speedo fast

[camaro69cool]

installed new ring gear 3.73 and i used the math formula out of npd catalog to find the drive gear i needed i have used this before on my 69 camaro and it work great this time it did not i'm 15 mph fast my tires are 27 inch tall drive gear is 8 and the driven is 22 any help would be great do i need to go up or down thanks again

[72BLUZ]

i googled it once and got a company in la. that was able to send me the speedo gears for the tranny. they also did the math to get it right.

[Green Machine]

I ran your info through 2 different online calculators and got 22.2 something for a driven gear, sounds right to me. Maybe the inside drive gear has more than 8 teeth ? Try checking your odometer against the mile markers on a highway, odometer should be fast also.

[72BLUZ]

Originally Posted by Green Machine

I ran your info through 2 different online calculators and got 22.2 something for a driven gear, sounds right to me. Maybe the inside drive gear has more than 8 teeth ? Try checking your odometer against the mile markers on a highway, odometer should be fast also.

just maintain your speed. what ever speed you are running, just see how many seconds it takes to go mile marker to mile marker. then divide those senconds into 3600.
example 60 seconds marker to marker divide 60 into 3600 = 60 mph
"""""""""" 51 seconds marker to marker divide 51 into 3600 = 70.5 mph

or if you have a gps it can calculate for you