New Motobilt 4-Link Suspension

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rasband said:
Where was this said? I do see criticisms of the design from a few of us (myself included, pg1 and 2), but nothing saying you "don't know what you're doing".

For what it's worth you didn't really refute any of those criticisms and instead reject all thoughts/criticisms/ideas/questions based on what you perceive of our experience/profession/etc.
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1st page 17th post in by Fouldplugs

“It surprises me bc I always had the impression that Rob Park (Bender) really knew his shit when it came to design and fab work.”

The whole first page is full of assumptions about geometry when the only part of the suspension equation is the chassis side suspension mounts. The axle ends of the suspension and their mounting locations are up to the end user. Those mounting locations change link angle, Instant center and roll center. So again geometry based on assumptions.
The comments about the mounting points or “hangy down bits” being somehow a rock anchor don’t pass muster either. I pointedly asked for answers on how and where with no explanation. I can’t debate against an opinion that isn’t based or backed with explanation.
There are many different criticisms but those criticisms aren’t based off any practical knowledge and are just opinions. I ask for specifics on terrain or any build parameters so that we could design a rig around a specific goal together as a learning exercise but got no reply.
I have nothing to prove, my resume speaks for itself. I challenged anyone here to post up their own resume to judge practical knowledge so I can word responses tailored to fit each individual question. That didn’t happen.
A comment was made that my background is in building buggies so it somehow doesn’t translate into building Jeeps so I specifically posted a few of the Jeeps I’ve built over the years and somehow got blasted for posting pictures.
invested too much time on this thread already and the kicker was when I posted a picture of a forklift used to cycle the suspension when the vehicle is sitting on its own weight only to be blasted about using a great tool to do so.
Again, I’m debating a topic that I’m more than familiar with to people who don’t understand the very basics.
I could spend weeks on here trying to explain simple things or the basics but why? It seems as though people are happy regurgitating things like “flat belly” with no real understanding of how it works or the thought behind it. One comment even went as far as to say “up travel wasn’t even a thought in this design” when that was one of the biggest.
 
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Fouledplugs said:
How is Cayleb’s TJ I posted not a TJ? What is a buggy type TJ?
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I never said anything about anything you posted.

What this kit is for has now been answered.

I used the word buggy to describe a less streetable TJ. If that's not correct ,oh well my bad.
 
@Bender
You mentioned earlier in the thread that using a flat belly and link mounts mounted high carries a disadvantage…at least, that was my impression. Obviously the new MB link kit uses a stock YJ/TJ/LJ skid location to mount the links and it carries an advantage, could you elaborate on that a little bit?

No one seemed to debate this and it seems that this thread centers around this idea of a flat belly being the end all be all. I’ve noticed a lot of the Ultra4 guys and W.E. Rock competitors dont have flat bellys as well.

Anyone?
 
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Chris said:
If one was going through all the effort of installing this kit, why would you not want a flat belly skid?
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What advantages does a flat belly do for your link geometry? Is there any compromise in geometry if you were to go flat belly? There’s obviously a change, right?

Does wheelbase affect that in a positive or negative way?

Keeping your wheelbase at a stock ~94 with 35’s and going flat and raising link mounts does what to the performance of suspension?

That’s the part I want to understand.
 
Fouledplugs said:
@Bender
You mentioned earlier in the thread that using a flat belly and link mounts mounted high carries a disadvantage…at least, that was my impression. Obviously the new MB link kit uses a stock YJ/TJ/LJ skid location to mount the links and it carries an advantage, could you elaborate on that a little bit?

No one seemed to debate this and it seems that this thread centers around this idea of a flat belly being the end all be all. I’ve noticed a lot of the Ultra4 guys and W.E. Rock competitors dont have flat bellys as well.

Anyone?
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He did go into this a little bit earlier when it was brought up. The belly that he has is intended to keep more clearance between the axles and frame, allowing for more theoretical up-travel than with flat belly holding the frame closer to the axles.
 
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@Bender can you elaborate more on the concept of purposefully using low uptravel so that the closed shock becomes the Jeeps roll center?
 
Fouledplugs said:
What advantages does a flat belly do for your link geometry? Is there any compromise in geometry if you were to go flat belly? There’s obviously a change, right?

Does wheelbase affect that in a positive or negative way?

Keeping your wheelbase at a stock ~94 with 35’s and going flat and raising link mounts does what to the performance of suspension?

That’s the part I want to understand.
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The flat belly doesn’t give the geometry an advantage, it just gives you more clearance.
Belly height can affect geometry though in regards to how it changes the CoG. For instance the higher the CoG, the more anti squat a given link suspension will have. The flat belly poses challenges to getting ideal geometry. That being said, that problem can and is solved by adding a 1.25” body lift which allows the upper links to go high enough for good geometry and climbing characteristics even with a flat belly and LCA mounts that are tucked as high as possible.

If you were to take a given kit with set arm lengths and bracket distances from the axle, the longer the wheelbase is, the worse the geometry would be. For instance a short arm setup is actually worse geometry on an LJ than it is on a TJ. That is why on the savvy midarm, for instance, the LJ kits mounts are further forward of the axle than the TJ.

Raising all our stuff up just gets things out of the way. We want the most clearance possible while maintaining good geometry. Given the trade off, I wouldn’t trade good geometry for clearance though. But again that’s where the body lift comes in. That is what allows us to do things like have a flat belly and raise the LCA mount AND have good geometry. Normally raising that LCA frame mount would make geometry worse, but a body lift allows the UCA to be raised to the tub which compensates for raising the lower.
 
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Bender said:
The comments about the mounting points or “hangy down bits” being somehow a rock anchor don’t pass muster either. I pointedly asked for answers on how and where with no explanation.
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4F4A05AF-4835-4AB1-B4B5-8E7122C69F97.jpeg
 
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Chris said:
Could you make it any more clear? It seems that many in this thread are having trouble with this very simple concept :LOL:
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The black on red is a little aggressive on my eyes. Perhaps a white piece of paper and Crayon would/could be more visually appealing?







And no, I'm not bashing Motobilt's kit. I'm 100% sure that a Jeep with his kit, 43" stickies, king coil overs and super duty axles would be rather potent off road.
 
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Y'all familiar with Ian Johnson and Marvin Stammel? Idk a lot about their builds, other than they appear lcg, is the MB kit similar or achieve similar results?

Because up travel has come up several times, I have a, genuine question.

With regards to crawling, is there really a difference in 3in of up travel vs 6in and upsetting the attitude of the rig when the obstacles are large enough the stuff the tires?

I don't remember the exact wording earlier about up travel and upsetting the rig, but I think this is rhe question I wanna ask
 
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