[DeTomaso] Shift Happens - Broken Motor Mount Bolt

Tue May 15 10:44:44 EDT 2018

Mike,

I always appreciated your (and many others on this list) engineering approach! There is always reasoned engineering 
thought that went into these wonderful machines!  

Terry

"A Purple Heart proves you were smart enough to hatch a plan,
 stupid enough to try it and lucky enough to survive!"

Terry W. Himes 
JPL Jet Propulsion Laboratory
Dawn Spacecraft Team
Rosetta Sequence Team Lead
Phone: (818) 393-6261
Cell:     (818) 653-8213
thimes at jpl.nasa.gov
🇺🇸

On 5/14/18, 7:37 PM, "DeTomaso on behalf of Mike Drew via DeTomaso" <detomaso-bounces at server.detomasolist.com on behalf of detomaso at server.detomasolist.com> wrote:

    Larry,

    Grade 8 bolts are stronger in tension and weaker in shear. They are more brittle, and they break when Grade 5 bolts bend.  

    The fix is to use Grade 5 bolts—as originally installed (for a reason).  The engine subjects the bolts to shear loading and Grade 8 bolts will snap when Grade 5 bolts distort. A distorted bolt is still doing its job after a broken bolt isn’t!  (Thats also why A-arm bolts are Grade 5 instead of Grade 8).

    There are lots of other applications where Grade 8 bolts are appropriate.  It depends on the nature of the job they are being asked to do. But neither Grade 5 or 8 bolts are ‘better’. They are instead ‘different’. 

    The Ford engineer guys are no dummies. 

    Scott—you should be able to support the engine from below (or suspend it from above), then unbolt the bottom half of the engine mount, remove the through bolt, and withdraw it. Then you can remove the other upper mount bolt (hope it isn’t broken too) then remove the upper mount. Then you can determine if you can extract the broken bolt with an EZ-out. Frame rails might make access difficult, so you may have to unbolt the other side mount and raise it up with a hoist to get better access. 

    If the bolt is broken off inside the block and the EZ-out doesn’t work, you may need to take the block to a shop that can do EDM, Electro Discharge Machining, and have it zapped out. Or perhaps a machinist can extract it for you. Dismantling the engine might be part of either of those operations however....

    Mike

    Sent from my iPad

    > On May 14, 2018, at 11:04, Larry Stock <larrys at panteraparts.com> wrote:
    > 
    > There should be 2 bolts Scott, so I assume you sheared the other one also.
    > Since you so good with that camera, shoot me a photo of the other side as
    > well, I¹d like to see what the bolt heads indicate what grade of bolts you
    > had in there. Factory came with grade 5, and after Radial tires were
    > invented and installed the true nature of the difference of a monocoque vs
    > Unibody became evident with the shearing of the grade 5 bolts with the
    > engine being engineered as stressed member of the chassis. The fix has
    > been to use grade 8 or higher to keep that engine as a stressed member
    > brace of the chassis design. More Grip, more stress.
    > 
    > Larry
    > 
    > On 5/14/18, 10:47 AM, "DeTomaso on behalf of Scott Mead Photography"
    > <detomaso-bounces at server.detomasolist.com on behalf of
    > scott at scottmeadphotography.com> wrote:
    > 
    >> Hi Everyone -
    >> 
    >> 
    >> I was under the car this weekend, diagnosing my paperweight of an A/C
    >> system, when I noticed something a little unnerving: The right-front
    >> motor mount bolt had sheared off in the block, and the motor had
    >> shifted. With the hole in the motor mount no longer lining up with bolt
    >> remnants, there's no way I can "easy out" the bolt. Aside from pulling
    >> the engine/ZF, can I take out the other bolt, loosen the bolts on the
    >> other side and (using a block of wood under the oil pan), jack the
    >> engine up a bit to re-align or remove the motor mount to extract the
    >> bolt? Are there any other options I haven't thought of?
    >> 
    >> 
    >> Thanks,
    >> 
    >> 
    >> Scott (caretaker of 5638)
    >> 
    >> 
    >> 
    >> SMP-Slogo
    >> 
    >> PO Box 1190
    >> 
    >> Lake Arrowhead, CA 92352
    >> 
    >> T: 626-660-8075
    >> 
    >> E: scott at scottmeadphotography.com
    >> 
    >> W: www.scottmeadphotography.com
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