Speedo gear for AOD after changing to 3.73:1 rear gear June 30, 2014, 09:53:07 PM I have an '87 Thunderbird with a 5.0, AOD, and 7.5 rear end. I had 3.73 rear gear installed, but not sure how to get the right speedometer gear to make the speedometer accurate again. I guess Ford never put this gear ratio in this car. Any help would be appreciated. Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #1 – June 30, 2014, 10:30:11 PM I run this one: http://www.latemodelrestoration.com/item/LRS-17271J-K/83-95-Mustang-23-Tooth-Speedo-Gear-Kit-AutoShould make the speedometer accurate within 1-2mph. Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #2 – July 01, 2014, 01:22:11 AM Thank you Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #3 – July 02, 2014, 10:44:32 PM 23 teeth is where you want to be. Or 1 tooth for every 5 MPH depending on the gear count of your original gear. have a great evening guys. Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #4 – July 03, 2014, 01:12:23 PM 23 is the one. Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #5 – July 03, 2014, 05:40:57 PM I've heard the 23 tooth gear doesn't mesh well and gets eaten up every little bit.i plan on swapping a 6 tooth driven gear into my t-5 when i can get around to swapping the tailshaft. Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #6 – July 03, 2014, 11:54:11 PM Quote from: Haystack;435435I've heard the 23 tooth gear doesn't mesh well and gets eaten up every little bit.i plan on swapping a 6 tooth driven gear into my t-5 when i can get around to swapping the tailshaft.The gear I posted is for auto transmissions. The T5 gear gets eaten by the auto trans. Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #7 – July 04, 2014, 02:27:05 AM I just changed the rear gears and my speedo is 10mph off down low and more so at 70mph. I used this link http://www.latemodelrestoration.com/products/Mustang-Transmission-Speed-Correction to choose a 17 tooth manual trans white gear and clip. Hopefully I'll be spot on with it. I still need to update my sig for the rear end change. Just changed over the whole rear end to a 7.5 trac loc with slapper bars. Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #8 – July 04, 2014, 02:45:09 AM Sweet, didn't know they had a kit with clips and a driven gear. maybe i can finally get my speedo to read less then 85mph in first gear. it is kinda fun watching the odometer though.i'll bet the car thinks its way over 400k miles by now. Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #9 – July 04, 2014, 06:09:30 AM Some later/rebuilt AOD's may have an 8 tooth drive gear as opposed to the 7 tooth that these cars came with. Just something to look out for. Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #10 – July 04, 2014, 04:17:35 PM The T-5's drive gear for the speedo can be changed but I believe the ones on the AOD's are machined into the output shaft so if you have an 8 tooth on your AOD and it is machined you will have to find a 7 tooth output shaft and swap them. I run the black 6 tooth drive gear in the T-5 in my Coupe so that I could run a lower numerical driven gear for the 3.73's.This is an excellent site to calculate the correct driven gear for almost any application:http://www.sccoa.com/faq/speedgr.htmlDarren Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #11 – July 04, 2014, 05:05:48 PM Quote from: V8Demon;435469Some later/rebuilt AOD's may have an 8 tooth drive gear as opposed to the 7 tooth that these cars came with. Just something to look out for.Actually 86-88 Thunderbirds/Cougars with the AOD had an 8 tooth drive gear. The 86-89 Mustang AOD had a 7 tooth drive gear and the 90-93 cars had a 8 tooth drive gear. Confused yet?The AOD in my Thundebird has an 8 tooth drive gear. It's the factory trans that has been rebuilt. Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #12 – July 05, 2014, 07:41:14 AM yeah, that rattled my brain.gotta deal with this on my bronco,, speedo needle just bounces but only does so once in a while. the time it does not it lays at zero. Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #13 – July 05, 2014, 09:19:28 AM Quote from: thunderjet302;435489Actually 86-88 Thunderbirds/Cougars with the AOD had an 8 tooth drive gear. The 86-89 Mustang AOD had a 7 tooth drive gear and the 90-93 cars had a 8 tooth drive gear. Confused yet?The AOD in my Thundebird has an 8 tooth drive gear. It's the factory trans that has been rebuilt.The case on my transmission has an '89 part #. Came out of a Super Coupe. The 8 tooth drive gear/tailshaft in mine has the revised holes for better fluid dispersal/lubrication. It's staying.... Quote Selected
Speedo gear for AOD after changing to 3.73:1 rear gear Reply #14 – July 05, 2014, 11:18:40 AM Quote from: V8Demon;435515The case on my transmission has an '89 part #. Came out of a Super Coupe. The 8 tooth drive gear/tailshaft in mine has the revised holes for better fluid dispersal/lubrication. It's staying....The SC got the 8 tooth drive gear in 89. Mustangs got it in 90. I have no idea why it took a year longer. Quote Selected
Topic: Speedo gear for AOD after changing to 3.73:1 rear gear (Read 5917 times)
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Topic: Speedo gear for AOD after changing to 3.73:1 rear gear (Read 5917 times)
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