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Hot Rods OH NOOO! 32 WRECK!!

Discussion in 'The Hokey Ass Message Board' started by hotrodA, Sep 17, 2017.

  1. Torana68
    Joined: Jan 28, 2008
    Posts: 1,061

    Torana68
    ALLIANCE MEMBER
    from Australia

    the way it looks in the photo (may be different away from the keyboard) it appears not to have a gusset on the underside, that being the case I reckon I could bend it up with a big shifter.... there will be a lot of weight transferred to that if something brakes, might still work even if it bends though, the idea is good, especially if hidden.
     
    RODIST likes this.
  2. This was just the first pic i found, may not be the prettiest, however it was a requirement to get the suicide front licensed here in Australia, like X38 mentioned. Although it probably requires better design for it to actually work in the event of a failure.
     
    Last edited: Sep 23, 2017
    Stogy likes this.
  3. Yep...didnt read the whole thread before posting....i thought I had seen this before.
     
  4. Torana68
    Joined: Jan 28, 2008
    Posts: 1,061

    Torana68
    ALLIANCE MEMBER
    from Australia

    you know I've never read this bit (Mine is spring over) "If a transverse spring is mounted behind a beam front axle, a positive limiting device must be fitted above the axle to prevent any part.....................making contact with ground in the event of a spring failure" surely our rules are not actually good and reasonable???
     
    Last edited: Sep 24, 2017
    Runnin shine and DeLuxe 32 like this.
  5. Stogy
    Joined: Feb 10, 2007
    Posts: 11,837

    Stogy
    ALLIANCE MEMBER

    Just found this searching for something else and it has some relevance to what I asked.

    https://www.jalopyjournal.com/forum/threads/fabricators-how-did-you-learn-your-trade.1034004/

    https://www.jalopyjournal.com/forum...way-you-design-build-cars.95868/#post-1135204
     
    Last edited: Sep 25, 2017
  6. hotrodderhaag
    Joined: Jan 22, 2007
    Posts: 2,106

    hotrodderhaag
    Member

    MY spring has plenty of clearance , and it was even lifted up some after the car settled in place ..
    Picture from the car , hard to see , but my spring has never touched the frame . Ever . Simply a Porus material in the part . Half the part was a nice forged metal , the other half was like a vise from harbor freight.. junk
     

    Attached Files:

    Hackerbilt, Runnin shine and Stogy like this.
  7. Lowbuckboz
    Joined: Apr 2, 2008
    Posts: 499

    Lowbuckboz
    Member

    So sorry about your car. Very happy to see you walked away. You no doubt, built a badass, very well built hot rod! Seems to me, a definite part failure. Would have failed quicker in Jersey, cause these roads suck. Hopefully this brings cheap parts to light. I was into low rider full size Chevy trucks. I had a slammed 79 Chevy everyday driver. I used off brand 3" dropped spindles. The driver side failed, broke in between the wheel bearings. I kept that part to remind me about inferior overseas junk that is offered here. Best of luck with your rebuild!
     
  8. Hackerbilt
    Joined: Aug 13, 2001
    Posts: 6,222

    Hackerbilt
    Member

    Well theres the answer to the bottomed out spring idea!
    Someone needs to be taken to task for these inferior parts.
    How is it they can do this anyway? You would THINK that the parts should have to meet or better exceed OEM requirements.
    Seems they are counting on the false assumption that our cars only get pushed on and off a trailer!
     
  9. Mussman photo.jpg Mussmans photo #2.jpg Mussmans photo #2.jpg Mussman photo #3.jpg This is how Gary with Cornhusker hot rods does all of his and have not had any problems with this set up.
     
    redroaddog, Fern 54, my2nd40 and 8 others like this.
  10. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,436

    Blues4U
    Member
    from So Cal

    Seems to me the blame on a porous casting is a bit premature. Sorry, I know everyone would like to think that it was just a bad part, but from what's been posted, I'm not convinced. I'm not an expert chassis builder or engineer, and I'm just an average welder, but I have been trained by Caterpillar in the application of failure analysis, and to this point I don't see the evidence to blame a porous casting. Of course, I don't have access to everything the owner/builder has, just the picture of the failed part, and it's not clear and not a great angle. But the patterns in the break will tell the tale. The initiation point of the break should be identifiable, and if the material is porous it should be evident, but I'm not seeing anything in this pic.
    broken perch bolt 1.jpg

    I hate to be negative, but it's important to get to the bottom of things in order to prevent a re-occurrence. If you aren't trained in metallurgical analysis I would be sending that bolt out to someone who is. A good clean hi def picture that can be blown up and remain clear would be a good start. I like to get 50x to 200x magnification to look for things like inclusions and other clues as to the cause of failure.
     
  11. HotRodWorks
    Joined: Dec 6, 2005
    Posts: 231

    HotRodWorks
    Alliance Vendor

    There has been some discussion of the orientation of the spring perch and the chamfer vs. small corner radius on the stress of the perch. I thought it would be interesting to do a quick analysis to see the difference. This is a quick sketch of a perch, so the dimensions may not be totally accurate and the actual stress values may be off. However, it shows a good side by side comparison of the 1st principle stress on the part in the different configurations.

    1st photo: Stock orientation with stock chamfer: 700 lbs static load
    2nd: Sideways, stock chamfer, 700 lbs static load
    3rd: Sideways, .032" corner radius, 700 lbs static load
     

    Attached Files:

    Last edited: Sep 27, 2017
  12. Ok, so what are the numbers representing?
    1- stock 26,400
    2 - sideways - nearly 2x
    3 -SW radius removed nearly 3x
    image.jpeg image.jpeg image.jpeg
     
  13. HotRodWorks
    Joined: Dec 6, 2005
    Posts: 231

    HotRodWorks
    Alliance Vendor

    Max stress in pounds per square inch. (tension)
     
  14. brsturges
    Joined: Oct 22, 2008
    Posts: 645

    brsturges
    ALLIANCE MEMBER
    from Miami, FL

    So it gets stronger placing it sideways and removing the radius? I must be missing something.
     
  15. HotRodWorks
    Joined: Dec 6, 2005
    Posts: 231

    HotRodWorks
    Alliance Vendor

    You’re missing something.
    0 psi would be no stress on a part. The higher the number, the higher the stress. Stress is the pressure on a part.


    Sent from my iPhone using The H.A.M.B. mobile app
     
    clem and Stogy like this.
  16. HotRodWorks
    Joined: Dec 6, 2005
    Posts: 231

    HotRodWorks
    Alliance Vendor

    I added support to the taper as it would be supported in a wishbone or in a tapered bung as shown in post # 220. It makes a bigger difference between the stock tapered perch and a corner with a small radius.
    1ST PRINCIPLE 700 LBS CHAMFER UPRIGHT.JPG 1ST PRINCIPLE 700 LBS CHAMFER SIDEWAYS.JPG 1ST PRINCIPLE 700 LBS 032R SIDEWAYS.JPG
     
  17. Beautiful car Ben built, glad to hear it will rise again. Better times. He drove it hard, I ran across El Mirage next to him at 100+. Happy it didn't fail at a worse time. 20953341_10214216091983258_5417472973207677371_n.jpg 20953219_10214216084863080_6148769253851520964_n.jpg 20992523_10214216090423219_1496646783728589049_n.jpg 20992837_10214213411436246_8176712849789047391_n.jpg 20770043_10214114592285829_7911063656713524047_n.jpg
     
  18. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,436

    Blues4U
    Member
    from So Cal

    Damn! Wish I would've been there on that run!
     
    mctim64 likes this.
  19. Blues4U
    Joined: Oct 1, 2015
    Posts: 3,436

    Blues4U
    Member
    from So Cal

    So basically, the forces applied to that point in the bottom arrangement are close to 4 times the load of the middle image, and ~ 7x the load on the top standard perch arrangement. Right?
     
  20. HotRodWorks
    Joined: Dec 6, 2005
    Posts: 231

    HotRodWorks
    Alliance Vendor

    In this model, which is a simplified example of the real world application, you are correct. The stress on the perch, at that point, is 7x the stress on the upright perch. The actual load on the part, 700 lbs static, is the same in all 3 examples. The only difference is the orientation of the part and the shape of the transition from the shaft to the upper perch part. One design minimizes the stress on the part, and the other design increases the stress on the part. You can take the results of an FEA such as this and compare it to the yield strength of the proposed material.
     
  21. CTaulbert
    Joined: Apr 8, 2007
    Posts: 1,031

    CTaulbert
    ALLIANCE MEMBER
    from Detroit

    Ken/Nick - thank you for doing a FEA study on the perch. It's (unfortunately) great to see the data highlight the area of concern. I hope anyone reading this thread takes away the importance of radii, tapers, and clamp load in suspension joints.
     
    Texas36, Chris, Hamtown Al and 3 others like this.
  22. I also thank you Ken & Nick for this great information as it sure makes me feel better about my front perches. Gary from Cornhusker Rods done my perch set up done in the best way according to your study's.
     
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  23. alchemy
    Joined: Sep 27, 2002
    Posts: 13,722

    alchemy
    Member

    Hotrodworks, in the original vertical application I would think the downward force would be more of a 45 degree angle, instead of the straight down. Don't you agree? The shackle is pulling at an angle, right? Does that make much difference in the stress on the part in a vertical environment?

    Granted, your comparisons showing a 7 times increase in stress is amazing.
     
    kidcampbell71 likes this.
  24. HotRodWorks
    Joined: Dec 6, 2005
    Posts: 231

    HotRodWorks
    Alliance Vendor

    Any load at an angle can be broken down into the forces that are vertical and horizontal. In this case, the angle would depend upon the shackle angle. If the angle is exactly 45 degrees, 1/2 the total load would be horizontal and 1/2 the total load would be downward.
     
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  25. Asphalt Demon
    Joined: Jan 19, 2014
    Posts: 288

    Asphalt Demon
    ALLIANCE MEMBER
    from Australia

    Can't be assed reading the whole thread so my apologies if already pointed out, and a horrible thing to happen, here's my 2cents .being an aircraft engineer going on 30 years. Spring perches of this design are designed to take tension load only with even a taper, removing that taper and square edging it , is just plain stupid! With removing the taper you've taken a part designed to take tension load and put it under shear , even just by mounting it sideways , it's under shear load. Leave the taper set up the front end dimension and weld it and you have a chance, otherwise that taper in my eyes would need to be replaced with the biggest possible radius you could fit on the perch and sleeve through the wishbone, Johnny
     
  26. edwardlloyd
    Joined: Aug 2, 2003
    Posts: 2,034

    edwardlloyd
    Member
    from Germany

    I have done exactly the same thing on my Model-T. I'll be throwing out the Speedway perches and usìng original Ford parts with their taper intact. In addition I'll install axle catch hooks up front.

    Sent from my SM-G935F using The H.A.M.B. mobile app
     
    Asphalt Demon, Hombre and cactus1 like this.

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