my 1990 mustang has 4:10 gears and bigger tires. is there anything i can do to recalibrate my speedometer to make it read the correct MPH again? Thanks
Do you have an automatic transmission or a manual transmission. You can change the driven gear for the speedo cable in order to try and correct the speedometer. There are a few different calculators out there to help determine which gear you need.
i looked at the thread you gave me a link to, and i went to www.cjponyparts.com and there were TONS of different speedo gears. i didnt really know which one to pick, so i e-mailed them. what i got back was that they dont have a gear with enough teeth to get it pefect, but he said that the part # HW1289 would get me close. when i looked up the part #, 5 different speedo gears came up all having the same part #. the biggest gear ratio they go to is 3.50. could someone please tell me if the info is accurate and the C4 can only use one of those five speedo gears. and, the one i was looking at only had a description of "SPEEDOMETER GEAR 1969 V8 3.50 rear Gear C6 " will that work with my 1990 stang with a C4 trans? thanks guys.
LRS has 23-tooth gears. They are not a stock Ford part which is why you may have trouble finding what you need. A 23-tooth gear won't get you exactly right, but it should get you closer.
LRS also has "kits" to help you get a more precise calibration. The kits include both drive and driven gears. With 4.10s on a 5-speed you'll probably have to change the drive gear to one with fewer teeth.