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Another thing

I know this is listed in other threads but it may be good to put into this one. How to measure COG, do you just weigh the suspended part, or the entire vehicle? What do you guys do to find the COG? Do you measure the COG at the current height or the projected post lift height?
 

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408_jigga
did you make your upper bushings with the threded ends or buy them? if you maid them sweet job and what did you use to make them
if you bought them where at?:D
 

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Great info strangerover, you're explaining this WAY better than I can...

Try explaining this one... I think I understand it, but not well enough to explain it.

We've all seen the situation on the trail where a rig is off camber and "flexxed out" and everytime the driver touches the gas, some combination of squat and roll takes place, making the rig want to drive itself right over into a rollover. What suspension features cause this, and what can be done to minimize it?

Also, for those who do not understand calculating anti-squat, here's a good picture:



keep up the good tech guys!
 

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Re: How about some info on front link suspensions?

????? said:
When designing the front should you make all your anti squat and roll axis measurements based on the same point (COG), obviously the distance would be shorter to the COG from the front than the rear (in a jeep or truck type anyways). Does that matter? Do you just make the links accompany this shorter distance or do you make the links the same length as the rear links? Should the front have similar anti dive/ dive or more/less than the rear? Should the roll axis be equal to, greater than or less than the rear? Any other info on a front link susp that would compliment the rear would be great.:idea:
I dont think you can use the same design parameters when building the front links. The concepts of squat or antisquat only apply to the rear links when you are under power and gong forward. The only time the front links would cause any squat/anti squat would be if you put it in reverse and hit the gas, or if you like to go backwards up hills, correct? If so, then what are basic rules of thumb for the front links?

I would think that roll center would be a consideration, as well as some amount of symmetry with the rear setup to have similar articulation.
 

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What I was thinking about the front is; In 4wd the front will pull put does it put the same type force that causes squat as the rear? Also when using the brakes, that's seems like it's basically the exact opposite as giving it gas so you could design the suspension to not dive when applying the brakes, no?
 

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????? said:
Also when using the brakes, that's seems like it's basically the exact opposite as giving it gas so you could design the suspension to not dive when applying the brakes, no?
yes,its called anti-dive and thats all i know bout that.

hands down this is the best suspension thread ever. i have learned alot.
 

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HEREA A ??? FOR SOMEBODY.

AIRRIDE SAID IF THAT YOU SHOULD MOUNT THE LOWER LINKS ABOVE THE AXLE BECAUSE THE GOOD EFFECTS OBVERWEIGH THE BAD.

SO HOW DOES THAT MESS ALL THE DIFFERENT FORCES TAKEN INTO CONSIDERATION?

I KNOW THE AXLE WOULD PUSH ON THE LOWERS ROTATING ON THEM AND PULLING THE UPPERS .CORRECT???

THEN WHAT WOULD CHANGING THE UPPERS EFFECT???
 

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71RCKCRZR RYAN said:
HEREA A ??? FOR SOMEBODY.

AIRRIDE SAID IF THAT YOU SHOULD MOUNT THE LOWER LINKS ABOVE THE AXLE BECAUSE THE GOOD EFFECTS OBVERWEIGH THE BAD.

SO HOW DOES THAT MESS ALL THE DIFFERENT FORCES TAKEN INTO CONSIDERATION?

I KNOW THE AXLE WOULD PUSH ON THE LOWERS ROTATING ON THEM AND PULLING THE UPPERS .CORRECT???

THEN WHAT WOULD CHANGING THE UPPERS EFFECT???
everything is pretty much the same, just the forces on the links are greater.
 

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The urban wheeler said:
find a Peterson's four wheel drive issues june and july great write-up's and details on the need to knows. just my .02

-Grant
the Petersen's article is good but it is very basic and geared more toward links suspension in general and not just rock crawling link suspension.

IE the upper links being a lot shorter than the lower links. what they and Strange Rover say is true but it is much more true in street suspension than long travel RC suspension. Like I said in the other 4-link thread the lower links dominate the AS to the point that the upper links have little effect on AS during extreme travel situations.
Also were I wheel you need all the drop out you can get and the only way to get enough is by having the pinion rotate up(not down) as the axle drops out.
 

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Air Ride said:


everything is pretty much the same, just the forces on the links are greater.
Exactly. The force is greater on the LOWER links specifically, since they are closer to the axle.

And if your lowers are built tough enough to be able to take a beating on the rocks they'll get dragged over, they'll also be plenty strong enough to take the extra forces exerted on them due to their geometric location. :)

The forces on the upper links is proportional to their distance from the lower links (vertical separation). More separation means less force that the uppers have to endure, and better axle wrap control.

More separation also generally means your top links are higher, which also makes your roll center higher (for link setups triangulated at the top of the axle, i.e. top triangulated 4-link or top wishbone 3-link).
 

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This is my current design set up for my new EB project. I am sure it is not perfect ( because I have no REAL clue except common learning sence) but is close I think. I have designed in enough adjustment that every thing should work I hope.
 

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:confused:

I UNDERSTAND THE LOWER LINK WOULD GET MORE LOAD BUT THE UPPER???WOULDNT THE UPPER WANT TO PULL BACK INSTEAD OF PUSH FORWARD.

WITH THE LOWERS LEVEL WITH THE TUBE MOST OF THE FORCE IS APPLIED TO THE LOWERS RIGHT??? WITH THE UPPERS JUST CONTROLING AXLE WRAP WITH SOME BUT NOT A LOT FORCE APPLIED RIGHT???
WITH THE LOWERS ABOVE THE TUBE DOESNT THE AXLE WANT TO PIVOT ON THE LOWERES AND PULL BACK ON THE UPPERS??

IF IM TOTALLY WRONG DO YOU HAVE A DIAGRAM SO I CAN UNDERSTAND THIS??
 

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And the top view.
I also started with the peterson's write up and have adjusted 10-15 times from their to get where I am now. Check out my post "4 link and frame (with no cad skill)" And you can see what changes and why I have made. Alot of the corective info has come from the guy on this post. Again thanks guys for the help!!
 

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rokcrln said:
This is my current design set up for my new EB project. I am sure it is not perfect ( because I have no REAL clue except common learning sence) but is close I think. I have designed in enough adjustment that every thing should work I hope.
that set up will work better than most. Looks good.
 

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71RCKCRZR RYAN said:
:confused:

I UNDERSTAND THE LOWER LINK WOULD GET MORE LOAD BUT THE UPPER???WOULDNT THE UPPER WANT TO PULL BACK INSTEAD OF PUSH FORWARD.

WITH THE LOWERS LEVEL WITH THE TUBE MOST OF THE FORCE IS APPLIED TO THE LOWERS RIGHT??? WITH THE UPPERS JUST CONTROLING AXLE WRAP WITH SOME BUT NOT A LOT FORCE APPLIED RIGHT???
WITH THE LOWERS ABOVE THE TUBE DOESNT THE AXLE WANT TO PIVOT ON THE LOWERES AND PULL BACK ON THE UPPERS??

IF IM TOTALLY WRONG DO YOU HAVE A DIAGRAM SO I CAN UNDERSTAND THIS??
I am not sure about the link leverage but in life you are correct. This is why Air Ride said to make the brackets stronger and don't worry about it. With the lower above the axel housing it does create alot more force on the uppers from plain simple leverage. Now if you want to get rid of this just mount your lowers 1" off the gound and cut the upper force in half! Since this will not happen in rock crawling then go with Air Ride's thinking ( or fact, I have no idea) and mount just above the axel housing and gain ground clearance as well as a better angle for that convergance thingEE.
 

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Air Ride said:


that set up will work better than most. Looks good.
From the clueless (me) to the clued in...Thank you for the help. If I draw it enough I should get lucky right. I think their are only 1,956,895,893,001 combinations and I am at 15:D
 

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71RCKCRZR RYAN said:
:confused:

I UNDERSTAND THE LOWER LINK WOULD GET MORE LOAD BUT THE UPPER???WOULDNT THE UPPER WANT TO PULL BACK INSTEAD OF PUSH FORWARD.

WITH THE LOWERS LEVEL WITH THE TUBE MOST OF THE FORCE IS APPLIED TO THE LOWERS RIGHT??? WITH THE UPPERS JUST CONTROLING AXLE WRAP WITH SOME BUT NOT A LOT FORCE APPLIED RIGHT???
WITH THE LOWERS ABOVE THE TUBE DOESNT THE AXLE WANT TO PIVOT ON THE LOWERES AND PULL BACK ON THE UPPERS??

IF IM TOTALLY WRONG DO YOU HAVE A DIAGRAM SO I CAN UNDERSTAND THIS??
Yes, that's correct. In all forward-driving situations, the uppers will pull back compared to the lowers, no matter where the lowers are located. As Air Ride was saying, changing the locations just changes how MUCH.
 
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