Speedometer **Recalibration** 1992 HELP
Instructor
Joined: Sep 2006
Posts: 138
Likes: 0
From: toledo ohio
definitely not red
looks like you have a gray 15t drive gear.
you have a 35t orange driven gear
tire size 315/35/17 2.59 gear ratio
according to various speedometer calculators, you will need:
17t red drive gear
36t white driven gear
you already have a 35t driven gear so it should be close, depending on you're actual tire height
what gears did you start out with?
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
Disregard all references to the "DRIVE GEAR" - you mention you've an error that's something 2 - 5 MPH but you haven't mentioned SLOW or FAST! Your concern now is only to correct the error! That needs to remain your ONLY concern regarding the speedometer error.
Is it FAST or SLOW? How did you check it? GPS? Is the error you mention accurate?
Maybe post some comparisons. I usually suggest using a GPS and post the speedometer reading using 40/xx - 50/xx - 55/xx - 60/xx - 70/xx on the GPS. The error should reflect a consistent percentage.
You do need to be concerned with the VSS identity! You need to be sure that the VSS is correct for the tooth count of the driven gear you end up with. The correct one will reduce the wear on both gears. The VSS ID is important!
Is it FAST or SLOW? How did you check it? GPS? Is the error you mention accurate?
Maybe post some comparisons. I usually suggest using a GPS and post the speedometer reading using 40/xx - 50/xx - 55/xx - 60/xx - 70/xx on the GPS. The error should reflect a consistent percentage.
You do need to be concerned with the VSS identity! You need to be sure that the VSS is correct for the tooth count of the driven gear you end up with. The correct one will reduce the wear on both gears. The VSS ID is important!
Last edited by WVZR-1; Apr 8, 2012 at 04:50 PM.
Thread Starter
Advanced
Joined: Sep 2010
Posts: 71
Likes: 2
From: Jacksonville FL
Disregard all references to the "DRIVE GEAR" - you mention you've an error that's something 2 - 5 MPH but you haven't mentioned SLOW or FAST! Your concern now is only to correct the error! That needs to remain your ONLY concern regarding the speedometer error.
Is it FASIT or SLOW? How did you check it? GPS? Is the error you mention accurate?
Maybe post some comparisons. I usually suggest using a GPS and post the speedometer reading using 40/xx - 50/xx - 55/xx - 60/xx - 70/xx on the GPS. The error should reflect a consistent percentage.
You do need to be concerned with the VSS identity! You need to be sure that the VSS is correct for the tooth count of the driven gear you end up with. The correct one will reduce the wear on both gears. The VSS ID is important!
Is it FASIT or SLOW? How did you check it? GPS? Is the error you mention accurate?
Maybe post some comparisons. I usually suggest using a GPS and post the speedometer reading using 40/xx - 50/xx - 55/xx - 60/xx - 70/xx on the GPS. The error should reflect a consistent percentage.
You do need to be concerned with the VSS identity! You need to be sure that the VSS is correct for the tooth count of the driven gear you end up with. The correct one will reduce the wear on both gears. The VSS ID is important!
I have the white VSS.
car displays slower than actual speed. Verified with GPS. its about 5 slower at speeds above 60.
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
Is your "exploded" rear still around? If it is it might be interesting to check the tooth counts on the ring gear and pinion or all of the information off of the perimeter surface of the ring gear. A possible explanation for the "mismatch" in your car could be that a gear change was done by a PO and when it was done the drive/driven was done to accomplish a correction.
I've PM'd you!
Last edited by WVZR-1; Apr 9, 2012 at 07:10 AM.
Instructor
Joined: Sep 2006
Posts: 138
Likes: 0
From: toledo ohio
if it doesn't correct the error, why bother?
replacing the drive gear is NOT difficult or expensive.
the drive gear is cheap-$10
here's a how to
http://www.digitalcorvettes.com/foru...d.php?t=110978
if you want an accurate speedometer
replacing the drive gear is NOT difficult or expensive.
the drive gear is cheap-$10
here's a how to
http://www.digitalcorvettes.com/foru...d.php?t=110978
if you want an accurate speedometer
Thread Starter
Advanced
Joined: Sep 2010
Posts: 71
Likes: 2
From: Jacksonville FL
Well the shop is fixing it for free since I payed them and they quote "it left the shop wrong"
I suspect the PO changed the rear end ratio and the speedometer/tranny drive shaft gears to match.
I've been driving and I've noticed that the "car's speed" is about 5 mph slower than the GPS speed from 35+
Ex: 35 its actually 39-41
40 its actually 45-46
And so on.
I currently have an orange vss gear and green transmission drive shaft gear.
315/35/17 rear wheels 297/35/17 front wheels.
White vss from AutoZone. vss harness was repaired (caused erratic number display)
My mpg is matching that of stock now after resetting computer (removing negative battery terminal for 1min)
They are willing to work with me until the issue is resolved.
What is my next step to have my Speedo read -5 than the current displayed speeds?
I suspect the PO changed the rear end ratio and the speedometer/tranny drive shaft gears to match.
I've been driving and I've noticed that the "car's speed" is about 5 mph slower than the GPS speed from 35+
Ex: 35 its actually 39-41
40 its actually 45-46
And so on.
I currently have an orange vss gear and green transmission drive shaft gear.
315/35/17 rear wheels 297/35/17 front wheels.
White vss from AutoZone. vss harness was repaired (caused erratic number display)
My mpg is matching that of stock now after resetting computer (removing negative battery terminal for 1min)
They are willing to work with me until the issue is resolved.
What is my next step to have my Speedo read -5 than the current displayed speeds?
Instructor
Joined: Sep 2006
Posts: 138
Likes: 0
From: toledo ohio
have them order and install:
red 17t drive gear
white 36t driven gear
this is correct for
315/35/17 tires w/ 2.59 gears
however, actual tire size varies between brands, so the 35t orange gear may work with the new 17t red drive gear
red 17t drive gear
white 36t driven gear
this is correct for
315/35/17 tires w/ 2.59 gears
however, actual tire size varies between brands, so the 35t orange gear may work with the new 17t red drive gear
Thread Starter
Advanced
Joined: Sep 2010
Posts: 71
Likes: 2
From: Jacksonville FL
Update: speedometer spikes random numbers. As 5/5/2012 8pm
last week it would randomly "go off" from normal.
Is this because I didn't replace the drive gear to the red one? Have the gears worn down?
last week it would randomly "go off" from normal.
Is this because I didn't replace the drive gear to the red one? Have the gears worn down?
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Cruising
Joined: Jan 2018
Posts: 12
Likes: 0
speedo help
hi. I heard you could maybe help me also. I have a 93 and changed from 3.08 to 3.55. my speedo is off 25mph to the high side. 70mph reads 95mph. now I know it looks great rolling down the road taking pictures but its driving me nuts. thanks
Team Owner
Joined: Sep 2003
Posts: 25,394
Likes: 2,741
Are tire sizes 'stock'? If sizes are stock a 15 tooth (drive) and a 43 tooth driven would get you as close as possible mechanically. The console SPID info could be helpful. Look for D8L and maybe G92 & G44. Those options should be present I believe for a '93 with 3.07.
If those aren't present (all bets are off).Post tire size confirm axle ratio now.15 & 43 aren't difficult to source and if D8L is present you could use the same VSS>
***************You should have started your own thread and NOT used a 7 year old 'conversation'.
Last edited by WVZR-1; May 14, 2019 at 04:11 PM.
