New Ring and Pinion Advice for 70 Camaro GM 10 bolt

Discussion in 'Transmission & Driveline Topics' started by Robert M Mrozek, Aug 29, 2020.

  1. Robert M Mrozek

    Robert M Mrozek Veteran Member

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    I have a 70 Camaro and I am looking to lower the ratio so I can drive it at 70 mph at a reasonable rpm. But also looking to balance that with maintaining the monster off-the-line grunt it currently has. Reading the forums it looks like my options are 3.42, 3.55 or 3.73. Leaning towards 3.55. I take the car mostly to shows and a few spirited runs but no drag racing.

    Vehicle Details: 1970 Camaro 350SBC. TH350 Transmission. 3500 Stall. 10 bolt rear axle. Auburn carrier with Richmond racing gear set with 4.56 ratio. Bought it this way and when I bought it the ad said posi-traction but mechanic said it was limited slip. Rear tires are P275/40R18.

    I live in Macomb County, a suburb of Detroit, and was planning to take it to a local shop to make the change. Looking for some general advice on who and what to consider.

    1. What brand of ring and pinion to chose? How important are brand and specs? Not looking for cheap but I only put around 500 miles a year on the car.

    2. Should I buy the ring and pinion and have the shop install or just have them change it?

    3. Any members here local to my area and would recommend a good shop? There is a small shop called the “Ring and Pinion Shop” in Clinton Township that I am considering. All they primarily do is ring and pinion. Last year they estimated about $800 for parts and labor.

    4. Should I replace the diff cover while I am at it. Attached is a picture of mine. I noticed some covers have adjustment screws to preload main bearing cap and add fill and drain tubes. Not sure how important that is considering the low mileage I put on. Any recommendations here?

    Thanks in advance! - Rob
    rear axle picture.jpg
     
  2. Jodi

    Jodi Veteran Member

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    With your current set up RPM at 70 mph with be around 4000.
    If you change the R&P ratio to 3.55.1 you would reduce that to around 3100 rpm.

    Limited Slip is the actual terminology... Positraction is more of a brand name.
    For example... ViseGrip- Brand name. Actual- Locking Pliers

    Any reputable shop such as Strange, Moser, Mark Williams, Currie etc.. (they are all good IMO).
    A lot of shop nowadays don't really care if you provide them the parts (pay labor only) or if they order it for you (parts and labor.

    For extra security... I would say go ahead with swapping diff cover with a cap girdle (plus it looks bad [email protected]$). Lets everyone know you have something special in there :)
     
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  3. big gear head

    big gear head Veteran Member

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    If your car is a '70 then someone has swapped the whole rear end in your car. The rear end that you have is a 8.5 10 bolt, which didn't go into production until '71. Your car would have had the 8.2 10 bolt.

    The 3.42 is the common gear ratio for the 8.5 10 bolt. This is a very popular ratio for may people who drive their cars without overdrive. Motive Gear makes a cheap gear and a more expensive gear. The cheap one will probably make noise. AAM makes the better gear, but it's priced higher and requires a little different set up than others. Richmond makes a gear that is supposed to be quiet, but cost more than their regular gear.

    Limited slip is the correct name for differentials like yours. "Posi" is Eaton's trade mark name for their clutch type limited slip differential. I do not like the Auburn differential, but if you want to keep it then that's fine. Just don't abuse it or it won't last long and you will need a complete rear end rebuild to clean all of the powdered metal out of the rear end. If yours is spinning one tire then it's already worn out. The Auburn can not be rebuilt.
     
  4. Robert M Mrozek

    Robert M Mrozek Veteran Member

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    Thanks Jodi and Big Head Gear.....very helpful advice. Still looking for a shop to do the swap for me. First one I went to just wanted to replace the R&P with an OEM and "not the aftermarket" stuff. Didn't give me a warm and fuzzy so need to find another shop. Also was waved down by someone today saying that my right rear wheel was wobbling. Gotta figure out what is wrong with that. Going to post a question about it in the troubleshooting forum. Thanks again! - Rob
     
  5. big gear head

    big gear head Veteran Member

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    If you want quiet gears and are willing to pay more for them then the OEM gears are more likely to be quiet. AAM makes the OEM gears, but they are 2 cut gears and must be set up different than the 5 cut gears. If you are not worried about them being quiet then any after market gears will work. US Gear and Richmond are making gears that are supposed to be quieter than other aftermarket, but they cost about $100 more and are also 2 cut gears.
     
  6. Knuckle Dragger

    Knuckle Dragger Mayor of Simpleton Staff Member Lifetime Gold Member

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    Best price on AMM gears I found https://www.ronsmachiningservice.net/ I won't use anything other than AMM in anything I own again.

    Your wobble is the axle, I responded in that thread too. Might as well do it all at once.
     
  7. Camaromurph

    Camaromurph Veteran Member

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    Ron’s stands behind their products.
     
  8. Fbird

    Fbird Veteran Member Lifetime Gold Member

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    i keep HEARING about these "quite" gears!!! I have personally set up around 40 new gears.( GM 8.5, ford 8.8, 9",9.75 even got a couple dana 60 (PITA)) and a dozen "used" gears. All makers too, Richmond, Youkon, US gear, ZOOM, FoMoCo,.....

    I personally have only HEARD a whinning gear set 3 times!!!!! 3 out of 50 ...(2 used sets and 1 ZOOM)
     
  9. badazz81z28

    badazz81z28 Veteran Member

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    I’m waiting for a review of the 9” stealth gears from USgear
     
  10. muscl car

    muscl car Veteran Member Lifetime Gold Member

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    My Ford 9" street set up 3rd member has some high dollar US gears !!!!!
     

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