Transmission vs Speedo Rading

[Bullitt-]

I had my rear end (742 casting) built by Cass aka Dr. Diff,

MMMM bet you got a different rear gear now...

[MEK-Dangerfield]

One tooth will only mean 4-5MPH difference at hiway speed. If your speedo is reading fast, you need a speedo gear with more teeth, not less. I'll bet 33-34 is what you need Glennster.

[purple1]

Are you sure it is a 3.23 rear gear? Check the chart here. http://www.yearone.com/yodnn/tech/TechFAQ/TransmissionFAQ/MoparSpeedoGearChart/tabid/415/Default.aspx

Dave

[Glennster]

I'm pretty sure my old 7 1/4 rear end and my new 8 3/4 both have 323 gears....

[MEK-Dangerfield]

I'm pretty sure my old 7 1/4 rear end and my new 8 3/4 both have 323 gears....

Sooo, if your rear tires are in the 26" range in diameter, then you need a 33-34 tooth gear, like I mentioned. Mine took a 34.

[Bullitt-]

Think I have a 33-tooth ...I'm gonna have to change to a 28....Want to swap?

[Glennster]

I think I'd like to swap, but let me get out with a GPS so I can check my actual speed before I commit to anything.
THANKS for the offer, I hope we can work out a win win deal!
Either way, I'll end up with a 28 or 29 that I can swap. If this thing is as far off as I think it is, you'll have you choice of a 28 or 29.

[the_engineers]

Think I have a 33-tooth ...I'm gonna have to change to a 28....Want to swap?

I've got one you can have.  PM me your address if a trade doesn't work out.

[Glennster]

THANK YOU Sir!
It might be a week before I car get the car out, the roads are packed with a little snow, salt and sand. Temperatures are supposed to stay low......

[the_engineers]

Your inbox is full.  I should've been more clear.

"Hey Bullitt, I've got a 28 you can have.  PM me your address if a trade doesn't work out."

Sorry Glenn   

[Bullitt-]

Your inbox is full.  I should've been more clear.

"Hey Bullitt, I've got a 28 you can have.  PM me your address if a trade doesn't work out."

Sorry Glenn  

  Appreciate it, lets see what the Glennster comes up with, I'm in no hurry.
    BTW I confirmed I have a 33-tooth. 

[Glennster]

 I should have gone for a test drive last night when the roads were half way clean, instead, we did a little reloading. Got to keep plenty of ammo around.
  I planned to get out for a test drive tonight but we got more stinking SNOW ! ! ! ! !   The roads are filled with salt, dirt and slush...AGAIN!!!

Please hang on to that 33, I suspect that's what I'll need, pray for warm dry weather ! ! ! ! ! !

[70burntorangeT/A]

pray for warm dry weather ! ! ! ! ! !

  amen to that brother

[Bullitt-]

No rush here...not going anywhere.

[Glennster]

I got the Challenger out for a short spin, when the cars speedo say 60 mph, the TOMTOM (GPS) says 49-50mph. Sooooo, looks like I need that 33 gear, maybe more............
  It also looks like I'm running around 2,600 RPM's at 56 MPH, that sounds like too many RPM's for a 323 rear gear doesn't it? Could it be that I'm not getting a good reading because the torque converter is not fully engaged?