Driveline Angles Please Help Me Wrap My Head Around this

Discussion in 'Got gears?' started by guyver002, Oct 14, 2019.

  1. guyver002

    guyver002 Well-Known Member

    I think it may be a case of I have all the info I need but I just dont know what to do with it for some reason! So I was curious how my drive line angles were after having to get my drive shaft shortened. I bought a digital angle finder and set about getting some numbers. I got off the tail shaft of the transmission 2.7 degrees going down, driveshaft is 1.8 degrees down and the pinion yoke is 1.0 degree up. I plug them into the spicer angle finder

    https://spicerparts.com/calculators/driveline-operating-angle-calculator

    ( which I assume is finding U Joint angles)

    and get an operating angle of 0.9 at the transmission and 2.8 at the yoke. Admittedly this is where i think i start to mess up.

    The car is not stock 70 now so I'm looking at the 71 service manual for a skylark coupe because the rear is a 71 but it still has the TH350 for a transmission so I figure these numbers are correct not the GS ones (since I believe GS refers to GS 455 because that's how it is in the 70 manual). It tells me to have 2 3/4 for the front and 1 3/4 for the rear.

    Should I use the book numbers for spec or is there a general rule that works regardless of combo types?

    How would i start to bring these numbers into spec? Trans lowered or raised ? Do coil spring rears even have some amount of adjustment?

    I don't doubt some of you guys that have raced or restored see those numbers and instantly know whats up. I honestly have never done this type of work before and feel I am going in the right direction but I still feel a little fuzzy on the whole thing. I'm curious how an experience person would start to tackle it so I can learn the right way.
     
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  2. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

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  3. BillA

    BillA Well-Known Member

    I installed an app from Tremec on my iPhone that takes a reading from the engine/trans, driveshaft, rear in that order. It then tells you if you're in or out of spec. It also has an angle finder feature if you prefer to do the math yourself. You can adjust the rear if you have adjustable upper control arms, otherwise any adjustment will have to come from shimming the trans mount at the crossmember.
     
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  4. Donuts & Peelouts

    Donuts & Peelouts Life's 2 Short. Live like it.

    Was the app free?
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

  6. Donuts & Peelouts

    Donuts & Peelouts Life's 2 Short. Live like it.

  7. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD"

    Google is your friend Ronnie.:):):)
     
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  8. guyver002

    guyver002 Well-Known Member

    Hey Bill I just wanted to say watch out because although the app is free and in the end it can be just as accurate as what I quoted from larry below (went out and got one myself, pretty awesome tool) you may be getting an inaccurate measurement if there are buttons on the side of your phone or your phone case is compressible or uneven. I noticed that's what happened to me after quite a few measures and re-measures for other reasons and then I started to notice the wide inconsistency.






    thanks larry although its hard to explain just simply stating this and allowing my mind to just reverse engineer how you came to that just did wonders for breaking the information overload and ensuing knot it made. I threw out a lot of what I was taking into account without even realizing it and it finally cleared up!
     

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