Will swap from 2.73 to 3.73 gears help acceleration?

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Apr 23, 2001 | 02:12 PM
  #1  
Hi everyone,

I currently have an 87 Formula with the LG4/5spd combo, and an open diff 2.73 out back. I've been offered a free 3.73 open diff. rear end out of an 84 or 86 camaro v-6, or so he said. Will this bolt up to my car, and what kind of a difference would I see in acceleration (0-60 or quarter mile?) The car is near stock except for an open element, catback and high flow cat. Also would my rpm's be unreasonable on the highway? Thanks alot,

Steve
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Apr 23, 2001 | 02:43 PM
  #2  
It should bolt right up. You wil DEFINATELY notice a difference, probably a substanstial difference.

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My 1986 Z28
GM350, T-5, 3.23's, lots of go fast goodies, 4th gen Firebird interior etc...
85 IROC w/ 1364 miles!

You'll always find what you've lost in the last place you look

R.I.P Dale Earnhardt
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Apr 23, 2001 | 03:03 PM
  #3  
That 3.73/open/drum axle probably came out of the rare '84 Camaro H.O. car... no V6 came with 3.73's. The lowest gear the V6's got was 3.42's. I think the manual transmission'd 2.5l 4cyl f-bodies recieved 3.73 axles, though. All of GM's rear f-body axles were built to the same strength, no matter what engine went into the car.

[edit] Oh the only thing you should replace is the body-to-axle brake hose, for safety's sake. I went from a 3.42/open/drum axle to an '84 3.73/posi/disc, and the gears made my car feel much stronger- you should feel one helluva improvement from 2.73 to 3.73!

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-Tom P (Hot rodded 1986 Firebird 2.8l) from http://www.f-body.net/mailbag/3rd/3rd_mailbag.html message boards
---Think your car could be pic of the week? Visit http://www.f-body.net for details!

[This message has been edited by TomP (edited April 23, 2001).]
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Apr 25, 2001 | 10:06 AM
  #4  
You will definetly feel a huge improvement in acceleration. The hardest part with the swap will be the speedo gear replacement. Its just a pain to get the driven gear off the output shaft on the trans. Remember to replace the flexible hose from the body to the axle.

I did this same swap in my 89 305 TPI. Say good bye to fuel economy and hello to fun though!

I found that i get bad vibration above 80 MPH. Let me know if you have the same problem.


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  • 89 Formula 305 WS6
    SFC's
    LCA's
    Spohn Panhard Bar
    Air Foil
    Flowmaster Cat Back
    Tranny Cooler
    A/F Ratio Meter (not a mod but it sure spurs interest)
    Trans Temp Gauge
    Most "Free" Mods
    3:73, Zexel Torsion Posi
  • 90 Eagle Talon 2.0
    (Winter Beater)
    Mods? Um, no
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