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yet another driveline angle question

Discussion in 'The Hokey Ass Message Board' started by drptop70ss, Jun 25, 2012.

  1. drptop70ss
    Joined: May 31, 2010
    Posts: 1,166

    drptop70ss
    Member
    from NY

    I know this has been hashed to death, I have ready many posts on the subject as well as online info, but I want to clarify something because I dont want to have issues later. This is for my 47 cadillac which will be a street car with leaf springs, no racing, so I do not think I have to worry about pinion climb issues.<p>
    I normally set my frame level, set the trans at 3 degrees down, pinion at 3 degrees up, build my engine / trans mounts and am done. Because of the accessory drive system on the engine I am using I cannot get 3 degrees, everything fits nice with the engine 5 degrees down. I do not know yet if I have enough room to shim up the trans to go to 3 degrees but I do not think I do because of clearance in the X frame. So I plan on putting the pinion gear 5 degrees up to match the engine.<p>
    I have read that ujoints want 3 1/2 degrees max angle, question is that the angle of the engine tilt / pinion angle or is it the working angle? Is the 5 degrees NG or is really ok if my working angle is 0 degrees? (5 degree engine angle +2 degree driveshaft angle = 7 degrees, minus the 5 degree pinion angle +2 degree driveshaft angle = 7 degrees, subtracting them gets 0 degrees).
    I have seen some pretty steep engine angles in drag cars but what about for the street? 5 degrees is not all that steep but not the 3 degrees I normally can get.
     
  2. Sting Ray
    Joined: Mar 24, 2012
    Posts: 969

    Sting Ray
    Member

  3. pitman
    Joined: May 14, 2006
    Posts: 5,027

    pitman

    One issue is to have the phases correct so that the angular velocities are constant, w/rpm leaving the tailshaft and arriving at the pinion. If the angles cancel and are at least 3*, then the lube 'motion' will be sufficient to serve the needle bearings. Another degree or two? I'd like to hear some war stories on this. (I suspect post #4 refers to post#2)
     
  4. drptop70ss
    Joined: May 31, 2010
    Posts: 1,166

    drptop70ss
    Member
    from NY

    Thanks, I will make sure to have the joints in phase when I make the driveshaft.

    The car craft info is good but it is for spring wrap in a drag car, other than normal suspension cycles and an occasional burnout this car should not see that kind of spring wrap.
     
    Last edited: Jun 25, 2012

  5. V8 Bob
    Joined: Feb 6, 2007
    Posts: 2,720

    V8 Bob
    ALLIANCE MEMBER

    You bring up a very important point, and one very often ignored or mis-understood. The maximum working angle for a single cardan U-joint is 3 degrees, which equates to about 5500 maximum drive shaft RPM. So, with the vehicle at ride height, the engine/tranny angle should be within 1 degree of the pinion angle, along with working angles under 3 degrees. The actual engine angle really depends on the intake (carb angle), vehicle rake, personal preference, etc. :)
     
  6. drptop70ss
    Joined: May 31, 2010
    Posts: 1,166

    drptop70ss
    Member
    from NY

    Excellent, that was the info I needed, thank you. 5 degrees is what I will have to use.
     
  7. 58_Ford
    Joined: Feb 23, 2010
    Posts: 118

    58_Ford
    Member
    from Phoenix

    So if the trans is 5 degrees down, the pinion should be 5 degrees up?
     
  8. drptop70ss
    Joined: May 31, 2010
    Posts: 1,166

    drptop70ss
    Member
    from NY

    Yes, with the suspension at ride height. Leaf springs get longer as the suspension get compressed, and my pinion angle goes from 3 degrees up with the rear of the car with no load (think of the car on a lift and the rear end hanging free with the wheels off the ground) and then to 5 degrees up when compressed to ride height. I used ratchet straps to compress the rear suspension to drive height during initial mock up, set the pinion to 5 degrees up with the rear centered, and tacked the spring pads to the housing.

    [​IMG]

    This car is not a drag car so I set everything up as it would be during normal driving conditions.
     
    Last edited: Aug 4, 2012
  9. Key is to install engine with carb mounting surface LEVEL in both directions then measure the degree of the trans output shaft and match it with the pinion angle. You need the carb level so floats work properly. you can also check the angle at the pad where the starter mounts.
     
  10. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,899

    gimpyshotrods
    ALLIANCE MEMBER

    Yes, and 5º is totally fine. If you are using very soft leaf springs, you can put the pinion at 4º. In most cases, this is not necessary.
     
  11. gimpyshotrods
    Joined: May 20, 2009
    Posts: 17,899

    gimpyshotrods
    ALLIANCE MEMBER

    He's showing a picture of what appears to be a GM poly tank, most often used to fuel an LT or LS engine. This one looks like a Camaro unit, so no carburetor, more likely EFI.

    +/- 1º-2º on a carburetor base is not going to make or break a setup. There are few truly level roads.
     
    Last edited: Aug 5, 2012
  12. drptop70ss
    Joined: May 31, 2010
    Posts: 1,166

    drptop70ss
    Member
    from NY

    Good eye on the FI tank, it is from a 95 caprice wagon. Has a side fill that will work great with the 47 cad original gas tank filler tube and fits great after losing the spare tire well in the trunk. Engine will be fuel injected LT1 with a 4L60E so no worries about carb level.

    [​IMG]
     
    Last edited: Aug 6, 2012
  13. edthomas
    Joined: Jun 14, 2012
    Posts: 7

    edthomas
    Member

    The 3 1/2 degrees max U-joint angle mentioned is the difference in degrees from the driveshaft to tailshaft or pinion centerline.
     
  14. +,- 1,2 degrees will work at carb base but shooting for zero is what your after. seeing this is F.I. it really doesn't matter since fuel system is closed loop not venturi based. centering engine/trans isn't critical either, manufactures have been offsetting power plants to clear steering boxes for years.
     

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