Offroad Trailblazers and Envoys

trans skid

Any special projects involving a decent amount of fab work (bumpers, sliders, roof racks, etc)

by v7guy » Sun Aug 11, 2013 7:03 am

gotcha, thanks for the suggestions!


and for James, and anyone else...



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by bartonmd » Sun Aug 11, 2013 8:35 am

JamesDowning wrote:
bartonmd wrote:All it will do is keep the flanges from folding under pressure.


AKA buckling


correct, thank you.

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by ErikSS » Sun Aug 11, 2013 1:34 pm

bartonmd wrote:To be honest, I don't know what I'd have that angled crossmember in there. What that does is take out 1.5" that the skid can flex before it hits the trans pan, and it doesn't add a whole lot to the strength of the skid. The ones that add all the strength are the ones at the sides. What would be as strong as anything, would be to gusset the side strips, so they don't fold over and lose strength when the skid is hit.

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This is the kind of thing that I gain the most from on this Forum. I would find the x concept to add the Most possible strength to the skid. However, I've installed some of Barton's product and therefore aware that I should take his advice seriously. lol I believe in the gussets, and understand his point about the 1 1/2" reduction. I'm picturing something hard hitting it in the middle buckling it even with gussets if you don't have anything going across it.
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by bartonmd » Sun Aug 11, 2013 3:58 pm

ErikSS wrote:
bartonmd wrote:To be honest, I don't know what I'd have that angled crossmember in there. What that does is take out 1.5" that the skid can flex before it hits the trans pan, and it doesn't add a whole lot to the strength of the skid. The ones that add all the strength are the ones at the sides. What would be as strong as anything, would be to gusset the side strips, so they don't fold over and lose strength when the skid is hit.

Mike


This is the kind of thing that I gain the most from on this Forum. I would find the x concept to add the Most possible strength to the skid. However, I've installed some of Barton's product and therefore aware that I should take his advice seriously. lol I believe in the gussets, and understand his point about the 1 1/2" reduction. I'm picturing something hard hitting it in the middle buckling it even with gussets if you don't have anything going across it.
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The issue is that it's 3x as long as it is wide, so even with the side flanges and no cross flanges, if you hit it in the middle, it's still going to buckle front to back. Yes, an X would make it stronger, but what does a skid really do? It minimizes or eliminates damage to your vehicle from hitting or sliding on an object. There are a lot of contacts where it would be fine with just side flanges, then there are a few where the X could make the difference between contacting and not contacting the trans pan, then there are a whole other set of impacts that will cause the skid to fail, either way. So, knowing that there are a whole set of contacts where the skid will fail either way, do you want a flat plate contacting your trans pan and spreading the load (more or less) evenly across the pan? Or do you want an "X" or a cross brace to put a bunch of concentrated pressure in one spot on the pan, kinking or cutting it and causing it to leak and/or break the filter (causing you to suck air, have little to no drive, and probably ruin the trans if you run it after that)?

The bottom line is that no skid will protect from everything, but when it does fail, you want it to fail in such a way that there is a better outcome (load distributed across pan, rather than a rock crushing the corner and causing it to leak, but otherwise be drivable) vs. making something that would likely make a worse outcome (cutting pan in half and breaking filter tube off flush from a cross support hitting the pan, vs. said rock just crushing the corner of the pan and causing a leak).

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by v7guy » Sun Aug 11, 2013 6:05 pm

We debated its failure for a bit, and there's about 3 1/2" between the diagonal brace and the deep pan. I think by the time the skid came up far enough to hit the pan it would have either bent the frame where it's mounted or sheared the bolts that mount it. The same event would also very probably destroy your trans pan without it though too. But if it did totally fail and the skid was flat under the pan it may help you slide off whatever you're on instead of folding/bending/puncturing the pan. For guys that haven't popped off the pan, the filter literally sits on the floor of the pan, it wouldn't take a tremendous amount of damage to the pan to starve the transmission of fluid.
I really wanted to use 3/16" for all the bracing but again, it primarily ended up like it did due to impatience lol. In my long rambling reply earlier I was trying to explain why it ended up the way it did. I'm not sure if it came off that way or not, but that was my intent. I badgered Matt to give me more time for most the evening but he wasn't having it. lol

I know Matt has jacked up the entire truck with the trans skid, so it'll take the weight of the vehicle, not a perfect test since coming down on something while moving is going to give you much much higher loads into it, especially if it's pointy instead of flat-ish.

I think the next one I'll probably build without the diagonal or a cross but with generous gussets from the edges of the skid that end around an inch or two from the perimeter of the pan. Mike has never steered me wrong yet and I appreciate the input a lot.
I imagine it should also be a good bit more sturdy if it connected out to the frame rails so if it does start to buckle it's pulling in tension from the sides instead of just relying on the gussets and flanges with bolt point front and rear. Obviously there is the cat issue we talked about in the other trans skid thread though.
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by ErikSS » Sun Aug 11, 2013 6:46 pm

:Iagree:
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by mikekey » Tue Oct 01, 2013 1:13 pm

Did you ever get those dimensions?
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by Moots1288 » Tue Oct 01, 2013 1:48 pm

mikekey wrote:Did you ever get those dimensions?

He did have it drawn on the steel and a picture of it.. I don't know if he posted it though
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by mikekey » Tue Oct 01, 2013 2:03 pm

Yeah, it's there, I had a noobie moment.

What's the thickness of the steel you used?
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by Moots1288 » Tue Oct 01, 2013 2:23 pm

mikekey wrote:Yeah, it's there, I had a noobie moment.

What's the thickness of the steel you used?

3/16ths
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by Moots1288 » Tue Oct 01, 2013 2:24 pm

You should be a badass and make it 1/2 plate haha
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by v7guy » Wed Oct 02, 2013 1:07 am

Yeah, virtually everything I've done is in 3/16" plate, I think Mike mentioned it works out to 7ga. that's what he seems to use as well.
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