Gearing Questions
 

I never really understood why people changed their gearing and what all the
gearing ratio numbers meant until switching from an '88 YJ to an '85 CJ7. My
YJ could go a long way in first gear compared to the CJ7 ...I'm almost
afraid to do anything serious with the CJ7 because shifting in the middle of
mud is a no-no and revving too high is a no-no. I'm guessing that the
gearing is to help solve this problem by extending the first gear? Maybe I'm
wrong ...I really don't know much about this stuff. What I'm asking more
than anything is if there is a tutorial somewhere that explains this in
depth for a numbnut like me :)

Thanks!

Re: Gearing Questions
 

>
>I never really understood why people changed their gearing and what all>the
>gearing ratio numbers meant until switching from an '88 YJ to an '85
CJ7.>My>YJ could go a long way in first gear compared to the CJ7 ...I'm almost
>afraid to do anything serious with the CJ7 because shifting in the middle of
mud is a no-no and revving too high is a no-no.

You are sort of backwards, EXCEPT maybe for mudbogging. Lower gearing (first
gear does not "last as long") is generally better, and is pretty much mandatory
when the tire size gets bigger.

You could always start in 2nd gear, if you don't want to shift in the middle of
a 'bog.

-jeff

Re: Gearing Questions
 

>
>I never really understood why people changed their gearing and what all>the
>gearing ratio numbers meant until switching from an '88 YJ to an '85
CJ7.>My>YJ could go a long way in first gear compared to the CJ7 ...I'm almost
>afraid to do anything serious with the CJ7 because shifting in the middle of
mud is a no-no and revving too high is a no-no.

You are sort of backwards, EXCEPT maybe for mudbogging. Lower gearing (first
gear does not "last as long") is generally better, and is pretty much mandatory
when the tire size gets bigger.

You could always start in 2nd gear, if you don't want to shift in the middle of
a 'bog.

-jeff

Re: Gearing Questions
 

>
>I never really understood why people changed their gearing and what all>the
>gearing ratio numbers meant until switching from an '88 YJ to an '85
CJ7.>My>YJ could go a long way in first gear compared to the CJ7 ...I'm almost
>afraid to do anything serious with the CJ7 because shifting in the middle of
mud is a no-no and revving too high is a no-no.

You are sort of backwards, EXCEPT maybe for mudbogging. Lower gearing (first
gear does not "last as long") is generally better, and is pretty much mandatory
when the tire size gets bigger.

You could always start in 2nd gear, if you don't want to shift in the middle of
a 'bog.

-jeff

Re: Gearing Questions
 

Hi Griffin,
I don't like to shift in the middle of a hill either so I start out
in second gear of my Corvette Muncie M22 at 1.64 ratio, directly through
the transfer to 5.38s, then keep the RPM between three and six thousand,
or a ground speed of between zero and to seventy miles an hour:
http://www.----------.com/pismo.htm Obviously you know your lowest gears
are for crawling over rocks, and that, that doesn't work for mud or sand
where you've got to keep compromise of speed and inertia working
together to blow over weak traction areas.
God Bless America, ßill O|||||||O
mailto:--------------------

griffin wrote:
>
> I never really understood why people changed their gearing and what all the
> gearing ratio numbers meant until switching from an '88 YJ to an '85 CJ7. My
> YJ could go a long way in first gear compared to the CJ7 ...I'm almost
> afraid to do anything serious with the CJ7 because shifting in the middle of
> mud is a no-no and revving too high is a no-no. I'm guessing that the
> gearing is to help solve this problem by extending the first gear? Maybe I'm
> wrong ...I really don't know much about this stuff. What I'm asking more
> than anything is if there is a tutorial somewhere that explains this in
> depth for a numbnut like me :)
>
> Thanks!

Re: Gearing Questions
 

Hi Griffin,
I don't like to shift in the middle of a hill either so I start out
in second gear of my Corvette Muncie M22 at 1.64 ratio, directly through
the transfer to 5.38s, then keep the RPM between three and six thousand,
or a ground speed of between zero and to seventy miles an hour:
http://www.----------.com/pismo.htm Obviously you know your lowest gears
are for crawling over rocks, and that, that doesn't work for mud or sand
where you've got to keep compromise of speed and inertia working
together to blow over weak traction areas.
God Bless America, ßill O|||||||O
mailto:--------------------

griffin wrote:
>
> I never really understood why people changed their gearing and what all the
> gearing ratio numbers meant until switching from an '88 YJ to an '85 CJ7. My
> YJ could go a long way in first gear compared to the CJ7 ...I'm almost
> afraid to do anything serious with the CJ7 because shifting in the middle of
> mud is a no-no and revving too high is a no-no. I'm guessing that the
> gearing is to help solve this problem by extending the first gear? Maybe I'm
> wrong ...I really don't know much about this stuff. What I'm asking more
> than anything is if there is a tutorial somewhere that explains this in
> depth for a numbnut like me :)
>
> Thanks!

Re: Gearing Questions
 

Hi Griffin,
I don't like to shift in the middle of a hill either so I start out
in second gear of my Corvette Muncie M22 at 1.64 ratio, directly through
the transfer to 5.38s, then keep the RPM between three and six thousand,
or a ground speed of between zero and to seventy miles an hour:
http://www.----------.com/pismo.htm Obviously you know your lowest gears
are for crawling over rocks, and that, that doesn't work for mud or sand
where you've got to keep compromise of speed and inertia working
together to blow over weak traction areas.
God Bless America, ßill O|||||||O
mailto:--------------------

griffin wrote:
>
> I never really understood why people changed their gearing and what all the
> gearing ratio numbers meant until switching from an '88 YJ to an '85 CJ7. My
> YJ could go a long way in first gear compared to the CJ7 ...I'm almost
> afraid to do anything serious with the CJ7 because shifting in the middle of
> mud is a no-no and revving too high is a no-no. I'm guessing that the
> gearing is to help solve this problem by extending the first gear? Maybe I'm
> wrong ...I really don't know much about this stuff. What I'm asking more
> than anything is if there is a tutorial somewhere that explains this in
> depth for a numbnut like me :)
>
> Thanks!

Re: Gearing Questions
 

I have an 86 CJ7 258 with 3.31 gears and when running trails I stay in
3rd low. I find it is the best power gear for my setup. When running
mud, I stay in 2nd low. I seldom need 1st low because I do not rock
crawl like the desert rats on here. I bush trail run. 1st is handy for
climbing over trees though.

I can walk up sand pit walls at 400 rpm in 3rd low and it has 'never'
stalled out. Just get too steep and it digs holes.

Last week I was crossing a big wash out and I was in 4 high by mistake.
I slipped off the hidden underwater 'trail' that was already up to the
top of my 33's and had to floor it. My wife was saying, 'more gas, more
gas, more gas' and I was 'well... I 'am' in 1st....' It barely chugged
through at 300 rpm, but it didn't stall!

When it comes to running at the mud or hill, the 258 engine won't rev
too high. If stock, the emissions computer governs the rpm to top out
at about 3200 to 3500 max under load. If you have dumped the computer,
the engine then will rev to it's mechanical redline of 4500 rpm under
load. For me, this means 50 mph in 2nd high.

Some folks do 'not' like my ratios. 5th high is useless unless I am
cruising over 80 mph. It still works at 65, but lugs the engine so gas
mileage sucks. If I don't use 5th, I get an extra 5 mpg or so.

When they re-gear, they go 'lower' not higher, so you can need 1st, 2nd
and 3rd before you are across an intersection, vs mine that will take
1st up over 20 mph.

Basically the lower the gear numbers, the higher or 'taller' the gears.
So a 3.07 will 'say' allow 1st gear to top out at 25 mph and a 4.56 gear
will only allow 1st to top out at 'say' 5 mph. Those numbers are not
accurate, but an example.

Hope this helps,

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

griffin wrote:
>
> I never really understood why people changed their gearing and what all the
> gearing ratio numbers meant until switching from an '88 YJ to an '85 CJ7. My
> YJ could go a long way in first gear compared to the CJ7 ...I'm almost
> afraid to do anything serious with the CJ7 because shifting in the middle of
> mud is a no-no and revving too high is a no-no. I'm guessing that the
> gearing is to help solve this problem by extending the first gear? Maybe I'm
> wrong ...I really don't know much about this stuff. What I'm asking more
> than anything is if there is a tutorial somewhere that explains this in
> depth for a numbnut like me :)
>
> Thanks!

Re: Gearing Questions
 

I have an 86 CJ7 258 with 3.31 gears and when running trails I stay in
3rd low. I find it is the best power gear for my setup. When running
mud, I stay in 2nd low. I seldom need 1st low because I do not rock
crawl like the desert rats on here. I bush trail run. 1st is handy for
climbing over trees though.

I can walk up sand pit walls at 400 rpm in 3rd low and it has 'never'
stalled out. Just get too steep and it digs holes.

Last week I was crossing a big wash out and I was in 4 high by mistake.
I slipped off the hidden underwater 'trail' that was already up to the
top of my 33's and had to floor it. My wife was saying, 'more gas, more
gas, more gas' and I was 'well... I 'am' in 1st....' It barely chugged
through at 300 rpm, but it didn't stall!

When it comes to running at the mud or hill, the 258 engine won't rev
too high. If stock, the emissions computer governs the rpm to top out
at about 3200 to 3500 max under load. If you have dumped the computer,
the engine then will rev to it's mechanical redline of 4500 rpm under
load. For me, this means 50 mph in 2nd high.

Some folks do 'not' like my ratios. 5th high is useless unless I am
cruising over 80 mph. It still works at 65, but lugs the engine so gas
mileage sucks. If I don't use 5th, I get an extra 5 mpg or so.

When they re-gear, they go 'lower' not higher, so you can need 1st, 2nd
and 3rd before you are across an intersection, vs mine that will take
1st up over 20 mph.

Basically the lower the gear numbers, the higher or 'taller' the gears.
So a 3.07 will 'say' allow 1st gear to top out at 25 mph and a 4.56 gear
will only allow 1st to top out at 'say' 5 mph. Those numbers are not
accurate, but an example.

Hope this helps,

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

griffin wrote:
>
> I never really understood why people changed their gearing and what all the
> gearing ratio numbers meant until switching from an '88 YJ to an '85 CJ7. My
> YJ could go a long way in first gear compared to the CJ7 ...I'm almost
> afraid to do anything serious with the CJ7 because shifting in the middle of
> mud is a no-no and revving too high is a no-no. I'm guessing that the
> gearing is to help solve this problem by extending the first gear? Maybe I'm
> wrong ...I really don't know much about this stuff. What I'm asking more
> than anything is if there is a tutorial somewhere that explains this in
> depth for a numbnut like me :)
>
> Thanks!

Re: Gearing Questions
 

I have an 86 CJ7 258 with 3.31 gears and when running trails I stay in
3rd low. I find it is the best power gear for my setup. When running
mud, I stay in 2nd low. I seldom need 1st low because I do not rock
crawl like the desert rats on here. I bush trail run. 1st is handy for
climbing over trees though.

I can walk up sand pit walls at 400 rpm in 3rd low and it has 'never'
stalled out. Just get too steep and it digs holes.

Last week I was crossing a big wash out and I was in 4 high by mistake.
I slipped off the hidden underwater 'trail' that was already up to the
top of my 33's and had to floor it. My wife was saying, 'more gas, more
gas, more gas' and I was 'well... I 'am' in 1st....' It barely chugged
through at 300 rpm, but it didn't stall!

When it comes to running at the mud or hill, the 258 engine won't rev
too high. If stock, the emissions computer governs the rpm to top out
at about 3200 to 3500 max under load. If you have dumped the computer,
the engine then will rev to it's mechanical redline of 4500 rpm under
load. For me, this means 50 mph in 2nd high.

Some folks do 'not' like my ratios. 5th high is useless unless I am
cruising over 80 mph. It still works at 65, but lugs the engine so gas
mileage sucks. If I don't use 5th, I get an extra 5 mpg or so.

When they re-gear, they go 'lower' not higher, so you can need 1st, 2nd
and 3rd before you are across an intersection, vs mine that will take
1st up over 20 mph.

Basically the lower the gear numbers, the higher or 'taller' the gears.
So a 3.07 will 'say' allow 1st gear to top out at 25 mph and a 4.56 gear
will only allow 1st to top out at 'say' 5 mph. Those numbers are not
accurate, but an example.

Hope this helps,

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's

griffin wrote:
>
> I never really understood why people changed their gearing and what all the
> gearing ratio numbers meant until switching from an '88 YJ to an '85 CJ7. My
> YJ could go a long way in first gear compared to the CJ7 ...I'm almost
> afraid to do anything serious with the CJ7 because shifting in the middle of
> mud is a no-no and revving too high is a no-no. I'm guessing that the
> gearing is to help solve this problem by extending the first gear? Maybe I'm
> wrong ...I really don't know much about this stuff. What I'm asking more
> than anything is if there is a tutorial somewhere that explains this in
> depth for a numbnut like me :)
>
> Thanks!