hayabusa

Ok I finally picked up my wifes 1980 Firebird Formula yesterday. The first order of business is changing out the rear end gears. First does anyone know what housing came stock on these cars? Second how bad is the rear end of this year. I know eventaully I am going to replace the whole rear end, but if I can get away with it for a year or two I would like to just change out the ring gear and pinion until I have the money to swap it out to a 12 bolt, or 9 inch ford. Will the stock rear end hold up for a year or so with 400ft/lbs of torque and slicks for at least a year? I want to be able to replace the motor as soon as possible and spending $2500 on replacing the whole rear end would put that off by at least a year. Slicks have to come first because even with the stock 2.43(or is it 2.41) it just spins due to the monster torque that the 455 buick makes.
By the way according to the numbers on the heads of the 455 it is a 1972 with the good heads. I think they called them stage 1. So the motor was rated at a mere 250hp but had way over 400ft/lbs of torque. The same heads and motor, albiet with a different cam and a bit higher compression ratio made 360 hp and 510 ft/lbs of torque in 1970 and propelled a 3700 lb car to a 13.3 second quarter mile. If I was going to stick with this motor it would be able to lay down some good times since this car weighs 3430pounds according to the stats I found. Probably quite similar to the 1973 Trans Am with the 455 which ran a 13.3 stock with the best driver. But since they are true stage 1 heads I should be able to get a pretty penny for the heads, if not the whole motor.

Hayabusa

badbird5.7

i just sold a 1972 pontiac 455 just the block and got $600, that motor you have there if you wanted to sell it could easily rake in around $2500 or more depending on how bad somebody wants it (they are very hard to find in good running condition) ,that motor is the one they used in the Buick GSX and with a little bit of work, head work,intake, cam, new carb,etc.. you could get some serious horsepower out of it. I know a small block is the way to go because there cheap and easy to build and you can get parts just about anywhere, but you already have a good running motor( big block) like i said a little work and maybe a supercharger or nitrous and you could easily have a 9 second car

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hayabusa

Well until I can afford to change it we are going to run a small shot of nitrous through it. I am not sure how much. I may do some work on it while I save up, but I am not going to go all out. It does run like a champ though.

Hayabusa

badbird5.7

I regret selling my 455, i went with a small block in my 1980 trans am i promise you won't regret it my friend had a 455 in his 79 and that car was insane that thing put you back in your seat so hard it made you sick. as far as the rear end goes i never had any problems with my 10 bolt i owned a 78 and now my 80 and they were both stock and very strong,my 80 rear end has 215,00 miles on it and still going strong but i am replacing the gears in it this summer, your gonna have a lot of fun with that car i love mine

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jester77

what size tires? tranny? good luck with the build it sounds like fun i love that type of shit, even if it takes a couple years...

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-94 Formula 383stroker,ps longtubes,tf heads,9inch w/ locker < lsx swap in '09
-94 Firebird for sale!!! or parts
-96 Blazer < lt1 transplant in '09

hayabusa

Right now everything is up for debate. I have not decided on anything yet.

Hayabusa

hellbird78

if you look on the center housing where the cast #'s are i think if there's a DL or ds it has to have a d they have super duty axle tubes and there supposed to be unbelievably strong for a 10 bolt i know people who run 5 ta 600hp running it with spools though but still these 10 bolts in these late 70's t/a are really strong run some 456's and you'll be pullin some mid 12's with some easy up grades good luck

joelster

The rear in that car is a 8.5" 10-bolt. They are pretty beefy. I'm not sure if the Formula's were all posi though. I would guess that they were. It can handle abuse for now, until you get real serious with the motor and spray and whatnot. 400lb/ft of torque is no problem even for a bone stock unit.

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1994 Z28 Black heads/cam th350 drag car
1995 Z28 Teal 'Vert bolt-ons 6-speed cruiser

SpecialK

Go with 4.10s for now if its' going to be a pretty much dedicated track car. And make sure it's a spool type rear. Not a posi. You want ti to just bang and lock, not spin a little then lock. eventually the posi will burn up spinning over slicks.

If your gonna swap rears eventually look into a Dana 60 type, best rear ends ever!

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23:23] blkIROC355: sometimes when i pee i make that sound the light sabers make
[23:23] SpecialK LS1: lmao
[23:23] blkIROC355: and play with the stream
[23:23] SpecialK LS1: that's just wrong

transamkid

my '80 t/a is auto and i still have the stock 2.73 gm 8.5in 10 bolt in it. i gotta have at least 400tq to the wheels too....1700 miles so far and no problems..and its been to the track

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-scarpa
1980 TransAm done by OLDSCHOOL at TTPerformance
1994 Firebird v6, auto, good sound system, 160k!
www.fquick.com/transamkid383
www.njfboa.org