Author Topic: Front Shock Mount  (Read 324 times)

Offline JaredD

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Front Shock Mount
« on: November 02, 2020, 10:51:25 PM »
I am trying to take care of the hole that is in the frame from removing my shock stud.  Currently considering welding in a 5/8" washer as shown from the inside of the frame using a lap joint or should I cut out and weld flush with frame?  Any other suggested approaches?  I'm also planning on either making a bracket or purchasing CPP's shock reinforcement brace after repair is made.

https://drive.google.com/file/d/1eDG1tU4nJOTZ0gis7NM1Lue33WcRBhAb/view?usp=sharing

https://drive.google.com/file/d/1zIOzDYEeJW9hO0awdKbyGrJBoD7BLg76/view?usp=sharing

https://drive.google.com/file/d/1srnDyeImob09gKkYjTxGPpVV1_bWu-q4/view?usp=sharing

Offline bd

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Re: Front Shock Mount
« Reply #1 on: November 08, 2020, 12:06:58 AM »
I've been mulling this over for a few days.  Were it mine, I would begin by meticulously locating the terminus of each crack and drilling 1/8" - 3/16" holes through the frame.  This will prevent the existing cracks from migrating any further across the frame rail face.  Next, I would grind the jagged hole as absolutely round as I could muster.  Then I would closely fit a similarly ground slug using 3/16" mild steel to fill the enlarged hole.  If the hole after grinding extends across a stamped frame radius, I would hammer form the slug to match the shape of the frame as closely as possible, ensuring that the slug maintains a flat face where the shock mount stud must penetrate the frame.  Bevel the mating edges of the rounded hole and the slug, and V-groove the full length of each crack.  Perform full penetration welds of all cracks and the slug from both sides of the frame rail.  Grind/sand/buff/blend the weld reinforcement down to the level of the surrounding frame face so that the bead is not proud of the surface and virtually disappears so as not to be visually defined or identifiable.  Drill/ream a new shock mount hole through the slug at the appropriate spot. 

At this point, weld a thick, broad washer on the inside of the frame making sure that the resulting weld bead is offset from the weld bead previously laid down and ground flat.  Offsetting the weld beads better distributes stress transferred to the frame and helps resist repeat tin canning of the frame.  Firmly clamp the washer in place before welding, using a properly sized, disposable grade 5 bolt and nut.  To prevent recurrence and finish the repair, fabricate an outboard shock mount reinforcement using 1/4" thick mild steel plate.  You should be able to fabricate upper shock mount reinforcements that are superior to any that are offered through the aftermarket.  Mount the reinforcement to the frame using Grade 8 flanged frame bolts, washers and torque prevailing flanged frame nuts.  Peruse all of the links posted in 87 chevy cracked frame from steering box fix for ideas and reference.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline JaredD

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Re: Front Shock Mount
« Reply #2 on: November 08, 2020, 12:22:59 PM »
I really appreciate your guidance on this and I plan to follow your advice.  It sounds like a repairing this hole with a plug using butt joints rather than lap joints provides more rigidity. 

Thanks for your help!

Offline bd

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Re: Front Shock Mount
« Reply #3 on: November 08, 2020, 04:38:33 PM »
Granted, the folds through the frame rail that cant the upper shock mount at an angle to the face increase frame rigidity in the immediate neighborhood of the mounting hole.  But increasing rigidity in the frame rail isn't the goal of the repair.  In fact, frame survival depends on flexibility. 

There are two goals, however:  1) locally rebuild the frame and restore integrity without introducing extraordinary stress risers, and 2) add the outboard shock mount reinforcement plate to provide adequate upper shock mount "stability" and avert a recurrence of tin canning.

As you develop your repair strategy don't be surprised if you modify your method numerous times.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline JohnnyPopper

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Re: Front Shock Mount
« Reply #4 on: November 08, 2020, 10:38:38 PM »
bd you sound like the ancient oracle: what walks on four legs in the morning, two legs at noon, and three in the evening.
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline bd

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Re: Front Shock Mount
« Reply #5 on: November 08, 2020, 11:38:53 PM »
A man.




It's an irrevocable illness. 

Maybe a curse.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)