ACCURATE SPEEDOMETER?
09-17-2007, 10:38 AM
#11
Guest
Posts: n/a
Re: ACCURATE SPEEDOMETER?
Your watch is a bit clunky, but the method is correct.
A stop watch works better. Ignore the odometer, and measure your miles with
the mile markers along the shoulder of all federal and most state highways.
Divide the time in seconds that it takes to travel a measured mile into
3600, the result will be your speed.
Set the Cruise Control at 60. Measure the time it takes to go a mile. Divide
3600 by the time. 3600 / 60 =- 60. 3600 / 52 = 70. 3600 / 45 = 80.
"Tracie" <brainart@upstate.edu> wrote in message
news:1190034987.028338.291940@19g2000hsx.googlegro ups.com...
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
A stop watch works better. Ignore the odometer, and measure your miles with
the mile markers along the shoulder of all federal and most state highways.
Divide the time in seconds that it takes to travel a measured mile into
3600, the result will be your speed.
Set the Cruise Control at 60. Measure the time it takes to go a mile. Divide
3600 by the time. 3600 / 60 =- 60. 3600 / 52 = 70. 3600 / 45 = 80.
"Tracie" <brainart@upstate.edu> wrote in message
news:1190034987.028338.291940@19g2000hsx.googlegro ups.com...
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
09-17-2007, 10:38 AM
#12
Guest
Posts: n/a
Re: ACCURATE SPEEDOMETER?
Your watch is a bit clunky, but the method is correct.
A stop watch works better. Ignore the odometer, and measure your miles with
the mile markers along the shoulder of all federal and most state highways.
Divide the time in seconds that it takes to travel a measured mile into
3600, the result will be your speed.
Set the Cruise Control at 60. Measure the time it takes to go a mile. Divide
3600 by the time. 3600 / 60 =- 60. 3600 / 52 = 70. 3600 / 45 = 80.
"Tracie" <brainart@upstate.edu> wrote in message
news:1190034987.028338.291940@19g2000hsx.googlegro ups.com...
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
A stop watch works better. Ignore the odometer, and measure your miles with
the mile markers along the shoulder of all federal and most state highways.
Divide the time in seconds that it takes to travel a measured mile into
3600, the result will be your speed.
Set the Cruise Control at 60. Measure the time it takes to go a mile. Divide
3600 by the time. 3600 / 60 =- 60. 3600 / 52 = 70. 3600 / 45 = 80.
"Tracie" <brainart@upstate.edu> wrote in message
news:1190034987.028338.291940@19g2000hsx.googlegro ups.com...
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
09-17-2007, 10:38 AM
#13
Guest
Posts: n/a
Re: ACCURATE SPEEDOMETER?
Your watch is a bit clunky, but the method is correct.
A stop watch works better. Ignore the odometer, and measure your miles with
the mile markers along the shoulder of all federal and most state highways.
Divide the time in seconds that it takes to travel a measured mile into
3600, the result will be your speed.
Set the Cruise Control at 60. Measure the time it takes to go a mile. Divide
3600 by the time. 3600 / 60 =- 60. 3600 / 52 = 70. 3600 / 45 = 80.
"Tracie" <brainart@upstate.edu> wrote in message
news:1190034987.028338.291940@19g2000hsx.googlegro ups.com...
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
A stop watch works better. Ignore the odometer, and measure your miles with
the mile markers along the shoulder of all federal and most state highways.
Divide the time in seconds that it takes to travel a measured mile into
3600, the result will be your speed.
Set the Cruise Control at 60. Measure the time it takes to go a mile. Divide
3600 by the time. 3600 / 60 =- 60. 3600 / 52 = 70. 3600 / 45 = 80.
"Tracie" <brainart@upstate.edu> wrote in message
news:1190034987.028338.291940@19g2000hsx.googlegro ups.com...
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
09-17-2007, 10:52 AM
#14
Guest
Posts: n/a
Re: Re: ACCURATE SPEEDOMETER?
On Mon, 17 Sep 2007 08:38:45 -0500, c <c@me.org> wrote:
>As far as 6th gear is concerned, using only 5th gear will cause more
>engine wear
On a foot note, I do not know were this myth started. The engine is
not going to wear out any sooner in 5th and may actually last longer
if 6th is so tall that engine lugs. A few extra RPM never hurt any
engine and lower RPM lugging is potentailly far more damaging and
tough on bearings.
-----------------
TheSnoMan.com
>As far as 6th gear is concerned, using only 5th gear will cause more
>engine wear
On a foot note, I do not know were this myth started. The engine is
not going to wear out any sooner in 5th and may actually last longer
if 6th is so tall that engine lugs. A few extra RPM never hurt any
engine and lower RPM lugging is potentailly far more damaging and
tough on bearings.
-----------------
TheSnoMan.com
09-17-2007, 10:52 AM
#15
Guest
Posts: n/a
Re: Re: ACCURATE SPEEDOMETER?
On Mon, 17 Sep 2007 08:38:45 -0500, c <c@me.org> wrote:
>As far as 6th gear is concerned, using only 5th gear will cause more
>engine wear
On a foot note, I do not know were this myth started. The engine is
not going to wear out any sooner in 5th and may actually last longer
if 6th is so tall that engine lugs. A few extra RPM never hurt any
engine and lower RPM lugging is potentailly far more damaging and
tough on bearings.
-----------------
TheSnoMan.com
>As far as 6th gear is concerned, using only 5th gear will cause more
>engine wear
On a foot note, I do not know were this myth started. The engine is
not going to wear out any sooner in 5th and may actually last longer
if 6th is so tall that engine lugs. A few extra RPM never hurt any
engine and lower RPM lugging is potentailly far more damaging and
tough on bearings.
-----------------
TheSnoMan.com
09-17-2007, 10:52 AM
#16
Guest
Posts: n/a
Re: Re: ACCURATE SPEEDOMETER?
On Mon, 17 Sep 2007 08:38:45 -0500, c <c@me.org> wrote:
>As far as 6th gear is concerned, using only 5th gear will cause more
>engine wear
On a foot note, I do not know were this myth started. The engine is
not going to wear out any sooner in 5th and may actually last longer
if 6th is so tall that engine lugs. A few extra RPM never hurt any
engine and lower RPM lugging is potentailly far more damaging and
tough on bearings.
-----------------
TheSnoMan.com
>As far as 6th gear is concerned, using only 5th gear will cause more
>engine wear
On a foot note, I do not know were this myth started. The engine is
not going to wear out any sooner in 5th and may actually last longer
if 6th is so tall that engine lugs. A few extra RPM never hurt any
engine and lower RPM lugging is potentailly far more damaging and
tough on bearings.
-----------------
TheSnoMan.com
09-17-2007, 10:52 AM
#17
Guest
Posts: n/a
Re: Re: ACCURATE SPEEDOMETER?
On Mon, 17 Sep 2007 08:38:45 -0500, c <c@me.org> wrote:
>As far as 6th gear is concerned, using only 5th gear will cause more
>engine wear
On a foot note, I do not know were this myth started. The engine is
not going to wear out any sooner in 5th and may actually last longer
if 6th is so tall that engine lugs. A few extra RPM never hurt any
engine and lower RPM lugging is potentailly far more damaging and
tough on bearings.
-----------------
TheSnoMan.com
>As far as 6th gear is concerned, using only 5th gear will cause more
>engine wear
On a foot note, I do not know were this myth started. The engine is
not going to wear out any sooner in 5th and may actually last longer
if 6th is so tall that engine lugs. A few extra RPM never hurt any
engine and lower RPM lugging is potentailly far more damaging and
tough on bearings.
-----------------
TheSnoMan.com
09-17-2007, 11:17 AM
#18
Guest
Posts: n/a
Re: ACCURATE SPEEDOMETER?
Tracie wrote:
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
The (ones that have posed here) older TJ speedometers became correct
when 31" tire were put on.
Your mile per minute is a good base to tell it is close.
The only other way is to find a measured mile or a friend with a GPS or
even ask a cop to pace you because 'you just got new tires and don't
want to break the law'. Only a cop's speedometer would be reliable for
this, cars can be off too according to tire size.
I find 'my' engine 'much' prefers to be running at 2300-2500 rpm on the
highway which I get with my 4th gear. (have 33's and 3.31 gears) That
rpm gives me good throttle control and prevents engine lugging. I also
get a pretty stable 11L/100km or 23 mpg running there.
If I go to overdrive or 5th gear, the rpm drops to 1750 or so at 65 mph
which makes for the need of the full gas pedal travel to adjust speed or
hold a hill or wind vs a twitch of the pedal in 4th. This low rpm drops
my gas mileage by at least 5-8 mpg.
You can find out easy. Just compare gas mileages when using only 5th on
the highway and when using 6th mostly. I have one trip I do lots to get
bush camping which is 201 km from gas station to gas station so I have
an easy check point.
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)
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
The (ones that have posed here) older TJ speedometers became correct
when 31" tire were put on.
Your mile per minute is a good base to tell it is close.
The only other way is to find a measured mile or a friend with a GPS or
even ask a cop to pace you because 'you just got new tires and don't
want to break the law'. Only a cop's speedometer would be reliable for
this, cars can be off too according to tire size.
I find 'my' engine 'much' prefers to be running at 2300-2500 rpm on the
highway which I get with my 4th gear. (have 33's and 3.31 gears) That
rpm gives me good throttle control and prevents engine lugging. I also
get a pretty stable 11L/100km or 23 mpg running there.
If I go to overdrive or 5th gear, the rpm drops to 1750 or so at 65 mph
which makes for the need of the full gas pedal travel to adjust speed or
hold a hill or wind vs a twitch of the pedal in 4th. This low rpm drops
my gas mileage by at least 5-8 mpg.
You can find out easy. Just compare gas mileages when using only 5th on
the highway and when using 6th mostly. I have one trip I do lots to get
bush camping which is 201 km from gas station to gas station so I have
an easy check point.
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)
09-17-2007, 11:17 AM
#19
Guest
Posts: n/a
Re: ACCURATE SPEEDOMETER?
Tracie wrote:
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
The (ones that have posed here) older TJ speedometers became correct
when 31" tire were put on.
Your mile per minute is a good base to tell it is close.
The only other way is to find a measured mile or a friend with a GPS or
even ask a cop to pace you because 'you just got new tires and don't
want to break the law'. Only a cop's speedometer would be reliable for
this, cars can be off too according to tire size.
I find 'my' engine 'much' prefers to be running at 2300-2500 rpm on the
highway which I get with my 4th gear. (have 33's and 3.31 gears) That
rpm gives me good throttle control and prevents engine lugging. I also
get a pretty stable 11L/100km or 23 mpg running there.
If I go to overdrive or 5th gear, the rpm drops to 1750 or so at 65 mph
which makes for the need of the full gas pedal travel to adjust speed or
hold a hill or wind vs a twitch of the pedal in 4th. This low rpm drops
my gas mileage by at least 5-8 mpg.
You can find out easy. Just compare gas mileages when using only 5th on
the highway and when using 6th mostly. I have one trip I do lots to get
bush camping which is 201 km from gas station to gas station so I have
an easy check point.
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)
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
The (ones that have posed here) older TJ speedometers became correct
when 31" tire were put on.
Your mile per minute is a good base to tell it is close.
The only other way is to find a measured mile or a friend with a GPS or
even ask a cop to pace you because 'you just got new tires and don't
want to break the law'. Only a cop's speedometer would be reliable for
this, cars can be off too according to tire size.
I find 'my' engine 'much' prefers to be running at 2300-2500 rpm on the
highway which I get with my 4th gear. (have 33's and 3.31 gears) That
rpm gives me good throttle control and prevents engine lugging. I also
get a pretty stable 11L/100km or 23 mpg running there.
If I go to overdrive or 5th gear, the rpm drops to 1750 or so at 65 mph
which makes for the need of the full gas pedal travel to adjust speed or
hold a hill or wind vs a twitch of the pedal in 4th. This low rpm drops
my gas mileage by at least 5-8 mpg.
You can find out easy. Just compare gas mileages when using only 5th on
the highway and when using 6th mostly. I have one trip I do lots to get
bush camping which is 201 km from gas station to gas station so I have
an easy check point.
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)
09-17-2007, 11:17 AM
#20
Guest
Posts: n/a
Re: ACCURATE SPEEDOMETER?
Tracie wrote:
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
The (ones that have posed here) older TJ speedometers became correct
when 31" tire were put on.
Your mile per minute is a good base to tell it is close.
The only other way is to find a measured mile or a friend with a GPS or
even ask a cop to pace you because 'you just got new tires and don't
want to break the law'. Only a cop's speedometer would be reliable for
this, cars can be off too according to tire size.
I find 'my' engine 'much' prefers to be running at 2300-2500 rpm on the
highway which I get with my 4th gear. (have 33's and 3.31 gears) That
rpm gives me good throttle control and prevents engine lugging. I also
get a pretty stable 11L/100km or 23 mpg running there.
If I go to overdrive or 5th gear, the rpm drops to 1750 or so at 65 mph
which makes for the need of the full gas pedal travel to adjust speed or
hold a hill or wind vs a twitch of the pedal in 4th. This low rpm drops
my gas mileage by at least 5-8 mpg.
You can find out easy. Just compare gas mileages when using only 5th on
the highway and when using 6th mostly. I have one trip I do lots to get
bush camping which is 201 km from gas station to gas station so I have
an easy check point.
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)
> Hello all. I have a 2006 Wrangler X with 6 speed manual tranny, 3.07
> gearing, and D30 front/35 rear. I recently upgraded my tires from the
> stock 215/75/15 to 31/10.5/15 BFG All Terrain T/A KO. I am looking
> for a reliable way to tell if my speedometer is off at all with the
> tire upgrade. I do not have access to a GPS system. What I HAVE done
> is to use the tripometer (with tenths), and hold steady at 60 mph (my
> speedometer said 60) for one mile while watching my clock. I am
> EXTREMELY close to going 1 mile in 1 minute by using this method. Is
> this reliable to tell whether or not my speedometer is dead on? I
> have NOT changed the speedometer gear yet, or had the computer changed
> to reflect the larger sized tires. Also, I am not using my OD (6th)
> much on the highway, but when I get up to 65 (the speedometer says
> 65), I am running at about 2500 rpms in 5th. Is this bad, or should I
> be shifting into the OD (6th)? I do fine with 1st through 5th. Just
> not sure what speed or what rpms I should be using 6th. Any help is
> really appreciated.
>
The (ones that have posed here) older TJ speedometers became correct
when 31" tire were put on.
Your mile per minute is a good base to tell it is close.
The only other way is to find a measured mile or a friend with a GPS or
even ask a cop to pace you because 'you just got new tires and don't
want to break the law'. Only a cop's speedometer would be reliable for
this, cars can be off too according to tire size.
I find 'my' engine 'much' prefers to be running at 2300-2500 rpm on the
highway which I get with my 4th gear. (have 33's and 3.31 gears) That
rpm gives me good throttle control and prevents engine lugging. I also
get a pretty stable 11L/100km or 23 mpg running there.
If I go to overdrive or 5th gear, the rpm drops to 1750 or so at 65 mph
which makes for the need of the full gas pedal travel to adjust speed or
hold a hill or wind vs a twitch of the pedal in 4th. This low rpm drops
my gas mileage by at least 5-8 mpg.
You can find out easy. Just compare gas mileages when using only 5th on
the highway and when using 6th mostly. I have one trip I do lots to get
bush camping which is 201 km from gas station to gas station so I have
an easy check point.
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)