3 link vs radius arms

[XJoachim]

Correct, we don't have rocks but sometimes some climbs too

I control my front axle with my front winch cable hooked up at the center of the axle on those climbs so i can adjust anti-dive with my in-cab winch control.

The Cs were already turned during the pumpkin swap from passenger to driver side. On the street i have 6° caster and a perfect pinion angle.

 

[BrettM]

a winch cable does not adjust your anti-dive, but it does adjust the ramifications of poor anti-dive

a winch cable or limiting strap is a good idea for radius arms, but it is a bandaid and not as good as actual proper geometry. I can understand you wanting to keep your suspension in your circumstance, but there ARE benefits to running a 3link w/ panhard, they just don't apply as strongly to your type of wheeling.

 

[XJoachim]

OK, besides the unloading of the front on steep climbs (that happens more or less on any suspension type) where are the downsides of the single radius arm style that i run in your opinion and why is a 3-link better than that?

I'm always interested to learn from different opinions but just telling me that something else is better doesn't teach me anything. I want to know why and discuss it. :wave:

I'm far away from a so called "perfect suspension" and if i can make it work better i will get out the welder in no time. :wave:

 

[cyrus]

BrettM; Why would a 3 link unload less than radius arms? I don't quite understand that theroy, or truth. But please explain. Like I stated yesterday, I could still change my direction, but I need to be convince myself of why I should do it, and an in depth explination would be very benificial.

 

[hackedxj]

OK, besides the unloading of the front on steep climbs (that happens more or less on any suspension type) where are the downsides of the single radius arm style that i run in your opinion and why is a 3-link better than that?

I'm always interested to learn from different opinions but just telling me that something else is better doesn't teach me anything. I want to know why and discuss it. :wave:

I'm far away from a so called "perfect suspension" and if i can make it work better i will get out the welder in no time. :wave:

Since you seemed to have an open mind on this disscusion, I'll give my opinion on the differences, and this is just an opinion. I wheel a 3 link with three seperate longer arms and panhard bar, my brother wheels with radius arms with one driver side upper, he removed the passengers side arm because it ate up the bushing on the d30 pumpkin to quickly from binding.For starters, I have less binding, great flex, better center vehicle clearence, mine front end stays lower on climbs, no noticable brake dive, caster works like stock, feels like stock suspension on the road with a good ride, The 3 link will work excellent even with a short lift height, long arm radius style won't. His ride is slightly better and if we put them to a test I'll would say he could drop a coil farther than I can due to his longer arms, which impresses me none.The best way I can put it, my Jeep just feels more "balanced" than his. We done his suspension first, then mine, after driving mine he wants to change his when we get the time. No doubt, both suspension are excellent upgrades but I think more people should take a longer look at the 3link.

 

[cyrus]

Hacked, Thanx for the opinion, and your discription. I will give that some thought and leave my options open to the three link.

 

[XJoachim]

OK, got your point, but what lift height do you have? I'm at about 14" of lift with coilovers f/r and there is no way i can put shorter arms on that thing. And no, i will not remove a single inch of lift. :laugh3:

I still miss the "why" in your explanation, maybe it feels more comfortable for you but why is the 3 link better than a single radius arm?

If i would replace my long arms with shorter ones and go 3-link what would my front driveshaft do (at 14" of lift and again, no i won't loose a single inch of lift) at droop? If you drop your drivers side of the front axle, what does the differential output do? Does it dive? Sure, because you have a shorter upper arm than the lower.

What will your ride feel if you put it to that lift height since your brothers feels better on road now?

Transfer your suspension to a 14" lift height and then tell me again that shorter arms and a single upper long link works better for m and please explain why, i still miss that explanation.

 

[BrettM]

anti-dive is the main thing.

if you ran the numbers on a radius arm with more than a few degrees of angle on it you will see that the anti-dive numbers get real high real quick.

anti-dive is massively influential in affecting how effectively your vehicle puts power to the ground (traction)

 

[XJoachim]

Do you think you get better numbers on a 3-link with 14" of lift?

 

[BrettM]

Do you think you get better numbers on a 3-link with 14" of lift?

absolutely!!

radius arms that are pretty flat (like a stock Ford) aren't too bad, but with the 15+% angle you probably have on your arms the anti-dive numbers will be HIGH. As I mentioned earlier, upper(s) 75% the length of the lowers and 75% as much verticle seperation at the frame as at the axle is a good place to start. If you want to get more detailed (not too hard) get the free 4-link calculator. The version I have (there might be an update) does not have it set up for a front suspension, but you can plug it in the same as the rear and just read "anti-dive" wherever it says "anti-squat". I would shoot for numbers between 80% and 120% and build some adjustability in so you can find what you like best for your terrain.

 

[tealcherokee]

Brett, im really just looking for your help on that, seeing that your the only one that seems to know what hes talking about here

i currently have 28.5" lowers, and stock uppers

im swapping in a full width 44 tmrw, and i want to run a 3 link set up

you say make the upper 75% of the lower, thats like 21", now thats not going to even reach the lower part of the frame, let alone my skid, where id like to mount it to, can u give me some insite?

 

[BrettM]

search for pictures of Goatman's "midarm" 3 link or the URF 3 link on Jes or CRASH's rigs

get creative, make it fit

 

[MaXJohnson]

so you would have to turn the knuckles if you wanted to run a superior suspension, not that big of a deal in the grand scheme of things.

radius arms have very little control of anti-dive (like anti-squat, but for the front) and generally have far too much. a 3 link w/ panhard allows a huge breadth of anti-dive possibilities.

of course the few pictures I remember seeing of your rig aren't on steep rock climbs, which is where good anti-dive numbers are most beneficial.

Radius arms (long arms) generally have a lower anti-dive percentage than typical 3-link and 4-link designs seen on this forum. This is why radius arms usually have better(softer) ride characteristics. Anti-dive, however, is based on deceleration(braking) forces and consequently has no affect on putting power to the ground.

For climbing, discussions regarding the front axle should be concerned with anti-lift, which applies to acceleration. Variations in anti-lift probably have more effect on the dirvers pucker factor (when the nose points skyward) than on actual climbing ability. There is a difference though. The tendancy towards a light front end will result in moving the CG slightly upward and to the rear. This results in increased weight transfer to the rear axle, and therefore, less overall traction. For this reason, a limiting strap can be an effective method of controlling anti-lift forces.

 

[MaXJohnson]

I still miss the "why" in your explanation, maybe it feels more comfortable for you but why is the 3 link better than a single radius arm?

3-link (and 4-link) suspensions allow more design flexibility. With radius arms, the instance-center is fixed(not really an instance-center) at the chassis attachment point. This will generally be somewhere along the lower edge of the frame rail and ahead of the vehicle centerline. With a 3-link or 4-link, you can design the instance-center to be just about anywhere; on the roof, at the rear bumper, what ever you want. This allows you more freedom in determining the amount of anti-pitch (lift & dive). The downside is that the instance-center constantly moves as the suspension cycles. That's why it's called an instance-center. With the IC always moving, the amount of anti-pitch is always changing.

 

[XJoachim]

I was at the drawing board and did some calcs. I see the advantage of the 3-link but the pinion angle change at 3" of suspension droop will be too much for my driveshaft and i already run a high angle driveshaft in front. The control arm angles of a midarm would be not too bad but that's only for the street.

You may have better numbers at anti-dive (or anti-lift) but you would have to limit the suspension to avoid driveshaft breakage and to minimize axle steer during flex (droop).

At a certain amount of lift, i'm actually at about 14" or so, it's simply not possible to run midarm lengths or allow for pinion angle changes to keep the driveshaft alive. I see more downsides in my application than advantages, the anti-lift is controlled by center straps front and rear, my anti-squat is at 105% and i have lots of (usable) flex in my suspension.

The 3-link may have some advantages but i don't think you can use it on a 14"+ lift.

 

[BrettM]

I was at the drawing board and did some calcs. I see the advantage of the 3-link but the pinion angle change at 3" of suspension droop will be too much for my driveshaft and i already run a high angle driveshaft in front.

is your pinion pointing right at the t-case output at ride-height? sounds like either your pinion angle is screwed up or your drawing board version of a 3 link is screwed up. there are plenty of guys running 3 links and getting full travel out of 14 and 16" travel coilovers.

You may have better numbers at anti-dive (or anti-lift) but you would have to limit the suspension to avoid driveshaft breakage and to minimize axle steer during flex (droop).

axle steer isn't much of an issue since it's a steering axle anyways, but regardless, there is no reason a 3 link would have any more axle steer than radius arms.

The 3-link may have some advantages but i don't think you can use it on a 14"+ lift.

I can see why you want to keep the radius arms, and I probably would in your situation. HOWEVER, there are only more advantages to a 3 link when you get into higher lift heights because that's where radius arm geometry goes to crap with no chance of improving it (without dropping the frame mounts) but a 3 link can be very well tuned.





MaXJohnson, thanks, I've gotten into the habit of always referring to it as anti-dive when dealing with a front axle. It's odd terminology anyways, why do people even talk about 80% anti-squat rather than an amount (120%?) of squat... or why not call it lift rather than anti-squat... why not dive rather than anti-lift... why not lift rather than anti-dive... etc, etc

 

[XJoachim]

Brett, at droop the pinion angle will change, the shorter the upper arm the more the angle will change. I call it "pinion dive" because the pinion is rotated down. My pinion is pointed directly towards the t-case output and a pinion that is rotating down would make my driveshaft angles worse.

People using 14" or 16" travel coilovers do not have the same amount of lift, don't interchange the amount of travel and the amount of lift. I can build a rig with 16" coilovers and only 4" lift. I'm at approx. 14" of lift.

The shorter the arms are the steeper are the angles and the more axle steering is there during droop. Since your 3-link arms will be shorter than my long arms there will be more axle steer.

 

[BrettM]

Since your 3-link arms will be shorter than my long arms there will be more axle steer.

where did I say that? there's no reason 3 link arms need to be shorter than radius arms. For 14" of lift I would do a 3 link with arms around 40 inches. A properly designed 3-link will not have issues with pinion dive.

my whole point is that a 3-link w/ panhard (designed right) is basically the ideal suspension for a vehicle using a steering box and panhard (or very low, tight clearance buggys with full-hydro). Radius arms are great for simplicity, but nothing really matches the balance in geometry, adjustability, clearance, (lack of) bind, and flex as a 3 link w/ panhard.

 

[David Taylor]

Three links can run into drive shaft issues. Goatmans DS starts to bind at the CV
at full drop. That's why he unlocks the hubs for fast stuff when he might be air born. That's with a HP axle. The angle's with an LP axle would make getting any travel very difficult with a three link. XJoachim said he had his 60
pumpkin moved to the drivers side. So I'm assuming it must be LP.
If he were to go to really long three link arms that would start to make more issue's.

I run radius arms and like them. I tried removing one upper and didn't like they way it felt. Sloppy is the only way I could describe it. But, that was
with rubber bushings on the axle end.

That being said, if I were to build new I would go with the three link. But we only run aprrox 7" lift around here.

 

[XJoachim]

You got exactly my point, i have a LP Chevy D60 front and my driveshaft is at its limits.