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Topic: Speedogear for TC - How many teeth do you have? (Read 2406 times) previous topic - next topic

Speedogear for TC - How many teeth do you have?

Hi guys. I have a problem with wrong reading speedometer. You told me some time ago that I need to change my speedogear. I had a look on it and I have 17 teeth speedogear (green). I have swapped transmission from some Mustang (my father did it), so that must be the reason. I don't know what rear-end ratio that stang had. So please tell me, how many teeth speedogear I need. Here is a small help:

I'm driving 90 km/h (56,25 MPH) and the speedometer shows 70 MPH.

I think I need 19 or 20 teeth speedogear, but I'm not sure.


PS: I have stock rear axle and a bit smaller tires (215/60R15 I think).

Speedogear for TC - How many teeth do you have?

Reply #1
Each tooth added to the gear will reduce it 3-4 MPH, I'd go with the 20...

Speedogear for TC - How many teeth do you have?

Reply #2
Quote from: TurboCoupe50;323917
Each tooth added to the gear will reduce it 3-4 MPH, I'd go with the 20...
It will reduce the reading 3-4 MPH in which speed? 30 MPH, 50 MPH, 100MPH,...?

Speedogear for TC - How many teeth do you have?

Reply #3
Is this new transmission a 5 speed or an automatic?
What was the original? 


Also, what is your axle ratio?
-- 05 Mustang GT-Whipplecharged !!
--87 5.0 Trick Flow Heads & Intake - Custom Cam - Many other goodies...3100Lbs...Low12's!

Speedogear for TC - How many teeth do you have?

Reply #4
60mph...


Speedogear for TC - How many teeth do you have?

Reply #6
Quote from: V8Demon;323926
Is this new transmission a 5 speed or an automatic?
What was the original? 


Also, what is your axle ratio?
It's C3 automatic. Original was C3 too. Rear end ratio is 3,45, as all TCs have.

So, please tell me, what YOU have. I know all the links with speedogears and calculators, but I don't know one number (how many teeth have the drive shaft gear), so I can't get the result.

Speedogear for TC - How many teeth do you have?

Reply #7
Unless you find someone with same combo that you have, their gear info will be useless to you... The '87-'88 automatics used a A4LD tranny and 3.73 rear gears... With a Super Coupe AOD, 225/60/16", and 3.73s I run a 21 tooth gear to be correct... The Std Fox Bird AOD & 3.73 requires 23 tooth gear(which Ford doesn't make), aftermarket suppliers sell a Chrysler gear for this application...

Speedogear for TC - How many teeth do you have?

Reply #8
What's wrong with my 86? I thought that all these 4 eyed turbo coupes had C3 and 3,45 LSD. Don't worry about tires, it's only minimal difference.

Speedogear for TC - How many teeth do you have?

Reply #9
Here is a speedo gear calculator that I use and it works very well.

http://www.angelfire.com/mb/mustangsrule/speedogear.html

Typically you can use a flash light and look up into where the speedo cable goes into the tranny and determine the color of the drive gear (gear on the output shaft of the tranny).  Once you have this, the cirspoogeference of the rear tire (typically you can find this on your tire from http://www.tirerack.com), and the rear gear ratio you can find the closest driven gear to get the speedo correct.

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp

Speedogear for TC - How many teeth do you have?

Reply #10
Quote from: Aerocoupe;324015
Typically you can use a flash light and look up into where the speedo cable goes into the tranny and determine the color of the drive gear (gear on the output shaft of the tranny).

While I'm not sure of the C3 trannys, most automatics have the teeth cut into the output shaft, thus it has no color, I doubt color listed for the T-5 would be correct anyway...

Quote from: Trinom;324013
What's wrong with my 86? I thought that all these 4 eyed turbo coupes had C3 and 3,45 LSD. Don't worry about tires, it's only minimal difference.

Nothing unique about your combo, just that I don't know of any others that have a 86 TC with automatic...


Speedogear for TC - How many teeth do you have?

Reply #12
Well, my donor car was a 86 XR7 with a C3 and 3.45s.  What information do you need?
1986 Mercury Cougar - 2.3T/T5 swap, TC brakes and suspension and rearend, 3" exhaust, 255 lph fuel pump, Stinger BOV, Gillis MBC @ 18 psi
2003 Chevy Suburban Z71 - Daily driver
2015 Chevy Volt - Wife's daily driver

Speedogear for TC - How many teeth do you have?

Reply #13
Quote from: Loaded87IROC;324050
Well, my donor car was a 86 XR7 with a C3 and 3.45s.  What information do you need?
How many teeth does your speedogear have.

I've send you a message with link to this thread, but you were faster :-D

Speedogear for TC - How many teeth do you have?

Reply #14
Was not aware the teeth were cut into the output shaft on the C3.  Learn something new everyday!

Darren

83 351W TKO'd T-Bird on the bottle


93 331 Mustang Coupe - 368 rwhp