What is this dent/crack in my frame?

[somecatchyphrase]

I was spelunking under my F150 and noticed two dent/cracks in the frame, both similar sized/shape but not exact. I checked the other side of the truck frame and saw another two similar dent/crack features in the frame. At first I suspected damage (any maybe still do) but what are the odds of having them on both sides of the frame? There are located approximately under the transition from cab to bed. Do these serve a purpose or do I have an issue here?

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[FDHog]

Looks like part of production. Definitely not cracks.

 

[somecatchyphrase]

I'm glad to hear that it is not damage of any sort. They were not uniform like the other cutouts in the frame so that had me concerned. Now I'm just curious what the purpose of them is?

 

[Bryan Simon]

Most likely “bite” marks from the dies or jigs while assembling and welding the frame.
The slots may be for a laser type position sensor for the clamping.

 

[Pedaldude]

Could also possibly be marks from improper jacking technique during a tire rotation or other service.

See it all the time; especially on unibody vehicles.

If they were using a floor jack either without, or an insufficient jack pad and the steel edge of the jack swivel was all that contacted the frame it’s pretty easy to do that damage when half the weight of the truck is on a small area.

That’s why when I do even a front to back tire rotation; I’ll lift the whole truck up on axle stands in the rear and under a suspension bracket in front. Even though it takes 4X as long as just jacking up one side at a time and risking it falling off with no wheels.

 

[notabot]

Could also possibly be marks from improper jacking technique during a tire rotation or other service.

Are we sure a floor jack with just the point load at that location could dimple a frame in that manner? FWIW, I have crimped/crumpled the body sheet metal seam under the rocker with a floor jack and now use a hockey puck with a slot routed in the center to keep that from happening.

 

[Snakebitten]

That frame under your F150 is an amazing piece of steel structure.
It's not indestructible, of course, but supporting the static weight of the cab/bed and cargo isn't much of a threat to it.

There's safe and safer ways to lift the truck by it, but I'd be stunned to see its integrity injured with floor jack.

 

[Davexxxx]

I don't think a jack did that. I'd think it more likely to be parts handling points, used during manufacture.

 

[bfastr]

I crawled under my '23. its there as well, the divot is clearly an alignment design that keeps the second side of the box frame in place for welding, you will see a straight edge on the inboard side thats welded holding the frame together. looking carefully in the divot you will see the inside edge of that frame piece resting against the pushed in dimple,

its not even on the flat part of the frame where a jack would be placed. in fact if you tried jacking here the jack would slide towards the rear as this area is not parallel to the ground. or even in an area a Goober would try to jack the truck up.

 

[mnstang]

I don't think a jack did that. I'd think it more likely to be parts handling points, used during manufacture.

Yeah if a jack caused that, there would be some big questions on if the frame got annealed by accident, which would make steel soft. If that happened it would have to be on purpose in a production environment. Must just be part of the process, robots or jig holder bites of some sort.

 

[Ziggy73]

Most likely “bite” marks from the dies or jigs while assembling and welding the frame.
The slots may be for a laser type position sensor for the clamping.

That's the first thing that came to my mind as well. Looks normal.

 

[Pedaldude]

its not even on the flat part of the frame where a jack would be placed. in fact if you tried jacking here the jack would slide towards the rear as this area is not parallel to the ground. or even in an area a Goober would try to jack the truck up.

On my 141.5” WB truck; it’s on a flat section of frame. Clearly though; everyone else is right, as the divots are even visible on the top of the frame on the Lightning display model.

Are we sure a floor jack with just the point load at that location could dimple a frame in that manner?..

I’ve creased the frame on my other trucks using standard axle stands without the rubber caps. You would have to know it was there though when looking for the dents.

My theory above isn’t using a jack with care but just one of the prongs on the edge. Though, I guess it is a bit far fetched that it would displace the metal that much.

That frame under your F150 is an amazing piece of steel structure.
It's not indestructible, of course, but supporting the static weight of the cab/bed and cargo isn't much of a threat to it.

There's safe and safer ways to lift the truck by it, but I'd be stunned to see its integrity injured with floor jack.

Again, not that it could hurt the integrity but when using a jack with disregard; I’m not underestimating an annoyed worker’s capacity for destruction when in a hurry and JNGAF.

A friend’s frame and underbody was given the business bad enough at a dealership by a raccoon that they gave him a new truck the next trim up. Though, it was a Chevy!

Yeah if a jack caused that, there would be some big questions on if the frame got annealed by accident, which would make steel soft. If that happened it would have to be on purpose in a production environment. Must just be part of the process, robots or jig holder bites of some sort.

I don’t even know if it’s a grade of steel that can be annealed. Ford says it uses 70,000PSI tensile strength steel but doesn’t specify the grade. It also looks like they’re being selective about where on the frame the higher strength steel is used which suggests that some of the frame is still mild steel.

https://www.repairerdrivennews.com/...ength-steel-frames-on-body-on-frame-vehicles/

It’s a pretty big consideration these days, since a minor rear end collision can total a truck if the manufacturers won’t sell frame replacement parts.

 

[somecatchyphrase]

Lot's of great discussion to read through here. I'm glad that this is not unique, whew.

I suppose it is more accurate for me to have referred to them as "divots" vs cracks/dents as in the title to this post.

Thanks to those who crawled up under their truck to confirm they also had these divots. Now I am just curious to see what this supposed jig that bites into the frame looks like...

 

[Pedaldude]

...the divot is clearly an alignment design that keeps the second side of the box frame in place for welding, you will see a straight edge on the inboard side thats welded holding the frame together. looking carefully in the divot you will see the inside edge of that frame piece resting against the pushed in dimple...

Lot's of great discussion to read through here. I'm glad that this is not unique, whew.

I suppose it is more accurate for me to have referred to them as "divots" vs cracks/dents as in the title to this post.
...Now I am just curious to see what this supposed jig that bites into the frame looks like...

As in Bfastr’s description, the divots are already there and aid in assembly and alignment of the frame before welding. Kind of sorta like the tab on a cereal box.

 

[somecatchyphrase]

I see. Thanks @Pedaldude and @bfastr for the detailed description. I also found this description for anyone else like me who had a hard time visualizing the purpose of the divots: Steve83: " It's a stop. Note that they ONLY appear on the outer piece of the boxed frame, and only on boxed areas. That's so that the inner piece slides in & stops at the exact depth it's designed to, before they're welded together. If you look inside, you'll see the inner layer against the stop. "

Hopefully anyone else who enjoys spelunking under their truck and notices them with (false) concern will find this thread and be put at ease!

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