Which speedo gear?

stprorolla49

Active Member

Oct 9, 2004

1,455

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39

Fairfield, CT/North Jersey

Jan 2, 2006

#1

• Jan 2, 2006

• #1

my buddies got a 90 LX w/ 3.90 gears and a t-5...what speedo gear would he need to at least compensate for a 3.73 gear ratio if 3.90 speedo gears arent' available?? if so, where can i get one?

 

bobcatv8

Member

Aug 25, 2004

141

1

16

Ocala,FL

Jan 2, 2006

#2

• Jan 2, 2006

• #2

First, find out what gear is in there now.
Gears are available from Ford in 16,17,18,19,20,21 teeth.
What rear gear ratio did you have, and what gear ratio did you put in? That info along with current gear tooth count will determine what speedo gear will get you the closest.

 

stprorolla49

Active Member

Oct 9, 2004

1,455

15

39

Fairfield, CT/North Jersey

Jan 2, 2006

#3

• Jan 2, 2006

• #3

bobcatv8 said:

First, find out what gear is in there now.
Gears are available from Ford in 16,17,18,19,20,21 teeth.
What rear gear ratio did you have, and what gear ratio did you put in? That info along with current gear tooth count will determine what speedo gear will get you the closest.

Click to expand...

not sure what was in there before....he bought it with the 3.90's in there.,..

 

F

FordGuy88

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Nov 15, 2004

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Park Ridge, IL

Jan 2, 2006

#4

• Jan 2, 2006

• #4

Go on Brothersperformance.com They look it up they have a chart if you look under the gears.

 

Michael Yount

Mustang Master

Apr 10, 2002

9,039

6

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Charlotte, NC

Jan 2, 2006

#5

• Jan 2, 2006

• #5

http://www.geocities.com/mgnedell/notchback/tech/speedo.html

 

cobradvm

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Sep 2, 2003

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Woodinville, WA

Jan 2, 2006

#6

• Jan 2, 2006

• #6

I just put in a 6 tooth black driver gear and a yellow 18T driven gear - this was for my 3.73 gears - originally I tried a 23 tooth white gear on the 8 tooth drive gear and it just ripped it to shreds. If the tranny out, its a fairly simple matter of removing the rear end part of the tranny, and popping on the new gear. There are a couple of fiddly parts to deal with but it wasn't that bad. Some folks do it in the car, but I can't imagine doing that - I had to stand the tranny on its end to help get it all back together - buts that's just me - I'm sofa king we todd did!

Best place to get this stuff is www.fivestarford.com - ask for Max

 

bobcatv8

Member

Aug 25, 2004

141

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16

Ocala,FL

Jan 2, 2006

#7

• Jan 2, 2006

• #7

Is the speedo is accurate now?
If so, I read that you are going FROM 3.90 rear gear TO 3.73 rear gear.
I all that is so, after determining what tooth count gear is in there now, ADD one tooth. That will be as close as you are going to get unless you need to change the DRIVE gear on the output shaft {PITA!}.
It's a beeotch follwing up behind others work, Aint it!!
Plus there are only so many gears available to solve these kinds of problems!

 

cobradvm

New Member

Sep 2, 2003

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Woodinville, WA

Jan 2, 2006

#8

• Jan 2, 2006

• #8

From the site Michael recommended, you would need a 6 tooth drive gear in the tranny, and a pink 19 tooth driven gear in the cable - that will put you exactly right for 3.90s which is what I think you are asking.

One question - what is in it right now - is the speedo just way off?

 

Michael Yount

Mustang Master

Apr 10, 2002

9,039

6

79

Charlotte, NC

Jan 2, 2006

#9

• Jan 2, 2006

• #9

cobra - "I'm sofa king we todd did!" We're gonna need an interpretation....

Another alternative is to have one of the speedo shops make you a conversion box. Basically it's a box that plugs into your speed, and your cable plugs into it -- it allows you to change easily accesible gears in the box and alter your speedo cable speed just about anyway you like. It's not as cheap as replacing the driven gear, but it's a lot cheaper than pulling the tranny and replacing the drive gear. I've done the latter - not hard, but time consuming.

 

cobradvm

New Member

Sep 2, 2003

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Woodinville, WA

Jan 2, 2006

#10

• Jan 2, 2006

• #10

Hey Michael, if you like that one, here's another one - my dixie wrecked!!










Hint: say it out loud without emphasizing any syllables - even better - say it to your wife and see what she says!!


Hey - I just saw you are from Knoxville TN - spent at year at UT and lived out in Maryville (or should I say Mir-uhhh-ville!). The Alcoa highway is quite the fun little drive - some serious tail gating from what I remember. Fall and Spring were just gorgeous times of the year - the summer you can keep!

 

Michael Yount

Mustang Master

Apr 10, 2002

9,039

6

79

Charlotte, NC

Jan 2, 2006

#11

• Jan 2, 2006

• #11

I'm sorry I asked for the interpretation -- groan....

That's Mare-vul. I moved here from Houston -- so summer's are all relative. Compared to Houston summers (basically March through mid November), Knoxville summers are a cool breeze....