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

Milens Pit Stop · Dec 10, 2025

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 · Dec 10, 2025

No EEC, Duraspark.

You have to change the speedo gear:

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

Milens Pit Stop · Dec 10, 2025

Noobz347 said:
No EEC, Duraspark.

You have to change the speedo gear:

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

Ok... thanks....

rednotch · Dec 10, 2025

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.

Milens Pit Stop · Dec 10, 2025

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.

This has the 18 tooth driven gear, and the drive is yellow....

rednotch · Dec 10, 2025

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

Qtrhrse23 · Jan 5, 2026

Yes the 23 tooth will be off. As for going out, last time I ran one it went for 150K no problemo

KRUISR · Jan 5, 2026

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.

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

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

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