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Technical Stock leaf springs in 49-54 Chevy drag car

Discussion in 'The Hokey Ass Message Board' started by deto, Dec 27, 2014.

  1. deto
    Joined: Jun 26, 2010
    Posts: 2,620

    deto
    Member

    Had anybody out there run a hot 49-54 Chevy with the stock rear leafs?

    If I were going for an early 60's look would traction bars be appropriate?

    I am building my car as if it was built just shy of a committed track car. I would think that ladder bars would look more at home with a straight axle rather than the stock IFS.

    If the stock leaf springs cant hang in an 11 second car, then what would you guys recommend?
     
  2. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,264

    gimpyshotrods
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    Brand-new, stock type leaves might do it, along with housing floaters and ladder bars.

    For pure function, Cal-Tracs would be the ticket. Not sure exactly when those came on the scene.
     
  3. deto
    Joined: Jun 26, 2010
    Posts: 2,620

    deto
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    What are housing floaters?
     
  4. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,264

    gimpyshotrods
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    They replace the leaf spring perches, and u-bolts with a coupling system that allows the axle to swing on the arc of the ladder bars, without binding. I will post a picture in a minute.
     

  5. gimpyshotrods
    Joined: May 20, 2009
    Posts: 23,264

    gimpyshotrods
    ALLIANCE MEMBER

    upload_2014-12-26_23-38-45.png
    [​IMG]
    [​IMG]
    [​IMG]
    There are a couple of different takes on the design, but they all do the same thing, essentially. My favorite is the gold set.
     
  6. codeblu
    Joined: May 11, 2006
    Posts: 606

    codeblu
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    I believe Cal-Tracs came out around 68, a guy running one of the original factory S/S 68 Mustangs designed and manufactured them. If that is incorrect someone please straighten me out.
     
  7. Chev38
    Joined: Nov 3, 2007
    Posts: 39

    Chev38
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    I believe the Cal-Tracs devices are an improved version of a product called Traction Masters that dates back to the early to mid 1950's. Shelby Mustangs used them and live axle Corvettes up to 1962 had a similar device mounted above the leaf spring. It kept the leaf spring from wrapping on both acceleration and braking to minimize wheel hop. To my knowledge Traction Masters was still in business in Los Angeles a couple of years ago. A bar tied at center of leaf spring to frame just ahead of front spring bushing. They worked great, or Shelby wouldn't have used them.
     
  8. my son has a '54 Chevy and he bent up his rear springs, so we built some "Cal-Tracks" now all is fine.
     
  9. High5
    Joined: Jul 2, 2012
    Posts: 185

    High5
    Member

    Traction bars for an early 60's build would be appropriate. Stock springs should be fine. But you will need some form of traction device for the track. Ladder bars for the street came along later in the decade. Cannot think of a car in the early 60's running them. The photo below is the traction bars on my '54 Chevy. No floater system. Disregard the height of the car. Traction bars were used on stock height and lowered cars also.

    Traction bar stainless.jpg
     
  10. squirrel
    Joined: Sep 23, 2004
    Posts: 55,935

    squirrel
    Member

    I made a pair of "cal tracs" that look like "traction masters", and they work great. Car runs low tens. There are a few more pics in my build thread, I'll have to see if I can find them... I'm using stock springs, they were monoleafs on the early Chevy II.

    [​IMG]

    [​IMG]

    [​IMG]
     
  11. deto
    Joined: Jun 26, 2010
    Posts: 2,620

    deto
    Member

    How does the rear end not bind with that set up?
     
  12. deto
    Joined: Jun 26, 2010
    Posts: 2,620

    deto
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    I will look this up
     
  13. squirrel
    Joined: Sep 23, 2004
    Posts: 55,935

    squirrel
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    the mounting of the rear end of the bar might explain that...it's not a ladder bar, it's a traction bar that pivots at the rear mounting point. Sorry for not including this picture earlier. (yes the shock mount was broken, it's fixed now)


    [​IMG]
     
  14. deto
    Joined: Jun 26, 2010
    Posts: 2,620

    deto
    Member

    OK. So what's the geometry related to it?

    How much lower does the traction bar pivot need to be in relation to the leaf spring eyelet?

    And what distance does the rear pivot need to be from the axle centerline?
     
  15. squirrel
    Joined: Sep 23, 2004
    Posts: 55,935

    squirrel
    Member

    Yes....

    Based on the Cal Tracs, there is some variation, and they generally have a couple different holes to try, so you can adjust as needed to make it work with your particular car. I just guessed, and it worked fine with the initial setup.

    I think I used 4" from the front spring eye down to the front rod end, and also 4" from the spring eye to the bolt that goes over the spring. And about 4" down from the spring plate to the rear rod end.
     
  16. joel
    Joined: Oct 10, 2009
    Posts: 2,467

    joel
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    The lower bar is very close to the same length as the distance from the front spring eye to the centerbolt.
    I say close because you adjust the length of the round bar to control / limit the spring wrap up.
    Nice pic Jim, I've been planning on building something similar for my 40.
    To the OP, I go-fered for my neighbor, who built a 53 Chev for B/G. He used the stock springs.tri 5 rear and made clamps for the front of the spring to limit the springs movement. I think he had some M&H 8 " slicks on the back. This was 61/62.
     
  17. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    56sedandelivery
    Member Emeritus

    The stock rear springs are very narrow; they did't have to be very heavy duty with the torque tube driveline. Things change a little when you swap to an open driveline. We built my nephews 51 Bus Coupe, that I gave him, with left over parts from my Tri-Five cars. Slapper type traction bars where the snubber almost contacts the front spring eye when static. Used the Tri-Five shock plate mounts and a coil wrapped, overload style rear shock. The shocks really help with body roll due to the narrow leaf springs. It works great! .030 over mild 350, one of my built Powerglides with a 2500 stall converter (could really use more stall), and a 4.88:1 geared Positraction in a 56 housing. The driveshaft came from a Tempest/GTO Pontiac, and is an elastomer type, but you still feel every shift, and when the slapper bars make contact. It is a street car, so at some point a TH350 is going in; Glides are too boring on the street. I am Butch/56sedandelivery.
     
  18. deto
    Joined: Jun 26, 2010
    Posts: 2,620

    deto
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    So you did use stock leaf springs?
     
  19. I am using the stock rear springs in my dodge gasser they are even narrower than the chevy ones I run a set of original traction masters . They were still in bis. a few years ago I ordered some new bushings for mine. The car has over 500 hp I run 10.5 slicks and the car gets out of the hole real good, 6+ years and the spring are fine.
     
  20. deto
    Joined: Jun 26, 2010
    Posts: 2,620

    deto
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    That's great info
     
  21. seb fontana
    Joined: Sep 1, 2005
    Posts: 8,442

    seb fontana
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    from ct

    Just a note..It would be good to reenforce the the spring pad with a strap that goes from end of pad to end of pad over axle housing welded to pad ends and axle housing..That pad(s) transfer all the torque to your traction bars and I have seen them squash letting the axle rotate; if the U bolts don't break [bad] then the housing has already rotated enough to mess up your rear u-joint/drive shaft [bad enough]..
     
  22. squirrel
    Joined: Sep 23, 2004
    Posts: 55,935

    squirrel
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    I just had the rearend out of mine, so I could fix some other issues, and there is no evidence that it's squashing the pads, or anything else strange there. I guess it depends on how thick the metal is, how tight the U bolts get, how much twist it gets on the housing when you launch, etc.

    Slapper bars are a reasonable way to go. And Traction Master is still around, you might see what they have.

    http://www.tractionmaster.com/

    .
     
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  23. blue 49
    Joined: Dec 24, 2006
    Posts: 1,820

    blue 49
    Member
    from Iowa

    It doesn't show very well, but here is my variation of Cal-Tracs. I have a short urethane snubber to contact the spring. I hadn't drilled all the bolt holes for the snubber mount yet when this picture was taken.

    Blue 002.JPG
     
  24. deto
    Joined: Jun 26, 2010
    Posts: 2,620

    deto
    Member

    So the snubber contacts the top of the leaf spring just aft of the leaf spring eyelet?
     
  25. deto
    Joined: Jun 26, 2010
    Posts: 2,620

    deto
    Member

    I noticed that the traction master set up locates the front pivot for the bar on front of the front leaf spring pivot.

    Will this cause bind?
     
  26. blue 49
    Joined: Dec 24, 2006
    Posts: 1,820

    blue 49
    Member
    from Iowa

    Yes, right above the end of the 2nd leaf.

    Blue
     
  27. seb fontana
    Joined: Sep 1, 2005
    Posts: 8,442

    seb fontana
    Member
    from ct

    Not enough to worry about as the spring doesn't have a definite arc when it moves anyways and actual movement is not that much..The traction masters are longer to reach the bottom of the frame forward of the front spring eye as directly below the eye the frame or bracket is usually open bottom, need area to weld mount to...
     
  28. deto
    Joined: Jun 26, 2010
    Posts: 2,620

    deto
    Member

    Good to know
     
  29. 56sedandelivery
    Joined: Nov 21, 2006
    Posts: 6,695

    56sedandelivery
    Member Emeritus

    Yes, stock rear springs with the overload type of coil wrapped shocks, Tri-Five shock mount plates and U-Bolts, shocks also mounted to stock floor location, snubber slapper traction bars made with stock Tri-Five spring mount plates. You can stand beside the car and push it back and forth, but it moves very little because of the overload shocks (also meant for a Tri-Five). Big rear tire on 7 inch wide Cragar S/S wheels; skinnies on the blocked up stock front end (even kept the worn out front shocks for front end lift at launch). I am Butch/56sedandelivery.
     
  30. daliant
    Joined: Nov 25, 2009
    Posts: 692

    daliant
    Member

    I have a homemade set of traction masters w/stock leaves on my 46 Plymouth, it's not an 11 second drag car though. The original skinny leaf springs couldn't handle the stock 318 by themselves, with the bars I can dump the clutch as hard as I want. 100_1369.jpg 100_1373.jpg
     
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