Technical Trying to calibrate trans to my speedo...

Need someone that has done this before so I dont order the wrong driven gear for a GM WC T5.

I need to increase the speedo ratio out of the T5 from 825 turns to 1000 turns...per mile. So, I need to increase it by @1.21.

I am running a 7 tooth drive gear and 18 tooth driven gear. Can someone point me in the right direction in terms of where I need to be to get the speedo reading about right. Not looking for swiss clock like precision, just something a lot closer.

The way I see it I need to increase by 1.21 (825 increased by 121% gives me @1000). So, does that mean I need to decrease the number of driven teeth from 18 to something like a 14-15 or am I ass backwards on this????

 

If ya give this guy info he ask for,you'll be on the right mark,I used this placa to set up my own speedo an is right,great job right stuff;
http://www.transmissioncenter.net/speedometer_calibration_______va.htm

 

To increase the RPM of the cable, you need a bigger DRIVE gear, or a smaller DRIVEN gear, or maybe both.

 

Most speedo's are set up and rated for the 1000 turns per mile. What is your rear gear and rear tire diameter?

 

You need 21% fewer teeth on the driven gear, so a 14T gear will be the closest.....

 

Thanks, that's all I needed to know.

I just needed to confirm which way to go teeth-wise, up or down.

Thanks again.

 

No such thing as 14 tooth driven gear. I have 8 and 9 tooth t5 drive gears for sale.

 

Yup, no 14s.

When I realized that I decided to leave it till I get back from Austin. Might just get an external ratio adapter to prevent having to take trans out. No room under the car etc.

 

Ummm, when I divide 18 by 1.21, I get 14.87, so I would figure a 15 tooth driven gear is the preferred one.

 

21% of 18 is 3.78. Deduct that from 18 and you get 14.22