speedo gear drive teeth on 4r70w, anyone know?

85 Coupe 5.0 · Mar 18, 2006

I had just recently put 3.73:1 gears in my '96 GT. I purchased a white 23T speedo gear from Steeda to correct the speedo, they claim it has 8 drive teeth on the transmission output shaft. I have came across some articles on the net that say 4r70's could have 8 or 9 tooth drive counts. It seems to me my speedo might be a bit slow, anyone got some solid info on this??

Mike97gt · Mar 19, 2006

well the vss is easy enough to pull out

take it out and count the gears.

1LowGT · Mar 19, 2006

i have a 98 auto car and have the steeda gear,take my advice get a speedcal mine is still off because even steeda says the gear is not right for the car and will shred eventually,and is only accurate to 3.55 i too installed 3.73 s and its on average 6 mph fast when i go through radar traps from the street dept

DropTopPony · Mar 19, 2006

1LowGT said:
i have a 98 auto car and have the steeda gear,take my advice get a speedcal mine is still off because even steeda says the gear is not right for the car and will shred eventually,and is only accurate to 3.55 i too installed 3.73 s and its on average 6 mph fast when i go through radar traps from the street dept

Same here, i used the 23T gear and over the years its warn down. I found a new Speedcal on ebay for $80 so i'm gonna fix mine soon.

85 Coupe 5.0 · Mar 19, 2006

svttech76 said:
well the vss is easy enough to pull out

take it out and count the gears.

asking people that have already had this problem and are willing to share their experience is easier.

Thanks for the help..........

Back on track now, thanks guys, I too think my speedo is fast, and I noticed that the steeda gear calls for the same one for both 3.73's and 4.10's. I have read that the service life on the 23T is limited to less than 20000 miles.

so a speedcal is definately in my future. back to the output shaft tooth situation, does anyone know if the 4r70w uses both 7 and 8 tooth output shaft drive teeth? I will probably end up counting mine on the lift at work this week, but any advice in advance would be great.

nyuk98gt · Mar 19, 2006

85 Coupe 5.0:

For my '98, the original rear had 3.08s and the VSS was (is) an orange (20-tooth) gear driven by 8 teeth.

The 23-tooth gear will only get you part way:

23/20 = 1.150 versus 3.73/3.08 = 1.211

so the speedo/odo will be off by 1.211/1.150 ==> +5.31% (higher than actual speed and mileage).

A SpeedCal can be dialed in to accommodate ANY rear gear and/or tire combination. This will allow you to have essentially perfect speed and mileage tracking.

HTH,

Chris

85 Coupe 5.0 · Mar 19, 2006

thanks for clarifying Chris, that makes things much clearer.

looks like a speedcal is in my near future

TGJ · Mar 20, 2006

The 4R70W's are either 7 tooth or 8 tooth. Your 96 is a 7 tooth and you need to have the 21 tooth purple gear for 3.73's and you will be bang on. 98, they went to an 8 tooth gear set and you will need a speedcal for that one.

Mike97gt · Mar 20, 2006

85 Coupe 5.0 said:
asking people that have already had this problem and are willing to share their experience is easier.

Thanks for the help..........

I know I was just messing with you. I see in your sig that your a parts guy, and one of my parts guys at my work when you ask him to look at part up tells you to pull it out and get the numbers.

I have always wanted to say that to a parts guy after dealing with him

since I did not know the answer to your question offhand this was a good time to do it.

nyuk98gt · Mar 20, 2006

TGJ said:
The 4R70W's are either 7 tooth or 8 tooth. Your 96 is a 7 tooth and you need to have the 21 tooth purple gear for 3.73's and you will be bang on. 98, they went to an 8 tooth gear set and you will need a speedcal for that one.

Thanks for setting the record straight, TGJ!

Chris

speedo gear drive teeth on 4r70w, anyone know?

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