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Discussion Starter · #1 ·
Hey All,

What is invovled in changing my speedo gear in my AOD, and how difficult is it? Tx.
 

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Remove the small bolt and retaining clip and pull the cable (and speed sensor if you have cruise control) out of the transmission. When you get it out you'll see the speedometer gear on the end of the cable, it is held on with another retaining clip. Remove the clip and the gear will slide off the end of the cable. Install the new gear and retaining clip, insert the end of the cable into the transmission, and install the cable retaining clip. You may need to rotate the driveshaft when inserting the cable to get the gear teeth to align.
 

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Discussion Starter · #3 ·
Thats some great info, 85...thanx much.
 

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He said it all...
 

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The AOD's up to '89 have a 7 tooth driven gear (inside trans) which is machined into the rear housing thus making changing the driven gear a trans teardown project. Early AOD tail housings also had an oiling issue that was rectified in '89. Using this year housing is suggested when rebuilding the trans.
'90 and up housings had the 8 tooth driven gear which makes drive gear swaps a little more of a PIA. The extra tooth on the driven gear makes drive gear selection somewhat troublesome. The extra tooth makes the drive gear tooth count go up. For example, the 7 tooth '89 gear w/ factory 3.27 gears uses a "red" 19 tooth drive gear, but the '90 and up 8 tooth makes this a "purple" 21 tooth drive gear. This is the largest drive gear that Ford makes. What to do if you have 3.73's or higher with the '90 and up housing? In this case you will need a "23" tooth gear which can be found on certain Jeep vehicles. If you have 4.11's you're SOL. The 23 tooth gears are flimsy at best, (too many teeth for a small diameter) so you'll be changing them frequently. So the conclusion of this may be to change to the '89 tailshaft housing or frequently change your drive gears. This is just an FYI as I went thru this when I had my AOD and did change my gears to 3.73's. I chose to change the tailshaft housing and never looked back.
 

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Discussion Starter · #6 ·
More good info, never knew about this. Thanks soda.
 

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The AOD's up to '89 have a 7 tooth driven gear (inside trans) which is machined into the rear housing thus making changing the driven gear a trans teardown project. Early AOD tail housings also had an oiling issue that was rectified in '89. Using this year housing is suggested when rebuilding the trans.
'90 and up housings had the 8 tooth driven gear which makes drive gear swaps a little more of a PIA. The extra tooth on the driven gear makes drive gear selection somewhat troublesome. The extra tooth makes the drive gear tooth count go up. For example, the 7 tooth '89 gear w/ factory 3.27 gears uses a "red" 19 tooth drive gear, but the '90 and up 8 tooth makes this a "purple" 21 tooth drive gear. This is the largest drive gear that Ford makes. What to do if you have 3.73's or higher with the '90 and up housing? In this case you will need a "23" tooth gear which can be found on certain Jeep vehicles. If you have 4.11's you're SOL. The 23 tooth gears are flimsy at best, (too many teeth for a small diameter) so you'll be changing them frequently. So the conclusion of this may be to change to the '89 tailshaft housing or frequently change your drive gears. This is just an FYI as I went thru this when I had my AOD and did change my gears to 3.73's. I chose to change the tailshaft housing and never looked back.
the speedo drive gear is machined to the output shaft not the extension housing. There is nothing wrong with the oiling system in any extension housing because there is no oiling system in the extension housing. there is a lube mod you can do however which involves plumbing some brake line from the line pressure tap and drilling a hole in the extension housing and bushing.
 

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Discussion Starter · #9 ·
arlo, is this mod something that you think is necessary?
 

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Discussion Starter · #11 ·
OK Thanx for the help
 

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the speedo drive gear is machined to the output shaft not the extension housing. There is nothing wrong with the oiling system in any extension housing because there is no oiling system in the extension housing. there is a lube mod you can do however which involves plumbing some brake line from the line pressure tap and drilling a hole in the extension housing and bushing.

This was told to me by a racing trans shop here in Jersey. Oiling problem/lube problem, what's the difference? You still need to disassemble the trans to change the driven gear was my point. 5-Speeds don't.
 
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