Changing driven gear in tailshaft for speedometer

**streetstang67** · 09-22-2003, 04:46 PM

After changing from 2.79s to 3.55s, I need to change my speedo cable gear to a 17 tooth, and change my driven gear to 6 tooth. The driven gear is somewhere in the tailshaft? How do you change it?

BTW, its a C-4 tranny
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**1965FALCON** · 09-22-2003, 05:27 PM

The driven gear is part of the output shaft, so it can't be changed. Best you can do is a 21 tooth gear, or get reduction box.
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**Steve** · 09-22-2003, 05:29 PM

I don't know about the C4, but if it is like a top loader, You have to remove the tailshaft housing. The drive gear is held on to the tailshaft with a clip. Comes off easily. Toughest part is set up. You have to support the engine on the trans/pan or something. Then remove the drive shaft. Then remove the speedo cable. Then unbolt the trans mount. At that point you can get to the tail shaft. I don't remember about the other stuff under there. Swapping the drive gear out is about a 30 second job.

**1965FALCON** · 09-22-2003, 05:41 PM

Check out this post:

http://www.fordmuscle.com/phpBB/view...12&forum=1
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**streetstang67** · 09-22-2003, 08:35 PM

Where can I find a gear reduction box to use? If not that, then what jeep gear works?
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**streetstang67** · 09-22-2003, 08:45 PM

I just found that TCI makes a 23 tooth gear, but it says it will last a maximum of 20,000 miles. Ford makes a 22 tooth gear, and it doesn't say anything about how long it will last...what should I do? Which should I get?
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**1965FALCON** · 09-23-2003, 01:50 PM

Depending on your tire size, you most likely need the 22 tooth to get the speedo the closest. If ford makes one I'd go for that. I always thought the "purple" 21 tooth was the most? Do you have a part number or anything on the Ford one? I'd like to get one if It'a available...
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