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front 3 or 4 link planning....some brainstorming needed

G

gearwhine

NAXJA Forum User
Location
Denver, CO
ok, I've got a roll cage to build before this, but i'd like to know what I'm doing prior to the cage to try and incorporate mounts into the cage and stuff like that.

I've got some idea, and need some help to see if they'll work


basically what I'm looking for.....
- 3 OR 4 link front suspension USING a track bar
- Link mounts tucked up above frame rails

those are pretty much my only basic needs.

Now, with the way I was looking into mounting my lower arms was from the center like of the jeep, in front of the crossmember, NOT on them, i take the crossmember off too often.

Problem is there...I run into mounting problem if they are too be tucked up above the frame rail in the center....they would be mounted off the transsmision....and we don't want none of that.

Now, my plan is to run them right off the inside of the frame rail with a bolt through the rail. The problem I run into there is the links will not be able to points to near stock location...frame rail is in the way. So my thought was to converge them right to the center of the front axle next to the pumpkin. I checked it out and it will clear the driveshaft underneath it.

The problem here is....it gets into triagulation territory, cuasing it to fight a track bar. What is the typical angle you need for a triagulated link system to work?

With what I'm thinking, I will have 32"-34" lower link. converging 15" to the center. little draw up of the angle....ok that pics not working for some reason, but the traingle it makes creates a 63* angle between the link and the axle. So with two links, the angle from link to link will be 180-126 = (((54*))).

Now with that, I need to know if that's too much of an angle to ALSO have a track bar. Will they fight each other too much, or will it be good.

BTW, I want the track bar to stay away from bump steer as I drive this almost everywhere. And I am using all RE joints, and Heims, so there will be pretty much no give at all.

Here is a pic of the driver side lower link placement.

170272_71_full.jpg



now there is more. The upper links. They will be coming straight almsot perpendicular to the axle....no problems cutting through the floor, so i'm not worried about squat stuff at all right now. What I'm asking now is...with the lower links pointed to the middle of the axle, there is not much keeping that axle from shimmying around that middle point....I was wondering if you think one upper(doesn't matter what side yet) will be enough to hold the axle in place. I would think it would be....but then thinking...if I smash the tire opposite the side the upper is on, that's a lot of tension being put on one arm...

I have no problem going to 2 uppers, just wondering what your thought on that would be.

This is a long post, but I've been looking at how I can mount these things, and this is one of my thoughts so far. let me know what you think, and thanks for reading. :) _nicko_
 
You are right.......the way you described it won't work for the very reasons you've stated. Either triangulate the arms or use a track bar, but don't do both. This has been done successfullly many times, don't be afraid to copy someone's design that has already proven to work.

If you're going to use a track bar anyway (which you should), why do you want to triangulate the lower arms? I don't see that you gain anything and you create major clearance issues. I don't see how the arm would clear the driveshaft unless you mounted it low enough, which would then compromise ground clearance.

I see you already have drop brackets. You're going to do a lot of work and see little noticeable difference.
 
The drop brackets suck, I've hated them ever since I put them on. eat up bushings, completely eat up ground clearance...more than "long" arms when mounted up high, and they do not slide over things very well, they just get stuck. no more on that, no drop bracket debate here.

I'm not afraid to copy someone else's design at all, but from waht i've seen, i don't like much thats out there. mounted on the frame, they are way below the frame rail..... on the crossmember...well they're on the crossmember.

for triangulation to work to keep the axle centered, there needs to be a minimum angle involved....that's what I'm asking. I do not BELIEVE(not positive) I would have enough here to accomplish that. The search on Pirate4x4 is down, so i can't find this info out...i will search here right now and see if anyone has that posted up.

The reason I am triagulating is for fitment from where i want to mount my lower links on the frame, not because I want to triangulate them. I want them to fit, but not cause that much of a tracking effect, so i can still use a track bar. If these angles are too much, I will have to mount the links somewhere else....that's about it.

beleive me, the link will clear the driveshaft with minimal loss in clearance, at least the stock driveshaft, any larger diameter, and I may have trouble. I would choose hitting my lower links over my driveshaft any second of the day, so that clearance under there can go to hell. :) Also, I may have trouble if I ever change out the Hp 30. it will never fit with a LP, and if a HP44 or HP60's pinion is lower, it will not fit.

I'm not worried about my exhaust, that's something that can be worked around if it ends up in the way.

jsut remember, I have not yet thought this through much, haven't noticed all the clerance issues yet, if there are any and stuff like that, just getting ideas in my head to work off of. thanks. _nicko_
 
you should copy CRASH's 3 link, it's pretty amazing how he fit it all in. His lowers are pretty normal off the front of the (flush mounted) crossmember, and he has a single upper on the driver's side that's mounted way up next to the tranny, and ties through the floor to his cage. It's all on a HP D44.

I think that mounting to the crossmember is by far the best way to go, but free up your thinking on the crossmember a bit. make it like the Clayton's crossmember where the center is removable allowing you to drop the tranny while leaving the arms in place.

here's a thread with CRASH's setup: http://www.naxja.org/forum/showthread.php?t=26717
 
yes, I saw that and think he did a great job on it, fit it all up beautifully. I WILL mount them to my crossmember if I don't find any other options to get what I want, but that's a last resort.

I have plenty of time to think about stuff and would rather not compromise on some things unless I absolutely have to, and that will take time to figure out all the little things that will make other little things not work correctly. Compromises will be made, but I will try to keep it to a minimum. :)
 
BrettM said:
are you against radius arms?
Click to expand...

haha...yup. :)

I know where this thread will probably go with this...so here are my thoughts before the debate that will most likely begin, begins

I feel even if they can work well and will suit me well, I will still try to be unique and try something different. I am not really against copying others when I need to, but this is something with so much freedom to do almost anything you want where I find blatantly copying something is a diss to myself, much like cheating on a test. You know you'll do well on the test if you cheat, but you (usually) don't because it doens't feel right. Same thinking is involved here.

I could care less if someone tries to tell me to copy one design because it's been proven to work well.....that proven design started somewhere didn't it? I'm not saying something I make will ever be a proven design, or a completely new design that's breathtaking (I can assure you, it wont be :) ), but that's half the fun in this little hobby of mine. Building my jeep, trying different things, not just being able to wheel the poo poo out of it. If it doens't work, oh well, I'll fix it. Just like I read about vintagespeeds 3-link, he re did it 2-3 times before he was happy with it. Beezil and Crash both got rid of their long arms to try something new, and the list keeps going, new stuff will keep coming out.

Goatman, you are very into these "proven" designs. You're telling me to not be afraid to copy another design. If someone told you that and you listened, would you ever have your mid-arm set up that you oh so fondly love.... probabaly not. It's your own design, you built it, and you love it. And that's what this is about to me as well.

sorry that was all deep and stuff, but if you think you have the ability to do something different, why not give it a shot and see what happens?

So back on topic, radius arms are out.

Now...can anyone answer any of my questions? I read ~40* is the minimum for the triangulation to use without a track bar for a single triangulated link susp., but what angle are they measuring, frame to link, axle to link, link to link?

thanks _nicko_
 
gearwhine said:
haha...yup. :)

I know where this thread will probably go with this...so here are my thoughts before the debate that will most likely begin, begins

I feel even if they can work well and will suit me well, I will still try to be unique and try something different. I am not really against copying others when I need to, but this is something with so much freedom to do almost anything you want where I find blatantly copying something is a diss to myself, much like cheating on a test. You know you'll do well on the test if you cheat, but you (usually) don't because it doens't feel right. Same thinking is involved here.

I could care less if someone tries to tell me to copy one design because it's been proven to work well.....that proven design started somewhere didn't it? I'm not saying something I make will ever be a proven design, or a completely new design that's breathtaking (I can assure you, it wont be :) ), but that's half the fun in this little hobby of mine. Building my jeep, trying different things, not just being able to wheel the poo poo out of it. If it doens't work, oh well, I'll fix it. Just like I read about vintagespeeds 3-link, he re did it 2-3 times before he was happy with it. Beezil and Crash both got rid of their long arms to try something new, and the list keeps going, new stuff will keep coming out.

Goatman, you are very into these "proven" designs. You're telling me to not be afraid to copy another design. If someone told you that and you listened, would you ever have your mid-arm set up that you oh so fondly love.... probabaly not. It's your own design, you built it, and you love it. And that's what this is about to me as well.

sorry that was all deep and stuff, but if you think you have the ability to do something different, why not give it a shot and see what happens?

So back on topic, radius arms are out.

Now...can anyone answer any of my questions? I read ~40* is the minimum for the triangulation to use without a track bar for a single triangulated link susp., but what angle are they measuring, frame to link, axle to link, link to link?

thanks _nicko_
Click to expand...

You're missing one VERY big point. I didn't ask everyone else what they thought, or what they had done. I crawled under my rig with a tape measure and figured out what would work the way I wanted it to, and then built it. If you're going to ask, don't criticize the answers.

I understand that fabrication is part of the fun. BUT, even though I enjoy the fabrication, I don't enjoy it nearly enough to do it just for fun. I ONLY fabricate to improve the performance of the rig, and so I can wheel reliably. I also don't do ANYTHING just to be different.......the only thing that matters is what works, and if someone has done it before I'll copy it.

I was where you are now at one point. I did what I did after dealing with the exact issues you're considering..........just one way to make it work.

Have fun,
 
Goatman said:
I understand that fabrication is part of the fun.
Click to expand...

fabbing and suspension design used to be a ton of fun for me......I enjoyed every project I ever started.


but ya know what sucks? Its spending 50 hours designing and building something that gets thrown out after one or two test runs because the shit just didn't work well......

My long radius arm set-up? junk. terrible balance and unloading.

Front suspension design is complicated and DIFFICULT to master, and presents many fabrication challenges. No matter how fun you have designing and fabbing, it is useless to go into a project just for the sake of doing something different. You MUST have a purpose, and you must understand how to build to accomplish your goals. I've seen dozens of rigs with suspension systems that were just thrown at the jeep blindly, with the only apparant function being to locate the axle, and thats it. No performance gains looked like they were ever considered. I saw a rear 4-link design once that looked like a lot of care was placed into it. I asked the owner what his anti squat and rol axis was, and he looked at me like i had twelve heads......what motivates people to throw link suspensions under thier rigs when there are no performance expectations? Is it all cool factor?

It must be.

just a thought or two on the matter.....not directed at anything you said.....just a thought.

Study hard, and best of luck.
 
Goatman said:
You're missing one VERY big point. I didn't ask everyone else what they thought, or what they had done. I crawled under my rig with a tape measure and figured out what would work the way I wanted it to, and then built it. If you're going to ask, don't criticize the answers.
Click to expand...


I think this comment is way out there. I understand what you're saying, but it's just kind of ridiculous to me. I can just as well do that, but I pretty much had 2 technical questions that were in a long slew of blabberings to see if my idea had a chance of working, because I didn't know....still trying to figure out why I didn't just ask the questions straight up, but those haven't been answered yet, so there really no answers here to be critcized, just some conflict of opinions, that's all.

Beezil, I definitely know this will be difficult. I'm ready for all the paper work, reading, and all that cool stuff. That's because I find it so interesting how all this seemingly redundant crap can affect how something works so drastically.

I'm all set up to go to a weigh station and get my exact COG of my jeep from the COG calculator on jeepaholics, just so I know I'm making this for my own jeep, and not someone elses. All I need first is a basic idea of what will work for me to start, and then think and change and think and change until I end up with something. I will try to start with something different, and it might as well just lead me right into copying someone else's.

Nothing will be thrown together here, and If I feel that I am going to end up throwing crap together...well, that's what radius arms are for, aren't they?
 
gearwhine said:
I think this comment is way out there. I understand what you're saying, but it's just kind of ridiculous to me......
Click to expand...

I read in some arogance in your replies to Goat as he apparently picked up on as well. No big deal, everyone on Naxblah is an arrogant a-hole and they all have THE BEST suspension setup out there, especially me! :)

Getting to your question of a triangulated 3 or 4 link with a TB and what angles for max triangulation & etc..........you already have one to measure. The stock XJ front is a semi-triangulated 4 link + TB and is probably about the max as evident by it's somewhat driveable state even without a TB connected. If it was a true non-T 4 link it'd just spit the body off of the axle. when you turned.

If you want to experiment, remove one of your UCAs on your stock front setup, this will be a 3 link + TB. Base your link separation off of the stock attachment points & you'll be golden. And try to make your link angles match the stock link angles on a stock XJ for maximum street behavior.

PS, one of the things I forgot to address, this silly notion that you can mount your LCAs directly behind the axle centerline....... Everyone who's never built a suspension setup will say this is THE spot for your LCA mounts and that you wont lose clearance & blah blah blah. By attaching your TWO LCAs at this point the joint becomes a pivot for the axle to rotate around and ALL OF THE STRESS of braking and accellerating in 4wd is forced to be dealt with by the smaller SINGLE upper control arm (or two in a 4link). The point in designing is to alleviate failure points NOT to enhance them. Your links must SHARE the stresses of braking & accelleration to split the torque loading amongst all of the arms. Thus harmony :yingyang:

-jb
 
this is still a good thread.....

when it gets this individualistic, theyre all good.....

your first question was kinda a statement, but then it was a second guess, so I can see why goatmans reply might have been read as "arrogance"

you were SURE about keeping the tracbar, but then you seemed to entertain the idea of triangulation, but that is really only necessary on tracbar-less suspensions....

so it begs the question.......

are you 100-percent certain yo want a tracbar-type suspension?

aint NOTHING wrong with one, except a MINISCULE points.

if you are keeping your tracbar, then we're done with the "triangulation" discussion all-together
 
thanks for the replys.

to beezil...yes I am against a tracbarless suspension....the only reason the triangulation came up was link placement.....then the question of "is this too much triangulation to have a tracbar?" That has pretty much been established as, yes, it's too much, so that lower link plan is out.


Vintage, I never really thought about the stock set-up as triagulated at all, but yeah it is.

And I'm still pondering about the link placement on the axle thing. I don't believe all the stress goes to just the upper arms. The links are solid, so there will be no stretching or compressing of the metal (so minute, I say none) Say....the upper arm started stretching in tension when you hit the gas in 4wd....you will notice the axle rotating around the bolts of the lower links.
But as you know, the upper does not stretch. Once that's in tension, there needs to be an equal and opposite force, and that will be those lower joints pushing straight on that axle tube centerline. It will cause more stress defintiely, but it's the same type of rotation you would be getting if the link was mounted 5 feet under the axle tube. You are just exerting more force on it and need to raise the upper link attachments even higher. That's my way of thinking about it, hopefully it makes sense.

_nicko_
 
gearwhine said:
I understand what you're saying, but it's just kind of ridiculous to me. ?
Click to expand...

Really? Let's see....

gearwhine said:
I pretty much had 2 technical questions that were in a long slew of blabberings to see if my idea had a chance of working, because I didn't know....

I feel even if they can work well and will suit me well, I will still try to be unique and try something different.

I could care less if someone tries to tell me to copy one design because it's been proven to work well

sorry that was all deep and stuff, but if you think you have the ability to do something different, why not give it a shot and see what happens?
Click to expand...

Now, you're asking us, who have done it, but here's what you say.

gearwhine said:
I'm not afraid to copy someone else's design at all, but from waht i've seen, i don't like much thats out there.
Click to expand...

Ok, enough of that. You're right that there isn't much room to mount control arms inside of the frame rail if you don't want to use the crossmember. I tried to figure out doing the same thing but didn't like the options, which is why I went with mid arms instead of long arms.

The lower control arms usually control the axle placement, and absorb impacts. Locating them in the middle of the axle detracts from both of those functions, especially absorbing impact. I also think that you will have clearance issues with the driveline because of the movement of the pinion during droop. To keep the pinion pointing straight at the t-case, in the same relative position to the LCA's, requires radius arms or something similar. If the links are designed to minimize castor change, then the pinion will be lower relative to the control arms in droop causing clearance issues, unless you mount the arms really low.......which defeats the purpose of trying to design a link suspension with good ground clearance.

IF a center axle mounting location can be made to work, then the UCA's (you'll definitely need 2) will need to contribute to locating the axle and absorbing impact, meaning that they'll need to be mounted much closer to the axle center line than would be normal. This complicates things by having the spread between the lower and upper links too close together, putting extra strain on the joints to resist axle wrap, and very likely contributing to poor anti-dive. Because it's so tight to locate links in the front of an XJ, you'll likely need rubber bushings somewhere to keep the suspension from binding, and the closer lower to upper link placement will increase axle wrap allowed by bushing deflection, and will shorten the life of the bushings.

Hope this is more of the type of feedback you're looking for, :)
 
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