Just installed tko 500 on my 02 gt I'm having problems with my speedometer reading 20 mph when I'm going about 70.. I know that the signal that the mechanical sensor gives is different from the one The electronic sensor from my tr3650..any way this can be fixed with a special part? Any advise will be helpful thanks.. Ernest
Speedo Reads Off On 02 Gt After Tko500 & Tr3650 Swap
- Thread starter hboy2v
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Rusty67
Dirt-Old 20+Year Member
You need to find out how many teeth the tone ring in the TKO500 has on it. T45/T56/3650 transmissions typically have a 12 tooth tone ring.
See the section entitled "Swapping an older transmission into a 99-04 car" on this page for more info:
http://www.accutach.com/Pages/VSSvsOSSSwaps.aspx
See the section entitled "Swapping an older transmission into a 99-04 car" on this page for more info:
http://www.accutach.com/Pages/VSSvsOSSSwaps.aspx
so according to this formula i have a 3.73 gear ratio a 7 tooth yellow colored drive gear and a 21 tooth driven gear which is red color. 3.73*(7/21)*(8/4) which tells me i need to enter a ratio of 2.48 into my tune to make it work?
i dont think this tko has a tone ring at all.. its all gear driven as far as the vss..
my other problem is my sct programmer only goes down to 2.73 axle ratio as far as recalibrating.. im thinking if i swap my driven gear to a 16 tooth and doing this same equation i could calibrate my tune to 3.27 axle ratio and make it work.. i really hope im doing this right correct me if im doing it wrong.... thanks for the info by the way, it was exactly what i needed to know. i just only hope i can make it work..
i dont think this tko has a tone ring at all.. its all gear driven as far as the vss..
my other problem is my sct programmer only goes down to 2.73 axle ratio as far as recalibrating.. im thinking if i swap my driven gear to a 16 tooth and doing this same equation i could calibrate my tune to 3.27 axle ratio and make it work.. i really hope im doing this right correct me if im doing it wrong.... thanks for the info by the way, it was exactly what i needed to know. i just only hope i can make it work..
Rusty67
Dirt-Old 20+Year Member
Sounds like you are on the right track. The TKO has the old style nylon drive gear and is using the VSS instead of an OSS. Does the SCT not have the option of changing the amount of holes the OSS is expecting ? Maybe contact SCT and check with them.
Otherwise, your option is to do some calculations and pick an axle ratio that is closest.
The other option is to switch to using Binary Editor which will give you direct read/write options to the tune and let you set any value you want.
I'm not sure if you can get a speed cal that will fix the issue. The article I linked you mentions an exteded speed cal unit.
If you want to get crazy you can put an OSS tone ring on the output shaft of the new trans and use an OSS sensor in instead of a VSS and it will fix everything.
Otherwise, your option is to do some calculations and pick an axle ratio that is closest.
The other option is to switch to using Binary Editor which will give you direct read/write options to the tune and let you set any value you want.
I'm not sure if you can get a speed cal that will fix the issue. The article I linked you mentions an exteded speed cal unit.
If you want to get crazy you can put an OSS tone ring on the output shaft of the new trans and use an OSS sensor in instead of a VSS and it will fix everything.
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