Re: ACCURATE SPEEDOMETER?
 

Jeff, I'm relieved that at least someone chimed in with the relevant answer
on the speed - virtually ANY speedometer will be dead on if you use the
odometer to measure your mile since both the speed and distance shown is
derived from how fast a shaft turning, not from actual distance covered.
The same error in speed is translated to distance. You need a "measured
mile" - I like a 4-5 mile stretch since it averages out the speed better
and minimizes timing errors.

As for engine loading, a cheap vacuum gauge will tell you an awful lot about
the best gear to use in a given situation. Basically, the higher the
vacuum, the easier the engine is working for a given situation. Of course,
the position of your right foot on the skinny pedal tells you about the
same thing, but the calibration is a tad suspect <g>.

Jeff Strickland wrote:

> 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.
>>

--
Will Honea

--
Posted via a free Usenet account from http://www.teranews.com

Re: ACCURATE SPEEDOMETER?
 

Jeff, I'm relieved that at least someone chimed in with the relevant answer
on the speed - virtually ANY speedometer will be dead on if you use the
odometer to measure your mile since both the speed and distance shown is
derived from how fast a shaft turning, not from actual distance covered.
The same error in speed is translated to distance. You need a "measured
mile" - I like a 4-5 mile stretch since it averages out the speed better
and minimizes timing errors.

As for engine loading, a cheap vacuum gauge will tell you an awful lot about
the best gear to use in a given situation. Basically, the higher the
vacuum, the easier the engine is working for a given situation. Of course,
the position of your right foot on the skinny pedal tells you about the
same thing, but the calibration is a tad suspect <g>.

Jeff Strickland wrote:

> 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.
>>

--
Will Honea

--
Posted via a free Usenet account from http://www.teranews.com

Re: ACCURATE SPEEDOMETER?
 

Jeff, I'm relieved that at least someone chimed in with the relevant answer
on the speed - virtually ANY speedometer will be dead on if you use the
odometer to measure your mile since both the speed and distance shown is
derived from how fast a shaft turning, not from actual distance covered.
The same error in speed is translated to distance. You need a "measured
mile" - I like a 4-5 mile stretch since it averages out the speed better
and minimizes timing errors.

As for engine loading, a cheap vacuum gauge will tell you an awful lot about
the best gear to use in a given situation. Basically, the higher the
vacuum, the easier the engine is working for a given situation. Of course,
the position of your right foot on the skinny pedal tells you about the
same thing, but the calibration is a tad suspect <g>.

Jeff Strickland wrote:

> 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.
>>

--
Will Honea

--
Posted via a free Usenet account from http://www.teranews.com

Re: ACCURATE SPEEDOMETER?
 

Mike Romain wrote:
> twaldron wrote:
>
> Tracie wrote:
>
>>>
>>>
>>> So, assuming that my speedometer is correct, running approximately
>>> 2500 rpms in 5th gear at 65 mph will NOT hurt my engine or cause
>>> increased engine wear? If I were to shift into OD (6th), what is the
>>> approximate rpms that I should be running so as to not cause lugging
>>> or increased engine wear?
>>>
>>> THANKS
>>>
>>
>> Your minimal tire size increase likely made your speedo/odo more
>> accurate as they tend to read high from the manufacturer. That way
>> warranties expire sooner and manufacturers save money. I'd bet you are
>> very close now. For fuel economy, use the highest gear you can while
>> staying in the power band (not lugging). Lugging will become
>> immediately apparent and you do it by feel, not by someone telling you
>> what RPM to run. If you shift into too high a gear, you will notice a
>> power response loss and ultimately your engine will lug. Downshift.
>>
>> tw
>
>
> Jeep especially seems to like to have the speedometer high for some reason.
>
> The largest stock tire that is listed for my 88 Cherokee on the sticker
> is P225's, yet P235's make my speedometer accurate according to measured
> 'miles' and many GPS checks. The cops must think so too, because they
> don't stop me.
>
> Same for most TJ's. They 'do' list a 31 as the largest stock tire and
> according to what has been reported here, that makes them accurate with
> no t-case speedo gear change needed.
>
> I don't know how it worked, but my 86 CJ7 is accurate with 33's. It was
> 4mph + off with 31's (reading 65, doing 60) when I got it.
>
> 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)

Yup, exactly. I'm thinking she'll be closer with that tire change.

tw

Re: ACCURATE SPEEDOMETER?
 

Mike Romain wrote:
> twaldron wrote:
>
> Tracie wrote:
>
>>>
>>>
>>> So, assuming that my speedometer is correct, running approximately
>>> 2500 rpms in 5th gear at 65 mph will NOT hurt my engine or cause
>>> increased engine wear? If I were to shift into OD (6th), what is the
>>> approximate rpms that I should be running so as to not cause lugging
>>> or increased engine wear?
>>>
>>> THANKS
>>>
>>
>> Your minimal tire size increase likely made your speedo/odo more
>> accurate as they tend to read high from the manufacturer. That way
>> warranties expire sooner and manufacturers save money. I'd bet you are
>> very close now. For fuel economy, use the highest gear you can while
>> staying in the power band (not lugging). Lugging will become
>> immediately apparent and you do it by feel, not by someone telling you
>> what RPM to run. If you shift into too high a gear, you will notice a
>> power response loss and ultimately your engine will lug. Downshift.
>>
>> tw
>
>
> Jeep especially seems to like to have the speedometer high for some reason.
>
> The largest stock tire that is listed for my 88 Cherokee on the sticker
> is P225's, yet P235's make my speedometer accurate according to measured
> 'miles' and many GPS checks. The cops must think so too, because they
> don't stop me.
>
> Same for most TJ's. They 'do' list a 31 as the largest stock tire and
> according to what has been reported here, that makes them accurate with
> no t-case speedo gear change needed.
>
> I don't know how it worked, but my 86 CJ7 is accurate with 33's. It was
> 4mph + off with 31's (reading 65, doing 60) when I got it.
>
> 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)

Yup, exactly. I'm thinking she'll be closer with that tire change.

tw

Re: ACCURATE SPEEDOMETER?
 

Mike Romain wrote:
> twaldron wrote:
>
> Tracie wrote:
>
>>>
>>>
>>> So, assuming that my speedometer is correct, running approximately
>>> 2500 rpms in 5th gear at 65 mph will NOT hurt my engine or cause
>>> increased engine wear? If I were to shift into OD (6th), what is the
>>> approximate rpms that I should be running so as to not cause lugging
>>> or increased engine wear?
>>>
>>> THANKS
>>>
>>
>> Your minimal tire size increase likely made your speedo/odo more
>> accurate as they tend to read high from the manufacturer. That way
>> warranties expire sooner and manufacturers save money. I'd bet you are
>> very close now. For fuel economy, use the highest gear you can while
>> staying in the power band (not lugging). Lugging will become
>> immediately apparent and you do it by feel, not by someone telling you
>> what RPM to run. If you shift into too high a gear, you will notice a
>> power response loss and ultimately your engine will lug. Downshift.
>>
>> tw
>
>
> Jeep especially seems to like to have the speedometer high for some reason.
>
> The largest stock tire that is listed for my 88 Cherokee on the sticker
> is P225's, yet P235's make my speedometer accurate according to measured
> 'miles' and many GPS checks. The cops must think so too, because they
> don't stop me.
>
> Same for most TJ's. They 'do' list a 31 as the largest stock tire and
> according to what has been reported here, that makes them accurate with
> no t-case speedo gear change needed.
>
> I don't know how it worked, but my 86 CJ7 is accurate with 33's. It was
> 4mph + off with 31's (reading 65, doing 60) when I got it.
>
> 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)

Yup, exactly. I'm thinking she'll be closer with that tire change.

tw

Re: ACCURATE SPEEDOMETER?
 

Mike Romain wrote:
> twaldron wrote:
>
> Tracie wrote:
>
>>>
>>>
>>> So, assuming that my speedometer is correct, running approximately
>>> 2500 rpms in 5th gear at 65 mph will NOT hurt my engine or cause
>>> increased engine wear? If I were to shift into OD (6th), what is the
>>> approximate rpms that I should be running so as to not cause lugging
>>> or increased engine wear?
>>>
>>> THANKS
>>>
>>
>> Your minimal tire size increase likely made your speedo/odo more
>> accurate as they tend to read high from the manufacturer. That way
>> warranties expire sooner and manufacturers save money. I'd bet you are
>> very close now. For fuel economy, use the highest gear you can while
>> staying in the power band (not lugging). Lugging will become
>> immediately apparent and you do it by feel, not by someone telling you
>> what RPM to run. If you shift into too high a gear, you will notice a
>> power response loss and ultimately your engine will lug. Downshift.
>>
>> tw
>
>
> Jeep especially seems to like to have the speedometer high for some reason.
>
> The largest stock tire that is listed for my 88 Cherokee on the sticker
> is P225's, yet P235's make my speedometer accurate according to measured
> 'miles' and many GPS checks. The cops must think so too, because they
> don't stop me.
>
> Same for most TJ's. They 'do' list a 31 as the largest stock tire and
> according to what has been reported here, that makes them accurate with
> no t-case speedo gear change needed.
>
> I don't know how it worked, but my 86 CJ7 is accurate with 33's. It was
> 4mph + off with 31's (reading 65, doing 60) when I got it.
>
> 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)

Yup, exactly. I'm thinking she'll be closer with that tire change.

tw

Re: ACCURATE SPEEDOMETER?
 

Tracie wrote:

> On Sep 17, 3:49 pm, "L.W. \(Bill\) ------ III"
> <LWBillHug...@------.net> wrote:
>
>> Doesn't your Rubicon automatically correct for tire size? Probably by
>>this '06 it also measures the distance from the ground.
>> God Bless America, Bill O|||||||O
>>mailto:LW------...@aol.comhttp://www.----------.com/
>>
>>"twaldron" <d...@hairsproutingbunions.com> wrote in message
>>
>>news:WcxHi.1705$ec2.502@trnddc03...
>>
>>
>>
>>
>>>Your minimal tire size increase likely made your speedo/odo more
>>>accurate as they tend to read high from the manufacturer. That way
>>>warranties expire sooner and manufacturers save money. I'd bet you are
>>>very close now. For fuel economy, use the highest gear you can while
>>>staying in the power band (not lugging). Lugging will become immediately
>>>apparent and you do it by feel, not by someone telling you what RPM to
>>>run. If you shift into too high a gear, you will notice a power response
>>>loss and ultimately your engine will lug. Downshift.
>>
>>>tw
>>
>>--
>>Posted via a free Usenet account fromhttp://www.teranews.com
>
>
> Well, I do have an appt at the dealership tomorrow around 5 pm
> (eastern time). When I find out whether or not my speedo is right on
> or off a few mph, I will certainly post the results to let you all
> know. In the meantime, I really don't have a lugging issue or a power
> loss with the 3.07s and 31s. I can start up a moderate sized hill
> doing 65 (according to the speedometer) in 5th gear, and not have to
> stomp the gas pedal to continue going up the hill at a nice pace. I
> am wondering if the spec sheet on my jeep is wrong, and I actually
> have 3.73s. I will look at the rear diff case tonight and see what
> the stamp says.
>

Are you making a special trip to the dealer to check your speedo??

tw

Re: ACCURATE SPEEDOMETER?
 

Tracie wrote:

> On Sep 17, 3:49 pm, "L.W. \(Bill\) ------ III"
> <LWBillHug...@------.net> wrote:
>
>> Doesn't your Rubicon automatically correct for tire size? Probably by
>>this '06 it also measures the distance from the ground.
>> God Bless America, Bill O|||||||O
>>mailto:LW------...@aol.comhttp://www.----------.com/
>>
>>"twaldron" <d...@hairsproutingbunions.com> wrote in message
>>
>>news:WcxHi.1705$ec2.502@trnddc03...
>>
>>
>>
>>
>>>Your minimal tire size increase likely made your speedo/odo more
>>>accurate as they tend to read high from the manufacturer. That way
>>>warranties expire sooner and manufacturers save money. I'd bet you are
>>>very close now. For fuel economy, use the highest gear you can while
>>>staying in the power band (not lugging). Lugging will become immediately
>>>apparent and you do it by feel, not by someone telling you what RPM to
>>>run. If you shift into too high a gear, you will notice a power response
>>>loss and ultimately your engine will lug. Downshift.
>>
>>>tw
>>
>>--
>>Posted via a free Usenet account fromhttp://www.teranews.com
>
>
> Well, I do have an appt at the dealership tomorrow around 5 pm
> (eastern time). When I find out whether or not my speedo is right on
> or off a few mph, I will certainly post the results to let you all
> know. In the meantime, I really don't have a lugging issue or a power
> loss with the 3.07s and 31s. I can start up a moderate sized hill
> doing 65 (according to the speedometer) in 5th gear, and not have to
> stomp the gas pedal to continue going up the hill at a nice pace. I
> am wondering if the spec sheet on my jeep is wrong, and I actually
> have 3.73s. I will look at the rear diff case tonight and see what
> the stamp says.
>

Are you making a special trip to the dealer to check your speedo??

tw

Re: ACCURATE SPEEDOMETER?
 

Tracie wrote:

> On Sep 17, 3:49 pm, "L.W. \(Bill\) ------ III"
> <LWBillHug...@------.net> wrote:
>
>> Doesn't your Rubicon automatically correct for tire size? Probably by
>>this '06 it also measures the distance from the ground.
>> God Bless America, Bill O|||||||O
>>mailto:LW------...@aol.comhttp://www.----------.com/
>>
>>"twaldron" <d...@hairsproutingbunions.com> wrote in message
>>
>>news:WcxHi.1705$ec2.502@trnddc03...
>>
>>
>>
>>
>>>Your minimal tire size increase likely made your speedo/odo more
>>>accurate as they tend to read high from the manufacturer. That way
>>>warranties expire sooner and manufacturers save money. I'd bet you are
>>>very close now. For fuel economy, use the highest gear you can while
>>>staying in the power band (not lugging). Lugging will become immediately
>>>apparent and you do it by feel, not by someone telling you what RPM to
>>>run. If you shift into too high a gear, you will notice a power response
>>>loss and ultimately your engine will lug. Downshift.
>>
>>>tw
>>
>>--
>>Posted via a free Usenet account fromhttp://www.teranews.com
>
>
> Well, I do have an appt at the dealership tomorrow around 5 pm
> (eastern time). When I find out whether or not my speedo is right on
> or off a few mph, I will certainly post the results to let you all
> know. In the meantime, I really don't have a lugging issue or a power
> loss with the 3.07s and 31s. I can start up a moderate sized hill
> doing 65 (according to the speedometer) in 5th gear, and not have to
> stomp the gas pedal to continue going up the hill at a nice pace. I
> am wondering if the spec sheet on my jeep is wrong, and I actually
> have 3.73s. I will look at the rear diff case tonight and see what
> the stamp says.
>

Are you making a special trip to the dealer to check your speedo??

tw