ProTekt Bumper Skidplates (pics)

[GTO2BRZ]

Originally Posted by mitch t

Good question!

The skid plates are made from 3/8 thick HDPE plastic, and are specifically designed to scrape the ground over and over, and keep looking good!

Also, all the mounting hardware is fully countersunk, and are nuts, washers and bolts. (No drywall screws or self tapping stuff)

I've been selling these for a little more than a year, and I have never seen one worn out, even when they are abused.

Thanks Mitch! Appreciate you taking the time to respond and efforts to bring forth products for our platform.

Please don't take my comments as criticism, as a design engineer myself (aerospace), I know it's a lot easier to "critique" than "create".

• Why is there a relatively large gap between the center and side pieces? I'm thinking you did this intentionally for some reason (that I'm not seeing).

• For the BRZ kit, looks like we're mounting closer to the leading edge than the FRS, making it more readily visible. If you designed the center and side pieces to butt (flush) together I'd think it'd look nicer. Rather than countersinks, could you have gone with counterbores, larger holes, washers under the fastener heads to allow for more hole positional tolerance and overall adjustment (to obtain flushness between pieces and the leading edge)?

• Did you do much testing with different ramp angles and depths? I was wondering if a radius followed by a shallower chamfer (say 30 instead of 45 degrees?) would give you more wear thickness / better durability / longer life. I realize it's sorta "catch 22". The lower the part hangs the more it's gonna get hit.

I like your material choice and thickness.

Thanks again!

[RickyBobby]

Thanks Mitch for fixing your Paypal checkout pages. I'm also on the fence between a lip which would cover all the scratches and the skid plates. I don't like the fact that lips add ~2" to the front bumper while your skid plates only add 3/8", and do not stick out.
I also like do not want to change the lines of the front bumper. I like it just the way it is.

[mitch t]

Originally Posted by GTO2BRZ

Thanks Mitch! Appreciate you taking the time to respond and efforts to bring forth products for our platform.

Please don't take my comments as criticism, as a design engineer myself (aerospace), I know it's a lot easier to "critique" than "create".

• Why is there a relatively large gap between the center and side pieces? I'm thinking you did this intentionally for some reason (that I'm not seeing).

• For the BRZ kit, looks like we're mounting closer to the leading edge than the FRS, making it more readily visible. If you designed the center and side pieces to butt (flush) together I'd think it'd look nicer. Rather than countersinks, could you have gone with counterbores, larger holes, washers under the fastener heads to allow for more hole positional tolerance and overall adjustment (to obtain flushness between pieces and the leading edge)?

• Did you do much testing with different ramp angles and depths? I was wondering if a radius followed by a shallower chamfer (say 30 instead of 45 degrees?) would give you more wear thickness / better durability / longer life. I realize it's sorta "catch 22". The lower the part hangs the more it's gonna get hit.

I like your material choice and thickness.

Thanks again!

No problem!

Here are a few answers for you.


1. The parts I make are made from 3/8 flat sheet, which limits me a little bit in what I can make. Typically, I make the parts to fit a specific "flat" spot on the bottom or the bumper cover, which is why the FRS and BRZ parts are so different. The brz bumper cover has a planar surface that extends out to the outer edge of the bumper, while the BRZ has a smaller flat spot, resulting in a smaller, more tucked in skid plate.

2. If you look carefully, you can see in the last pic that the plane that the center piece is not quite parallel with the outer two. Since it isn't really possible to get them to "butt together" perfectly, I made a little space between them, so it doesn't look like they were poorly fitted. In real life, the plates are extremely subtle, and the gap between them is positioned to minimize it visually.

2. The countersunk bolts offer the lowest profile that I could find, and will allow for maximum wear distance before the bolt heads are exposed to damage. Regular bolts plus washers can be counterbored to sit flush, but just barely, and wouldn't last as long before the bolt heads started to scrape the ground. Also, even with the countersunk bolts, there is some freedom to position the parts, as the factory holes in the bumper are a few millimeters oversized.
Plus, I think the countersunk bolts just look cleaner!

[mitch t]

Originally Posted by RickyBobby

Thanks Mitch for fixing your Paypal checkout pages. I'm also on the fence between a lip which would cover all the scratches and the skid plates. I don't like the fact that lips add ~2" to the front bumper while your skid plates only add 3/8", and do not stick out.
I also like do not want to change the lines of the front bumper. I like it just the way it is.

I know what you mean. I worked to make the plates look as OEM as possible, and I feel like I did a pretty good job, as most of the time, even when I point out the plates on my car, (the one in my avatar pic) people don't really realize that they are aftermarket.

Plus, with the FRS and BRZ, it is pretty easy to step over the line into "ricey" territory.

[GTO2BRZ]

Originally Posted by mitch t

No problem!

Here are a few answers for you.


1. The parts I make are made from 3/8 flat sheet, which limits me a little bit in what I can make. Typically, I make the parts to fit a specific "flat" spot on the bottom or the bumper cover, which is why the FRS and BRZ parts are so different. The brz bumper cover has a planar surface that extends out to the outer edge of the bumper, while the BRZ has a smaller flat spot, resulting in a smaller, more tucked in skid plate.

2. If you look carefully, you can see in the last pic that the plane that the center piece is not quite parallel with the outer two. Since it isn't really possible to get them to "butt together" perfectly, I made a little space between them, so it doesn't look like they were poorly fitted. In real life, the plates are extremely subtle, and the gap between them is positioned to minimize it visually.

2. The countersunk bolts offer the lowest profile that I could find, and will allow for maximum wear distance before the bolt heads are exposed to damage. Regular bolts plus washers can be counterbored to sit flush, but just barely, and wouldn't last as long before the bolt heads started to scrape the ground. Also, even with the countersunk bolts, there is some freedom to position the parts, as the factory holes in the bumper are a few millimeters oversized.
Plus, I think the countersunk bolts just look cleaner!

Thanks Mitch!

You didn't address my last comment on the leading edges but that's ok.

Think I gotcha on the difficulty trying to get the pieces to match up due to the different planes / surfaces.

I guess at that point, if you had the ability to, I would have considered machining the mating surfaces to match so you can have flush parts on the lower, exposed surface. Yes, I realize that would increase cost. But it would also allow you to butt the parts together and / or revise the "splice" locations as required to enable a more integrated, one piece look. I realize you probably didn't do a one piece design for cost reasons as well.

On my second point, I was not suggesting "regular" (hex head?) bolts. You could use standard "pan" head (eg phillips drive) screws which are typically lower height. I wouldn't think you'd need to worry about wear where the fasteners are. I'd think the leading edges are going to wear thin first. However, if you were worried about it, you could simply counterbore a little deeper and have the heads about the same place they are now. If you're worried about tension / pull thru strength, keep in mind the washer (of proper material, thickness, outside diameter) will distribute load over a wider area. I get the "looks" thing of the countersunk fasteners, I was considering the "functionality" of gaining adjustment range (if it allowed parts to line up better and produce a flush / one piece look).

Anyways, I was just throwing out ideas that I thought might help. It's your design and your business, not mine. I'll stick to airplanes for now.

Peace!

[2superblus]

Originally Posted by GTO2BRZ

Thanks Mitch!

You didn't address my last comment on the leading edges but that's ok.

Think I gotcha on the difficulty trying to get the pieces to match up due to the different planes / surfaces.

I guess at that point, if you had the ability to, I would have considered machining the mating surfaces to match so you can have flush parts on the lower, exposed surface. Yes, I realize that would increase cost. But it would also allow you to butt the parts together and / or revise the "splice" locations as required to enable a more integrated, one piece look. I realize you probably didn't do a one piece design for cost reasons as well.

On my second point, I was not suggesting "regular" (hex head?) bolts. You could use standard "pan" head (eg phillips drive) screws which are typically lower height. I wouldn't think you'd need to worry about wear where the fasteners are. I'd think the leading edges are going to wear thin first. However, if you were worried about it, you could simply counterbore a little deeper and have the heads about the same place they are now. If you're worried about tension / pull thru strength, keep in mind the washer (of proper material, thickness, outside diameter) will distribute load over a wider area. I get the "looks" thing of the countersunk fasteners, I was considering the "functionality" of gaining adjustment range (if it allowed parts to line up better and produce a flush / one piece look).

Anyways, I was just throwing out ideas that I thought might help. It's your design and your business, not mine. I'll stick to airplanes for now.

Peace!

I think you maybe overthinking this too much.

You have seen this picture right?

This is a Skid plate for your Bumper, designed for function and fit. This is basic simplistic functional design, it offers great price point that most any of us can afford. We are supposed to use it as designed, scratch it, rub it on aprons and entries in driveway parking lots and poorly built roads. It will last longer than most of us will own are cars.

Honestly when I saw his design I wanted it. It does what I need it to do without majorly decreasing my ground clearance.

I mean after all I could go really high end and have the same thing made out of a sheet of 10mm Jabroc. Of course that would be if price was not an object/
https://www.pegasusautoracing.com/pr...p?Product=6180

[mitch t]

Originally Posted by GTO2BRZ

Thanks Mitch!

You didn't address my last comment on the leading edges but that's ok.

Think I gotcha on the difficulty trying to get the pieces to match up due to the different planes / surfaces.

I guess at that point, if you had the ability to, I would have considered machining the mating surfaces to match so you can have flush parts on the lower, exposed surface. Yes, I realize that would increase cost. But it would also allow you to butt the parts together and / or revise the "splice" locations as required to enable a more integrated, one piece look. I realize you probably didn't do a one piece design for cost reasons as well.

On my second point, I was not suggesting "regular" (hex head?) bolts. You could use standard "pan" head (eg phillips drive) screws which are typically lower height. I wouldn't think you'd need to worry about wear where the fasteners are. I'd think the leading edges are going to wear thin first. However, if you were worried about it, you could simply counterbore a little deeper and have the heads about the same place they are now. If you're worried about tension / pull thru strength, keep in mind the washer (of proper material, thickness, outside diameter) will distribute load over a wider area. I get the "looks" thing of the countersunk fasteners, I was considering the "functionality" of gaining adjustment range (if it allowed parts to line up better and produce a flush / one piece look).

Anyways, I was just throwing out ideas that I thought might help. It's your design and your business, not mine. I'll stick to airplanes for now.

Peace!

Would it be possible to handle this more PM style?

All of the issues that you bring up have been considered during the surprisingly involved development process, which included material studies, work with all types of fastening schemes, as well as overall design questions like how many pieces we should make it out of, what the edge profile needs to be, and how to handle things like the factory hardware.

I would love to answer all of your concerns, but I would prefer to do it without publishing a step by step guide to skid plate development on the internet. The knowledge and development has been a long and expensive process, and I would like to keep the advantages that I have earned with my own time and money.

expect a PM this evening.

I will talk about the bolts, however, as that seems to be a real sticking point.

First, there is no "adjustability" disadvantage with the countersunk hardware. The factory holes are slightly larger than 8mm diameter, which allows for plenty of adjustment to make the plates line up perfectly with the outer edge of the bumper, which is the most critical part of fitment. If you need to adjust the fitment even after you drill the new holes, you can easily just drill them out to slightly oversize, and reassemble. Even with a counterbored hole, I would be uncomfotrtable making an oversized, sloppy hole just to allow For adjustment after drilling.

Second, while I do like the look of the installed bolts as is, they were chosen specifically to be "functionally" superior. They provide a clean, snag free fastener, with the smallest feature diameter, (allowing the greatest possible freedom in placement) and the best possible wear clearance, so that the bolt heads do not scrape the ground. You suggested washers and pan head bolts, so here is the math on that.

The plates are about 9mm thick.

A countersink bolt has a head thickness of about 3mm

With a 7 mm chamfer, I can get about 4mm of wear, before exposing the bolt head to damage.
A washer is 1.4 to 1.8 mm thick.
A Phillips pan head screw has a head thickness of 4.7mm
Even with a 7mm counterbore, leaving only 2mm of material under the washer, there is less than 1mm of wear, before the bolt head is touching.

I hope that provides some clarity on the bolt situation...

[mitch t]

Originally Posted by 2superblus

I think you maybe overthinking this too much.

You have seen this picture right?

This is a Skid plate for your Bumper, designed for function and fit. This is basic simplistic functional design, it offers great price point that most any of us can afford. We are supposed to use it as designed, scratch it, rub it on aprons and entries in driveway parking lots and poorly built roads. It will last longer than most of us will own are cars.

Honestly when I saw his design I wanted it. It does what I need it to do without majorly decreasing my ground clearance.

I mean after all I could go really high end and have the same thing made out of a sheet of 10mm Jabroc. Of course that would be if price was not an object/
https://www.pegasusautoracing.com/pr...p?Product=6180

Superblus,

I think that GTO is mainly concerned that the 3 piece construction leaves a gap that is visible. It seems that most of his suggestions are aimed at creating a 1 piece look to the installed part.

My question to you is this.....

Is the 3 piece design very noticeable or offensive to you?

[2superblus]

I personally think that the 3pc design doesn't change it's performance.

Would interlocking version be more eye pleasing? Maybe. Does the 3pc design stand out? Nope.

It would bring other aspects into play. Install, flex in the bumper which the 3pc thing allows, easy replacement of individual pcs if need be. Interlocking 3pc could warp over time or flex wonky too.

A 1pc unit would drive cost and shipping through the roof i would assume due to you couldn't make as many out of 1 sheet.

I guess it boils down to if I didn't like it I wouldn't have purchased it.

[Devante]

I have a question about this and sincerely not trying to be snarky.
The purpose of this is to protect the bottom of your front bumper, right?

But you have to drill holes in the bottom of your front bumper.

I'm not comprehending it. guess maybe the point is a few perfectly shaped holes is better looking than some scuffs? Is that the idea?

Oh and any plans on making a back bumper one? Something just big enough to protect the back lip and maybe the exhaust tips?

[2superblus]

Originally Posted by Devante

I have a question about this and sincerely not trying to be snarky.
The purpose of this is to protect the bottom of your front bumper, right?

But you have to drill holes in the bottom of your front bumper.

I'm not comprehending it. guess maybe the point is a few perfectly shaped holes is better looking than some scuffs? Is that the idea?

Oh and any plans on making a back bumper one? Something just big enough to protect the back lip and maybe the exhaust tips?

You are correct. A couple of added hole are way better than the scratched and scuff bumper underside.

[mitch t]

Originally Posted by Devante

I have a question about this and sincerely not trying to be snarky.
The purpose of this is to protect the bottom of your front bumper, right?

But you have to drill holes in the bottom of your front bumper.

I'm not comprehending it. guess maybe the point is a few perfectly shaped holes is better looking than some scuffs? Is that the idea?

Oh and any plans on making a back bumper one? Something just big enough to protect the back lip and maybe the exhaust tips?

Are you savoring the irony? I am!

In all seriousness though, you are not the first person to bring it up.

What it boils down to is that for me, (I originally designed this part to go on my personal car, the FRS in my avatar pic) drilling a few well placed holes, and bolting on an accessory, is different than damaging the leading edge of the bumper cover by scraping it on the ground. Also, drilling holes does "damage" the cover, but that is where it stops, so your bumper will stay in good shape for years to come, whereas scraping it on the ground adds up over time, eventually leading to needed repair or replacement.

Not everyone sees it that way though, and they see them both as a form of damage, and as much as I would like to help that guy, I cant.

I haven't really considered anything for the back! Are you scraping the rear bumper cover, or the tips? If that is a problem for folks I would sure look into it!

[GTO2BRZ]

Originally Posted by mitch t

Superblus,

I think that GTO is mainly concerned that the 3 piece construction leaves a gap that is visible. It seems that most of his suggestions are aimed at creating a 1 piece look to the installed part.

Thanks Mitch! Appreciate you taking the time to respond.

At this point, I think (no offense intended), we're sorta "talking across each other". That's ok. It's just part of typing words across the internet and not having drawings / figures / diagrams on PowerPoint or Word files.

I think you understood where I was going, with a "one piece look" or one piece being preferred, and I think I understand the jist of your message that (in my words, much abbreviated, perhaps oversimplified): Lots of thought, time and money spent, "it is what it is". I also understand "intellectual property" and "proprietary information", they make us very aware of that stuff in aerospace.

As I stated in my earlier post, my comments were not trying to criticize, I was just curious why things were the way they were. I think you can understand an engineer thinking that way. I did not intend anything more than that. I was not trying to bring down your product or insult anyone who purchases / purchased it.

I'd like to clarify just one more thing and be done (this is not intended to be offensive or derogatory either), it's just so you know where I was coming from regarding countersunk holes and adjustment.

If you're familiar: ANSI or ASME Y14.5-2009 Geometric Dimensioning and Tolerancing (GD&T) where interchangeable / matching hole patterns are treated, recall the concepts of "Fixed" vs "Floating" Hole patterns. Fasteners installed into countersunk holes are considered "Fixed" and effectively (all other things equal) reduce allowable tolerances on the mating part. Similarly, in our situation, once someone drills a matching hole pattern in their bumper they'd have to drill larger and larger holes in the bumper to gain adjustment as a countersunk hole in the skid plate is essentially "fixed", a bigger hole in the skid plate will not move the countersink itself. I'm assuming you're not relying on a crooked fastener installation (angled in the hole). Not sure that was the best explanation but again, please recall or revist ANSI / ASME GD&T Fixed vs Floating hole patterns.

Yes, I understand if one never needs or wants to adjust the pieces (as the kit stands now), this is all moot. This discussion was in the context of having adjustment to be able to "perfect" a "one piece look" once all the holes were drilled.

Ok, I think that's enough time spent for the both of us. I wish you the best. Heck, we may even meet one day (looks like we're both in SoCal) and we can kick this and whatever around - "engineer" to "engineer". Wouldn't that be fun!

Once again, thanks, have a good one!

[mitch t]

Originally Posted by GTO2BRZ

Thanks Mitch! Appreciate you taking the time to respond.

At this point, I think (no offense intended), we're sorta "talking across each other". That's ok. It's just part of typing words across the internet and not having drawings / figures / diagrams on PowerPoint or Word files.

I think you understood where I was going, with a "one piece look" or one piece being preferred, and I think I understand the jist of your message that (in my words, much abbreviated, perhaps oversimplified): Lots of thought, time and money spent, "it is what it is". I also understand "intellectual property" and "proprietary information", they make us very aware of that stuff in aerospace.

As I stated in my earlier post, my comments were not trying to criticize, I was just curious why things were the way they were. I think you can understand an engineer thinking that way. I did not intend anything more than that. I was not trying to bring down your product or insult anyone who purchases / purchased it.

I'd like to clarify just one more thing and be done (this is not intended to be offensive or derogatory either), it's just so you know where I was coming from regarding countersunk holes and adjustment.

If you're familiar: ANSI or ASME Y14.5-2009 Geometric Dimensioning and Tolerancing (GD&T) where interchangeable / matching hole patterns are treated, recall the concepts of "Fixed" vs "Floating" Hole patterns. Fasteners installed into countersunk holes are considered "Fixed" and effectively (all other things equal) reduce allowable tolerances on the mating part. Similarly, in our situation, once someone drills a matching hole pattern in their bumper they'd have to drill larger and larger holes in the bumper to gain adjustment as a countersunk hole in the skid plate is essentially "fixed", a bigger hole in the skid plate will not move the countersink itself. I'm assuming you're not relying on a crooked fastener installation (angled in the hole). Not sure that was the best explanation but again, please recall or revist ANSI / ASME GD&T Fixed vs Floating hole patterns.

Yes, I understand if one never needs or wants to adjust the pieces (as the kit stands now), this is all moot. This discussion was in the context of having adjustment to be able to "perfect" a "one piece look" once all the holes were drilled.

Ok, I think that's enough time spent for the both of us. I wish you the best. Heck, we may even meet one day (looks like we're both in SoCal) and we can kick this and whatever around - "engineer" to "engineer". Wouldn't that be fun!

Once again, thanks, have a good one!

Thanks!


first, i think that one thing we have established quite effectively is that my parts are just not really what you are looking for!

second, there is no amount of adjustment that will allow for a "perfect, flush, one piece look" on every car, due to variances from car to car. (There are planar angle variances, as well as overall curvature differences that cannot be resolved with oversized holes) also, i am not sure how i can achieve the required adjustability with oversize holes in the skidplate, while oversize holes in the bumper are unacceptable.

yes, i am aware of the ANSI standards! (i have been in the automotive engineering and development business for about 17 years now) but that doesn't really change my point. in practice (ie, "the real world") the part is still adjustable. the skidplate side is countersunk and therefore "fixed" but the inside, where the washer and nut are is still "floating" if that is what you want. (just maybe with a different mechanism). that being said, why wouldn't you get it in the right place before drilling the new holes? I've sold a bunch of these things, and i have never had anyone complain about adjustability. if you were looking to just kind of "get it close" start drilling, and then readjust, maybe you shouldn't be installing it in the first place. (no offense intended, of course)

at the end of the day, i had to make a choice between adjustability and wear, and i chose wear!

as you are an engineer, you should whip up a quick model, and have a set made, using whatever fastener setup you like! you probably have way more resources than i do (being an aerospace engineer), and i likely even have some material laying around that i will donate, free of charge.

also, i agree that this has taken up plenty of time for us both, and i have also sent you a PM, to try to explain the finer points.

if you have further questions, please feel free to PM me, as i feel we have gotten a little technical for the regular end user, who just wants a good part at a good price!

thanks again! have a good rest of your week, and maybe i will see you at an autocross or track day at some point!