• Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-

Fox Changed 2.73 ratio to 4.10.....how can I correct speedometer on 1985....EEK removed from car

  • Thread starter Thread starter Milens Pit Stop
  • Start date Start date Dec 10, 2025
M

Milens Pit Stop

New Member
Dec 10, 2025
3
0
1
Posen
Dec 10, 2025
#1
  • Dec 10, 2025
  • #1
So I changed rear ratio from 2.73 to a 4.10, how can I correct the speedometer....EEK system removed from car. 1985 HO with T5
 

Noobz347

Stangnet Facilities Maint Tech... Er... Janitor
Admin Dude
Jan 4, 1985
43,170
21,338
234
Box behind Walmart
Dec 10, 2025
#2
  • Dec 10, 2025
  • #2
No EEC, Duraspark.

You have to change the speedo gear:

https://www.cjponyparts.com/catalogsearch/result/?q=speedo+gear
 
M

Milens Pit Stop

New Member
Dec 10, 2025
3
0
1
Posen
Dec 10, 2025
#3
  • Dec 10, 2025
  • #3
Noobz347 said:
No EEC, Duraspark.

You have to change the speedo gear:

https://www.cjponyparts.com/catalogsearch/result/?q=speedo+gear
Click to expand...
Ok... thanks....
 

rednotch

I'd like to remain having one chocolate starfish
Founding Member
Aug 14, 2000
1,393
625
143
south jersey
Dec 10, 2025
#4
  • Dec 10, 2025
  • #4
Speedo gear on the cable to match the tire size and gearing, think stock 85 t5's had the black 6 tooth drive gear if I remember righf? So basically need to figure out what drive gear is in the trans, tire size, rear gear and use one of the online calculators for the Speedo gear. Or swap to a GPS speedo.
 
M

Milens Pit Stop

New Member
Dec 10, 2025
3
0
1
Posen
Dec 10, 2025
#5
  • Dec 10, 2025
  • #5
rednotch said:
Speedo gear on the cable to match the tire size and gearing, think stock 85 t5's had the black 6 tooth drive gear if I remember righf? So basically need to figure out what drive gear is in the trans, tire size, rear gear and use one of the online calculators for the Speedo gear. Or swap to a GPS speedo.
Click to expand...
This has the 18 tooth driven gear, and the drive is yellow....
 

rednotch

I'd like to remain having one chocolate starfish
Founding Member
Aug 14, 2000
1,393
625
143
south jersey
Dec 10, 2025
#6
  • Dec 10, 2025
  • #6
Drive gears are only 6 7 or 8 teeth, the gear on the out put shaft on the trans, 18th would be the cable gear. If I remember right, depending on tire size best way to correct for 4.10s is with the black 6tooth drive gear, or deal with it being off and using 23 tooth dodge gears that don't last long, going off memory so might not be exact.

https://www.cjponyparts.com/speedometer-gear-kit-for-use-with-4-10-rear-gears-t5-manual-transmission-1983-1993/p/SGK5/?gad_source=1&gad_campaignid=17339858533&gbraid=0AAAAAD1v5Vm-kpKCdeFgZ_RKgLEqzRSRZ&gclid=CjwKCAiA0eTJBhBaEiwA-Pa-hd_1FOaiLfnHNNwyotnLSi8AGN_4wDgXVCIb_7lMxzAlj_K5kpCNDRoCNrUQAvD_BwE
 
Q

Qtrhrse23

Member
Jul 2, 2024
26
10
13
Texas
Jan 5, 2026
#7
  • Jan 5, 2026
  • #7
Yes the 23 tooth will be off. As for going out, last time I ran one it went for 150K no problemo
 

KRUISR

10 Year Member
Apr 16, 2015
1,822
929
143
Jan 5, 2026
#8
  • Jan 5, 2026
  • #8
I had a 23 tooth in my AOD and it would last a year or two and then chew the cable gear teeth. The kit linked above should work well.
 
You must log in or register to reply here.

Similar threads

B
Where to go from here on my build…
  • B0udreaux
  • Jul 14, 2026
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
Replies
8
Views
220
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Jul 18, 2026
AeroCoupe
new :poo: box, may need to hit you guys up for 79-82 info when i fix thIs turd.
  • rednotch
  • Sep 27, 2025
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
  • 2 3
Replies
40
Views
2K
1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk- Apr 4, 2026
Noobz347
New Member with a 1992
  • Clutchfork
  • Oct 18, 2025
  • The Welcome Wagon
Replies
5
Views
309
The Welcome Wagon Oct 19, 2025
Clutchfork
W
Codes P2004 & P2005 after removing the Actuators. I locked them open with MMR Plates. How can I fix this? 2018 Gen 3 out of a Mustang GT into a 67.
  • wdsloan
  • Sep 18, 2025
  • 2015 - 2023 Specific Tech
Replies
0
Views
219
2015 - 2023 Specific Tech Sep 18, 2025
wdsloan
W
F
Electrical From scratch: alternator wiring
  • fox racer v2
  • Jun 23, 2025
  • Fox 5.0 Mustang Tech
Replies
0
Views
584
Fox 5.0 Mustang Tech Jun 23, 2025
fox racer v2
F
Share:
Bluesky Email Share Link
  • Mustang Forums
  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-
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?