Speedometer After Tranny Swap
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Senior Member

Joined: May 2003
Posts: 744
Likes: 0
From: California
Car: '91 Firebird
Speedometer After Tranny Swap
Hey guys, I'm getting ready to do my automatic to manual swap. I think I have everything I need now. The only thing I'm unsure about is if this will affect my speedometer in anyway. The transmission is from an '85 v6 bird, and I'm dropping it into a '91 v6 bird. To my knowledge the speedometer is cable driven on an '85, and electronically controlled on the '91. When I drop in the manual am I still going to be able to keep my electronic sending, or will I need to downgrade to cable? If it's possible I want to retain the electronic speedo because I've got a 4th gen dash I'm going to install and I don't want to spend the extra money on a dakota box.
Thanks!
Thanks!
Joined: Dec 1999
Posts: 3,544
Likes: 19
From: WI,USA
Car: 89 FORMULA 350, 91 Z28 Convertible
Engine: ls1, LB9
Transmission: t56, Auto
Axle/Gears: S60/ 3.73
the 4th gen dash is what will cause any problem if any. bassically if you look at it as putting in the 85 trans in the 91 stock vs stock just get the 91 t-5 sending unit and use that in the 85 t-5. you will still need to figure out the speedo gears for you rear diff. ratio. as far as the 4th gen dash well. I have no idea if it will work right. is it now?
Supreme Member
Joined: Aug 2001
Posts: 1,228
Likes: 1
From: Caldwell, NJ
Car: 88 IROC Convertible
Engine: 305 TPI
Transmission: Raptor 700
not sure if the T5 and the 700R4 speedo sending units for the same for 91-92, but i believe they are. if so shoot me an email i have one laying around that i can get rid of.
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