GX460 3rd Row "In-floor" Storage Solution (1 Viewer)

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What a couple weeks. Road trip through southern Utah was amazing. Cargo cache worked perfectly to keep our basic emergency supplies, small cooler, inflator, 5-gal water jug, and (half-of) our camping "toolbox" secure during mild to moderate off-roading. This past week has been the often inescapable post-vacation scramble to catch up on "work" work.
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Regarding the cargo cache, I've spent the past few days working to determine safe load ratings using online research, calculations, and FEA simulations. What I've found is that the aluminum structure is a bit more limiting than I hoped but still feel it's adequate for many people's uses, including mine.

Using the mfg. working load limit for the door latch (and a generous safety factor), the calcs show that the hatch door latch can contain 50 lbs of evenly distributed, un-secured items even in challenging off-road conditions. Probably pretty difficult to find 50lbs of things that fit in there. Regardless, securing heavy/hard items to the floor or walls of the cache would be the safest, quietest, and least abusive.

Total payload limit, inclusive of items secured on top and in the cache, varies depending on road conditions and driving style (based on g-loads). The load limits take material fatigue into consideration and assume evenly distributed cargo.

Load ratings, per side:
  • Pavement/Gravel/Mild off-road; 125 lbs 130 lbs
  • Moderate; 90 lbs
  • Difficult; 70 lbs
  • Extra-Difficult; 55 lbs
  • Severe; 35 lbs 40 lbs (guessing little to no GX460's are at this level)
  • Extreme; N/A (Rock buggies, trophy trucks, etc.)
*I'm loosely basing the technical ratings from trail curators like Trails Offroad, FunTreks, etc. But speed and driving style also matters. For example, driving a mild off-road trail fast and aggressively should lower the load rating to something like Difficult+1 (55lbs), in my estimation.

Comparing the payload ratings to other cargo solutions I've looked at or currently use (our Yakima SkyBox {max 62lbs; pavement/gravel} and the Yakima MOD drawers I had considered {max. ~100-125 lbs per side assuming stacked two high; mild/moderate OR}), it all seems reasonable.

I have considered the possibility of making a Heavy Duty version out of slightly thiner Mild Steel and Stainless instead of the 1/8" Aluminum, and it would bring the ratings up quite a bit. However, it would also raise the cost ~$130 due to the stainless. Or all powder coated mild steel, which would also cost ~$130 extra.
 
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What a couple weeks. Road trip through southern Utah was amazing. Cargo cache worked perfectly to keep our basic emergency supplies, small cooler, inflator, 5-gal water jug, and (half-of) our camping "toolbox" secure during mild to moderate off-roading. This past week has been the often inescapable post-vacation scramble to catch up on "work" work.
View attachment 3878945View attachment 3878947View attachment 3878946

Regarding the cargo cache, I've spent the past few days working to determine safe load ratings using online research, calculations, and FEA simulations. What I've found is that the aluminum structure is a bit more limiting than I hoped but still feel it's adequate for many people's uses, including mine.

Using the mfg. working load limit for the door latch (and a generous safety factor), the calcs show that the hatch door latch can contain 50 lbs of evenly distributed, un-secured items even in challenging off-road conditions. Probably pretty difficult to find 50lbs of things that fit in there. Regardless, securing heavy/hard items to the floor or walls of the cache would be the safest, quietest, and least abusive.

Total payload limit, inclusive of items secured on top and in the cache, varies depending on road conditions and driving style (based on g-loads). The load limits take material fatigue into consideration and assume evenly distributed cargo.

Load ratings, per side:
  • Pavement/Gravel/Mild off-road; 125 lbs
  • Moderate; 90 lbs
  • Difficult; 70 lbs
  • Difficult+1; 55 lbs
  • Severe; 35 lbs (guessing little to no GX460's are at this level)
  • Extreme; N/A (Rock buggies, trophy trucks, etc.)
*I'm loosely basing the technical ratings from trail curators like Trails Offroad, FunTreks, etc. But speed and driving style also matters. For example, driving a mild off-road trail fast and aggressively should lower the load rating to something like Difficult+1 (55lbs), in my estimation.

Comparing the payload ratings to other cargo solutions I've looked at or currently use (our Yakima SkyBox {max 62lbs; pavement/gravel} and the Yakima MOD drawers I had considered {max. ~100-125 lbs per side assuming stacked two high; mild/moderate OR}), it all seems reasonable.

I have considered the possibility of making a Heavy Duty version out of slightly thiner Mild Steel and Stainless instead of the 1/8" Aluminum, and it would bring the ratings up quite a bit. However, it would also raise the cost ~$130 due to the stainless. Or all powder coated mild steel, which would also cost ~$130 extra.
Great job on the calc's! Something that few fabricators do (or are capable of doing) when designing load bearing accessories.
To increase load, instead of steel/SS, how bout just using heavier gauge aluminum? Or even Delrin/polypropylene?
Just some thoughts from one eng to another eng.
 
It’d be great if I could use thicker alu, but think it affects the ability to use L-track fittings within the box. Need to verify this. Could switch to using L-track profile inside the box instead but will ultimately struggle with unit cost, I think.

Also, next thicker alu increases flange bend radii to .25” at SendCutSend (from .125”) and that may be the bigger hurdle. I’ll look into it though. Thanks!
 
Website and orders are live! First 10 backPAC Cargo Caches to be built are available to order.
backPAC Cargo Cache for Lexus GX460 - https://backpac.us/
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Wow, getting a product, business, and website set up and ready for sales is a lot of work for evenings and weekends. Way too many "i's" to dot and "t's" to cross for my taste but here we are!
 
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Wow, from initial post to an actual business taking orders in a month!!! Very impressive and congrats!
 
I didn't realize it was only a month! Thanks for pointing that out. I felt like things were taking ages to get going but... anyway, that made my day.
 
I upgraded to the IH8MUD Small Business membership so that I could continue to post backPAC updates in this forum. Comes with some perks of the other upgraded memberships, as well. I'll have to get used to the "Supporting Vendor" banner, though.

I just finished a subtle, but tedious, redesign to incorporate some fitment and assembly refinements identified with the prototype unit, as well as improvements learned with the FEA simulations. Next is re-quoting with SendCutSend and reaching out to their Commercial Projects Team to see about better pricing, DFM checks, etc. Fingers crossed.

Speaking of cost, I was going through my BOM (bill of materials) spreadsheet last night, updating and cross shopping component prices, and I found an error where I double counted some parts costs. Thinking this alone will allow me to lower prices by $100, or close to it. I'll wait to update prices on the website until I talk with SCS, though.
 
I upgraded to the IH8MUD Small Business membership so that I could continue to post backPAC updates in this forum. Comes with some perks of the other upgraded memberships, as well. I'll have to get used to the "Supporting Vendor" banner, though.

I just finished a subtle, but tedious, redesign to incorporate some fitment and assembly refinements identified with the prototype unit, as well as improvements learned with the FEA simulations. Next is re-quoting with SendCutSend and reaching out to their Commercial Projects Team to see about better pricing, DFM checks, etc. Fingers crossed.

Speaking of cost, I was going through my BOM (bill of materials) spreadsheet last night, updating and cross shopping component prices, and I found an error where I double counted some parts costs. Thinking this alone will allow me to lower prices by $100, or close to it. I'll wait to update prices on the website until I talk with SCS, though.
Nice little website.
When I first saw "Left", I was thinking that the model years were actually a count of how many you had left in stock!
You know you're getting old when....
 
Nice little website.
When I first saw "Left", I was thinking that the model years were actually a count of how many you had left in stock!
You know you're getting old when....
Thanks!
Haha, I don’t even know where I would put 23 of these in my house. Maybe I should reword it to “left-side” or something.
 
Thanks!
Haha, I don’t even know where I would put 23 of these in my house. Maybe I should reword it to “left-side” or something.
Left Side or Drivers Side (although that may confuse any of our mates down under if they're looking at getting one)
 
Been working with SendCutSend on pricing as well as DFM. Turns out my last redesign didn't quite work with their press brake tooling, but that's fixed now.

Long story short, with the new sheetmetal pricing, and my corrected spreadsheet calcs, I've lowered the intro pricing to $580!

I also changed my website domain to backpac.us. The previous one, backpa.co, felt too awkward to explain in conversation.
 

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