• Welcome to ClassicBroncos! - You are currently viewing the forums as a GUEST. To take advantage of all the site features, please take a moment to register. It's fast, simple and absolutely free. So please join our community today!
    If you have problems registering or can't log into your account, please contact Admin.

Speedo gear question

guidoverduci

Sr. Member
Joined
Mar 8, 2012
Messages
731
Loc.
NorCal
Currently have 18 tooth and I'm reading 55mph with 65mph on the gps. That's with 3.50s. I'm putting 4.11s in and wondering what effect that will have. I'll probably just order both 17 & 16 to be safe. Do they come lower?
 

Viperwolf1

Contributor
electron whisperer
Joined
Aug 23, 2007
Messages
24,448
Right now your speedo is 18% slow. After the change to 4.11 (17% rpm increase) it will be very close with your 18 tooth gear.
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
37,076
They only come as low as 16 tooth.
That 18 should be as good as you can get once you get the 4.10's in. Lower gears will make the speedometer read faster, so the 4.10s should fix everything for you. If you go to a taller tire then you will need to look at a 17 tooth gear.
 

dredgenot

New Member
Joined
May 23, 2004
Messages
49
I have 4.11's with 33" tires and I'm running a 19 tooth gear. The only calibration I have done is pacing a prius with a digital dash, but the speedo is right on now. I did have and 18 tooth, but it always read slow.
 
Top