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Technical Bolt on upper shock mounts- how strong?

Discussion in 'The Hokey Ass Message Board' started by radarsonwheels, Jul 17, 2019.

  1. radarsonwheels
    Joined: Dec 15, 2006
    Posts: 167

    radarsonwheels
    Member
    from Philly

    Howdy Hamb!

    I want to make some bolt in upper rear shock mounts for my hotrod 54 pickup. I’m always amazed that the super common racecar type tubing with ears crossmember is strong enough- they look flimsy to me but I’m no race car fabricator. Since this is a street build I tend to over build stuff instead of going for maximum light weight.

    My ears are welded to the axle already and I have it mocked up with some fancy shocks I bought. The measuring phase is all done.

    I ordered some bolt in shock pins/studs and my plan is to make an L that bolts to the bottom frame rail, then comes up inside the frame with a 3/16” plate that will hold the pin.

    I’m thinking either all 3/16” plate or maybe a 1”x 1/8”wall square tube with all the mount ears welded to it.

    Should I be looking at doing more than just one small gusset on the 90° if I use plate? Do I need three bolts or would two do the trick if it’s wide enough to resist fore/aft rocking?

    5/16” bolts seem like the ideal compromise between strength and not weakening the frame unnecessarily with big holes?

    Anyway, I have the shocks and the lower mounts, just gotta fab up the brackets to hold the upper studs when they come in the mail next week.

    Thanks for any thoughts!

    Radar
    01050BEA-296E-444D-BAF0-E3B40E025D6C.jpeg
     
  2. squirrel
    Joined: Sep 23, 2004
    Posts: 43,430

    squirrel
    Member

    that won't work for long. How about a vertical channel, with the bolt in the center web of the channel? then it will have some bending resistance.
     
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  3. radarsonwheels
    Joined: Dec 15, 2006
    Posts: 167

    radarsonwheels
    Member
    from Philly

    The C in the pic is the framerail. Which part are you seeing fail?
     
  4. lostone
    Joined: Oct 13, 2013
    Posts: 861

    lostone
    Member
    from kansas

    I think what the squirrel is saying is you have all the load.on the very bottom of the frame rail, so the mount itself will just flex the lower rail flange.

    That mount will work as if the "C" frame rail is nothing more than a flat piece of iron because you have no other support from bracket going to any other part of rail.

    At least that's what I'm seeing with your design, especially with the length of your mount and the leverage it will have against that lowly little bottom frame flange..
     
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  5. oldsman41
    Joined: Jun 25, 2010
    Posts: 1,132

    oldsman41
    Member

    It will probably snap or bend at the stud mount, or could bend at the bottom of frame i see it bending the frame myself.
     
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  6. squirrel
    Joined: Sep 23, 2004
    Posts: 43,430

    squirrel
    Member

    I was thinking it will likely break just below the stud mount. The rest of it seems to be pretty well reinforced. If you changed that gusset that is in the center of the lower half of the vertical flat piece, to two gussets (one on either side) and have them extend up all the way, it should be ok.

    the overall design looks kind of complicated...I'd do some more sketching of different ideas for a while before building.
     
    Johnny Gee likes this.
  7. The flange the shock stud is on will fail; that's almost identical to what the PO did on my car and both broke...

    I'd do a 'C' mount, attaching to both the top and bottom rails of the frame, and I'd use 1/4" plate for the stud mount.
     
    Hnstray likes this.
  8. If they are on the frame, what’s wrong with the stock ones? Even if you had to move them
    These are on my ‘57. Pretty sure they are the same

    [​IMG]
     
    Last edited: Jul 17, 2019
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  9. radarsonwheels
    Joined: Dec 15, 2006
    Posts: 167

    radarsonwheels
    Member
    from Philly

  10. radarsonwheels
    Joined: Dec 15, 2006
    Posts: 167

    radarsonwheels
    Member
    from Philly

    Nothing is stock back there and I do need to move them up to correct the angle from lowering. Sadly the originals were rotten and are long gone. I do have a pieces of frame rail from Z cut sectioning the frame that will be useful for use as a fixture so I can tig up the bracket on the bench.
     
  11. Gotcha


    Sent from my iPhone using H.A.M.B.
     
  12. s55mercury66
    Joined: Jul 6, 2009
    Posts: 3,677

    s55mercury66
    Member
    from SW Wyoming

    A piece of channel that spans the width of the frame would probably work. Drill holes and mount the shocks inside of it, using spacers as needed.
     
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  13. irishsteve
    Joined: Jan 10, 2017
    Posts: 398

    irishsteve

    Box the rail for 10 inches on each side.
     
  14. Maybe a 1/4" mount plate and a 1/2" arm to bolt the shock to. Similar to these I made for another car; but suited to your application.
    shock mount.jpg
     
  15. squirrel
    Joined: Sep 23, 2004
    Posts: 43,430

    squirrel
    Member

    usually takes me about ten different ideas to come up with one that I like. Keep going, you're getting closer!
     
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  16. radarsonwheels
    Joined: Dec 15, 2006
    Posts: 167

    radarsonwheels
    Member
    from Philly

    Seems like pulling the bed and off topic ignition etc. for welding in a new crossmember is the best idea. It’s just so dang hot out in the driveway I’d love to not go thru all that!

    Thanks and anybody else that has pics I’d love to see em- I’m still not done wanting to bolt them up
     
  17. If you decide on Speedway's upper shock mounts, be sure to grind and reweld the puny tig welds. Yeah, they're pretty but they have absolutely zero penetration. When mine broke, I rewelded the welds with my mig welder and attached them with 5/16ths bolts and welded them solid to my frame rails after boxing the rails.. 34shockmt.jpg 34shockmt2.jpg
     
  18. gene-koning
    Joined: Oct 28, 2016
    Posts: 1,364

    gene-koning
    Member

    How far away from the "C" channel frame will the stud have to be?

    Can you turn the shock 90 degrees and have the shock mounting hole running the same direction as the frame rail?

    Then you could just add a bracket attached to both the top and bottom flange of the frame, and have the shock mounting bolt go through the bracket so the shock is mounted between the two flanges of the bracket and the shock bolt is in double sheer. Gene
     
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  19. irishsteve
    Joined: Jan 10, 2017
    Posts: 398

    irishsteve

    The Chinese kid who made"m did the best he could........
     
  20. radarsonwheels
    Joined: Dec 15, 2006
    Posts: 167

    radarsonwheels
    Member
    from Philly

    Ok so I decided sometimes being lazy is more work that keeping it simple and doing it right. I ordered a weld up kit from comp engineering with a tube and ears meant to hold up over a coilover setup.

    I’m going to pull the bed, weld 3/16” boxing plates on the frame which are drilled so the tube is a snug fit passing through, then weld it all solid. That way the weld on the tube will just be keeping it from twisting and not need strength in shear (probably overkill but it will also guarantee alignment).
     
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  21. oldsman41
    Joined: Jun 25, 2010
    Posts: 1,132

    oldsman41
    Member

    Overkill is okay.
     
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  22. 19Fordy
    Joined: May 17, 2003
    Posts: 6,421

    19Fordy
    Member

    Boxing is the way to go. with hollow spacers inside from inner wall to inner wall.
    Then run bolts thru the boxed frame and the inner hollow spacers.
     
  23. pitman
    Joined: May 14, 2006
    Posts: 4,678

    pitman
    Member
    from Hampsha

    Great advice above. Open 'C' frames allow flex, I would want to box the upper mount region.
     
  24. radarsonwheels
    Joined: Dec 15, 2006
    Posts: 167

    radarsonwheels
    Member
    from Philly

    Well if I’m going to bother to pull the bed off to weld in boxing plates I’m not going to bother making cold connections for the shock mount- the bar and ears are getting burnt in for good.

    For a bolt in situation though I agree it’s no good putting a clamping force that can just crush the box tube- you gotta have sleeves welded in there.
     
  25. lostone
    Joined: Oct 13, 2013
    Posts: 861

    lostone
    Member
    from kansas

    How I'd do it, take a piece of 1/4" plate 5" long, bend into "C" to fit over the top and bottom of your rail, drill hole in middle for your shock mount and drill a couple holes on the top flange, a couple on the bottom flange and bolt together or if you don't care weld it on.

    You create a small box that will do everything you want it to do with no problem ;) and have double flanges to stop any flex.....
     
  26. lostone
    Joined: Oct 13, 2013
    Posts: 861

    lostone
    Member
    from kansas

    A pic, worth a thousand words...
     

    Attached Files:

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