1989 Firebird Formula
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Senior Member
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Joined: Apr 2012
Posts: 604
Likes: 1
From: Norwalk, Ohio
Car: 1989 Firebird Formula
Engine: 385
Transmission: Full Manual TH350
Axle/Gears: Moser 9" 3.70
1989 Firebird Formula
Just bought my bird about two weeks ago, and I'm wondering if anyone has factory specs on it.
It's a 1989 Formula with a 305 TPI, 700r4 trans, ws6 suspension package.
Also if anyone is curious, I paid $3500 for it. 94k miles, very clean interior. Perfect exterior minus one or two slight but noticeable scratches, and a Grand Am spoiler (lol). The previous owner has a shop bill of $800+ worth of work done in February, including all new fluids, all new filters, new exhaust, new alternator, etc. After I got it, I replaced a headlight motor (God help me) which was ~$110. I've heard a couple people say I got a pretty good deal, so comment if you'd like, but that's not the main point of this thread.
Anyway, was wondering if anyone has the factory specs for this, mainly what the factory rear end was in it, and the curb weight.
Thanks!
It's a 1989 Formula with a 305 TPI, 700r4 trans, ws6 suspension package.
Also if anyone is curious, I paid $3500 for it. 94k miles, very clean interior. Perfect exterior minus one or two slight but noticeable scratches, and a Grand Am spoiler (lol). The previous owner has a shop bill of $800+ worth of work done in February, including all new fluids, all new filters, new exhaust, new alternator, etc. After I got it, I replaced a headlight motor (God help me) which was ~$110. I've heard a couple people say I got a pretty good deal, so comment if you'd like, but that's not the main point of this thread.
Anyway, was wondering if anyone has the factory specs for this, mainly what the factory rear end was in it, and the curb weight.
Thanks!
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Joined: May 2005
Posts: 2,220
Likes: 68
From: Atlanta
Car: '02 T/A WS6, '91 T/A, '91 Camaro RS
Engine: LS1, LB9, L03
Transmission: T56, 700R4, 700R4
Axle/Gears: 4.10 10 bolt, 2.73 10 bolts
Re: 1989 Firebird Formula
Should be 2.73s in the rear-end. Weight should be in the 3300-3400 range. Looks like a good deal for the money.
Thread Starter
Senior Member
iTrader: (2)
Joined: Apr 2012
Posts: 604
Likes: 1
From: Norwalk, Ohio
Car: 1989 Firebird Formula
Engine: 385
Transmission: Full Manual TH350
Axle/Gears: Moser 9" 3.70
Re: 1989 Firebird Formula
Thank you. Everywhere I went for curb weight, it was all "no data." Couldn't find anything for factory rear end either. 
So far I've seen numbers ~15.9 for quarter times, that's slightly disappointing. Going to work at dropping a 350 in it, and see what happens from there.

So far I've seen numbers ~15.9 for quarter times, that's slightly disappointing. Going to work at dropping a 350 in it, and see what happens from there.
Senior Member

Joined: Aug 2008
Posts: 710
Likes: 32
From: pensacola florida
Car: 1989 Firebird Formula
Engine: 5.7 LS1
Transmission: 4L60E
Axle/Gears: 3.27
Re: 1989 Firebird Formula
the 305 TPI autos were slugs because of the 2.73 rear ends. Those are what kill you, but there good cruisers for those gears if your using it not to race.
Joined: Dec 2001
Posts: 9,946
Likes: 644
From: Chicagoland
Car: 1989 IROC-Z. Original owner
Engine: LB9. Dual Cats. Big Cam
Transmission: World Class T-5
Axle/Gears: BW 3.45
Re: 1989 Firebird Formula
Get a pic of the SPID sticker in the center cosole up.
Thread Starter
Senior Member
iTrader: (2)
Joined: Apr 2012
Posts: 604
Likes: 1
From: Norwalk, Ohio
Car: 1989 Firebird Formula
Engine: 385
Transmission: Full Manual TH350
Axle/Gears: Moser 9" 3.70
Re: 1989 Firebird Formula
Center console was empty when I got it, all that's left is a little glue residue that used to hold it on. 
Also, I'm definitely going to race it at some point or another, so I'll look into getting a better gear. Any specific suggestions?

Also, I'm definitely going to race it at some point or another, so I'll look into getting a better gear. Any specific suggestions?
Senior Member

Joined: Aug 2008
Posts: 710
Likes: 32
From: pensacola florida
Car: 1989 Firebird Formula
Engine: 5.7 LS1
Transmission: 4L60E
Axle/Gears: 3.27
Re: 1989 Firebird Formula
G92 off a third gen is the best factory one you can swap 3.42 rear end disc brakes or find a 98 or up 4th gen rear end to swap
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Joined: Nov 2007
Posts: 683
Likes: 4
From: Mountain Maryland
Car: 89 RS Vert, 89 Formula, 89 Bird
Engine: L03, TBI 350, none
Transmission: 700R4, 700R4, none
Axle/Gears: 3.42, 3.45, none
Re: 1989 Firebird Formula
My completely stock 87 Camaro with carb LG4, auto, and 2.73 gears was doing 15.9's all day. I suspect a TPI should be a little faster
Thread Starter
Senior Member
iTrader: (2)
Joined: Apr 2012
Posts: 604
Likes: 1
From: Norwalk, Ohio
Car: 1989 Firebird Formula
Engine: 385
Transmission: Full Manual TH350
Axle/Gears: Moser 9" 3.70
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