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Technical Garage build - drive shaft/trans/axle angles

Discussion in 'The Hokey Ass Message Board' started by gasserx, Mar 27, 2019.

  1. gasserx
    Joined: Jan 10, 2013
    Posts: 84

    gasserx
    Member
    from norway

    Im building a somewhat odd race car in my humble garage, with a Topolino body........ on a superlow budget.
    I found a few old pics of cars that has been my inspiration, and i have ended up building a somewhat square frame. It will be no suspension in the rear, and a traditional I-beam with leafspring setup in front. The rear end is from an old Volvo 240, and the trans is from an BMW :rolleyes:

    Next up is trying to set the angles on the rear end and trans/engine. Just wonder what would be the best way to do it... I assume a straight line on the drive shaft itself is the best solution. But i dont want the engine and trans to sit too low in the frame.
    So, to get the angle i want, i probably need to tilt the engine upwards in front to get it right....
    I can probably also mount the rearend on TOP of the frame (seen it done on a few old Altereds), that would make the engine/trans sit more in angle with the frame. However it might interfer with the cage at some point and make it a pain to remove the axle.
    Or am i way off... :eek:

    Any thoughts?

    fiat.jpg
     
    Last edited: Mar 27, 2019
  2. Phil P
    Joined: Jan 1, 2018
    Posts: 517

    Phil P
    ALLIANCE MEMBER

    Spicer recommends 1 to 3 degrees of u joint angle. Run a string between your transmission and rear end and measure the angles. If it is too much you might get away with tilting the transmission down a little and the rear end up the same. Phil
     
    BJR likes this.
  3. gasserx
    Joined: Jan 10, 2013
    Posts: 84

    gasserx
    Member
    from norway

    Wouldnt it be possible to make a driveshaft without the u-joint ? Both rear end and trans/engine will be rigid mount
     
  4. BJR
    Joined: Mar 11, 2005
    Posts: 10,477

    BJR
    Member

  5. gasserx
    Joined: Jan 10, 2013
    Posts: 84

    gasserx
    Member
    from norway

    Yeah, i know - but do i really need u-joints for a 1/4 mile racer? Why not just a straight line?
    Obviously the u-joints are there to compensate for suspension travel and flexing in rubber mounts, wich is not a factor in my build.
     
  6. If you want to set it up that way,,,
    Then it's got to be perfect.
    Start with a bare block and empty rearend case. They use a long pipe in the main bearings ran straight thru the pinion bearings of the axle. That gets everything in a straight line then weld your engine trans and rear end mounts.
    No UJoints has to be 100% straight and strings levels and angle finders isn't good enough.

    Otherwise, get the crank/output shaft parallel with the pinion and your good. Doesn't matter what angles just shoot for parallel. It's irrelative if the driveshaft runs up or down as long as the crank and pinion are parallel. If the rearend has an offset pinion you could have them on the same plane as well.
     
    gasserx likes this.
  7. gasserx
    Joined: Jan 10, 2013
    Posts: 84

    gasserx
    Member
    from norway

    I think thats the most doable way after all...
    However, then another concern pops up, and thats the driveshaft end that connects to the bmw trans, its not a u joint..
    e39driveshaft.jpg

    But i guess a proper machine shop can use the stock end and weld it to a u-joint
     
  8. tpw35
    Joined: Feb 6, 2007
    Posts: 342

    tpw35
    Member

    Look up southeast gassers on you tube, they have a good tech video about it.
     
    gasserx likes this.

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