what speedo gear do I need?

fordguy87

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Jul 15, 2005
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ok I have an 87 mustang with the 89 140mph cluster in it .. i just put an 83 T-5 transmission but i still used the 87 speedo gear and i know my speedometer has to be at least 10 mph slower than what i'm actually going. Does anybody know what speedometer gear I might need and also down the road i'm putting 3.73 gears what geat would i need when i do that as well? thanks guys
 
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Why would you go with such a mix of parts? I think you have to get your speedometer calibrated for the new 140 MPH you have in there first (not sure on this). That will solve the first problem of being 10 MPH slower. Then, once that's done, for an 83 T5 I believe you need a red 21 tooth driven gear to correct for the 3.73s.

If none of that work or makes sense, maybe try buying a gear kit and trying them all out until one works? :shrug:

http://cgi.ebay.com/ebaymotors/Ford...004QQitemZ140059246189QQrdZ1QQsspagenameZWD1V

http://cgi.ebay.com/ebaymotors/Ford...004QQitemZ140060033662QQrdZ1QQsspagenameZWD1V
 
To be honest the speedo gear you have now should be the correct one.

Putting a 140MPH speedo in shouldn't affect calibration at all since the speedo is already calibrated.

Only thing i can think of is that your '83 T-5 is one of the early non-WC t-5's that uses a black 6-tooth drive gear instead of a 7-tooth.

You'll have to pull the speedo cable out and take a peek with a flashlight at your drive gear.

If it's black it's a 6-tooth
If it's yellow it's a 7-tooth
If it's green it's an 8-tooth

Then you can look on this page to see what you'll need

http://www.steeda.com/products/speedometer_recalibration_gears.php
 
Well with the 140 speedometer it was right on or pretty close and then i swapped to an 83 T-5 but i was told it was a WC and then the speedometer went alot slower than what it should be .. but thanks!
 
Well, i've found out your t-5 is NON-WC. 1983 and 1984 were non-WC. Early 1985's were also non-WC as the World Class t-5 was an 85.5 debut.


That makes me think you have a 6-tooth speedo gear and not a 7-tooth....which makes sense since the speedo is now slower