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Technical Rear shock placement - model A

Discussion in 'Traditional Hot Rods' started by cederholm, Jan 18, 2024.

  1. cederholm
    Joined: May 6, 2006
    Posts: 1,748

    cederholm
    Member

    I'm in the planning stages for rear shock placement on my 29 full fendered high-boy project. Please share photos of what you've done.

    Thanks!
     
  2. '29 Gizmo
    Joined: Nov 6, 2022
    Posts: 960

    '29 Gizmo
    Member
    from UK

    On a stock model a axle and original top mount points on the frame...... 20221125_134935.jpg 20221213_092143.jpg 20221222_113628.jpg
     
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  3. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 4,675

    ekimneirbo

    Get some tubing and weld some nuts or plates on each end so you can thread an Eye Bolt in each end. Then use it to moch up the location and the length you need. Don't buy shocks and try to make them fit after you get them, use the adjustable tubes and buy the actual shocks later .
     
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  4. GordonC
    Joined: Mar 6, 2006
    Posts: 3,311

    GordonC
    ALLIANCE MEMBER

    Don't know if this will help or not but here is how I did mine. Just used plate and shock studs and welded them in place on the top of the rails. Sorry I don't have any better pictures.

    IMG_20141103_211256_196.jpg
     
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  5. cederholm
    Joined: May 6, 2006
    Posts: 1,748

    cederholm
    Member

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  6. cederholm
    Joined: May 6, 2006
    Posts: 1,748

    cederholm
    Member

    Smart! ...very smart.
     
  7. ekimneirbo
    Joined: Apr 29, 2017
    Posts: 4,675

    ekimneirbo

    I like the way you think:)..................but actually I got the idea from a magazine years ago. It worked well for me so I'm just passing it along. Depending on your setup, I usually put more than one mounting point so I can adjust the height by tilting the shock more or less when the car is done. Its not good to get an expensive (coil over) shock and find out later that its too long or too short.
     
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  9. '29 Gizmo
    Joined: Nov 6, 2022
    Posts: 960

    '29 Gizmo
    Member
    from UK

    Fitted last year... about 1100 miles so far
     
  10. Good question. I would be concerned about flex in the lower bracket over time. A gusset wouldn't go astray. Clean design though.
     
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  11. '29 Gizmo
    Joined: Nov 6, 2022
    Posts: 960

    '29 Gizmo
    Member
    from UK

    You can do your own design but its 5mm plate and is perfectly adequate for the application.
     
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  12. winduptoy
    Joined: Feb 19, 2013
    Posts: 3,626

    winduptoy
    ALLIANCE MEMBER

    Yes, but it is what you are attaching it to....and not all Model A radius rods are created equal however it looks like you have the more robust casting/forging to attach to.
    Nice design
     
  13. '29 Gizmo
    Joined: Nov 6, 2022
    Posts: 960

    '29 Gizmo
    Member
    from UK

    Thanks... Early A's had a pressed steel end which is extreemly flimsy. I upgraded to the later version which is forged. A worthwhile upgrade for any A.
     
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  14. PotvinV8
    Joined: Mar 30, 2009
    Posts: 495

    PotvinV8
    Member

  15. I do like the design. But also have some concerns like yours, though I'm not necessarily alarmed. I think he'd have seen problems by now, after 1100 miles. If he'd said 50 miles, I'd have a lot more reservations. Lol

    The weld is the weak link in my opinion. Not the plate. Though it all looks plenty good to me in the pictures. I'm not necessarily concerned either is an issue or will be. I'd have more reservations if you'd said 50 miles on it and I feel like you'd see issues already at 1100 miles if you were gonna have them.

    Just my thoughts. Neat design. Thanks for sharing
     
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  16. cederholm
    Joined: May 6, 2006
    Posts: 1,748

    cederholm
    Member

    PotvinV8(above) has his shocks in the corners and I've seen an IronTrap video where his are mounted closer to the banjo. Is there any advantage one vs. the other?
     
    Last edited: Jan 19, 2024
  17. -Brent-
    Joined: Nov 20, 2006
    Posts: 7,491

    -Brent-
    Member

    Here is how we did it on the back of my A.

    Upper Model A Rear Shock Mounted 3.jpg
    Rear View Shocks Mounted on Model A Chassis.jpg
    Model A Coupe Rear Slicks Pontiac Rear.jpg
     
    Last edited: Jan 19, 2024
  18. 282doorUK
    Joined: Mar 6, 2015
    Posts: 472

    282doorUK

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  19. Artworx
    Joined: Mar 4, 2008
    Posts: 42

    Artworx
    ALLIANCE MEMBER

    Fendered highboy??
     
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  20. PotvinV8
    Joined: Mar 30, 2009
    Posts: 495

    PotvinV8
    Member

    Typically speaking, the closer they are to the end of the axle, the more effective, as it's the shocks job to try to dampen the movement of all that unsprung weight (wheel, tire, brake, etc.). A slight inward angle also helps as each side of the axle travels in an arc.
     
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  21. cederholm
    Joined: May 6, 2006
    Posts: 1,748

    cederholm
    Member

    Thanks for that!
     
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  22. From a best practice perspective, PotvinV8 has his in an ideal location. It may not always be possible, but this is what you should aim for, for reasons he has given.
     
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  23. PotvinV8
    Joined: Mar 30, 2009
    Posts: 495

    PotvinV8
    Member

    You're welcome!
     
  24. -Brent-
    Joined: Nov 20, 2006
    Posts: 7,491

    -Brent-
    Member


    I don't recall. I took my measurements and went on Monroe's website and found a shock that fit my needs. The body of the shock has been the same forever so there are tons of options.
     
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  25. GuyW
    Joined: Feb 23, 2007
    Posts: 648

    GuyW
    Member

    Yes - with the closer-to-the-banjo shock location, the tire/wheel/brake has greater lever arm on the shock, so that theoretically, one would need a stiffer shock there, than if the shock is located further outboard.
     
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  26. PotvinV8
    Joined: Mar 30, 2009
    Posts: 495

    PotvinV8
    Member

    I like the brackets on the crossmember, very clean!
     
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  27. ydopen
    Joined: Mar 14, 2010
    Posts: 237

    ydopen
    Member

    I used bolt on shock studs. Lower ones on 48 Ford style brackets mounted to axle ends.
    IMG_0938.jpeg
     
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  28. dmar836
    Joined: Oct 23, 2018
    Posts: 376

    dmar836
    Member

    Consider the movement of the rear end. Fore and aft movement is minimal. Most all movement is in an arc around the driveshaft and in that plane. I wouldn’t feel comfortable mounting the pivoting eyes in any other plane. Henry used the dog bone links to prevent issues with his original shocks that pivoted in the “wrong” plane.
     
    Last edited: Jan 20, 2024
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  29. cederholm
    Joined: May 6, 2006
    Posts: 1,748

    cederholm
    Member

    Cool! Would love to see the lower shock mount better.

     
  30. shortypu
    Joined: Dec 22, 2010
    Posts: 226

    shortypu
    Member

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