Which speedo gears to put after a 3.73 gears on a 98 GT?

Chiper91

New Member
Sep 23, 2018
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98 GT with an OEM T45 8 drive teeth Manual transmission .

Recently I swapped gears from 2.73 to 3.73. My speedometer shows incorrect speed (15-20 mph difference) after the gear swap. I believe I need to change the driven gears but I don't know which ones to put.I have 285/40/17 in the rear. I searched around different forums and people suggest 21 teeth driven speedo gears for my car. Can anyone confirm this? I used the CJPonyParts driven gear calculator and it suggested the 23 teeth driven speedo gears but also mentioned that they should not be put on a T45 transmission because they will get damaged easily.
 
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Chiper91

New Member
Sep 23, 2018
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Miami, FL

I used this when I changed the rear end in my car, went from 2:73:1 to an axle with 3:27:1 and it was correct

I used that calculator and it says that I should used the 23 teeth drive gear but then in the "considerations" section it says that the 23 teeth should not be put with my trans as the speedo gears will get damaged.
 

Chiper91

New Member
Sep 23, 2018
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Miami, FL
I have a T5, could call

LATE MODEL RESTORATION 1-866-507-3786

Wont hurt to give customer service a call and explain it to them and see what they have to say
Just called them and they said that the 1996-8 T45 don't cooperate with the 23 teeth as they are supposed to. They suggested I go with 21 teeth driven gears