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I am trying to PROPERLY design a 4 link rear suspension. I am confused on if or how the math or measurements change if a 404 portal is thrown into the equation. Do I mathematically calculate with a larger tire size to compensate for the hub "lift"??? If my plan is to run 40s. Do I do the math for 45"s??? I am just a little lost on this.

YES I DID A SEARCH. But I was kinda Wolfgang would know this since he is a master in this, i think!!!
 

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this will be interesting, as I dont think many have considered how a portal box will effect suspension geometry.



People will actuall have to think, rather than just spouting off some BS that they have read somewhere else. :D
 

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Here are some Mog portal pics I took at RCAA since I will be doing the same thin soon in the rear of my rig.

They all told me to make sure my lower links were STOUT. No other calculations were talked about, just make them STOUT to deal with the leverage of the portal.
 

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In your first pic nolen have you got any more close ups of the steering, i know the mogs normally have it under the pinion, but the steering appears to be way high on that one and out in front?!?!?!

also the one you posted larryboy the steering is out behing the axle (out in front) but not as high.... is someone making high steering?
 

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Scraprock-

I am definately not the pro, but I did a couple drawings here (freehand) and I see your delema..... All I can say is, logically, it seems that you should add the vertical height that the portal box gives you to the height of the tire (radius) when calculating. I would think that the AS would put its' effect into the axle housing where the torque of the rotating pinion gear is, and not down at the hubs, and therefore the calculations should be made at that height. Just my thoughts, could be wrong.... Interesting thread...... good luck.


Ryan
 

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without thinking, and spouting shit off the top of my head

roll axis and such is still defined the same way, you just need to compensate for the increased load that the portal gives you aka the stronger links.

to properly designing it you need to take a look at the foces due to acceleration and see what they do to the vehicle
 

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scraprock said:
Do I mathematically calculate with a larger tire size to compensate for the hub "lift"??? If my plan is to run 40s. Do I do the math for 45"s???
What math? Oh, are you just doing it like they say to in 4W&OR magainze? :confused:
 

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We have some swedish midsize monstertrucks with the mog portals and the leverage makes them a bit tricky to figure out. They upper links seem to take more of a pouding than in a non-portal setup, having to do with the reverse force-thingy at full throttle...:confused:
If not with completely neutral caster when hitting the ground you will build some additional stress transferred to the links, and with portals this effect increases. And with some pretty normal caster the upper links will suffer the most.

Either way, I would not change anything fundamental - that would require alot of thinking - just keep it simple, beef it up a bit and I think you'll be fine. GL!
 

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I'm not sure what calcs you are doing that figure in wheel size. The portals can affect the Instant center and roll center calcs because of the added height of the links on the axle. This can bee addressed some by link placement.

The thing you have to really account for is the added leverage of the axle because of the height above the centerline of the wheel. Like others stated above build strong links, and link separation at the axle is important. I would try to get the lowers as close as you are comfortable to the wheel centerline without sacrificing too much clearance.

I know you didn't mention it, but read up on issues you will face with drivetrain clearance, esp the engine. In stock form 404s are not so friendly to oilpans and such on low a slung chassis (if thats what you are building)

I have several pics of my buildup on my site, click the link in the sig.
 

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I am building a nine inch/mog hybrid with dual triangulated links in a YJ. I have the rear done and the links in place. I went with 8 inches of vertical seperation between the uppers and the lowers. I couldnt go any higher above the axle because of clearance issues with the Jeep tub. I cant comment too much because it hasnt been driven yet, but looking at the picture of that higher stress wishbone link suspension in the above pic, I think that mine should be okay.

As for link geometry, I modelled it without accounting for the portals. The angles are nice and flat at ride height.

(I hope)
 
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