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Official Radiator Skid Plate Design Thread!

39779 Views 136 Replies 20 Participants Last post by  bartonmd, 
bartonmd
OK, so here it is... I got the bumper off of the TB last night (for the wife to take to the body shop today, for a small parking infraction she may have had... Scraped another car pulling into a parking spot)

This will probably go from the bottom of the front bumper (the steel part, under the plastic), under the radiator, and to the front of the oil pan skid plate. It will also be mounted to the radiator supports in the location of the stock radiator shield, and have a brace that goes up to the frame, for the larger amount of vertical load. I wanted to go to the bottom of the steel bumper, because the PS cooler is pretty "out there" if I don't... It will have holes in it for the PS cooler. I will probably provide some sticky-backed foam to go under the radiator, and cut down on hot air being sucked through the rad time after time.

This will require drilling (4) holes in your steel bumper support, and it'd be good if you wanted to put 1 hole in each side of your frame (for the vertical load supports, above the radiator), but it won't be required. It will use the same 2 bolts in the rear, that mount the oil pan skid plate, at the front.

It must be noted much like the oil pan plate, that this is protection, but more than likely won't withstand going bonsai through rock gardens at 30mph...

This will fit under the stock Trailblazer front bumper, but I have not been under an Envoy, to check if it will go under the stock Envoy bumper.

These will be made of 3/16" steel, and will be able to be powder-coated (gloss black, mainly, but we can talk about any other "normal" color, and I can see if my P/C guy has any in stock) for somewhere around an extra $30

I'm going to SWAG a GB price in the $230 range, though I won't know for sure until I get it designed and prototyped for mine. I also won't know shipping until I actually get it made...

I have a few questions and ideas to start out...

1. How many people are getting one of these? I don't mean "I think it's a neat idea, and want to up the numbers, like the 6" lift thread"... I mean a serious "you can count on me to buy one of these during the GB" (job situations not withstanding)... Since there's a setup charge to amortize, these numbers are important for the GB price. If not as many people pony up as say they will (per standard Internet forum procedure), I'll have to go around and get an extra $x.xx from people who have already paid. I want to get an accurate count, so that I don't over-charge too much, but I also don't have to go back and get more money from people.

I will add that you can say "I will probably get one, but it depends on finances", but please don't say "I'm in", if you actually mean "maybe"

2. How many people will want one of these, who have any of the GMT-360/370 vehicles that are NOT a "Trailblazer"?

3. How many people who want this, will be leaving their stock bumper cover on? (I'm doing it to fit the cover, but just want to get an idea)

Thanks,
Mike
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bartonmd
JamesDowning said:
Ya know, I was looking at it again, and the part of the hook immediately under the main mounting bolt doesn't necessarily have to mount flat to the skidplate. Try this with your prototype before you cut any large recesses out. Drill the holes for the pin and the small mounting nut (the inside end of the tow hook will mount flush to your skidplate). Mount the tow hook in place on the skidplate, then install the skidplate. Now just crank down on your mounting bolt that threads into the tow hook. I don't think it needs any special spacers or anything now that I look at it again. The bolt will have a little bending moment in it, but not significantly more than it has in the stock configuration. I don't see any negative side effects of doing it that way.
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Yeah, I'm heading there first... I'll check and see how big the angle is, there... I was trying to stay away from having the angle, but it may make everything else a lot easier to just keep it...


Zero said:
why does this rad skid plate even get mounted to the rad support part of the truck frame?

why not just run in from the front bumper mount, down to where the aluminum skid plate u made is mounted.

this would put the whole skid plate on a single angle, and would only require it to me mounted by for bolts.

i love ur designs, i just want to understand why all the extra bends, and mounting locations.

it seems to me if u were to hit it, it would transfer the force and share it with the rad mount instead of taking all the abuse it self, saving the rad and its mounts.
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I'm sure Mike will also answer this, but because of the mounting points, it cannot span the entire distance in a straight line, as mine could. As you put more bends in the material, it gains strength along the bend, but not through the bend. Thus the design transfers vertical weight well to the left/right. However if you were to lift directly under the radiator without the radiator bracket in place, the plate would bend upward because of the bends.

The radiator mounting brackets are actually very strong in the vertical axis. The issue is loading the brackets from side to side. The brackets can easily twist, which is what causes most of the issues of binding the radiator into the fan. So the radiator brackets are mainly there to absorb vertical loads. They also serve to strengthen and reinforce the radiator mounting brackets themselves.

Hopefully I didn't overuse the words 'radiator' and 'bracket'... :duh:
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Yeah, what James said... I'll also add that I'm not vertically loading the actual rad brackets, hardly at all... If you look at any of the models after the second page (or the picture of the metal, on the scale), there is a flange at the top of the rad support bracket, that is specifically there to transfer the force up directly to the frame...

Also, if I went from the bumper, directly to the oil pan plate, that's a pretty long span with no side-bracing, and nothing to transfer force too in the middle... If you want to order one without the radiator brace, I'll sell you one...

_____________________________________

Also, for those who have body lifts, or who want to do something different with the front bumper, I'll also be selling one just like the one pictured above, but that stops at the front of the radiator... It'll just include the radiator support piece, and the angled piece that goes from the front of the rad support, down to the front of the oil pan plate... It may still have the 45-degree piece in the front of the radiator, but will be boxed as a triangle with the vertical front portion of the rad brace..

Mike
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Zero
thank you for answering my questions bro. i think i have a much better understanding now as to why u did things the way u did.

i cant wait to get one of these from ya, just need to get my bumper made first.
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bartonmd said:
There may be an issue with mounting the factory tow hooks, though... put the bumper support on from the front (while the radiator part has to be put on from the bottom)... This is not doable...

There are a couple of ways I think it could be done...

Either one would require cutting the area behind the upper mounting bolt out .... and both would require cutting .... for the mounted end of the hooks...

Mike
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I definatelly want some sort of front tow hook/eye and I am not willing to do any welding to my truck. Am I the kind of customer you are designing for?

May I suggest approaching the tow hook to skid plate interference from another direction? Instead of working around the factory tow hooks (which some people on this board consider to be marginal at best) have you considered incorporating a different hook or eye into your radiator shield? Or using shield mounting hardware to also mount new style hooks? Several folks in various tow hook threads have suggested they have a better idea. PM all of them and see who has progressed from "I have not actually measured, but in theory.." to "buy a pair of 2007 Ford Super Duty hooks and some Grade Eight 5/8 x 6" long bolts and drill a hole...."

A bolt on skid plate /tow hooks combination might attract customers who originally just wanted to add hooks to their hookless Envoys and TB's.

Drilling holes in the frame is not aproblem for me. Relocating my existing tow hooks is not a problem. Buying parts designed for another vehicle and adapting them to my TB is not a problem. Buying a radiator skid plate that is flawed from the start because it has to fit around OEM hooks IS a problem for me.
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bartonmd
PAblzr said:
I definatelly want some sort of front tow hook/eye and I am not willing to do any welding to my truck. Am I the kind of customer you are designing for?

May I suggest approaching the tow hook to skid plate interference from another direction? Instead of working around the factory tow hooks (which some people on this board consider to be marginal at best) have you considered incorporating a different hook or eye into your radiator shield? Or using shield mounting hardware to also mount new style hooks? Several folks in various tow hook threads have suggested they have a better idea. PM all of them and see who has progressed from "I have not actually measured, but in theory.." to "buy a pair of 2007 Ford Super Duty hooks and some Grade Eight 5/8 x 6" long bolts and drill a hole...."

A bolt on skid plate /tow hooks combination might attract customers who originally just wanted to add hooks to their hookless Envoys and TB's.

Drilling holes in the frame is not aproblem for me. Relocating my existing tow hooks is not a problem. Buying parts designed for another vehicle and adapting them to my TB is not a problem. Buying a radiator skid plate that is flawed from the start because it has to fit around OEM hooks IS a problem for me.
Click to expand...

I was talking about me taking the material out (cutting on the prototype, punching on the production versions), but I completely agree... In another thread, I put up (and James did the ANSYS on) what is basically my front skid plate with a 2" reciever on the front of it, for a shackle mount... It was pretty loaded at 9000#, but then again, the stock hooks won't take anywhere near that, either...

I'm still up in the air about it... Got a couple other repairs to do (second half of head gasket on a Taurus, and a radiator on my S-10 Blazer) this week, though, before I mess with it any more...

Mike
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JamesDowning
PAblzr said:
Instead of working around the factory tow hooks (which some people on this board consider to be marginal at best) have you considered incorporating a different hook or eye into your radiator shield?
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Just a note here, the hooks themselves are fine. It's the fact that they mount into the reinforcing bar that is their flaw. The reinforcing bar is designed to bend before anything else in the front of the vehicle. This makes for a weak point. The hooks themselves are quite strong, but they tend to bend the peices they mount to when under a heavy load.

If Mike designs his skid to do so, it could take the place of the stock mounting location of the hooks and actually improve the whole hook system.
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bartonmd
JamesDowning said:
Just a note here, the hooks themselves are fine. It's the fact that they mount into the reinforcing bar that is their flaw. The reinforcing bar is designed to bend before anything else in the front of the vehicle. This makes for a weak point. The hooks themselves are quite strong, but they tend to bend the peices they mount to when under a heavy load.

If Mike designs his skid to do so, it could take the place of the stock mounting location of the hooks and actually improve the whole hook system.
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I agree, but it gets to the point of the next weakest link... The bolts on the ends of the hooks are ~1/4" diameter... The large bolt is roughly in the middle of the hook, so you could call it the pivot, around which the stress is approximately evenly applied (5000# pulling = ~5000# in shear on the small bolt)... Consider that a grade 8 1/4-28 bolt has a shear strengh of about 4400#, and even if you take away the weak reinforcing bar, you've still got a bolt that was meant to be only slightly stronger than the weak reinforcing bar...

Not a big deal with my plate, because if the small bolt breaks, the hook will rotate slightly, but will end up resting on the vertical part of the skid plate, anyway... Just something to think about...

Mike
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JamesDowning
bartonmd said:
Consider that a grade 8 1/4-28 bolt has a shear strengh of about 4400#, and even if you take away the weak reinforcing bar, you've still got a bolt that was meant to be only slightly stronger than the weak reinforcing bar...
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Ah, but you are forgetting the extreme frictional force that results from the bolt being torqued down. Just like a wheel stud. The bolt itself probably won't get more than a few hundred pounds of shear force if torqued properly.
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bartonmd
JamesDowning said:
Ah, but you are forgetting the extreme frictional force that results from the bolt being torqued down. Just like a wheel stud. The bolt itself probably won't get more than a few hundred pounds of shear force if torqued properly.
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Yeah, that's why I was trying to get the whole length of the thing sitting flush on the plate... As it is, with the hook slightly cocked, to still mount the bolt through my plate, there's just the edge of the 1" square area touching the plate... Not nearly as much friction there, as it would be from the 1" square raised block sitting flush...

Mike
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JamesDowning
bartonmd said:
Yeah, that's why I was trying to get the whole length of the thing sitting flush on the plate... As it is, with the hook slightly cocked, to still mount the bolt through my plate, there's just the edge of the 1" square area touching the plate... Not nearly as much friction there, as it would be from the 1" square raised block sitting flush...
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Hmm, didn't realize the two surfaces weren't parallel. Dang engineers always making things complicated... However, that shouldn't actually make a difference, as long as you can get the bolt threaded through your plate and torqued down properly. The friction between two surfaces is actually independent of the contact patch size and only dependent upon the normal force pushing the surfaces together.

If you haven't already, can you attempt to get the hooks on there and bolted in (you know, on your own schedule)? I'd kinda like to see what you're dealing with geometry wise. (you know, only if you'd like to share) I still think that reusing the stock hooks will be the simplest, most cost effective recovery hook design... and it should still be plenty strong.
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bartonmd
JamesDowning said:
Hmm, didn't realize the two surfaces weren't parallel. Dang engineers always making things complicated... However, that shouldn't actually make a difference, as long as you can get the bolt threaded through your plate and torqued down properly. The friction between two surfaces is actually independent of the contact patch size and only dependent upon the normal force pushing the surfaces together.

If you haven't already, can you attempt to get the hooks on there and bolted in (you know, on your own schedule)? I'd kinda like to see what you're dealing with geometry wise. (you know, only if you'd like to share) I still think that reusing the stock hooks will be the simplest, most cost effective recovery hook design... and it should still be plenty strong.
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I'd agree with you if we were talking about the difference between 1 sq-in and 2 sq-in, but we're talking about 1 sq-in vs an edge contact... an edge contact parallel with the direction of potential movement... Not getting the warm-fuzzies about it, being that I've had stuff that I have improperly machined (off a degree or 3... mill table slightly off level) move around and break bolts, then when I went back, cleaned up the parts, and got the angles perfectly lined up, they lasted as long as I worked there...

yeah, I'll get some pics, when I get the bumper back off, and get the hooks back off (installed the hooks)

I wouldn't actually have a big problem with spacing the hooks down the 3/16" on the mounting side (solving all of this), except it looks like that will have them in space competition with the WAAG mount...

Mike
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bartonmd said:
I wouldn't actually have a big problem with spacing the hooks down the 3/16" on the mounting side (solving all of this), except it looks like that will have them in space competition with the WAAG mount...

Mike
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Trying to be funny part below.
WTF
All this talk of 1 degree milling errors, contact patch friction, ANSYS, grade 8 shear strength, vertical axis load deflection, and geometry of edge contact parallel to potential movement is to accomodate a grill guard I do not have ??????

How about owners of Wagg grill guards buy a spacer and/ or a new wheel for their angle grinder and bartonmd builds the rest of us a radiator shield with better geometry, more contact friction, and parallel edges w/o movement?

Just my opinion below.

Hey, seriously though. I realize Mike agreed to accomodate owners of Wagg grill guards and if he said he would he should follow thru. Plus I am very grateful that bartonmd is doing all he is for us. However from where I sit (far, far away from where the work is being done) maybe Trailvoys with aftermarket grill guards and those w/o are two different engineering challenges with two similar, but different, solutions.:undecided Mike's excellent oil pan shield comes in two versions, why not the radiator shield? Mike has already offered Zero a version w/o a radiator brace and has offered forum members with body lifts a plate that stops just in front of the radiator so why not another box that needs to be checked or left blank on the order form, [] Wagg grill guard installed?
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JamesDowning
PAblzr said:
is to accomodate a grill guard I do not have ??????
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That is the secondary issue at hand. The tow hooks don't exactly align perfectly even without a grille guard. The issue is that Mike's skidplate's hook mounting surface is flat, and the hook mounting face is on two different planes. that is what is making it somewhat tricky... not so much accommodating the WAAG.
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bartonmd
JamesDowning said:
That is the secondary issue at hand. The tow hooks don't exactly align perfectly even without a grille guard. The issue is that Mike's skidplate's hook mounting surface is flat, and the hook mounting face is on two different planes. that is what is making it somewhat tricky... not so much accommodating the WAAG.
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PA, I do agree with you... That's the way it may end up being... May even be one with and without cutouts in the ends of the vertical parts, for the factory tow hooks... It's probably more like 10-degrees out, though... it's not something that would deform to be a good mating surface...

James is right, though... The 2 seperate planes are what the issue is... I'll just have to cut on mine, to mount the tow hooks, and see how it works out...

Mike
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Foosh
:undecidedmike, so when are you gonna step up, stop this small one step at a time stuff and just make a kick @$$ metal bumper for us... it'd be a big seller hint hint:m2:
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Zero
bartonmd said:
PA, I do agree with you... That's the way it may end up being... May even be one with and without cutouts in the ends of the vertical parts, for the factory tow hooks... It's probably more like 10-degrees out, though... it's not something that would deform to be a good mating surface...

James is right, though... The 2 seperate planes are what the issue is... I'll just have to cut on mine, to mount the tow hooks, and see how it works out...

Mike
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bro your a great guy offering us a great service. but just becareful and remember. you cant make everyone happy all the time. ya know??

so personaly i would say, dont worry sooo much about making soo many different kinds of rad skid plates. at least not until u have sold a few and got back ur losses.
i just dont want to you or the proj fall apart trying to please everyone and ending up with a part no one wants.

so my 2 cents are to keep it simple. make 1 or 2 versions right now, and get ur cash flow going. then see if there is still a worth while market to add an additional kit. or maybe ull have a v2.0 updated design by then that would be a plate that could work for everyone.

if people are really pressed on getting something special done for their truck, then charge them xtra for the work on the spot. because right now, those of us that dont need these changes, are just sitting and waiting. and by all means, if u want to charge me for the xtra work i may need. then so be it.


its plain and simple guys. look at any manufacturer of anything. they make their part a particular way for a particular application. if your aplication needs something different, then your SOL. or buy what they have and mod it ur self.
after all isnt that what most of us are doing when we convert our rear suspension parts to that of an avalanche or tahoe.



Z
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bartonmd
Zero said:
bro your a great guy offering us a great service. but just becareful and remember. you cant make everyone happy all the time. ya know??

so personaly i would say, dont worry sooo much about making soo many different kinds of rad skid plates. at least not until u have sold a few and got back ur losses.
i just dont want to you or the proj fall apart trying to please everyone and ending up with a part no one wants.

so my 2 cents are to keep it simple. make 1 or 2 versions right now, and get ur cash flow going. then see if there is still a worth while market to add an additional kit. or maybe ull have a v2.0 updated design by then that would be a plate that could work for everyone.

if people are really pressed on getting something special done for their truck, then charge them xtra for the work on the spot. because right now, those of us that dont need these changes, are just sitting and waiting. and by all means, if u want to charge me for the xtra work i may need. then so be it.


its plain and simple guys. look at any manufacturer of anything. they make their part a particular way for a particular application. if your aplication needs something different, then your SOL. or buy what they have and mod it ur self.
after all isnt that what most of us are doing when we convert our rear suspension parts to that of an avalanche or tahoe.



Z
Click to expand...

Yeah, that's kind of where I'm ending up... I think I do need to make it fit some kind of tow hooks (factory are fine, I think), and if it fits the WAAG, then it fits the WAAG... I'll try and get it to fit, but if it doesn't, then the people with WAAGs may have to modify their mounting brackets, or something...

Mike
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Zero
sounds like you got the plan now. id say just make it to fit the factory tow hooks really really well. and like u said great, if it fits waag. if not im sure someone with a few tools a brain and some free time could make it work for their application.
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Zero
so whats the good word???
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bartonmd
Zero said:
so whats the good word???
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The good word right now is a new water pipe from the road to the house, to replace the leaking one... and has been a new radiator on the S-10 blazer that I'm selling, and a head gasket/engine on a Taurus that I'm fixing and flipping, and doing all the fluid changes on my new/used '90 12-valve 4x4 5-speed Cummins, and getting ready for the trip that I was going to take this weekend, except that money is now being given to a plumber to put in a new water line across the yard, and runnind over a 3" tall piece of wood and bending the front wheel of my motorcycle, and finding a used/good wheel for it...

Ya know... the usual...

Mike
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Zero
damn bro!!! now thats news!!! good luck getting ur stuff done!! sorry to hear about ur plumbing problems.
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