Speedo Gear

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FordGuy88

New Member

Nov 15, 2004

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Park Ridge, IL

Apr 3, 2008

#1

• Apr 3, 2008

• #1

I have an 89 mustang with a c4 and 410s out back. Any one know what speedo gear I need?

Thanks,
Dave

 

TRWXXA

Member

Jan 18, 2003

190

1

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RIGHT BEHIND YOU!!!... Made you look.

Apr 4, 2008

#2

• Apr 4, 2008

• #2

What size tires?

How many speedometer drive teeth on the C4's output shaft?

 

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FordGuy88

New Member

Nov 15, 2004

241

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Park Ridge, IL

Apr 4, 2008

#3

• Apr 4, 2008

• #3

Do I have to take the tail shaft housing off, or can I just count the teeth on the tail shaft where the drive shaft slips on to?

 

7-UP BILL

Founding Member

Jan 4, 2001

885

19

49

My other car is a Firetruck

Apr 4, 2008

#4

• Apr 4, 2008

• #4

The drive gear is inside the trans tailshaft. It's not the splines on the tailshaft where the D/S inputs. It's either a 7 or 8 tooth.

 

Bullitt347

I have been doing it wrong this whole time

15 Year Member

Mar 23, 2007

3,944

2,898

194

Middle of Maine

Apr 4, 2008

#5

• Apr 4, 2008

• #5

On average, you will need a 23 tooth speedo gear., That is the gear that works MOST of the time, your results may vary. You can also go to a speedometer drive service shop and they can install a reduction or step up unit in the speedometer cable and get it dead to nuts right.

 

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FordGuy88

New Member

Nov 15, 2004

241

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0

Park Ridge, IL

Apr 5, 2008

#6

• Apr 5, 2008

• #6

Thanks guys. What is the easiest way to count the teeth on the gear? Can I do it with the tail shaft housing on the trans?

 

mustangfan1990

New Member

Jul 17, 2005

505

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Lenoir, North Carolina

Apr 5, 2008

#7

• Apr 5, 2008

• #7

where is the factory speedo gear that came with the c4 you count those or find out what c4 that came with factory and that should tell you too

 

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FordGuy88

New Member

Nov 15, 2004

241

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Park Ridge, IL

Apr 7, 2008

#8

• Apr 7, 2008

• #8

Thanks everyone.

 

68keyblr

20+ Year Stangneter

Mar 17, 2003

946

20

49

Arizona

Apr 7, 2008

#9

• Apr 7, 2008

• #9

You will likely have to change out the transmission speedo drive gear. I have a c4 in my '68 with 3.73 gears and I will have to install a 6 or 7 tooth gear on the transmission. I think the highest tooth speedo gear you can get is 23 and that's not even close...

 

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FordGuy88

New Member

Nov 15, 2004

241

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0

Park Ridge, IL

Apr 10, 2008

#10

• Apr 10, 2008

• #10

68keyblr said:

You will likely have to change out the transmission speedo drive gear. I have a c4 in my '68 with 3.73 gears and I will have to install a 6 or 7 tooth gear on the transmission. I think the highest tooth speedo gear you can get is 23 and that's not even close...

Click to expand...

Has anyone else heard of this?

 

TRWXXA

Member

Jan 18, 2003

190

1

19

RIGHT BEHIND YOU!!!... Made you look.

Apr 11, 2008

#11

• Apr 11, 2008

• #11

FordGuy88 said:

Has anyone else heard of this?

Click to expand...

Yes.