Speedometer

[steve from staten island]

I had 14 inch rims but now have 15 inch. Also I went with 3:55 rear gears. I noticed the speedo is off. How do I find out what speedo gear to use. in my 727 to correct this?
Thanks

 

[91r/t]

https://www.google.com/url?sa=i&url=http://www.moparts.org/Tech/tech/pages/speedo.html&psig=AOvVaw1UJK0AAV9ksgDWxOOD-pi5&ust=1582209205555000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCIDvid_q3ecCFQAAAAAdAAAAABAJ

Rim size wont matter. It is based on overall tire diameter. This chart will work for ya on Brewers. 4 speed and 727 is 1:1 so they will both be very close. There is an auto chart on their as well, but The two will be so close it isn't worth worrying about.

 

[hunt2elk]

And the charts are not always spot on. Usually takes a little trial and error to get them perfect. As a rule of thumb, for a one tooth change on the gear will change your mph reading on the speedometer about 2 mph.

 

[Dipstick]

Rim size wont matter. It is based on overall tire diameter.

Rollout is more accurate.

 

[91r/t]

Rollout is more accurate.

With a stock speedo I’m happy within a couple miles an hour. I’m not looking for NASCAR lap time accuracy lol.