23 tooth question....

95GTS · 04-26-2000, 10:45 AM

with my 3.73s, when i put in the 23 tooth speedo gear, how close will my speedo be? Right on or off by how much? The car had stock 2.73s. has 5-speed T-45.

------------------
1996 Mustang GTS
K&N, removed air silencer, 3.73s, turndowns after H-pipe (no mufflers)

T-Bone · 04-26-2000, 04:24 PM

See 97 snakedrivers response under my post "Gears Question".

97snakedriver · 04-26-2000, 10:27 PM

Looking in my Ford catalog, they have this little equation:

Driven Gear Teeth = (Drive Gear Teeth * Axle ratio * Tire Rev. Per Mile)/1000

Plug in your numbers and see how close it is to 23. The speedo reading will vary as the tires wear down, so the only real way to know how close you are is to have it tested, but that will give you a pretty good idea of how close you are.

95GTS · 04-27-2000, 09:57 AM

how do you figure tire revs per mile? Might be alittle hard to count it.

------------------
1996 Mustang GTS
K&N, removed air silencer, 3.73s, turndowns after H-pipe (no mufflers)

97snakedriver · 04-27-2000, 12:51 PM

Use the overall wheel+tire diameter. Should be published with the tire, or you can find it on tirerack.com. Then Pi X diameter to figure out how far the wheel rolls in one turn. Divide 5280 ft by that, and there you go.

Again this is just a rule of thumb sort of thing, but it will give you a good idea.

Or... You could glue a peice metal to the side wall and count the number of whacks in a mile on the interstate...

[This message has been edited by 97snakedriver (edited 04-27-2000).]

04-26-2000, 10:45 AM	#1
95GTS Git jiggy Join Date: Oct 1999 Location: MO USA Posts: 865	23 tooth question.... with my 3.73s, when i put in the 23 tooth speedo gear, how close will my speedo be? Right on or off by how much? The car had stock 2.73s. has 5-speed T-45. ------------------ 1996 Mustang GTS K&N, removed air silencer, 3.73s, turndowns after H-pipe (no mufflers)

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04-26-2000, 04:24 PM	#2
T-Bone Registered Member Join Date: Jan 2000 Location: Minot AFB, ND Posts: 138	See 97 snakedrivers response under my post "Gears Question".

04-26-2000, 10:27 PM	#3
97snakedriver Registered Member Join Date: May 1999 Location: Blacksburg, VA Posts: 1,526	Looking in my Ford catalog, they have this little equation: Driven Gear Teeth = (Drive Gear Teeth * Axle ratio * Tire Rev. Per Mile)/1000 Plug in your numbers and see how close it is to 23. The speedo reading will vary as the tires wear down, so the only real way to know how close you are is to have it tested, but that will give you a pretty good idea of how close you are.

04-27-2000, 09:57 AM	#4
95GTS Git jiggy Join Date: Oct 1999 Location: MO USA Posts: 865	how do you figure tire revs per mile? Might be alittle hard to count it. ------------------ 1996 Mustang GTS K&N, removed air silencer, 3.73s, turndowns after H-pipe (no mufflers)

04-27-2000, 12:51 PM	#5
97snakedriver Registered Member Join Date: May 1999 Location: Blacksburg, VA Posts: 1,526	Use the overall wheel+tire diameter. Should be published with the tire, or you can find it on tirerack.com. Then Pi X diameter to figure out how far the wheel rolls in one turn. Divide 5280 ft by that, and there you go. Again this is just a rule of thumb sort of thing, but it will give you a good idea. Or... You could glue a peice metal to the side wall and count the number of whacks in a mile on the interstate... [This message has been edited by 97snakedriver (edited 04-27-2000).]