Setting up pinion angle

Discussion in 'Transmission & Driveline Topics' started by CamaroMan79, Apr 12, 2018.

  1. CamaroMan79

    CamaroMan79 Veteran Member Lifetime Gold Member

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    0EBD3351-2A45-4E73-AFBE-B615FD0E2D70.jpeg

    Let me start by saying that this is not on my Camaro. It’s on my lowered 1984 Chevy C10 2wd pickup. I’m a member of a C10 forum but can’t get an answer over there. Seems like it’s just a bunch of punk kids on that forum that really don’t care about helping anyone. I plan on ditching that group.

    I am trying to figure out where my pinion angle needs to be. This is a leaf spring truck but I am running Cal-Tracs so I’m not sure how much those will factor into to determine the best angle. I cannot raise my transmission angle any higher than it is because it will hit the transmission tunnel (Th400). Both my transmission and my pinion are setting at 4 degrees down (86*). I know the hypothetical lines are suppose to be parallel that run through the engine and rear but than that would mean that I would have to have my pinion angle at 4* up (94*) for a total of 8* up correct? I didn’t think the pinion was suppose to be pointed upward, so that’s where I’m getting confused. Someone please set me straight lol.


    As you can tell from my drawing, I’m quite the artist
     
    Last edited: Apr 13, 2018
  2. CamaroMan79

    CamaroMan79 Veteran Member Lifetime Gold Member

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    I did. Still doesn’t really tell me what I need to know.

    From everything I’ve gathered on line, since my transmission is pointed down 4* from 90*(86*), then I would want my pinion to be pointed up 4* from 90*(94*) give or take a degree. So in essence I need to raise the rear pinion 7-8* correct?

    Am I right in that assumption?

    Also I forgot to add that my truck has an axle flip kit in the rear which gives it a 6” drop
     
    Last edited: Apr 12, 2018
  3. CamaroMan79

    CamaroMan79 Veteran Member Lifetime Gold Member

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    7F5E5F33-1F17-4F71-AE0B-DF9A42D742DE.jpeg 05A6BF43-C874-4486-B142-1F74040847B3.jpeg Always thought the hypothetical line through the engine and rearend were suppose to be parallel. But your picture is showing them insert at an angle.
     
  4. John Wright

    John Wright Veteran Member Lifetime Gold Member

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  5. CamaroMan79

    CamaroMan79 Veteran Member Lifetime Gold Member

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    I used the app. And my setup is way off.

    I’m going to buy some shims (6* and 8*) and see where I stand after that.
     
  6. CamaroMan79

    CamaroMan79 Veteran Member Lifetime Gold Member

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    Ok, I got a set of 6* shims installed. Right now my pinion is sitting at 88* tilted up. (My angle finder only goes to 90* then it starts counting back down to 0). The pinion is down 2* from being parallel with the trans. As I understand it, the centerlines need to be parallel when under load. Should I leave the pinion as it is? I’m not sure how much the pinion will rise underload. I have Cal-Tracs so I doubt the pinion will wrap up much. I can’t do a road test till I get my Hydraboost unit. I just want to get the angle close as I can for time being.
     
  7. Jeep43

    Jeep43 Veteran Member

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    Where are you measuring??

    If your tailshaft is facing 4* down and the pinion is 4 degrees down, I'd throw a 6* shim in it to rotate the pinion to 2* up so under power you are equal.

    Another question is could you raise the rear of the tranny to reduce the down angle?
     
  8. 71RS6SPD

    71RS6SPD Veteran Member

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    you are close. i have heard from calvert a 2-4 pinion degree rise for normal hp. more with higher hp although i believe this is at launch not during medium accell or cruise. street car and track car setup is very different. i just set mine up too - street car with caltracs and gw shackles. i am 4 down up front - my t56 is up to the floor. the car is sitting high so the ds is down 1.4. i added 5 degree of shims to bring the pinion up to 3 degrees. i will test from here. i used shims above and reversed below the springs to keep the spring pack level thickness.

    the tremec phone app likes it.

    if you car is lowered and the ds is uphill to the pinion - you must check the 'working angles' of the ujoints - 3 degree max. less is better. the ujoint working angles on my 71 are about 0.4 degrees or less. i have had vibes for the first 1500 miles since rebirth.. when the rain stops.. i will see if they are gone.
     
    Last edited: Apr 25, 2018
  9. CamaroMan79

    CamaroMan79 Veteran Member Lifetime Gold Member

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    I’m measuring on the flat spot of the pinion yoke where the ujoint saddles bo,t to and then on the fla surface of the trans where the rear output shaft seal goes.
     
  10. CamaroMan79

    CamaroMan79 Veteran Member Lifetime Gold Member

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    Yeah, I’ve been reading about driveshaft angle as well. I think that’s where a lot of my confusion is coming into play. I know with a 4* shim my driveshaft angle was 1* where the pinion meets the ds and it was 1.10* where the ds meets the trans output shaft. My understanding is that I want those 2 numbers as close to each other as possible to help cancel out vibrations.
     

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