is basically an engine
on wheels that goes like a scalded cat, but still.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Re: RE-GEARING TO EITHER 3.73 OR 4.11 (repeat -- sorry)
 

nrs wrote:
> On Sep 21, 10:47 am, Tracie <brain...@upstate.edu> wrote:
>> I have posted this once today, but for some reason it did not post.
>> If anyone finds it, sorry for the duplicate post.
>>
>> Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or
>> the 4.11 ratio would be better for me. I currently have 31" BFG All
>> Terrain T/A KOs, but will definitely upgrade to a 33" tire of some
>> sort in the future when these wear out. I will never upgrade to
>> bigger than a 33" tire. As for off-roading, I do some light trail
>> riding and the occasional hop in the mud puddle when I find one that
>> looks fun. 80% of my driving is highway at approximately 70 miles
>> round trip at a speed of anywhere from 60-70 mph. The other 20% is
>> split between city driving (10%), and off-roading (10%). My main
>> goal
>> is to get my Jeep to drive as close as possible to the way it did
>> bone
>> stock (being able to use my 6th gear on the freeway) and to prevent
>> excessive wear and tear on my clutch and engine parts. Someone
>> please
>> help! : D
>>
>> '06 TJ (4.0L with I-6)
>> 6 speed manual
>> Dana 30 front/35 rear
>> current 3.07s
>>
>> P.S. Would I also need to upgrade my Dana 30/35 to a bigger one
>> (like
>> 44s)? I don't know if this makes any difference as far as which gear
>> ratio to go with, but where I live (upstate NY), there can be quite a
>> bit of snow from Dec. - Apr.
>
> If you want it too run like it does now the ideal gear ration would be
> 3.07*33/31 = 3.27 rounded up to what is available. 3.55 seems to be
> available. The 3.73 or 4.1 would give you better performance off road
> but your fuel economy would suffer on the road.
>

Unfortunately the flying bricks we drive don't react the same as cars
when it comes to low revs.

Once you get the axles 'into' the air stream by raising the body away
from them with a suspension lift, it reacts 'strongly' to wind resistance.

On a lifted Jeep, anything much below 2000 rpm at highway speed will
start the engine lugging so you need way too much gas pedal to keep up
with wind twitches or slight hills.

Everyone I know and that has posted on the newsgroups that has 'dropped'
the overdrive with large tires and tall gears gets better mileage at
highway speeds.

My CJ7 came with overdrive (5th) and 3.31 gears or 'mileage' gears.
When I lifted it 3" and put 33's on, my mileage dropped by about 8 mpg
after calibrating the odometer when I drove it the same as before using
all the gears. It just 'doesn't' like 1750 rpm at 65 mph...

As soon as I stopped using 5th so I stayed in the 2300-2400 rpm range at
65 mph, my mileage jumped way up and has stayed a consistent 23 mpg to
this day.

Now I do have a manually 'tuned' carb engine with a 'hot' spark and
timing curve that insists on 91+ octane with a super light fiberglass
body (it only takes two people to 'easily' pick up the whole body tub
'with' the seats and roll bar in it) so the thing is basically an engine
on wheels that goes like a scalded cat, but still.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

Re: RE-GEARING TO EITHER 3.73 OR 4.11 (repeat -- sorry)
 

nrs wrote:
> On Sep 21, 10:47 am, Tracie <brain...@upstate.edu> wrote:
>> I have posted this once today, but for some reason it did not post.
>> If anyone finds it, sorry for the duplicate post.
>>
>> Anyhoo, I definitely want to re-gear but I am not sure if the 3.73 or
>> the 4.11 ratio would be better for me. I currently have 31" BFG All
>> Terrain T/A KOs, but will definitely upgrade to a 33" tire of some
>> sort in the future when these wear out. I will never upgrade to
>> bigger than a 33" tire. As for off-roading, I do some light trail
>> riding and the occasional hop in the mud puddle when I find one that
>> looks fun. 80% of my driving is highway at approximately 70 miles
>> round trip at a speed of anywhere from 60-70 mph. The other 20% is
>> split between city driving (10%), and off-roading (10%). My main
>> goal
>> is to get my Jeep to drive as close as possible to the way it did
>> bone
>> stock (being able to use my 6th gear on the freeway) and to prevent
>> excessive wear and tear on my clutch and engine parts. Someone
>> please
>> help! : D
>>
>> '06 TJ (4.0L with I-6)
>> 6 speed manual
>> Dana 30 front/35 rear
>> current 3.07s
>>
>> P.S. Would I also need to upgrade my Dana 30/35 to a bigger one
>> (like
>> 44s)? I don't know if this makes any difference as far as which gear
>> ratio to go with, but where I live (upstate NY), there can be quite a
>> bit of snow from Dec. - Apr.
>
> If you want it too run like it does now the ideal gear ration would be
> 3.07*33/31 = 3.27 rounded up to what is available. 3.55 seems to be
> available. The 3.73 or 4.1 would give you better performance off road
> but your fuel economy would suffer on the road.
>

Unfortunately the flying bricks we drive don't react the same as cars
when it comes to low revs.

Once you get the axles 'into' the air stream by raising the body away
from them with a suspension lift, it reacts 'strongly' to wind resistance.

On a lifted Jeep, anything much below 2000 rpm at highway speed will
start the engine lugging so you need way too much gas pedal to keep up
with wind twitches or slight hills.

Everyone I know and that has posted on the newsgroups that has 'dropped'
the overdrive with large tires and tall gears gets better mileage at
highway speeds.

My CJ7 came with overdrive (5th) and 3.31 gears or 'mileage' gears.
When I lifted it 3" and put 33's on, my mileage dropped by about 8 mpg
after calibrating the odometer when I drove it the same as before using
all the gears. It just 'doesn't' like 1750 rpm at 65 mph...

As soon as I stopped using 5th so I stayed in the 2300-2400 rpm range at
65 mph, my mileage jumped way up and has stayed a consistent 23 mpg to
this day.

Now I do have a manually 'tuned' carb engine with a 'hot' spark and
timing curve that insists on 91+ octane with a super light fiberglass
body (it only takes two people to 'easily' pick up the whole body tub
'with' the seats and roll bar in it) so the thing is basically an engine
on wheels that goes like a scalded cat, but still.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's - Gone to the rust pile...
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
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