Rear end Gear swap questions

Discussion in 'Transmission & Driveline Topics' started by Kixxis, Apr 11, 2019.

  1. Kixxis

    Kixxis New Member

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    Hello everybody!

    I have a '79 RS that is mostly bone stock. From what I believe the rear end is original with a limited slip (I believe, I didn't look it up) 3.73.
    Now I'm looking to lower my rpms and gain highway speed drivability. I have an '83 K10 with a (again haven't looked at it but have spun and measured it) measured 2.71ish. The big question is will that gear pack fit in my '79 with minimal issues? I have the muncie 4 speed and 60 mph at the moment is about 3100 rpms. Any input is appreciated. Thank you!
     
  2. camaro71/holland

    camaro71/holland Veteran Member

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    3100 equals 3.9 to 4.11 with 1:1 trans end ratio depending on the tire size. Recheck your gear ratio..
     
  3. Kixxis

    Kixxis New Member

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    Okay I guess I will have to tear into it when I get some time. Is a swap possible between the two?
     
  4. tom3

    tom3 Veteran Member

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    Any junk yards around? Pick a part etc? Be a whole lot simpler to do the whole axle swap and keep yours intact, might be worth some serious money too. About any V8 automatic would have a 3:08 or 2:73 gear and lots of posi gears up there in your area I'd think. I'd try that route first.
     
  5. big gear head

    big gear head Veteran Member

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    A gear in the 2.73 range is going to make life hard on your clutch. I would not recommend it at all.

    As for your original question, yes, the K10 gears and differential will fit in the Camaro rear end, but a complete rear end swap from another Camaro or Firebird would be MUCH easier.

    I'm never going to get use to all of the people who have 3.73 gears that want a 3.08 and all of the people who have 3.08 gears that want a 3.73. I guess that is what keeps the gear manufacturers in business.
     
    Dave Nelson likes this.
  6. Gary S

    Gary S Administrator Lifetime Gold Member

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    Before you do anything else, determine what gear ratio you currently have in the car. In 1979, only the Z28 with manual tranny could have a 3.73 rear end. You say you have an RS. The RS couldn't get anything deeper than 3.08, and depending on engine and tranny, it could even be a 2.56 or 2.41.
     
  7. DesmoEd

    DesmoEd Veteran Member

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    I'd also determine what 4 speed you have as 1974 was the last year GM used a Muncie in any car. The later Borg Warner tranny's had a few different gear sets depending on year.
     
  8. Kixxis

    Kixxis New Member

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    -I do have some pick n pulls around here but everyone act like vultures when they show up at the yard, understandably.
    -If the smaller gears would be not so good for the clutch, is there another way of getting better highway drivability besides a different tranny?
    -I will look into the ratio this weekend if I get some time and just spin it and get a quick measure.
    -When I had the clutch replaced they said it was a muncie but it's probably a Saginaw but I will also double check to be sure.

    Thank you all for your replies!
     
  9. 70-camaro

    70-camaro Veteran Member

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    I would go for a 3.42 gear
     
  10. tom3

    tom3 Veteran Member

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    A muncie would have an aluminum case, Saginaw is cast iron, a magnet will tell. The Saginaw might have a real low ratio first gear that would work well with a taller rear gear. Ultimate solution would be a Tremec 5 or 6 speed box.
     

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