How far is speedo off with 4.10's and a 23 tooth gear?

[NEEDA5.0]

So I installed the 4.10's and a 23 tooth speedo gear. According to my calculations I would actually need a 27 tooth gear to make the speedo accurate.

8 x 4.10 x 815
____________ = 26.732

1000

So, my question is how far is my speedometer going to be off with the 23 tooth vs 27 tooth?

 

[94CobraPace]

It should be app 10% off, maybe 12%.

 

[NEEDA5.0]

Really? I was thinking alot more.

 

[slytherin]

what tranny stock or after market, i,ve got the 3550 w/23tooth and my deputy sherrif buddy paced me down his road and my speedo was right on, those crown vics have certified calibrated speedos so i took his word on it.

 

[NEEDA5.0]

Its an automatic. There is no speedo gear that will compensate for a 4.10 gear in the AODE because the drive gear is an 8 tooth.

 

[HazMat404]

well i had a friend drive next to me with a walkie talkie when i got my gear install last year. i have the white tooth gear (think thats 23). with the stock auto and the t-5 in there now, i am 1mph off for every 10mph i go. works all the way up to 100mph too.

the mph should be more off the faster you go and there is no set amount of mph that you will be off.

 

[LT1Killa]

NEEDA5.0, How in the world did you go slower with 4.10's as opposed to the 2.73's?? Just curious.

 

[NEEDA5.0]

I didn't have a chip. The 2-3 shift was really bad. I just got the chip, so I'll find out this weekend what the 4.10's really did (if the rain stays away ).

 

[AznStanger3v]

NEEDA5.0, How in the world did you go slower with 4.10's as opposed to the 2.73's?? Just curious.

damn, that was random.