Adjusting anti-squat?

[meatmonkey]

I am building a USA-1 up for crawling (go ahead and laugh, it was free) and have locked out the independant suspension and set it up for dual four links.

What I am looking for with the front suspension may seem a little odd, but I want it to squat on acceleration, alot if possible. This way the truck essentially lowers its CG on traction filled hillclimbs. This should, in theory, make the truck more stable. While this will lower my center ground clearance when on the throttle I feel that since it should have almost five inches it will be worth the tradeoff.

What I am looking for is a guide that says something like "extend upper links to make truck squat", or "raise upper link mount on gearbox to reduce squat". Does anything like this exist? I would really like to try out this theory, so any help is appreciated.

And, by the way, say you make an adjustment to the rear suspension, would making the same adjustment to the front suspension have the opposite effect since the links face the opposite direction?

[SR5Dave]

Well, having too much AS is bad, on steep hill climbs the truck will roll over backwards because all the weight will shift to the back. Having no squat or anti-squat (you're looking for squat right now) Will do very well in hill climbs, because you will still keep weight on the tires, but you won't roll over backwards.

Imagine where the center of gravity is on your truck... Now look at your truck from the side, basically, look at your links and draw a line straight out from them, and find where your uppers and lowers intersect. If that is above your COG, you will have lots of anti squat, if they converge below, you'll have lots of squat. I'll try to find a picture. There are way more variables, but with that you can get a feel for it.

So, to make your truck squat more, you want your uppers to be flat, as long as they're mounted below your COG.

[TwistedCreations]

dave,

for antisquat- you want your uppers up higher than your COG right?

do you want uppers and lowers higher or just uppers?


im gonna try for more antisquat than what i had before on my last tube rig and just want to make sure before i start on the links

[meatmonkey]

I have a couple of questions. What is the effect of your links being parrellel to each other? What if they are parrellel at ride height, but the upper links are shorter than the lower links?

When you refer to the COG, do you mean the COG of the sprung weight, or the entire truck?

[jeep94xj]

General rule...
Axle mounting point has more seperation, chassis mounting point has less seperation = anti squat
Axle mounting point has less seperation, chassis mounting point has more seperation = squat

Here is a link to pirate that will help you to understand more about linked suspensions.

http://www.pirate4x4.com/forum/showt...ension+dummies

[jeep_boy02]

So in other words a dual triangulated Four link gives you both Squat and Anti-Squat which in turn cancels each other out?

[jeep94xj]

Separation and triangulation are two different things.

[SR5Dave]

Originally Posted by TwistedCreations

dave,

for antisquat- you want your uppers up higher than your COG right?

do you want uppers and lowers higher or just uppers?


im gonna try for more antisquat than what i had before on my last tube rig and just want to make sure before i start on the links

Yes, for ANTI squat you want the uppers to be above the COG, because then your instant center will be above the COG. I don't know why you would EVER want antisquat, but thats just me. IMO 95% AS is about perfect, which is the instant center being just below the COG, some weight gets transfered back, but otherwise pretty balanced.

As for if the links are parralel, you get what is called an infinite instant center, I don't quite know how to explain what it does, but its the easiest way to get great dynamics out of your suspension.

For the COG, you are looking at Full curb weight, because all of it gets moved ;)

And as said, triangulation and Squat/AS are totally different, triangulation prevents lateral movement of the axle. Its a good thing ;)

[meatmonkey]

Thanks for the help. I wish I had known about the seperation between the links before I mounted my upper links way up ontop of the gearbox. Well, I guess I will just have to raise my upper links on the chassis.

[TwistedCreations]

Originally Posted by SR5Dave

Yes, for ANTI squat you want the uppers to be above the COG, because then your instant center will be above the COG. I don't know why you would EVER want antisquat, but thats just me. IMO 95% AS is about perfect, which is the instant center being just below the COG, some weight gets transfered back, but otherwise pretty balanced.

i want AS so i don't flip over backwards on hillclimbs,but yet, i dont want a ton of anti-squat so i hop and buck around when trying to climb either. i just want a happy middle. on my last setup, i had my links seperated about 1.5" on both ends, but my top links were mounted lower than my COG. i was also running a softer spring which all together seemed to have a lot of squat altough i was running a dual triangulated setup. so on this one, i will try and mount my top links higher than COG and put my links closer together at the chassis and also run the same length links.hopefully that will give me some more AS doing it that way( hopefully )

if you mount your chassis links using the same bolt/mounting hole for both your uppers and lowers,will that help with AS also

hey beat the meatmonkey sorry to hijack your thread, but to answer one of your questions. if you run your top links shorter, it will change your pinion angle if your running a truck with a driveshaft. most try and run them about the same length. my last setup had shorter uppers and if it would drop completely, it would get the shaft into a bind

[jeep94xj]

[quote="TwistedCreations"]

Originally Posted by SR5Dave

if you mount your chassis links using the same bolt/mounting hole for both your uppers and lowers,will that help with AS also

Can't tell you what it did for A/S as I never ran my buggy set up that way. I was origanally going to run it that way, but after mock up I changed my mind. Pinion angle change was scary looking, and if I remember right it also had a lot of axle steer to it. I wanted to try dobule triangulated and I like it much better! I think dirk would be able to answer questions about setting up the links that was. Obviously working for him.

[SR5Dave]

Originally Posted by TwistedCreations

i want AS so i don't flip over backwards on hillclimbs,but yet, i dont want a ton of anti-squat so i hop and buck around when trying to climb either. i just want a happy middle. on my last setup, i had my links seperated about 1.5" on both ends, but my top links were mounted lower than my COG. i was also running a softer spring which all together seemed to have a lot of squat altough i was running a dual triangulated setup. so on this one, i will try and mount my top links higher than COG and put my links closer together at the chassis and also run the same length links.hopefully that will give me some more AS doing it that way( hopefully )

if you mount your chassis links using the same bolt/mounting hole for both your uppers and lowers,will that help with AS also

hey beat the meatmonkey sorry to hijack your thread, but to answer one of your questions. if you run your top links shorter, it will change your pinion angle if your running a truck with a driveshaft. most try and run them about the same length. my last setup had shorter uppers and if it would drop completely, it would get the shaft into a bind

Honestly, aim for about 95%, you'll be happy. Hell, just try to get none and you'll wind up with some. Try to get your uppers near flat at where you think the COG is, and your lowers can do pretty much anything else. Or try to get it so they both point towards a horizontal line right at the COG..


OR consider this.. they're not real trucks, so it doesn't apply as much ;) Just make it so its adjustable, then you can play with it.

Dave

[TwistedCreations]

alright smartass, i know they're not real trucks i would just like to get some practice doing this right on a smaller scale before i build my 1:1 tube rig since i sold my Yota. i just went and made a few things for the chassis, so all the links are adjustable now. that way i can play with it