Just installed 4.10s what speedo gear do I need?

[WilwoodFiveO]

I'm on 50 resto bout to order a new speedo gear but have no idea how many teeth speedo I need for 4.10 rear gears. Please help. Thanks.

Tyler

 

[djk8705]

http://forums.stangnet.com/showthread.php?t=539575&highlight=correct+speedometer

 

[KK6695GT]

7 tooth drive gear with a 23 tooth driven gear.

What drive gear do you have? Good question? What rear axle gears did you have originally in the car and what was the driven tooth you took out?

Couple possiblilties.

If you had 3.08s originally and took out a 20 tooth driven, you have an 8 tooth drive gear. Bad because you have to pull the trans tailshaft to put in a 7 tooth drive gear for the 4.10s. If you pulled an 18 tooth driven out, you already have a 7 tooth drive.

If you had 2.73s, you probably pulled a 19 tooth which again means you only have an 8 tooth drive gear.

 

[Anthony85stang]

If you have a yellow gear inside the tranny you need the white gear not sure on how many teeth it is if you have a different color gear in the tranny its either the red or black one

 

[tjm73]

I'm on 50 resto bout to order a new speedo gear but have no idea how many teeth speedo I need for 4.10 rear gears. Please help. Thanks.

Tyler

I fyour '93 has the OEM tranny you need a 23 tooth speedo gear. 90-93 T5's haev 8 tooth drive gears and with that the closest you can get to correct is the 23 tooth speedo gear.

TO calculate your needed speedo gear, use this formula

(Drive Gear X Tire Revolutions per Mile X Axle Ratio)/1000

833 = 255/40R17 tire revolutions per mile

(8 x 833 x 4.10) / 1000 = 27 Tooth Speedo Gear

 

[squeeeg]

You absolute best bet to be most accurate would be the 6 tooth drive gear and the 20 tooth speedo gear. The most common and close to accurate would be 7 tooth drive gear and 23 tooth speedo gear. Either way you have to change the drive gear but that is the way to go.