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Old 01-08-2009, 10:27 AM
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Cobra Make, Engine: RUCC, 289 c.i. with a T-5 "Living the Cobra Experience"
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Quote:
Originally Posted by J Persons View Post
To compute what speedometer gears you need -

Driven gear tooth count = Drive gear tooth count X Axle ratio X Tire revs per mile, divided by 1000

All T5 and Tremac trans have a replaceable drive gear. But it's a PITA to get to, the tailshaft housing requires removal to get to the gear. The good news is: Aftermarket T5 and Tremacs use a 7 tooth drive and don't normally require replacement. Most '90 through '95 OEM T5's use a 8 tooth gear, and it should be replaced with a 7 tooth drive gear.

There is a chart in most all Ford motorsport catalogs that list all the available drive and driven gears and what rear ratios they apply to.

Don't be tempted to use a 23 tooth driven gear to get the correct reading. These are not Ford spec gears, the pitch is wrong and sooner or later they will fail.
Thanks guys, I ran the numbers, looks I need a 17 tooth gear, right now there's a 16 tooth installed.

Just so there's no confusion, I'm not the original poster for this thread, my speedo is reading too fast, not too slow.
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