I’m wondering why a 3 link is so much better than a radius arms set up.
I would think that the joints limit atrticulation , not the style of suspension.
or is this mostly a d44 thing..I pretty sure I havent seen one on a D30
just curious
BrettM
08-29-2005, 21:46
3 links (w/ panhard) give much more control over anti-dive characteristics and will bind less than radius arms. the advantage of radius arms is simplicity.
VegasAnthony
08-29-2005, 22:55
3 links (w/ panhard) give much more control over anti-dive characteristics and will bind less than radius arms. the advantage of radius arms is simplicity.
Ok but how does it bind less??
I would think that the binding would be dependent on what kind of links are used at the end of the lower arms
as in RE joints VS heims
like in this pic
sure the joint on top of the diff lets the axle articulate as much as the arms will allow at the “frame end”
but cant the same be said for radius arms?
http://www.xjdb.com/albums/xjs/xj0378.sized.jpg
oh and can ya define anti dive for me ?
Wil Badger
08-30-2005, 03:09
the binding comes in the axle tubes wanting to twist.in a radius arm set up the arms are fighting each other.in a 3 link the axle is allowed to rotate on onside so to speak.
there are ways of fighting this in using a raduis arm set up.if you were to sleeve the short drivers side tube with another tube and placed the arm on the sleeve it would allow the axle to do the same thing and rotate inside the tube on one side.
Roxtar
08-30-2005, 07:05
Radius arms have only the frame end spherical joint (heim, johnie, or RE) moving with the axle end fixed.
With a 3 link you can have sphericals on both ends of the control arms, essentially doubling the ability to twist.
XJ_ranger
08-30-2005, 08:13
the binding comes in the axle tubes wanting to twist.in a radius arm set up the arms are fighting each other.in a 3 link the axle is allowed to rotate on onside so to speak.
there are ways of fighting this in using a raduis arm set up.if you were to sleeve the short drivers side tube with another tube and placed the arm on the sleeve it would allow the axle to do the same thing and rotate inside the tube on one side.
http://bcbroncos.com/store/product_info.php?cPath=24_61&products_id=527
I thought about a 3 link, then decided to keep the 4 link, only i raised the axle mounts ~2.5″ in the process so i could keep my short arms ground clearance…
Dirk Pitt
08-30-2005, 08:27
http://bcbroncos.com/store/product_info.php?cPath=24_61&products_id=527
I thought about a 3 link, then decided to keep the 4 link, only i raised the axle mounts ~2.5″ in the process so i could keep my short arms ground clearance…
Did you raise the uppers too?
How’s it drive?
XJ_ranger
08-30-2005, 09:23
Did you raise the uppers too?
How’s it drive?
yup uppers are also 2.5″ higher
drives fine, need to work out a small steering bug, but other than that - all is well.
see you in Attica on the 10th?
Jes
08-30-2005, 09:31
http://www.xjdb.com/albums/xjs/xj0378.sized.jpg
Why are those lower links bent like that?
Dirk Pitt
08-30-2005, 10:03
see you in Attica on the 10th?
I’ll be there man.
Dirk Pitt
08-30-2005, 10:03
Why are those lower links bent like that?
Isn’t that Matt/WanderingWillys???
4ward
08-30-2005, 10:05
Isn’t that Matt/WanderingWillys???
Yup.
Lawn Cher’
08-30-2005, 10:14
Why are those lower links bent like that?
Just to be wacky.
hackedxj
08-30-2005, 11:01
I run a 3 link with a track bar on a D30 with longer dropped CAs for the reasons BrettM mentioned above, another plus is that it drives and feels more like stock on the road and trail but with a nice ride and excellent flex.
XJoachim
08-30-2005, 15:07
Try ti run a radius arm setup on a D60 and flex it up to the limits. One of your links will rip off the axle, been there, done that. :wave:
Ramsey
08-30-2005, 15:31
but that arm was designed with a dana 30 in mind
XJ_ranger
08-30-2005, 17:45
but that arm was designed with a dana 30 in mind
oh - this argument again…
BrettM
08-30-2005, 19:22
Why are those lower links bent like that?
if i remember correctly, he had a massive failure (I think the upper link broke) and it bent the lowers up. rather than re-making the links he added the plate to regain some strength
VegasAnthony
08-30-2005, 21:30
Why are those lower links bent like that?
I jsut posted that pic cause it really shows what a 3 link looks like
Yea I thought that was kinda funny but Im not one to flame anyone for design
flaws
BrettM
08-30-2005, 21:33
typically when you’re talking about an XJ with a 3-link front, that means 3 basically parallel links and a panhard bar, since there are very, very few people running full-hydro on XJs. That picture is a wishbone, triangulated 3 link. If you’re going to have a steering box and draglink, the best suspension you can run is a 3 link with panhard, the URF version is superb, search for that.
JeepFreak21
08-30-2005, 22:52
if i remember correctly, he had a massive failure (I think the upper link broke) and it bent the lowers up. rather than re-making the links he added the plate to regain some strength
Yup.
Billy
Jes
08-31-2005, 07:55
if i remember correctly, he had a massive failure (I think the upper link broke) and it bent the lowers up. rather than re-making the links he added the plate to regain some strength
That is totally retarded.
XJZ
08-31-2005, 10:32
That is totally retarded.
Hard braking + curved lower arms = SNAP!!
How could you not see that coming?
Gussets seem like such a Band-Aid. Wouldn’t it just be easier to cut the joints off and get some new tube?
Jeff 98XJ WI
08-31-2005, 11:06
In my opinion, Wandering Willys setup used bent arms to clear the “frame” and allow the arms to bolt to the crossmember closer to the frame as compared to the URF design which uses straight arms, but mounts them closer to the middle of the Jeep to clear the frame. Matt also is using the stock lca mounts for his upper wishbone, so the lower arms must clear the stock lca mounts. The arms were also bent for ground clearance. I’m not sure why he added the plate, but I imagine he ended up with some bending of the lower links, so he reinforced them with plate. Jeff
Jes
08-31-2005, 12:26
So, bend the arms to gain ground clearance then add the plate to lose ground clearance.
Dumb.
tealcherokee
08-31-2005, 15:36
typically when you’re talking about an XJ with a 3-link front, that means 3 basically parallel links and a panhard bar, since there are very, very few people running full-hydro on XJs. That picture is a wishbone, triangulated 3 link. If you’re going to have a steering box and draglink, the best suspension you can run is a 3 link with panhard, the URF version is superb, search for that.
thank you!!!! i hate when ppl confuse 3 links w/ other suspension links
cyrus
08-31-2005, 16:26
Please excuse my questions and statements here and correct or in form me otherwise if I am not relizing something. I do understand the concept of radially twisting the axle under extreme flex using a radius arm or “hard arm” style control arm. But if you were to remove, or at least remove one end of one of the two short “arms” on connecting the upper axle mount to the lower cotrol arm or radius arm. Would that not result in basiclly the same manerisms, as far as flex goes, as a true three link? Keepinf in mind this probably wouldnt be wise to run on the road, nut as a trail only rig, this should work, right?
hackedxj
08-31-2005, 16:37
Please excuse my questions and statements here and correct or in form me otherwise if I am not relizing something. I do understand the concept of radially twisting the axle under extreme flex using a radius arm or “hard arm” style control arm. But if you were to remove, or at least remove one end of one of the two short “arms” on connecting the upper axle mount to the lower cotrol arm or radius arm. Would that not result in basiclly the same manerisms, as far as flex goes, as a true three link? Keepinf in mind this probably wouldnt be wise to run on the road, nut as a trail only rig, this should work, right?
I’ve driven both and they definately don’t have the same manerisms. Someone here can probably explain why better than I can.
cyrus
08-31-2005, 16:46
I’ve driven both and they definately don’t have the same manerisms. Someone here can probably explain why better than I can.
What drove differnent about them?
I am in the middle of a long radius-arm build and can and will change my direction if I am convinced that the way I am going is wrong and/or not safe. I am looking for insite, and opinions on both the three link and radius arm. I have found plenty of opinions here, which is good, but not any real discriptive reasons. I can still switch to the three link if needed, but I want to know driving caracteristics.
zith
08-31-2005, 19:12
Figured I’d tack on a question of my own since I’m considering building a longarm setup and trying to decide which route to go.
A friend in my club swears by his 3-link, and I’ll admit it flexes like mad. What’s been confusing me is link separation at the frame side. He has all 3 arms pivot on the same line, making sure that the pinion angle is always pointing to the TC. Wouldn’t this behave almost exactly like a radius arm, except have not have that bind (more flex)?
BrettM
08-31-2005, 19:56
What drove differnent about them?
I am in the middle of a long radius-arm build and can and will change my direction if I am convinced that the way I am going is wrong and/or not safe. I am looking for insite, and opinions on both the three link and radius arm. I have found plenty of opinions here, which is good, but not any real discriptive reasons. I can still switch to the three link if needed, but I want to know driving caracteristics.
I would much rather have radius arms on both sides than on one side and the other with a single lower. The small loss in flex would be worth having even suspension characteristics. When you run only one upper (or wristed arms for Ford radius arms) all the anti-dive properties are transferred to only one side of the vehicle, meaning the suspension and traction will behave very differently with one side stuffed vs. the other side stuffed.
Better is a parallel 3 link (w/ panhard). Make the uppers roughly 75% of the lowers length, and the seperation at the frame roughly 75% of the seperation at the axle and it will function pretty well. If you want to get more complicated you can use the 4 link calculator (found on the Pirate board in Triaged’s sig) and figure out the exact anti-dive.
BrettM
08-31-2005, 19:57
Figured I’d tack on a question of my own since I’m considering building a longarm setup and trying to decide which route to go.
A friend in my club swears by his 3-link, and I’ll admit it flexes like mad. What’s been confusing me is link separation at the frame side. He has all 3 arms pivot on the same line, making sure that the pinion angle is always pointing to the TC. Wouldn’t this behave almost exactly like a radius arm, except have not have that bind (more flex)?
if the uppers and lowers are very parallel (same seperation at frame and axle) then it will be fairly neutral (100%) in anti-dive.
if the uppers and lowers have little to no seperation at the frame side they will have the same anti-dive characteristics of a radius arm.
cyrus
09-01-2005, 04:09
I would much rather have radius arms on both sides than on one side and the other with a single lower. The small loss in flex would be worth having even suspension characteristics. When you run only one upper (or wristed arms for Ford radius arms) all the anti-dive properties are transferred to only one side of the vehicle, meaning the suspension and traction will behave very differently with one side stuffed vs. the other side stuffed.
Better is a parallel 3 link (w/ panhard). Make the uppers roughly 75% of the lowers length, and the seperation at the frame roughly 75% of the seperation at the axle and it will function pretty well. If you want to get more complicated you can use the 4 link calculator (found on the Pirate board in Triaged’s sig) and figure out the exact anti-dive.
Thanks for the insite, that is the best explination I have gotten yet.
XJoachim
09-01-2005, 15:40
I would much rather have radius arms on both sides than on one side and the other with a single lower. The small loss in flex would be worth having even suspension characteristics. When you run only one upper (or wristed arms for Ford radius arms) all the anti-dive properties are transferred to only one side of the vehicle, meaning the suspension and traction will behave very differently with one side stuffed vs. the other side stuffed.
I run this setup and i’m really happy with it. The downside with 2 upper arms connected if you have a 60 in front with 1/2″ tubes is that you will have a big amount of bind in your suspension because this axle will not flex like a D30. One thing has to give and it will not be the axle. You will break control arms, rip off mounts or you limit flex with limiting straps.
It’s simply not possible to run a 4-link with panhard bar and a stout axle like a built 60 without breaking anything if you’re achieving full flex of your suspension. Had to learn it the hard way myself, broke 3 control arms and ripped off 2 mounts until i chose to ditch 1 upper arm. Since then no more problems. :wave:
bj-666
09-01-2005, 16:31
I run this setup and i’m really happy with it. The downside with 2 upper arms connected if you have a 60 in front with 1/2″ tubes is that you will have a big amount of bind in your suspension because this axle will not flex like a D30. One thing has to give and it will not be the axle. You will break control arms, rip off mounts or you limit flex with limiting straps.
It’s simply not possible to run a 4-link with panhard bar and a stout axle like a built 60 without breaking anything if you’re achieving full flex of your suspension. Had to learn it the hard way myself, broke 3 control arms and ripped off 2 mounts until i chose to ditch 1 upper arm. Since then no more problems. :wave:
i don’t agree there has to be something on every axle that limits the droop of the axle to say that with a 60 you will break more mounts is kinda a dumb truth if you have no bind and nothing to hold the axle up to the vehicle it will droop till it is back by the rear wheels. that is the reason for limiting straps to stop the axle from drooping so far that is hurts parts of the suspension in my mind everyone should be running straps because if it isn’t a strap limiting droop it is brakelines shocks etc. all are pieces of the suspension that should not have to handle that load. (this only applys to linked suspension):)
BrettM
09-01-2005, 17:26
I run this setup and i’m really happy with it. The downside with 2 upper arms connected if you have a 60 in front with 1/2″ tubes is that you will have a big amount of bind in your suspension because this axle will not flex like a D30. One thing has to give and it will not be the axle. You will break control arms, rip off mounts or you limit flex with limiting straps.
It’s simply not possible to run a 4-link with panhard bar and a stout axle like a built 60 without breaking anything if you’re achieving full flex of your suspension. Had to learn it the hard way myself, broke 3 control arms and ripped off 2 mounts until i chose to ditch 1 upper arm. Since then no more problems. :wave:
yes, with 2 radius arms, something has to give, that’s what bushings are for. if you’re going to the hassle of putting a 60 in the front of an XJ though, I can’t imagine why not spend the small amount of extra work to do a 3 link w/ panhard rather than running a single radius arm.
XJoachim
09-02-2005, 01:01
With the second upper arm connected and running rubber bushings on all control arms i had a slight wobble on the front. Since every thing else was new i started replacing the rubber bushings with RE joints on the frame side and since the axle side bushings were destroyed i replaced them too. The uppers remained unchanged and the wobble was still there.
The next time out i heard a big bang and the drivers side upper mount was ripped off the pumpkin so i simply removed it. On the way home i noticed that there was no wobble any more. Since i went to hydro assist i don’t even run a steering stabilizer any more.
I replaced the bushings of the remaining upper with polys to limit axle movement and i will in the future replace them with RE joints too.
BTW, i see no advantage to have a 3-link (1 upper arm connected to the frame) instead of running a radius style long arm on one side and a single lower long arm on the other side.
BrettM
09-02-2005, 01:17
BTW, i see no advantage to have a 3-link (1 upper arm connected to the frame) instead of running a radius style long arm on one side and a single lower long arm on the other side.
that’s because you know nothing about suspension geometry 
XJoachim
09-02-2005, 01:33
Why don’t you teach me? :worship: I can not see any advantage, caster change doesn’t affect me off road but my pinion angle doesn’t change like in a 3-link configuration. I’m already at the limits of my driveshaft angles and any dive of the pinion would result in driveshaft breakage.
BrettM
09-02-2005, 01:47
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.
XJoachim
09-02-2005, 02:08
Correct, we don’t have rocks but sometimes some climbs too
http://bilder.jeepcherokee.org/d/4745-2/IMG_4528.jpg
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
09-02-2005, 02:48
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
09-02-2005, 03:04
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
09-02-2005, 03:37
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
09-02-2005, 06:28
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
09-02-2005, 10:35
Hacked, Thanx for the opinion, and your discription. I will give that some thought and leave my options open to the three link.
XJoachim
09-02-2005, 11:33
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
09-02-2005, 13:48
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
09-02-2005, 15:12
Do you think you get better numbers on a 3-link with 14″ of lift?
BrettM
09-02-2005, 21:36
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
09-02-2005, 22:16
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
09-02-2005, 22:32
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
09-02-2005, 23:03
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
09-02-2005, 23:22
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
09-03-2005, 00:42
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
09-03-2005, 01:10
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
09-03-2005, 01:43
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
09-03-2005, 02:10
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
09-03-2005, 12:12
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
09-03-2005, 14:19
You got exactly my point, i have a LP Chevy D60 front and my driveshaft is at its limits.
MaXJohnson
09-04-2005, 22:44
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
the pitching moment that results in squat, dive & lift is always there(100%), based on the location of the sprung mass CG. Your suspension links counter-act (”anti”)the pitching moment to a varying degree(% “anti”) based on the side-view design of the links. 100% of the pitching moment is transmitted to the springs unless your suspension links are designed such that a percentage of the pitching moment is carried through the suspension links. At 100% anti-pitch(squat/dive/lift), the links are reacting to all of the available pitching moment, resulting in no change in compression or extension of the spring. Anti-squat/dive/lift does not change the amount of weight transfer at the axle, just the way it is applied. Too much anti-pitch increases the effective spring rate which is counter productive in maintaining tire contact with the ground.
Goatman
09-05-2005, 08:21
I would much rather have radius arms on both sides than on one side and the other with a single lower. The small loss in flex would be worth having even suspension characteristics. When you run only one upper (or wristed arms for Ford radius arms) all the anti-dive properties are transferred to only one side of the vehicle, meaning the suspension and traction will behave very differently with one side stuffed vs. the other side stuffed.
Better is a parallel 3 link (w/ panhard). Make the uppers roughly 75% of the lowers length, and the seperation at the frame roughly 75% of the seperation at the axle and it will function pretty well. If you want to get more complicated you can use the 4 link calculator (found on the Pirate board in Triaged’s sig) and figure out the exact anti-dive.
This advice is based on……….?
I love it when a front leaf spring guy gives advice about link suspesnsions. I think he should have to post on link threads with a disclaimer “take this advice with a grain of salt, I run leaves all around”.
Yeah, Brett, I’ve been gone for awhile…….but I’m baaaack. :wave:
I do have to say, though, in Brett’s defense, that he has studied link suspensions and has most of the concepts down…….though no direct experince. I get a kick out of him posting on both the link and leaf spring threads.
Goatman
09-05-2005, 09:44
anti-dive is the main thing.
anti-dive is massively influential in affecting how effectively your vehicle puts power to the ground (traction)
This sounds really good, but it’s not true. Anti-dive will effect how a lifted rig with big tires handles on the road, and can (should to a degree) be a concern, but has little to do with trail performance. The forces are minimal at slow trail speeds, and traction, rather than braking behavior, is the real issue.
Few of us have problems with traction in the front on boulder fields or ledges, it’s the steep climbs that make a difference.* Here weight transfer has a large effect, as well as how well the rear axle stays planted. Anti-squat in the rear will have a MUCH bigger effect on climbing performance than how much anti-dive is in the front. Since weight transfer is the big issue, a limiting strap helps out, and will mask any small effect of too much anti-dive/lift/pitch in the front. Basically, running an adjustable limiting strap on the front negates the point of most of these arguments that have to do with traction. Street/road handling is still an issue, though, especially on rigs with tall lifts.
Unloading also has a big effect on traction on steep climbs, and there are many factors that contribute to unloading. Too much anti-dive/pitch can have an effect, but there isn’t always enough traction in the front to get those forces involved. Spring height and spring force at full droop will effect unloading, where the spring can push up too much at close to full suspension extension in the front. In my opinion, too long of an arm can contribute to unloading. The weight of the front axle will pull down on the chassis to some degree, especially when the suspension is at or close to full extension, and the longer the arms are the further back on the chassis this weight is applied, further effecting weight transfer on steep climbs. Of course, again, a limiting strap will change the point at which this weight is applied, moving it much further forward, and virtually negating the argument.
* Front link suspensions inherently climb (in the front) better than leaf springs because the links tend to push the tire into the obstacle, creating more traction.
Beej
09-05-2005, 14:40
More please, I need more…
This is much better than sitting through class…
BrettM
09-05-2005, 18:59
This advice is based on……….?
I love it when a front leaf spring guy gives advice about link suspesnsions. I think he should have to post on link threads with a disclaimer “take this advice with a grain of salt, I run leaves all around”.
Yeah, Brett, I’ve been gone for awhile…….but I’m baaaack. :wave:
I do have to say, though, in Brett’s defense, that he has studied link suspensions and has most of the concepts down…….though no direct experince. I get a kick out of him posting on both the link and leaf spring threads.
1 Point for the Goatman
however, in my defense… I’ve done a lot of study and research (though mostly for rear link-suspensions, since I’m happy with my leafs up front and will very soon be linking the rear).
I’ve seen, ridden in, and drove a good handful of 4×4s with radius arm fronts, single radius arm fronts (one upper), and 3 links. I would personally rate the 3 links a 9 (nothing’s perfect), the dual-radius arms a 6 or 7, and the single radius arm a 3. (if you’re curious, I would rank front leafs a 5) I can’t stand the uneven characteristics of a single radius arm.
BrettM
09-05-2005, 19:09
More please, I need more…
This is much better than sitting through class…
more what? if you have any specific questions someone might be able to answer them.
cyrus
09-06-2005, 02:59
Thanks guys, this has been a very educational thread, even if most disussion was based off personal preference, with some very in depth explinations. I believe I will stay with the radius arms. Simplicity in this case wins. my rig will most likly not see more than a few miles of road time, from trail to trail. Goatman, thanks for the input.
Have a good one guys,
Thanks again for the help.
Beej
09-06-2005, 11:11
more what? if you have any specific questions someone might be able to answer them.Could you elaborate on your rating system above, and explain a bit more detail about how you came up with those comparisons and why? I just want to learn more…
XJoachim
09-06-2005, 12:48
This sounds really good, but it’s not true. Anti-dive will effect how a lifted rig with big tires handles on the road, and can (should to a degree) be a concern, but has little to do with trail performance. The forces are minimal at slow trail speeds, and traction, rather than braking behavior, is the real issue.
Few of us have problems with traction in the front on boulder fields or ledges, it’s the steep climbs that make a difference.* Here weight transfer has a large effect, as well as how well the rear axle stays planted. Anti-squat in the rear will have a MUCH bigger effect on climbing performance than how much anti-dive is in the front. Since weight transfer is the big issue, a limiting strap helps out, and will mask any small effect of too much anti-dive/lift/pitch in the front. Basically, running an adjustable limiting strap on the front negates the point of most of these arguments that have to do with traction. Street/road handling is still an issue, though, especially on rigs with tall lifts.
Unloading also has a big effect on traction on steep climbs, and there are many factors that contribute to unloading. Too much anti-dive/pitch can have an effect, but there isn’t always enough traction in the front to get those forces involved. Spring height and spring force at full droop will effect unloading, where the spring can push up too much at close to full suspension extension in the front. In my opinion, too long of an arm can contribute to unloading. The weight of the front axle will pull down on the chassis to some degree, especially when the suspension is at or close to full extension, and the longer the arms are the further back on the chassis this weight is applied, further effecting weight transfer on steep climbs. Of course, again, a limiting strap will change the point at which this weight is applied, moving it much further forward, and virtually negating the argument.
* Front link suspensions inherently climb (in the front) better than leaf springs because the links tend to push the tire into the obstacle, creating more traction.
Thanks, you second my findings. :wave:
BrettM
09-06-2005, 14:29
Could you elaborate on your rating system above, and explain a bit more detail about how you came up with those comparisons and why? I just want to learn more…
well obviously those are not scientific results, but just the way I feel about those systems. There are obvious simplicity (and cost) factors where leafs or radius arms beat out a 3 link.
3 links are great (when built right, any good idea can be screwed up), they flex great, they follow the travel of the steering, they can be built to counteract engine torque on the body, they don’t unload on climbs, etc.
Radius arms are also pretty good, they flex good enough, follow the travel of the steering, control axle wrap fairly well, are pretty easy to build, BUT they need a limit strap(s) to control unloading, and they need bushings in all then ends so there is a little more play than ideal.
Leafs are cheap and very simple to build, flex good enough, are very stable due to roll-center and interleaf friction, don’t unload on climbs, BUT do not follow the arc of the steering, and can experience axle wrap.
A single radius arm is simple to build, flexes great, follows the travel of the steering, BUT they need a limit strap to control unloading, and the big thing is they make for some scary situations off-camber and otherwise when the single radius arm is trying to flip the rig over to one side. I don’t at all think the small gain in flex between one radius arm and two is at all worth the often scary handling of all the axle’s rotational forces being sent to one side of the Jeep.
XJoachim
09-06-2005, 15:41
First, we did never talk about cost or simplicity, sure nothing beats a leaf setup in those categories, but that’s it.
Second, you may have been sitting in a similar rig but i doubt the suspension was something near than well engineered.
Third, leafs DO unload on climbs but since they do not flex much they don’t unload as much as any other working suspension.
Fourth, a bushing does not provide play, if it does it is defective.
I’m working on my suspension for about 18 months now and i still see some negatives to work out. But nothing extreme, that’s just fine tuning. I want to stretch the wheelbase another 5″ and redesign the rear crossmember but that’s all i plan to do. So bad i’m not able to show you what i’ve done and how it works, maybe i could be able to change your mind.
I don’t know why you’re saying that the single radius arm is “trying to flip the rig over to one side”. What side should that be relative to the radius arm, the same or the opposite? I’m running this setup for more than a year now and i never realized or recognized that.
bj-666
09-06-2005, 20:13
when you apply rotational forces to the tires (throtle/brake) it trys to twist the axle with a single radius arm that force is trancfered to only one side. but on the other hand i see the same thing happening in a 3 link (i’m no expert)
BrettM
09-06-2005, 21:04
this is true, but with a single radius arm you are applying a ton of anti-squat to one side, but with a well designed 3 link you are sending a fairly neutral anti-squat to the one side. You can even engineer it (there’s a specific equation for distance from center of the upper depending on gear ratio and link angles) so that it counteracts engine torque which pulls the vehicle to the passenger side.
XJ_ranger
09-08-2005, 23:33
More please, I need more…
This is much better than sitting through class…
dont you teach the class?

Beej
09-09-2005, 08:09
dont you teach the class?
:DTrue, but good lord, am I boring!
Dirk Pitt
09-09-2005, 09:01
True, but good lord, am I boring!
:speepin:
:laugh3:
jeep_87_cherokee
09-09-2005, 15:00
in the front with a dana 30. is a 3 link with panhard bar able to be used with the lower control arms trianglulated , and does it help for the to be that way or is it just better to keep them parrallel , and would there be a benefit of trianglulateing the lower control arms
All Rovers