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Old August 16th, 2007, 11:55 AM   #1
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Default suspension dynamics?

In a link style suspension:

The forces on the upper links, when accelerating forward, do you think they are important enough to figure into your anti squat values?

example: you have an anti squat value of say 50% and your link seperation at the axle is 8" with the lower at the axle centerline so you have a fair amount of force on the uppers while accelerating forward. with the AS at 50% the suspension will want to compress when the weight of the vehicle is moved by the rear axle but the force pushing forward on the uppers will reduce some of this value.

is it possible that with enough leverage you could see the opposite effect of 50% AS because the upper links are pushing so hard that the rear lifts?

just some of my random thoughts, feel free to add to them.
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Old August 16th, 2007, 12:05 PM   #2
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seems unlikely due to the rear should also be pushing, therefore I'd thing unless your on an obstacle where your climbing with little [or no] traction on the rear, but thats also what will give you good effects on getting traction as you clear a ledge with the frontend.
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Old August 16th, 2007, 12:20 PM   #3
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seems unlikely due to the rear should also be pushing, therefore I'd thing unless your on an obstacle where your climbing with little [or no] traction on the rear, but thats also what will give you good effects on getting traction as you clear a ledge with the frontend.
traction will give you this effect, with no traction on the rear you will not notice your suspension doing anything.

to simplify the discussion, lets say the truck is in RWD and on flat pavement accelerating from a stop.
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Old August 16th, 2007, 12:31 PM   #4
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in that scenario at worse case, if you would loose traction on the rear the effect would drop... sortta like gurnards on a plane. that could be an ill effect. Seems unlikely to happen due to the weight/leverage behind the front axle centerline. I see more issues with steering under said effect.
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Old August 16th, 2007, 12:31 PM   #5
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But wouldn't the lower arms also be pulling down to counter act the twist?
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Old August 16th, 2007, 12:49 PM   #6
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Quote:
Originally Posted by 99grandtj View Post
But wouldn't the lower arms also be pulling down to counter act the twist?
there is almost no pulling from the lowers since they are at the axle centerline, very neutral except for the compression force from moving the vehicle forward.
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Old August 16th, 2007, 12:54 PM   #7
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Ya, just thought about that :miff:

Alot more leverage on the uppers.
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Old August 20th, 2007, 09:01 AM   #8
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anyone else want to chime in?
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Old August 20th, 2007, 09:55 AM   #9
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so dont you add or subtract more or less seperation? that is why i see alot of people making them adjustable. they can put it more or less. i dont really understand the whole theary, i think there is alot of diffrent factors to figure in that change with each rig.
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Old August 20th, 2007, 09:12 PM   #10
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Quote:
Originally Posted by 99grandtj View Post
But wouldn't the lower arms also be pulling down to counter act the twist?
Quote:
Originally Posted by 95geo View Post
there is almost no pulling from the lowers since they are at the axle centerline, very neutral except for the compression force from moving the vehicle forward.
There is absolutely no pulling from the lowers, it's all pushing. Thats what makes the vehicle go forward.

With the lower at the axle centerline and the uppers 8 inches above the uppers will be doing most of the work of resisting the axle torque and will likely be pulling. Whether this adds to, subtracts from, or has no effect on squat would probably depend on the angle of the uppers.
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Old August 20th, 2007, 09:39 PM   #11
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Hmm, 50% is 50%... it still boils down to your instant center and your AS numbers. If you want it to lift, the go bigger than 100%. Its relative, the more force you apply, will also result in a roughly equal increase in force against it in weight transfer.
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Old August 20th, 2007, 09:55 PM   #12
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i just hit it and get it.
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Old September 4th, 2007, 08:18 AM   #13
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If you want to tease your brain for a while, this may help. I've spent many hours with this calculator from the guys at pirate 4x4. http://mysite.verizon.net/triaged/fi...arLinkV3.0.zip
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Old September 10th, 2007, 10:43 PM   #14
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I understand what your saying, but I don't think that the force will overcome that of the links wanting to squat the Jeep. At least enough to notice.
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Old September 14th, 2007, 09:06 PM   #15
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i just hit it and get it.
X2
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Old October 1st, 2007, 06:03 AM   #16
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On a slightly unrelated topic.....

My lowers are about 1.5" above centerline on the axle. there is about 8" of seperation on the axle end and 6" or so on the frame end. I have almost ripped my upper link mounts off the axle, I need to fix this really soon. I also bent the shit out of my upper frame mounts. All of these things are 3/16" or 1/4" steel and designed properly. I have to find out why this is happening. I think doubling the HP and running sticky 37s might have something to do with it
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Old October 1st, 2007, 05:08 PM   #17
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Quote:
Originally Posted by 95geo View Post
On a slightly unrelated topic.....

My lowers are about 1.5" above centerline on the axle. there is about 8" of seperation on the axle end and 6" or so on the frame end. I have almost ripped my upper link mounts off the axle, I need to fix this really soon. I also bent the shit out of my upper frame mounts. All of these things are 3/16" or 1/4" steel and designed properly. I have to find out why this is happening. I think doubling the HP and running sticky 37s might have something to do with it
get rid of those baby tires and get your rig off those rocks..
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Old October 1st, 2007, 05:45 PM   #18
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Quote:
Originally Posted by 95geo View Post
On a slightly unrelated topic.....

My lowers are about 1.5" above centerline on the axle. there is about 8" of seperation on the axle end and 6" or so on the frame end. I have almost ripped my upper link mounts off the axle, I need to fix this really soon. I also bent the shit out of my upper frame mounts. All of these things are 3/16" or 1/4" steel and designed properly. I have to find out why this is happening. I think doubling the HP and running sticky 37s might have something to do with it
Pics of the mounts?

Your running rubber on one end and some sort of johny joint on the other right?
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Old October 1st, 2007, 10:37 PM   #19
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Pics of the mounts?

Your running rubber on one end and some sort of johny joint on the other right?
rubber on the axle end and JJ's on the frame end







if they dont show up they are here: http://www.misfitoffroad.com/phpbb/v...=6951&start=75
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Old October 1st, 2007, 10:58 PM   #20
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I've personally found that trying and not making ledges that are larger than my wheelbase is very abusive on the rear links. That seems to be the worst suspension dynamic I've come across.

I'm guessing that with your new found hp and sticky tires, you've probably subjected the geo to this a bit more frequently than when you first built it.
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