Project MULE - Expedition build on a 1991 1500 4x4 Suburban

Wh1t3nukle

I gotz dis
Impressive running this large of a rig. It definitely has it's advantages for the storage capability. Good on you to share the experience. I saw the impact on the charcoal canister change as it seems related to your mpg. Can you break that down a bit more in depth? Just a OEM replacement from the auto parts store, is that correct understanding?

I like the slider design with the main rail and the kicker. It's a pretty robust setup for years. I do have to comment in kind with the other's concern regarding the runners (frame attachments). I follow about connecting them to the pinch seam. What I don't follow is the comparison between an XJ to your Suburban. XJs have to use the pinch seam b/c they lack a frame. Your suburban is a body on frame, just like fullsize trucks and other SUVs. Just as others have stated, you'll lose the rocker even if you are glancing off something given how much the Mule weighs. Running the bushings on the frame is asking for trouble on top of the lost rockers. I don't know, perhaps none of us are seeing it clearly. Ultimately, it's your choice and people would like to seem some sound rationale. Additionally, fullsize rigs need to keep in mind how much the frame will flex in the event that have the weight is resting on the slider. If the slider is not offset enough (e.g., .25"), then the slider will come into the rocker.

Here's a Sequoia that I spec'ed out and installed the main rail (similar to yours and kicker coming). The clearance in the photo is hard to see but it's little more than .25". The runners are closer. It was tested on a floor jack (unladen) and came within 1/8", all frame flex. But this is not a crawler or anything and how it's driven needs to be considered.

IMG_20130821_165921_949_zps215ec5eb.jpg


Here's an old picture just after install on my dodge. I clearanced off the width of a tape measure. :)

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Both rigs have 3 runners per slider.

Again, just trying to echo concerns and looking to see how you'll end up going. I wanted to show my stuff only to show I've got some of this under my belt and don't proclaim to be an expert.
 

PMA4x4

Adventurer
I guess it could be hard for some to understand. Coming from the crawling world I am used to seeing body punishment. I have seen what works and doesn't. Drivers over on CK5 (Fullsize Chevy forum) have done all three styles of mounts. Body only, frame only and the combo. all have worked. The one maybe weak one is the body only mounted but what that typically involves is two flat plates going straight up into two body braces and the entire slider is only connected at the ends.

I do like how yours are mounted on the Dodge with some serious box iron. I am still not locked in on the pinch seam deal. Just seeing the picture of your Dodge I am going to take some more measurements underneath. Nothing will be welded to the frame though. Whether I go with the bushing idea or a flat mounting plate for frame only everything will be bolted.

The flex does have me concerned being how long the suburban is but I want to make sure if I get in a tight spot I can come down on the slider or pivot around a rock on it if needed.

Ignore the rest of the video but this is the end result I am looking for. You come down on the slider and nothing happens. The guy in the video is not the best driver but I wanted to show a fullsize with sliders. I can find jeeps all day long on Youtube
http://youtu.be/DLgueo925OE?t=24s

Ok, I just found a production set of sliders for a Tacoma and that uses both pinch and frame with NO bushings.
http://www.youtube.com/watch?v=eaP3mROha3w

True, the XJ is a unibody but the fact is with the sliders being bolted along the entire pinch seam that distributes the impact keeping the body from buckling. I also stood on it and have had to hilift off of it. What I may do is actually take some measurements and then go flex it out and retake the measurements. and see what I am looking at. I will purposely max out the suspension but it's my intention to avoid such obstacles.

It's entirely possible people maybe misunderstanding my intentions. I want a rock crawl style beefy slider but I don't intend to rock crawl.
 
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98dango

Expedition Leader
I like your idea but.is see a pinch weld mount causing more damage than saving. Your suburban is not far off the ground so it will likely rub on water bars or.the ocasinoal stump.
 

Wh1t3nukle

I gotz dis
Sorry PMA not meaning to tread on your idea. I am interested in seeing how you implement it. This really hasn't anything to do with rock crawling in particular. It's the same issue...weight distribution and protection. You weighing (a guess) in at a modest 7K is something to consider. I will say I can see what you'd like to implement with the pinch weld. I'm just envisioning that small inch-ish in height material as not enough and that it will be more prone to bending. To your credit with this though, the whole idea of mounting to the body is to distribute the weight entirely. Great example are the Poison Spyder rails for Jeep JK where it's effectively a channel. The key here is that the channel has large surface area. Perhaps that (I hope) will be your method, in some way similar, to attain alot of surface area contact.

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Additionally, I do see the context of the bushings on the frame from the earlier picture you referenced. It allows the body and frame to move independent, albeit a slightly, in the vertical direction or they can separate some. It maintains stiffness in the lateral direction (passenger to driver direction) but has some give in the up/down. The load is diminished some back to the frame. I'm just trying to explain based on what is shown in the picture, so I may be missing something due to not seeing the system.

In addition to the frame flex and considering your desire to bolt to the frame, which is not problematic, however should be taken with care. I'm not saying this with the thought you don't know as evidenced by your research. Bolting through the frame is properly done by boxing the inside of the frame if it's open channel, followed by drilling the holes and then sleeving those holes for the bolts. Last piece is a welded on frame stiffener. Bolt size and torque values play a role as time goes on where rattling can develop due to loss of preload. The strength of the frame is in the flange, not the web.

Here's what was done for a FJ40 using MetalTech sliders (I think) for a friend of mine.

Welded gusset plates. We added the hole such that the interior portion was welded and no separation could occur.

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Runner attached

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Before lift clearance


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Lift test, both wheels up.

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Loaded and within about 1/8", however that bracket can be clearanced more. :)

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Note only 2 runners here and we changed from the 1.5" .120 wall tube to 2x2.188 square tube. That movement is all frame flex and it doesn't help open channel on the inside.

We used the same setup for the Sequoia but with 3 runners.


Here is the frame reinforcement used on my Dodge and all material is 3x3x.188 square tube.

IMG_20120401_094124.jpg



Looking forward to your progress as it will be unique to me, at least. Perhaps I'll be able to help a bud with their Burb and this will come to mind. Apologies for coming off over-critical. Lastly, I'm still interested in my questions about the evap can change. Thanks
 

PMA4x4

Adventurer
Thanks for the info and pics. Always good to get more input. I just want to be clear you know I will have a 1.75" tubing and 2x3 box iron below and protecting the pinch seam right, not just that 1" square tubing? I had one guy on another forum think I was bolting 1" square tubing to the pinch seam and using nothing else at all thinking that was my slider!

I cant remember if I said it here or on another forum on same subject but I plan to take the burb out and flex it as much as possible and take some measurements.
 

98dango

Expedition Leader
My 78 sub the po (muddytaz on cok5) built the slider 2x4and 1.75 tubing bolted to the pinch weld and run to the frame. I still bent them and they would flex. I'll see if I can find pictures.
 

PMA4x4

Adventurer
Do you have any pictures of them bent or how you mounted them up? those two pics are kinda small and far away.
 

98dango

Expedition Leader
That's the best I have on my phone. I can tell you I was hunting slid in to a stump and could not open either pass door till i cut the slider off. I had to beat the door seals back to use them. Honestly it ruined the truck for me that or hearing the GF complain every time she tried to open the door. I know you don't plan to rock.crawl with it but a poorly mounted slider can cause more damage than not having one at all.

I would just hate to see you bash a very nice truck for the want of $20 in tube and 10 lbs of weight.

My rule of thumb any more if I cant hold the truck up with it I'd rather it not be there. I still have the tube steps on my superduty because I have grown lazy in Az.
 

PMA4x4

Adventurer
I wish they were 10lbs They are around 40lbs a side so far.

So you had them bolted along the entire 7 feet of pinch seam? with how many bolts?
 

bigtrkltltrl

Observer
I love your build. I am taking a few of you ideas if you don't mind. On a side note. I had some sliders fabed for me and they look good but the frame flexes so much on a light hit it contacted my pinch seam and deformed them just a little bit. But for your type of wheeling it should be fine. After reading this I am tempted to lift my truck and see HOW much flex I get. But I am sure I will be ticked. I already was when I went to a local offroad fabricator to make them. He saw the truck and still made them out of the wrong material. I have 3 support tubes welded to the frame.
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Wh1t3nukle

I gotz dis
^What is the wrong material here? Rig looks good mang!

Have you considered cutting the pinch around the runner to clearance? You a cold chisel or similar to bend away, similar to this done on the Sequoia (the owner's choice, not mine).

IMG_20130821_181148_623_zps6b1db131.jpg
 

bigtrkltltrl

Observer
I found another local fabricator and he saw them before I installed them and he laughed. He said he wouldn't install them on his lawnmower. J don't remember the material. But he said they would crumple like beer cans. As per clearance of the pinch seam I figured I would let the truck make the clearance it needs.

Thanks for the compliment on the truck.


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