Yesterday i ordered some 3.73's and the trac-lok rebuild kit for my 90, manual mustang. I ws doing a seach to find out what the deal is with the speedometer gear. So it seems that i can get the 23 tooth white gear which will put me closer to the speed that i am actually going. Problem here is that sometimes the gear gets chewed up and needs to be replaced. How often does this happen? If i keep replacing the gear will it keep getting chewed up forever? How far off will the 23 tooth gear be? Originally i had 3.08s. The other option is get some other gear that is 6 tooth (i think) drive gear and a different corresponding 18 tooth yellow gear to match it. If i go this route, how hard is it to install the 6 tooth drive gear? Which method should i go? Are there any articals on replacing either of these gears. All advice will be apprectiated. thanks in advanced.
A few things i need cleared up
- Thread starter townethug
- Start date
The stock range of speedo gears work correctly with a limited range of tire sizes.
See http://www.corral.net/tech/gearcalc.html for more help
Check to see if there is a speedometer shop in your area. If there is, ask about the Stewart-Warner speedometer gearbox. I believe it is either a 777 Series Drive Joint Kits and Parts or 666 Series Drive Joint Kits and Parts. It is a small gear box that fits between the speedo pickup gear on the transmission and the speedometer. It has quick change gears that allow you to choose almost any tire size and rear end gear ratio you want. This will allow you to get the accuracy with within 1%-3%. The drawback is that it isn't cheap.
Please excuse the typo (their's, not mine) in the following picture - it should read Custom ratio adapters, not Custom radio adapters.
See http://www.gaugeguys.com/ratioadapt.htm for more info.
See http://www.corral.net/tech/gearcalc.html for more help
Check to see if there is a speedometer shop in your area. If there is, ask about the Stewart-Warner speedometer gearbox. I believe it is either a 777 Series Drive Joint Kits and Parts or 666 Series Drive Joint Kits and Parts. It is a small gear box that fits between the speedo pickup gear on the transmission and the speedometer. It has quick change gears that allow you to choose almost any tire size and rear end gear ratio you want. This will allow you to get the accuracy with within 1%-3%. The drawback is that it isn't cheap.
Please excuse the typo (their's, not mine) in the following picture - it should read Custom ratio adapters, not Custom radio adapters.
See http://www.gaugeguys.com/ratioadapt.htm for more info.
dcarlson
Member
The 23 tooth gears aren't usually too bad on the 5 speed cars. The Automatics chew them up pretty good.
You have an 8 tooth drive gear in your '90. To install the 7 tooth gear that came in the Mustang though 1989 you have to take the tailhousing off of the transmission. Once the tailhousing is off the swap is very easy.
You have an 8 tooth drive gear in your '90. To install the 7 tooth gear that came in the Mustang though 1989 you have to take the tailhousing off of the transmission. Once the tailhousing is off the swap is very easy.
crazypete
All my crevices are greased.
Here's an interesting tidbit!
Yes, they get chewed after a few thousand (3-5K) miles BUT they keep working like that for some reason. My 23 toother had half the teeth missing and my speedo was right on with no jumps.
Yeah baby! 4.56's and an auto!! You want gear chewing? Well, I got gear chewing right here.
Yes, they get chewed after a few thousand (3-5K) miles BUT they keep working like that for some reason. My 23 toother had half the teeth missing and my speedo was right on with no jumps.
Yeah baby! 4.56's and an auto!! You want gear chewing? Well, I got gear chewing right here.
