PROBLEM WITH SPEEDOMETER

[THE ZUKE]

Hello Guys 

A Forum member would have had my actually problem.

I do not know the tooth number of the transmission pinion which gives the correct speed to the speedometer.

My first job was to change the speedometer cable because it was down ( The picture  )

Today the speedometer speed turns too fast.

The bridge ratio is now a 3.23/1 (727 Torqueflite automatic box). I do not know for the original ratio...

The bridge is not the original because the engine was previously a 318 CI and not a 440 CI as today.

I do not know what pigon is good for my editing.

I found this page at a supplier.  https://www.yearone.com/Catalog/challenger.cuda/transmission/speedometer/pinions-.-aftermarket

Thank's for the answers 

[anlauto]

You need to know:
Current rear axle ratio
Tire size or height if aftermarket

[Brads70]

   What size are your rear tires? Need to figure out diameter first.

[anlauto]

Hey...I was just looking in my files for that chart

[Brads70]

Hey...I was just looking in my files for that chart

[THE ZUKE]

You need to know:
Current rear axle ratio
Tire size or height if aftermarket

Thank's 

Bridge 8 3/4 - 3.23 sure grip rear end (Verified)

Rear tire : 255/40/R17.

[THE ZUKE]

  What size are your rear tires? Need to figure out diameter first.

Thank's 

Rear tires : 255/40R17

[THE ZUKE]

Hey...I was just looking in my files for that chart

[anlauto]

You need a yellow 33 speedometer pinion 

[Jay Bee]

Your rear tires are 25 inch diameter.
https://tiresize.com/calculator/

[THE ZUKE]

You need a yellow 33 speedometer pinion 

Thank you for your great answer. 

You're going faster than me   

255/40 R17 = Diameter 636 mm or 25.0394 inches.

I agree  I have to choose a pinion with 33 teeth (yellow).

[THE ZUKE]

Your rear tires are 25 inch diameter.
https://tiresize.com/calculator/

Absolutly I agree    Exactly 25.0394 inches

[THE ZUKE]

Is the quality really different between both (aftermarket pinion and new Chrysler pinion) ?

The cost is the double for one of them !!! The new Chrysler look seems better but ... is it really the good choice to pay the double ?

https://www.yearone.com/Product/challenger-cuda/fd033#prettyPhoto

https://www.yearone.com/Product/challenger-cuda/td033

[Brads70]

Why don't you post a wanted ad on here? Might get a used one cheaper?

[THE ZUKE]

Why don't you post a wanted ad on here? Might get a used one cheaper?

Because I prefer buying a new one