• Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech

Speedometer gear?

  • Thread starter Thread starter jes72mustang
  • Start date Start date Apr 11, 2006

jes72mustang

New Member
Mar 31, 2005
224
1
0
S. Central PA
Apr 11, 2006
#1
  • Apr 11, 2006
  • #1
Well, Since I bought my 72 the speed-o has been WAY WAY off. It was reading about 80 MPH or more when doing 45MPH ( I was pacing my wife in the van). There were a number of mods done by previous owners, 4:10 Gears and wrong size tires (about 2 inches smaller in diameter). ANy way I put 225/70 R 14 on all around, and I replaced the 4:10s with 3:50s. Now the speed-o is still off reads about 65 MPH when doing 45 MPH. I have an FMX tranny. Does anyone know what speedometer gear I would need to bring this in closer to actual?

Thanks
 

Cannoball888

New Member
Dec 25, 2005
320
0
0
Gainesville, FL
Apr 11, 2006
#2
  • Apr 11, 2006
  • #2
I don't fully understand it, but maybe this will help

http://www.mustangsandmore.com/ubb/speedogear.html
 

72 fastback

Member
Apr 4, 2006
146
3
19
Hamden Ct
Apr 11, 2006
#3
  • Apr 11, 2006
  • #3
See what gear have in trans it is probally a 17 tooth gear try a 20 or 21 tooth gear. That should do the trick .I have 235 go r15 on my car with 3.70s in rear and it is only about 2 miles an hour fast.
 
You must log in or register to reply here.

Similar threads

M
4.10 gears = 200,000 miles ?
  • michaelleewebb
  • Apr 1, 2026
  • SN95 V6 Mustang Tech
Replies
5
Views
157
SN95 V6 Mustang Tech Apr 2, 2026
michaelleewebb
M
T
Drivetrain Can’t identify correct speedometer gear
  • townethug
  • Jul 12, 2025
  • Fox 5.0 Mustang Tech
Replies
6
Views
214
Fox 5.0 Mustang Tech Jul 21, 2025
FastDriver
5
Hello fellow Mustang fanatics.
  • 580HP*428Cj
  • Apr 2, 2026
  • The Welcome Wagon
Replies
2
Views
163
The Welcome Wagon Apr 2, 2026
General karthief
S
Engine Stalls when downshifting/coasting
  • Scott_S
  • Nov 5, 2025
  • Fox 5.0 Mustang Tech
Replies
11
Views
642
Fox 5.0 Mustang Tech Nov 6, 2025
Mustang5L5
B
Car limp mode no codes
  • Brysen
  • Dec 25, 2024
  • 2005 - 2014 S-197 Mustang -General/Talk-
Replies
2
Views
200
2005 - 2014 S-197 Mustang -General/Talk- Jan 2, 2025
89ripper
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1965 - 1973 Classic Mustangs -General/Talk-
  • Classic Mustang Specific Tech
Menu
Log in

Register

  • Forums
  • What's new
  • Media
  • Resources
  • Contact
  • Sponsor
X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?

X

Privacy & Transparency

We use cookies and similar technologies for the following purposes:

  • Personalized ads and content
  • Content measurement and audience insights

Do you accept cookies and these technologies?