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43-tooth purple driven speedometer gear

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Old 07-30-2018, 08:49 AM
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Car: 1990 Pontiac Firebird Formula
Engine: L31 350 TPI
Transmission: Tremec TKX
Axle/Gears: 3.23 Posi
43-tooth purple driven speedometer gear

Anyone know where I could buy one of these? I recently swapped out 2.73 for 3.23 and went with the supposedly correct 17/44 speedometer gear combo, but my speedometer is off almost 5 percent. 43 tooth should cut that error in half (if my calculations are correct).
Old 07-30-2018, 10:13 AM
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jmd
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Car: `86 SS / `87 SS
Engine: L69 w/ TPI on top / 305 4bbl
Transmission: `95 T56 \ `88 200-4R
Re: 43-tooth purple driven speedometer gear

It's 5% slow at 60mph?

If yes, proceed with that 43.

But also see if mile markers and your odometer agree over a 10 mile run.

If it is 5% fast, you need a 45.
Old 07-30-2018, 10:26 AM
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Car: 1984 Trans Am L69
Engine: Sniper EFI Powered 355
Transmission: WC T5 w/ Steel Support Plate
Axle/Gears: 3.42 10 Bolt Posi
Re: 43-tooth purple driven speedometer gear

Our speedometers are not always accurate. I would use GPS with your phone to confirm before taking anything apart.
Old 07-30-2018, 11:36 AM
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Car: 1990 Pontiac Firebird Formula
Engine: L31 350 TPI
Transmission: Tremec TKX
Axle/Gears: 3.23 Posi
Re: 43-tooth purple driven speedometer gear

Did three 60 mph timed runs over three mile section; averaged 3:086, so the speedometer is 4.7% slow (indicated 60 mph is ~57.2). Admittedly this isn't horrible, but it kinda bugs me. If I can't find a 43-tooth gear, won't be the end of the world. Just thought I'd check and see if anyone had one laying around.
Old 07-30-2018, 11:39 AM
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Car: 1984 Trans Am L69
Engine: Sniper EFI Powered 355
Transmission: WC T5 w/ Steel Support Plate
Axle/Gears: 3.42 10 Bolt Posi
Re: 43-tooth purple driven speedometer gear

Did you use GPS or the internal odometer to measure the miles?
Old 07-30-2018, 03:15 PM
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Car: 1990 Pontiac Firebird Formula
Engine: L31 350 TPI
Transmission: Tremec TKX
Axle/Gears: 3.23 Posi
Re: 43-tooth purple driven speedometer gear

Originally Posted by midias
Did you use GPS or the internal odometer to measure the miles?
Neither, I used a stretch of road that I know is 3 miles.
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