[dreamboat77]

I have a 1998 Cobra that has had 4:10 gears installed. Of course, the speedometer is off quite a bit. I have tires of the same height as stock and doing calculations I have determined that I need a 23 tooth driven gear. Does anyone know if this info sounds accurate and if so, where can I purchase a 23 tooth gear. Thank you

[spoc2560]

not sure of the gear size but you can purchase a larger and smaller speedometer gears from your local Ford dealer. I think the largest you can get is 25 tooth. If you have ever had your cobra put on a dyno they can recalibrate it for you. My Dad Put in a 3.73 gear in his gt and used a 23 tooth gear. it put him within 3 mph of actual speed.

[97 svt cobra]

hey dreamboat77 i have a question?just bought a 97 cobra and not sure which gears i have?i think they are 4.10.i heard if you do 80mph in 5th at 2900rpm it should be 4.10. also i have 275 tires in the back.how about you?can you give me some stats please? thank you

[STSVT]

23 tooth gear is right for 4:10's. But this only applies to Cobras since they have a 7 tooth drive gear in trans. Non-Cobras have 8 tooth gear only good for 3.55's. The problem with the 23 tooth gear is the teeth are very, very thin and wear out easily. I got mine from a guy on ebay and it turned out to be a Jeep speedo gear so at least it has some OEM durability. i'll see if i can find the part number for it.

can't get mine out to tell you what rpm at what mph..

[Lopez16]

Originally Posted by dreamboat77

I have a 1998 Cobra that has had 4:10 gears installed. Of course, the speedometer is off quite a bit. I have tires of the same height as stock and doing calculations I have determined that I need a 23 tooth driven gear. Does anyone know if this info sounds accurate and if so, where can I purchase a 23 tooth gear. Thank you

Hey guys, go to Brothers Performance.com or American Muscle .com to purchase any Mustang part you need. I strongly reccommend them. I have purchased multiple items from both places. Fast,reliable and accurate. I like Brothers Performance because they have "real" tech's that are very helpful and are faster with shipping.

[Glen]

Originally Posted by spoc2560

not sure of the gear size but you can purchase a larger and smaller speedometer gears from your local Ford dealer. I think the largest you can get is 25 tooth. If you have ever had your cobra put on a dyno they can recalibrate it for you. My Dad Put in a 3.73 gear in his gt and used a 23 tooth gear. it put him within 3 mph of actual speed.

You cannot recalibrate the speedo on pre-1999 Mustangs in a tune. They do not have the electronic speedo, they are mechanical. You have to physically change the speedo gear.

[98 yellow snake]

Hey Dreamboat
I also have 98 cobra. My trans (t-45) is electronic speedo. I just had 4.10s put in. I used electrontic speed calibrator. Installs in your shift console. Got mine over the net.
Hope this helps..............98 Yellow Snake