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change gear ratio, how to fix speedo

3K views 12 replies 6 participants last post by  unrreal 
#1 ·
after replacing the grinding/leaking 3.23 gov-loc with 3.43 gov loc, i noticed that when going 110kph on the speedo, my gps shows 100kph. on other vehicles (ex. civic), i can correct the speedo by removing the needle and replacing it back according to my gps speed. can i also do this on the astro/safari? thanks
 
#3 ·
thanks leeann, could you pinpoint where exactly this module it and what it looks like? sorry for the typo, 3.42 gear.
 
#5 ·
i was thinking, what if i change to a bigger tires say 235/75/15. it might match the current gear ratio i have? hmmm. but 235 rubs in front tho
 
#8 ·
unrreal said:
1992RS said:
I dont get it?? I have stock suspension and I run 235 75 15 tires and I have absolutely no rub?? IS there a way to see if my van was possibly lifted at some point??
the wheel wells in early astros are bigger than the 2nd gen thats why your tires don't rub.
Just another reason why the first gens are better.

Anyways, does the VSS have a plastic gear on it that can be changed to adjust the speed. At least you can do that on the 700r4s.



http://www.transmissioncenter.net/speedometer_calibration_______va.htm
 
#9 ·
K, found more info. By '97, the VSS fed the ECM directly, not through a VSS buffer. I'm not 100% sure, but I don't think there's a gear to change. I think it needs to be programmed - at least, it's that way with the '93 (except in that case, it's the buffer that needs to be programmed).
 
#10 ·
i think you're correct leeann, i heard that you need to get a programmer to change gear-ratio/tires etc. on obd2
 
#11 ·
bonjoey said:
i think you're correct leeann, i heard that you need to get a programmer to change gear-ratio/tires etc. on obd2
This is correct, it's a direct programming change to the PCM, You can change gear ratio, and tire/wheel circumference.
 
#12 ·
does anyone know what is kind of programmer this is? hypertech? thanks
 
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