Strut Bar Testing

[KillerBMotorsport]

Sweet, thanks!

[tazio]

Originally Posted by KillerBMotorsport

Me too and thank you!


We just made a bunch more for anyone that wants to spoil their ride for the holidays. In stock, boxed, and ready to ship!

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Is there really a noticeable difference in ride quality?

[KillerBMotorsport]

There is a very noticeable difference in in the weight savings (holding OEM and KBM in each hand) and street cred.

According to software simulations, they are stronger and deflect less than OEM, but it's not something I've felt in the seat of my parts just street driving. I've not done back-to-back comparison at any events, but this summer I will add that to my list. Swapping them out is easy enough to do between runs.

[jeepmor]

Did you do track the yield vs force curves, this would be really telling as I would expect your units to be quite a bit stiffer in side by side comparison with OEM. Marketing approach on that one with chart overlays of stock vs yours would be illustrative to the customer.

Also, looks like you don't have complete epoxy coverage on your glue up process. Is this on purpose to mitigate the squeeze out mess? Epoxy is not fun to clean up while trying to keep everything else neat and tidy.

We used copious epoxy in solar manufacturing. But a much different type than this application. That type is temporary. Managing the squeeze out was a major engineering undertaking during development due to it being so difficult to cleanly and consistently remove the excess. Automation helped a lot in the end once we got the robots. But the programing took a lot of iterations and proper jigging to make it robust. Entirely different process, but learned epoxy is difficult to cleanly manufacture with, especially in process development phase where every technician has a different technique.

Interesting thread OP and nice to see the epoxy to lug interface fail, and not the carbon fiber tube to epoxy interface. Even after the 10 ton press fail, should be able to slap some gorilla glue back on there (garage tech here) and be right back in business after some sanding prep, cleaning and 24 or so hours.

My last question would be is the lug interface powder coated or raw metal? That might be intellectual property, but I gather the lug would be strongest with a clean metal interface rather than a powder coated for no intermediary bonding between surfaces to count on. That looks like powder coating to me exterior to the lug, if it is anodized, ignore powder coat comments.

Regardless, it's plenty strong I'm sure. Saw a nice engineering discussion on this one to comment one. Great looking product, and super reassuring to see the engineering work being done to validate the work.

[KillerBMotorsport]

Originally Posted by jeepmor

Did you do track the yield vs force curves,

No, there was no logging. Aside from software and a press with a gauge, I don't have an actual tensile testing rig, but that would be nice.

Originally Posted by jeepmor

Also, looks like you don't have complete epoxy coverage on your glue up process. Is this on purpose to mitigate the squeeze out mess?

If you looked inside the aluminum end, you'd find the remaining epoxy. The aluminum pieces have a machined pattern inside to improve the bonding vs a smooth surface. The carbon fiber has a texture to it, and we scuff the ends as well.

Originally Posted by jeepmor

My last question would be is the lug interface powder coated or raw metal?

It's raw. The plug we use sits a wee bit below the edge, just so you don't see exposed aluminum at the plug/paint interface like you might if you just put standard tapered plug in the hole.

Originally Posted by jeepmor

Great looking product, and super reassuring to see the engineering work being done to validate the work.

Thank you for the kind words and posting!

[jeepmor]

Nice to see the actual epoxy be the failure mechanism as well. Thanks for sharing that aspect of quality testing on products. I dig that stuff having been engineering tech and engineer the past 25 years.

[KillerBMotorsport]

Originally Posted by jeepmor

Nice to see the actual epoxy be the failure mechanism as well. Thanks for sharing that aspect of quality testing on products. I dig that stuff having been engineering tech and engineer the past 25 years.

The epoxy is wicked expensive aerospace stuff that is very specific to this type of application. If I were to bet on what was going to fail, I would have expected the carbon fiber tubes to give first.

[jeepmor]

Originally Posted by KillerBMotorsport

The epoxy is wicked expensive aerospace stuff that is very specific to this type of application. If I were to bet on what was going to fail, I would have expected the carbon fiber tubes to give first.

I think you're overspending there, but when you need good stuff, aerospace specs don't let you down in quality control.

Our solar stuff let us down constantly. It was early in start up doing development though, in a half billion dollar factory. $10K failures were pretty common in the first year or two. Epoxy would fail and send a 65 pound ingot into a two foot diameter drum and waste it on a multimillion dollar tool, at 15m/s. Epoxy giving me flashbacks, don't mean to hijack the thread, just enjoy the trials and tribulations of engineering a product to market. It takes so much so many never even fathom.

It's been enough time that I can discuss this again, legally and all. Development is fun, I really do enjoy it. I've spent half my career in failure analysis of semiconductors, the other half making crappy equipment produce decent results for said semiconductors.

[tazio]

Originally Posted by jeepmor

Our solar stuff let us down constantly. It was early in start up doing development though, in a half billion dollar factory. $10K failures were pretty common in the first year or two. Epoxy would fail and send a 65 pound ingot into a two foot diameter drum and waste it on a multimillion dollar tool, at 15m/s. Epoxy giving me flashbacks, don't mean to hijack the thread, just enjoy the trials and tribulations of engineering a product to market. It takes so much so many never even fathom.

What were you making? Why were 65 pound ingots suspended ~11.5 meters (Did I do that back of the envelope math right? 15m/s final speed divided by 9.8m/s/s gives the time it fell; multiply by that by an average speed of 7.5m/s to find the distance.) above two foot diameter drums and how did that waste a multimillion dollar tool?

[jeepmor]

Originally Posted by tazio

What were you making? Why were 65 pound ingots suspended ~11.5 meters (Did I do that back of the envelope math right? 15m/s final speed divided by 9.8m/s/s gives the time it fell; multiply by that by an average speed of 7.5m/s to find the distance.) above two foot diameter drums and how did that waste a multimillion dollar tool?

Look up solar and semiconductor wire saw processes for details. Meyer Berger saws. It didn't waste a multimillion dollar tool, it was 10k plus to repair for each failure and replace the spools and clean up the bird's nest of piano wire. We were not aligned with the home company on process, we were doing the R&D. They were not cutting monocrystalline ingots in Germany, but we were in Oregon and Washington at the time. They knew there were resources in the area doing semi wafer cutting for decades on mono crystalline ingots and tried to tap in. They got the wrong people 2 miles down the road from Intel making processors, not wafers.

We were cutting a lot thinner than semis, and trying to run semi fast, at 2x the wafers per ingot. Heat failure was an issue in the early development phase of trying to instantly become 24/7 manufacturing. I was the grinder engineer, they blamed me for surface roughness issues making it too smooth or too rough ad nauseum. It was a dept of chemical engineers running a machine shop. I was one of two mechanical engineers. Subsurface damage was a big issue for yield. Grinding produced 7 um of subsurface damage versus 30 um from the wire saws. On each side of the wafer, that was only 120 um thick. They never listened.

Silicon is tough to handle at that level, lot of yield loss. Some of it can be recycled. Mono square cutting had us putting 30% back into the mix as a matter of routine of the shaping process. Always recycling 30% of your material is a business plan that isn't getting us to grid parity via renewables.

Back on point, I drove my FRS today and it was good. This application is a no fail process via the strut bars.

Solar epoxy in this case is one that's made to fail to release the wafers from sacrificial glass plate. The trick was running the saws cooler than the release temperature. Cutting at 15m/s wire speed cutting 1300 wafers with ~100um wire is tricky. Math is likely off, but we were producing 1300 or so wafers per 500mm ingot. And yielding only 80% from that.

Silicon solar reprocesses way too much material. I think they should tap into the reclaim semi wafers and reprocess the waste stream. And to be fair, still don't see a honey comb packing of the circles to process into panels, sill making squares.

[KillerBMotorsport]

Originally Posted by Racecomp Engineering

My bad guys! Short version is these bars are cool and good. We have a set on our 2nd gen car and it's a big thumbs up.

Wally and I will take our 1st gen conversation elswhere!

- Andrew

Thanks again for testing and the feedback. Any chance you have some track data?

[Racecomp Engineering]

Originally Posted by KillerBMotorsport

Thanks again for testing and the feedback. Any chance you have some track data?

I do not...my 1st gen car is currently set up for rallycross. Hoping to hit an event this April.

We also have a set on our 2nd gen which has been tracked a bunch but I don't know for sure if it has been tracked with these bars on it yet.

- Andrew

[KillerBMotorsport]

We have a set that was installed up for auction. Highest bidder wins...

https://www.ebay.com/itm/404125805940

.

[OkieSnuffBox]

Originally Posted by KillerBMotorsport

Thanks again for testing and the feedback. Any chance you have some track data?

There is unlikely to be anything meaningful. When I had my NA, for example, (even on big spring rate XIDAs) I couldn't tell a different with the "frog arms."

These were big braces that tied in the door jamb to the shock towers underneath the front fenders. And this is on an old, floppy convertible chassis. Absolutely no difference on track, the only thing you could tell was that the front didn't groan/flex as much pulling into the driveway. But on track there was no difference in feel or lap times.

https://fab9tuning.com/boss-frog-fro...hassis-braces/

So I wouldn't expect a modest increase in stiffness on an already braced portion of a modern car designed with FEA to have any impact.

They sure do look the tits though.