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Technical Model A rear spring

Discussion in 'Traditional Hot Rods' started by Avgas, Nov 6, 2025 at 2:41 PM.

  1. Avgas
    Joined: Dec 31, 2007
    Posts: 287

    Avgas
    Member

    Gentleman, has anyone on here used a narrow model A rear spring in a 32 frame with 36 radius rods? I have done this on 2 in previous times with good results but my spring guy has gone & so has my data & templates! Any info or guidance is well received, Wayne
     
  2. Tim
    Joined: Mar 2, 2001
    Posts: 20,083

    Tim
    Member
    from KCMO

    Which rear axle and which rear cross member?
     
  3. Avgas
    Joined: Dec 31, 2007
    Posts: 287

    Avgas
    Member

    Tim, model A rear crossmember & Halibrand rear
     
    Tim likes this.
  4. krylon32
    Joined: Jan 29, 2006
    Posts: 10,773

    krylon32
    ALLIANCE MEMBER
    from Nebraska

    Get me your e-mail for pictures.
     
  5. Avgas
    Joined: Dec 31, 2007
    Posts: 287

    Avgas
    Member

  6. This is easy enough to figure out, the spring you will need is dependent on the space between the perch eyes on the ends of the axle tubes. Get that measurement and the vendor selling the springs should be able to tell you which one you need. If you're using, say, a Posies spring all of that information is in their catalog. I'll admit, I am not quite sure this is what you were asking for but I think I am correct.
     
  7. Tim
    Joined: Mar 2, 2001
    Posts: 20,083

    Tim
    Member
    from KCMO

    ^ yeah perch distance is going to be the biggest factor.
     
    winduptoy likes this.
  8. Avgas
    Joined: Dec 31, 2007
    Posts: 287

    Avgas
    Member

    No, it’s not easy to figure out at all, especially if you have not done this! I’m using early ford parts, no vendors here! I did contact Posies but the narrow spring is too wide for my application. Kris atPosies was super helpful but they could not offer up a spring solution! Their narrowest spring is set for 44.5” perch centres, my perch centres are 36” & I require a “standard” ride height, you now have all of the relevant dimensions & scope for this spring, I look forward to your spring detail. Suggestions as I’m thinking this is far from easy for us hot rod guys!
     
  9. Avgas
    Joined: Dec 31, 2007
    Posts: 287

    Avgas
    Member

    Tim, 36” perch centres on this 32 frame, 36 Ford 48” centra’s , model A 48” centres
     
  10. Well good luck I guess.
     
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  11. Tim
    Joined: Mar 2, 2001
    Posts: 20,083

    Tim
    Member
    from KCMO

    So your needing a model A style spring that will fit a 36” spring perch center distance. If stock is 48 I’m not sure you’re going to find anything off the shelf as that’s incredibly narrow.

    when I was looking for a narrowed stock spring about a year ago I couldn’t find a spring shop within three hours in Kansas City that would still turn their furnace on for work. Not sure how they function? I guess just retail now.

    if I were in this position my first step would be find a spring shop that can even do the work. That failing I would find a black smith that could re roll the eyes on a stock spring to match your new spring center distance.

    then take a cut off wheel and trim your non main leafs to suit.
     
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  12. krylon32
    Joined: Jan 29, 2006
    Posts: 10,773

    krylon32
    ALLIANCE MEMBER
    from Nebraska

    I checked Posie and apparently they're no longer making the 44.5 inch reversed eye 2 inch lower Model A spring? I just built a deuce roadster with one and have used several over the years. Roadster Supply used to offer them but must be having a supply problem? I directed Ray to a spring company in Omaha but they must not be able to produce? Also check Millworks, they show a narrow A rear spring.
     
    Last edited: Nov 9, 2025 at 8:36 AM
    winduptoy likes this.
  13. winduptoy
    Joined: Feb 19, 2013
    Posts: 4,124

    winduptoy
    ALLIANCE MEMBER

    We have a (serious hobbyist) blacksmith group that usually will take on a challenge and seems to have a pretty deep, combined, wealth of knowledge....maybe some such group exists for you in your area that could help with modification of the spring material you already have
    just a thought and maybe an other dead end....good luck
     
  14. alchemy
    Joined: Sep 27, 2002
    Posts: 22,618

    alchemy
    Member

    St. Louis Spring made a bespoke front spring for my brother. Call and ask if they can do Model A rear style.
     
  15. krylon32
    Joined: Jan 29, 2006
    Posts: 10,773

    krylon32
    ALLIANCE MEMBER
    from Nebraska

    Just checked Millworks and they show a narrowed reversed eye Model A rear spring on their Black Friday monthly special.
     
  16. Tim
    Joined: Mar 2, 2001
    Posts: 20,083

    Tim
    Member
    from KCMO

    @krylon32 if he’s wanting 36” perch centers he’s going to need like a 33” spring. I don’t think I’ve ever seen a model A shaped rear spring that narrow before.

    I’m****uming the car is both very low and channeled and he’s trying to keep the radius rods inside the spring hangers. I can’t think of another reason to have them so close together
     
  17. krylon32
    Joined: Jan 29, 2006
    Posts: 10,773

    krylon32
    ALLIANCE MEMBER
    from Nebraska

    Your right, the Millworks narrow spring is 39.5 wide using a 45 inch perch center on the rear end. I've done all my buggy spring customer 32 chassis over the years both 40 style and Model A with the 44;5 inch spring perch centers with the Posie narrow spring and it worked fine. The 36 bones do present a clearance problem in a deuce. I think a 33 inch rear spring would ride like a rock.
     
    Tim likes this.
  18. Tim
    Joined: Mar 2, 2001
    Posts: 20,083

    Tim
    Member
    from KCMO

    Yeah I’ve seen the 36 bones mounted way further out, I have to****ume they are narrow to try to fit inside frame rails.
     

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