Do I need LS-1 Edit for this?
Thread Starter
Race Director
Joined: Oct 1999
Posts: 17,708
Likes: 1,218
From: Phila PA, Bonita Springs FL
Do I need LS-1 Edit for this?
Had rear tire size: 295/35/19 27.1" diameter
now have 285/30/20 26.9 diameter
Do I need to make this change for the speedometer cal & rpms for shifting or is it neglible??
Thanks
now have 285/30/20 26.9 diameter
Do I need to make this change for the speedometer cal & rpms for shifting or is it neglible??
Thanks
Instructor
Joined: Oct 2001
Posts: 249
Likes: 0
From: Mesa AZ
It will be very negligible. If you have an automatic transmission and are shifting on the ragged edge of the limiter right now, you may notice it hit the rev limiter between shifts, but I doubt it. With a manual, you won't have any troubles like that!
Mike
Mike
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Did you ever edit the car for the taller 19" tires you had?
If not, you are only closer to stock size than you were before, and your speedo should be even more accurate than it previously was with the 19's.
Either way, the difference is incredibly small and you'll probably not notice a difference.
If not, you are only closer to stock size than you were before, and your speedo should be even more accurate than it previously was with the 19's.
Either way, the difference is incredibly small and you'll probably not notice a difference.
Melting Slicks
Joined: Feb 2002
Posts: 2,613
Likes: 0
From: Winston Salem NC
Originally Posted by YO-EL
Had rear tire size: 295/35/19 27.1" diameter
now have 285/30/20 26.9 diameter
Do I need to make this change for the speedometer cal & rpms for shifting or is it neglible??
Thanks
now have 285/30/20 26.9 diameter
Do I need to make this change for the speedometer cal & rpms for shifting or is it neglible??
Thanks
Pro
Joined: Sep 2003
Posts: 564
Likes: 0
From: Cary NC
Originally Posted by YO-EL
Had rear tire size: 295/35/19 27.1" diameter
now have 285/30/20 26.9 diameter
Do I need to make this change for the speedometer cal & rpms for shifting or is it neglible??
Thanks
now have 285/30/20 26.9 diameter
Do I need to make this change for the speedometer cal & rpms for shifting or is it neglible??
Thanks
Race Director
Joined: Oct 2002
Posts: 16,477
Likes: 26
From: Gone
CI 6-7-8-9-10 Veteran
St. Jude Donor '03
Originally Posted by 2k1vert
C5's vehicle speed sensors are driven off the axle rather than the driveshaft, so the speedometer does not need rescaled when you change the rear ratios.
He isn't changing the rearend ratio, he is altering tire heights. The speedo will remain the same with a rearend ratio change, because the speed is sensed on the axle, and the axle speed doesn't change with any gear ratio....But tire size WILL alter the axle speed, and thus, the speedometer reading.
LS1-Edit does offer a means to correct the speedometer reading based on rear tire height, but in this case the change will be so insignifigant, unless you personally have the LS1-Edit program, it's not worth the bother to have a tuner correct such a small change.
Team Owner
Joined: Apr 2001
Posts: 54,204
Likes: 180
From: S.W. Ohio. . . . . . NRA Life Member
He isn't changing the rearend ratio, he is altering tire heights. ....But tire size WILL alter the axle speed, and thus, the speedometer reading.
Pro
Joined: Sep 2003
Posts: 564
Likes: 0
From: Cary NC
Originally Posted by Y2Kvert4me
You are correct in all you've said, if this concerned a rearend ratio change.
He isn't changing the rearend ratio, he is altering tire heights. The speedo will remain the same with a rearend ratio change, because the speed is sensed on the axle, and the axle speed doesn't change with any gear ratio....But tire size WILL alter the axle speed, and thus, the speedometer reading.
LS1-Edit does offer a means to correct the speedometer reading based on rear tire height, but in this case the change will be so insignifigant, unless you personally have the LS1-Edit program, it's not worth the bother to have a tuner correct such a small change.
He isn't changing the rearend ratio, he is altering tire heights. The speedo will remain the same with a rearend ratio change, because the speed is sensed on the axle, and the axle speed doesn't change with any gear ratio....But tire size WILL alter the axle speed, and thus, the speedometer reading.
LS1-Edit does offer a means to correct the speedometer reading based on rear tire height, but in this case the change will be so insignifigant, unless you personally have the LS1-Edit program, it's not worth the bother to have a tuner correct such a small change.
Thanks.
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Thread Starter
Race Director
Joined: Oct 1999
Posts: 17,708
Likes: 1,218
From: Phila PA, Bonita Springs FL
No sweat guys.. Thanks for all the replys...
Car was previously edited for the 295/35/19 tire, so not sure if the 285/30/20 diameter is that critical but may still get it anyway since I do have access to a guy with LS-1 Edit..
Ellis
Car was previously edited for the 295/35/19 tire, so not sure if the 285/30/20 diameter is that critical but may still get it anyway since I do have access to a guy with LS-1 Edit..
Ellis