Ring and pinion gear questions.

Discussion in 'Transmission & Driveline Topics' started by crazypurgatory, Sep 29, 2008.

  1. crazypurgatory

    crazypurgatory Veteran Member

    When I got my 1971 Camaro I was given a 3 series posi traction Carrier with some 4.10 gears.
    Now I know you are not suppose to mix up the ring and pinion gears but I really want to use the posi unit.
    If I use the ring gear for the 3 series carrier and the stock pinion I will have my stock ratio witch is 2.73.
    If I do this what kind of bad things could happen?
    I want to keep the 2.73 gears but I don't see them made for the 3 series posi traction Carrier.
    I'm not to crazy about using a ring spacer as my car has a 3000-3500 stall converter and the engine has a big cam and I'm going to guess around 300 to 350 HP the engine has aftermarket heads I forget the brand and a big cam so I know its got some power.
    I can do a one wheel wounder burn out around 200feet long.
    So would this work or am I going to destroy my rear gears by doing this?
  2. jdove

    jdove Veteran Member Lifetime Gold Member

    Oct 19, 2002

    Your not supposed to for a reason man, it's not even a possibility from what I've learned.
    A 3 series carrier don't fit a 2 series gear.

    You could blow the whole rear end out IMO (if it fit, which it won't). From what I know you have to step up the gear ratio with a 3 series.

    Why not go to a 3.08 or 3.42 with your 3 series carrier?

    Why do you want to keep the 2.73? Why not do a 2 wheel burn out?

    It's not a hard change to do based on my experience (which is limited).

    Make the change. You'll be glad you did IMO.

    Good luck..
  3. big gear head

    big gear head Veteran Member

    Jul 30, 2001
    Central City, Ky.
    The 8.5 10 bolt uses the 3 series differential for the 2.73 gear. There is no way that you can use the ring gear for the 4.10 gear with the pinion from a 2.73. The teeth will not mesh. Use your 2.73 ring gear with the 3 series posi and it will be fine. Be sure to reset the backlash to about .010 inch.
  4. 70 RS/Z28

    70 RS/Z28 Veteran Member Lifetime Gold Member


    I recently went though a rear end issue on my car. I fortunately have a friend who builds racing chassis and does a lot of rear end work for Strange(Chassis Services, North of Chicago).

    Basically my ring and pinion were smoked along with the bearings etc. It was a shame because the gears were original to the car. I had picked up a set of used dated gears I wanted to put back in. After talking to my friend it became apparent that you dont want to screw around with ring and pinion sets or run anything even remotely questionable. Now I have an original rear to my car (original drivetrain car) so grenading the rear carrier and housing are not an option. We set the used ring and pinion aside and went with a new ring and pinion. Essentially because of the way housings are built once the ring and pinion are used they become married to that housing, it has to do with the fact that the alignment will be slightly different from housing to housing. And even if the used gears do work it is almost certain that you will have a noisy rear. Considering that all the power your engine puts out makes a 90 deg turn through the ring and pinion it makes sense that you need to have it right or you will have big unhappy problems. Get a new ring and pinion set their not that expensive.

    Just My 2 cents

    Last edited: Sep 29, 2008
  5. crazypurgatory

    crazypurgatory Veteran Member

    We talked about this before remember?
    I put the 3 series carrier in with the 2.73 ring gear and it did not fit right I needed to use the adaptor shim.
    I like the 2.73's I want to keep them but I can't seem to find out if I can get them for the 3 series carrier.
    Let me see if I can find some pictures I took of the carriers.
    On the left is the 3 series positraction carrier the right is the open carrier
    that has the 2.73's thats in the car now.
    Last edited: Sep 29, 2008
  6. 74RAT

    74RAT Veteran Member

    Dec 28, 2003
    ft. stockton,tx,usa
    the one that puts the ring gear closer to the housing center is the 3 series carrier.

    think about it here,,,,, the 2.42 gears and 2.56 gears have 16 and 17 teeth on the pinion. those pinion's are bigger in diameter,, therefore the ring gear HAS to be positioned farther to the left when looking in the housing from the rear. see??

    the 2.73 is 41 teeth ring gear and 15 teeth pinion gear. smaller pinion diameter has to have the 3 series carrier to move the ring gear closer to the center of the housing.

    the carrier on the right in your pictures appears that it is the 3 series carrier. the other one appears to be a 2 series carrier. the one on the left would need the spacer behind the ring gear to move it over to work with your 2.73 gears. jmho.
  7. big gear head

    big gear head Veteran Member

    Jul 30, 2001
    Central City, Ky.
    You have it mixed up. The 2 series is on the left and the 3 series is on the right. The 3 series posi will have the casting number 410408. The one that you have is a 410409, which is a 2 series. This is why you are having problems with your 2.73. The 2.73 fits on the 3 series.
  8. crazypurgatory

    crazypurgatory Veteran Member

    Ok so can I get 2.73's for the 2 series carrier?
    And if the 2.73's have a 41 tooth ring gear and the 4.11's have a 41 tooth ring gear why would the pinion gear not mesh if I use the ring gear off the 4.11 gear set for the 2 series carrier.
    I would like to avoid buying a new posi carrier because they are not cheap and it seams that the stock one is rebuild able from what I have read.
    And I like the 2.73 gears.
    So what can I do?:confused:
  9. big gear head

    big gear head Veteran Member

    Jul 30, 2001
    Central City, Ky.
    No, you can't get a 2.73 for the 2 series differential. All 2.73 gears fit the 3 series. You CAN NOT use the ring gear from one set with the pinion from another set. Even if both gear sets were 2.73s, you can NOT mix gears. They are made in sets and are mated at the factory. They can NOT be mixed up. As for the 4.10 and 2.73, if you look at the helix angle of the gears you will notice that the curve of the teeth on the 4.10 does not match the curve of the teeth on the 2.73. Just get the right differential or use a 2.56 gear.

Share This Page