4.6L General DiscussionThis section is for non-tech specific information pertaining to 4.6L (Modular) Mustangs built from 1996 to 2004.
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So i recently had 4.1's installed, after my speedo was 50% fast! I chaged the speedo gear to a 23 tooth gear and i calcuated it to ~17.5% too fast... I'm not sadisfied i guess. I've been searching about and researching a drive gear swap and it doesn't look that hard, however my question is about the drive gear itself. I can't seem to find a site that sells a 6 tooth drive gear for a t45, only a t5. The sites say that its ONLY for the t5, so i'm guessing they are different gears. I can find a 20 tooth speedo gear fine but i can't find the 6 tooth drive gear, can someone help?
Here is some of my findings and figures i've done in case someone else finds this thread:
23 tooth speedo gear is not a ford part and doesn't go together perfectly, this causes a short life for the plastic gear. Since I'm changing the drive gear, i figured I'd do it right and get a combo that using a ford speedo gear and is closer to my orginal ratio by about half
18/8 oem is 2.25 ratio drive gears (2.73's) then final drive divided by ratio......1.2133333333
23/8 now is 2.875 ratio (with 4.10s).....................1.4260869 fast by...17.5346346 percent
20/6 is 3.333............................................. ....1.23 fast by 1.373626 percent
23/7 is 3.2857142857...................................... 1.2478260869 fast by 2.8428 percent
"perfect" is 3.37912 speedo/drive gear ratio (for 4.10's)
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