OK lads, here it is.

The rig is working quite well, but there's quite a lot of issues I need to solve.

Chief among them is my front suspension. You can see it at work in my trail pics thread or here: http://www.rightcoastcrawler.com/billaVista/SlipperyCreek/SlipperyCreek.htm

But, the problems are

1) It eats radius arm bushings on the left front frame point

2) I have some wicked axle wrap - most notably in reverse...the pinion wraps up something fierce. Machined the bellhousing with the driveshaft - lucky i didn;t lose the U-joint at the pinion. Here are pics of the problems - look at the difference between the angles of the upper and lower coil perches :eek:

eating a bushing
http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5170.jpg

axle wrap
http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5247.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5248.jpg

The setup is a bastardized hybrid combo experiment thing, and consists of 2 lower links with radius arm bushings at the frame, one upper link with bushing at the frame and rod end at the axle - but it's way off to the left side. And a panhard rod.

Pics below, but let me explain things tried and issues first.

1) Tried tractor type rod ends at the frame on lower links - more durable, but sooo noisy I couldn't bare it.

2) The radius arm bushings are prob too loose - i think i need to cut a 3/8" washer out and slip it in to tighten them up quite a bit. Also - it seems like the oEM rubber last better than the aftermarket poly (that just shears)...this make sense?

3) Rig has an intentional and much liked very low suspension height - problem this is - very little room under oil pan, starter, crank pully etc for linkages. Also - the present coils have a huge diameter (6-3/4":eek: ) that takes a lot of room. I'm thinking I'm going to be forced to run a smaller diameter coils with a couple inches lift for me - just to get some room to work. Suggestions? I'm thinking XJ or ZJ front coils...with an inch or so spacer if required.

4) PO / Builder once had a U style / wishbone single upper link but there were 2 issues. There were inteference problems with it between the driveshaft and starter and it didn't locate the axle laterally very well....when you steered, the body would move 2-3" taking up movement in the joints / bushings before the wheels reacted.

So here are the potential plans, pics to follow:


One other thing - I plan to go to full hydro steering (single single ram), and would like to move the tie rod up a bit (steering arms off the top of the knuckles.

So my plan / questions are:

Can I put a small bend in the panhard to clear the front pulley, so i can move it back at the axle mount a bit, giving more room for the tie rod on top the knuckles?

How do I best stop the axle wrap and bushing eating? I plan on replacing the poly with rubber, and adding 1/4" spacer to tighten them up. Also, am thinking of removing the single top link, and making the lower links mount in 2 places to the axle, where they are lower, and add a mount on top of the tube. How far apart should i make the 2 points on the axle? Also, as you can see - the coils are in the way a bit for this - can I angle the top bar that i will add to the lower links and have the upper axle mounting point not vertically above the lower - or am I asking for trouble?

Why does it eat bushings only on the left side? because the top link is on that side?

Have at it boys....rip into me, help, advise, flame, give it to me!

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5032.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5033.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5034.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5037.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5038.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5039.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5040.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5043.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5044.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5045.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5046.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5047.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5048.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5049.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5050.jpg

I would say your problem is that you do not have much seperation on you upper and lower links on the driver side. These two links are taking all the torque reaction of your front suspension, both in braking and on the gas. Since the links are not seperated much vertically, the brake and drive torque translates to very high axial forces on these links, this is most likely too much for the radius arm bushings. Think about what those radius arm bushings were designed for, a ford radius arm suspension where you had two radius arms and the forces on those bushings were shared. Also, any deflection in the bushings gives you rotation of your axle/pinion, since the upper and lower links are close together, you will have more deflection of you axle (axle wrap/hop) than if they were spread further apart.

I would suggest using a good quality rod end to replace the radius arm bushing on the lower driver frame joint. A 1" rod end would work fine.

The only way that you could have that much axle wrap is from having some serious play / compression in the radius arm and/or top link bushings. And to make things worse, it looks like your lower and upper axle attachment points are relatively close to one another in the vertical plane, resulting in amplification of the axle rotation due to compression.

Concerning the eating of the radius arm bushing, what about just placing a thick and large diamenter washer over the attachment stud and between the bushing and chassis?? Looks in the pic that the bushing is encountering a "sharp" edge on that chassis mounting black, resulting in it being cut.

You mention the removal of the upper link and incorporation of two radius arm mounting points on the axle. I run this setup on my Zuk with Dana axles. I fabricated the radius arms with removeable locking pins to allow one arm to articulate in the middle, thereby allowing for a lot more flex. To my surprise, I have not found the need to pin it while on road. Your results may be different however, as I suspect you´ve got a LOT more motor and weight than I do.......

FWIW, I spaced the two mounting points 200 mm (08 inches) from each other. An important thing to keep in mind is that the three fixation points (01 on the chassis and 02 on the axle) should form a straight line when seen from the side view. This allows for axle twist without creating lateral binding between the two axle bushings.

I´ve got a slight bend in both my front and rear panhards in order to clear the diff pumpkin. No problemas at all. As are my steering links, my panhards are made from 1" diameter solid 302 stainless.

Just 0.02 from one of the "little" guys.......:p

I will echo the first two replies.

Horizontal plane is ok for radius mounts, but not vertical. For the reasons stated in the previous replies. You have nothing to really PREVENT axle wrap.

On the arm bushing question: This has been a topic in the Rover world for years. I am a BIG fan of rubber instead of poly. From what it looks in the pictures, you have no offset in the arms. It is tricky, but since your mounts on the axle side are so close, they really funtion as one, and the arc of the radius from the axle is the same. Visually it looks offset, but it really isn't. I would either separate the radius arm (back to a true radius with two mounts) or go with the existing lower link mount with an more offset link and a triangulated three link to cure the wrap up. Without the cure for wrap, you are putting undue stress on the frame mounting side of the radius arm.

I am having to offset my arms as we speak, as I am getting horrorendous (SP?) bind on my arms, and I am worried about chewing rubber.

Just my usually worthless $.02

j

On the radius arm bushings there is a guy named kurt Millard that makes some extra soft poly ones that seem to last good. I was tearing up a bushing a trip or every other trip until I got these. I haven't lost one of them yet. I think BC Broncos (http://www.bcbroncos.com) caries them. For the axle wrap you need to get some stiffer bushings on the side with two axle mount points or move the two points farther apart verticaly. That is what I would do for the quick fix.

If you go full hydro the old triangulated front suspension would probably work OK because you don't have the horizontal forces between the axle and frame from steering anymore.

I have seen some pretty pretzled panhard bars that seem to work OK. I would say a slight bend like you would need would be OK.

Hello Billa,

The fact that you are experiencing this axle wrap is strange, that is the whole reason link setups work so well...so something is wrong with your front suspension :P

1) Since wrap is worst in reverse, the arms are weakest when the lower is in compression and the upper is in tension. I think what is happening is the rubber bushing on the frame lca mount is too soft and is allowing the effective length of the arm to change, especially on compression. My suggestion is to cut the radius arms off and use a better bushing. Your upper link looks fine and your steering looks close. If you use leaf spring bushings, you should be able to fix the wrap problem and have it handle very close to how it does now(minus the axle wrap). If you use heims I think you'll notice some more quirks.

CJ

Bill,

Take a look at these pics of when I was putting the Danas under my Sami, if ya wanna...

http://200.155.1.101/publicos/goto?AID=20594

What might be of interest to you is the method for connecting the radius arm to the chassis. Instead of using an in-line bushing configuration like you, I went with a cross bolted configuration with a 30 mm inside diameter spherical rod end. The cross bolt is an M12 with a 16 mm OD steel sleeve. To create a certain degree of dampening, I made some poly sleeves with ID 16 mm and OD 30 mm to go between the steel sleeve and rod end bearing.

I hope that made sense......:p


EDIT: I went and looked at those pics again. If one did not know the whole story, I could be accused of bootie fab. There are a few temporary things shown in those pics, solely holding shite together during the build-up. For the finished product, go here:

http://200.155.1.101/publicos/goto?AID=23215

I would replace the radius arm bushings with a couple of large heim joints. If those radius arm bushings are loose, they will get tore up really fast from what I've seen. Those bushings also are not helping your axle wrap problem. Secondly I would try and raise your upper axle housing mount an inch or two, that will greatly reduse the wrap.

How do you like the way that suspension articulates? Does it shift sideways and walk forwards or backwards depending which side is compressed?

In these two pics, it looks like the left link actually attaches to the axle lower than the right link. That could be a problem too.

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5034.jpg

http://www.rightcoastcrawler.com/billaVista/Frontsuspension/Dcp_5033.jpg

redrangie - is this what you are talking about to help fix the problem?

FWIW, my dodge half ton, and jeep XJ, both use a 4 link, (as in, two each, uppers and lowers) and the mounts are 7" apart vertically. It looks like your single upper link, is only separated by about 5". Couple that with your radius arm bushings being loaded in compression / tension, and I think you have the source of your axle wrap.

Originally posted by JohnnyJ
redrangie - is this what you are talking about to help fix the problem?

Close, but move the third link to the center of the axle, going to a center crossmember.

like this: http://www.safarigard.com/jek%20opening.htm
or this: http://www.rovertym.com/ourprod.htm

The first is from Greg at Safari Gard. Been making them for years.

The second is done by Drew at Rovertym. He is a member here, green rover.

Looks like its been covered. Maybe more seperation and move to either the bushing Gordon was talking about or a BIG (http://www.polyperformance.com/hardware_materials.htm) hiem as suggested above.

i will the suspension geometry to others.

as for the bushing. either replace it every trip or get some quality 1" x 1.25" heims. i bought mine from Pig at a great price and so far they have not made even a slight clank. they are teflon lined and in my experiance the big ones keep the linning for a long time.

yep what camo said those are the joints to buy and that is the guy to buy them from. You see that same joint used in desert racing classifieds, going for more than he sells it for new. But if funds are short, Kurt's bushings are cheaper, and I bet they will hold up for you, they did for me and a bunch of other EB guys.

Goat1

I would say your problem is that you do not have much seperation on you upper and lower links on the driver side.

They are 6" apart verticaly now - what should I shoot for (Can;t go tooo high - as the link will contact stuf on compression)

Also, any deflection in the bushings gives you rotation of your axle/pinion, since the upper and lower links are close together, you will have more deflection of you axle (axle wrap/hop) than if they were spread further apart.

Are you still talking vertically here, or laterally?

Billj

I´ve got a slight bend in both my front and rear panhards in order to clear the diff pumpkin. No problemas at all.

That's good to know - thanks. I enjoyed your pics too. I won't be able to place an axle mount out in front like that though as I know I will beat it off there....just look at the beating my linkage and diff took in the link I posted!

Gordon

If you go full hydro the old triangulated front suspension would probably work OK because you don't have the horizontal forces between the axle and frame from steering anymore.

I was hoping that might be the case. If I get enough room to do it, i may try that again after the full Hydro steering. But as the hydro conversion is going to take a while, In the short term I think I'll try the rod ends at frame, and increase vertical spacing of drivers side links.

CJLagos

The fact that you are experiencing this axle wrap is strange, that is the whole reason link setups work so well...so something is wrong with your front suspension :P

Yea - no kidding eh:p Call me dissapointed. Still, seems like I can get it sorted without too much drama or a complete re-design, which is very cool.

I agree with your analysis (now that you spelled it out for me!).

If you use heims I think you'll notice some more quirks.

What did you have in mind?

Billj

If one did not know the whole story, I could be accused of bootie fab

No worries mate, we can all be accused of that from time to time :D I still remeber my first welding project - I built a cart for it several years ago. I just took it out of the box, plugged it in, and pulled the trigger. I had NO idea of the principles or practices...I didn;t even know you were supposed to be melting the 2 metals together to join them...I just used the solid filler wore like a hot glue gun for metal :rolleyes:

Ant

Thanks for the input- I'm sensing a theme here :D

How do you like the way that suspension articulates? Does it shift sideways and walk forwards or backwards depending which side is compressed?

Apart from the wrap and bushin killer - it seems to work extremely well. Check out the pics in the link above. The pic in the thread at the link - I got on the gas in reverse a bit from there - and at that time it did seem like the drivers side rear walked under a bit - but I was really al bound up and there were big rocks behind me preventing a clean reverse. I was still able to back up and drive out. I have no complaints about the performance per se - it seems to work very well.

Curtis,

In these two pics, it looks like the left link actually attaches to the axle lower than the right link. That could be a problem too.

Damn good eye :D

You are right - the reasons are a) to get better seperation between upper and lower on the left (though apparently not enough) without puttin the lower left actually below the axle and in harms way and b) there's very limited room on the right because of the cast diff. It's essentially in the only place it can be, and I am not a fan of vere welding cast in a heavy structural situation.

Anyone else think I need to mess with this?

Camo


i will the suspension geometry to others.

Yea - I am too. Bwa ha ha ha. I know that's not exactly what you meant to say, but when you read it literally it's pretty damn funny :D

Thanks for the recommendation...i remember your side by each pic. Already in contact with PIG by PM. Nice to have thumbs up from a fellow equipment....uhhh...shall we say "heavy user"...abuser is such an ugly term :flipoff2:

Thanks all....wicked help.

Summary - going to try and raise upper axle mount, and replace the lower link chasis bushings with something else - prob a big rod end.

Last question (for now) - while I'm hacking around under there (can't really call anything I do "fabrication") Would it be worth it at all (or maybe even counter-productive) to make a short link, Heims at both ends, going from a brackt welded to the top of the right radius arm, to a bracket attached to the panhard bar axle bracket (only place to weld to in there by the diff). Will the vertical seperation have to be identical to the upper and lower seperation on the left? Will the observation Curtis made cause any grief? Just wondering

Last question (for now) - while I'm hacking around under there (can't really call anything I do "fabrication") Would it be worth it at all (or maybe even counter-productive) to make a short link, Heims at both ends, going from a brackt welded to the top of the right radius arm, to a bracket attached to the panhard bar axle bracket (only place to weld to in there by the diff). Will the vertical seperation have to be identical to the upper and lower seperation on the left? Will the observation Curtis made cause any grief? Just wondering

that's a bad idea. It will kill your articulation. You want wrap control on one side, or the otehr, not both, IMO. I also like to see the radius arm on the driver's side, because it counteracts drivetrain torque that way. just get fatty heims, and move the upper link up a couple of inches.

good luck!

I also like to see the radius arm on the driver's side, because it counteracts drivetrain torque that way

Please explain? Is that assuming drivers side front diff?

found the thread you need to read,bill.http://www.pirate4x4.com/forum/showthread.php?s=&threadid=44987&highlight=amigo

second pic in this thread is what you need to do. search for belly dragger if you need more info. very well set up suspension.

Hey Bill, it's been a while. For the most part I agree with the previous posts. The seperation between the upper and lower control arm mounts on the axle are just too damn close. Personally I feel that bushings are a little too soft to run a 3 link... If you switch to a 4 link with a trackbar it will still flex well because of the bushing crush you get... personally though, when retaining a steering linkage, I like to use a three link with track bar with all of the linkages being heim jointed. Then again, I feel that when you do this, the upper control arm really should be a decent amount above axle centerline... either mounted on top of a diff, or mounted on a relatively tall bracket similiar to what CJ lagos had on his short lived 3 link front (back when he was running the 40's). Although, if you try to emulate CJ's old setup... Brace that upper control arm mount better. As for the position of the lower control arms... it's not really that necessary to move the other lower to match... but what is effectively happening is that the drivers side is keeping the axle from rotating and the passenger side is simply locating the axle front to back. Due to your clearance concerns, I think it might be worthwhile to simply make your drivers side lower control arm into a radius arm. From approximately 1/2 way to 2/3 of the way towards the axle, have an arm come up like the rubicon express arms. This way you could probably get a taller mount in there, with less clearance problems from the control arm. It will function very similiarly to your current setup, but it will allow you to get better resistance to axle wrap. I'll look more at the pics later when I have more time.... but let me know if this helps any....

Regards,
Michael Rizzi

Alright, I didn't read through all of the responses but I think I know what it is. The problem isn't that there isn't enough separation between the links vertically it's that you have the top link on the wrong side.

Let me explain. This will basically work the same as a wristed arm on an EB. Take a look at any wristed arm on any EB. It's always done on the passenger side, which is the side away from the drive shaft. So the solid arm is near the drive shaft. This is for the same reason that people try and mount track bars close to the drive shaft in the rear. Because if it's too far away, the axle housing will twist. Especially with rod ends. You can probably feel the passenger side tire lift a bit when you really get on it.

So move that link to the other side and it will help A LOT!

-Jack

The reason the radius arm remains on the side that the diff is on is because the caster changes with the travel of the side with the radius arm, the wristed side doesn't control caster... or as it follows... driveshaft angle. Since it's best to have the caster change with the driveshaft angle, the radius arm is set up on the side with the diff... That is somewhat less necessary on Bill's three link because there is relatively less caster change with suspension travel. Theoretically it shouldn't really matter which side has the upper control arm from an axle wrap point of view... but then again, the world doesn't always work according to theory :-) The control arms are just seeing too much tension and compression... specifically the lower drivers side one... as evidenced by the failures of the drivers side radius arm mount. Lowering the axle side mount on the passenger side will alleviate some of the loading on the drivers side lower... but I'm somewhat skeptical as to how much of an improvement it will really make..

Please explain? Is that assuming drivers side front diff?

no no, diff placement is irrelevant. I am talking about the engine's rotational force. This force is transmitted to the chassis, and pushes down on the pass side. If you put the radius arm on the driver's side up front, it will pull down on the driver's side during hard acceleration, evening out the force of the engine. Make sense??

I am still running leafs, but I have a wrap bar in the rear. I put it on the pass side, to counteract engine rotation. It works nicely. When I romp on it, the front end lifts equally, not higher on one side or the other. See what I'm getting at??

Not to say that this is the most important design part to think about, but it is SOMETHING to be considered. Good Luck!

I agree w/ some of the others here...

I think you should attach the frame end of the upper CA to the lower CA (Rockstomper Mantis style). This would relieve the radius arm frame bushings from having to control axle wrap (which they obviously aren't up to doing), so it would save those bushings and solve the wrap problem at the same time.

Keeping the link that controls wrap on the same side as the driveshaft helps keep the u-joint angle at the pinion fairly steady through susp. travel, but that may not be absolutely necessary if you don't feel like swapping sides.

larryboy

thanks for the thread - interesting stuff. I do like the control arm / radius arm. I'm not wild about the ram mounting - never been a huge fan of attching them to the tie rod when not exaclt parallel - as every time you steer it will put a bending force on the toe rod.

XJGPN2

It HAS been a while eh? Great to here from you. Thanks for your input. I am going to try and raise the axle mount of the current UCA. What should I shoot for? 8" seperation?? If that gives me clearance problems - I will look at making the drivers side more of a radius arm like in larry's link or the RE arms.

IronBender and Elf

That's good info - I understand what you're saying. Great info for those starting from scratch, but for now, I simply don;t have the room on that side, and I don;t want to add 4" of lift to get any more - not if I can do it another way. FWIW I have never felt the passenger front lift when on the throttle, and I do like to rip up and down the fore roads a bit. Castor change with suspension travel is not really a big issue at this point, But it's great to know the theory in case it becomes an issue to me. Thanks for the input.

Erik B

I think you should attach the frame end of the upper CA to the lower CA (Rockstomper Mantis style). This would relieve the radius arm frame bushings from having to control axle wrap (which they obviously aren't up to doing), so it would save those bushings and solve the wrap problem at the same time.

How would doing this relieve the frame bushing? If anything, wouldn't it increase the load, effectively to the sum of the force fro both upper and lower parts now?

Keeping the link that controls wrap on the same side as the driveshaft helps keep the u-joint angle at the pinion fairly steady through susp. travel, but that may not be absolutely necessary if you don't feel like swapping sides.

You called it on that one! It's a good consideration and info...but it's not a high enough priority to merit tearing it down that much if I don;t absouloutely have to.

Question for all.

When I go to the Rod Ends on the lower link frame mounts - as you can see in the pics, I have the oppertunity to lengthen the lower links a coupl of inches or so. Worthwhile? hey are corrently about 32" long.

Again - thanks to all - this has turned into a grat front suspension design thread.

Billavista,

Are your rod ends going to be adjustable? If so, cool instant castor adjust, and the more positive castor, the quicker the steering.

Someone said bushings are "too soft" for a 3-link. I disagree. This is not a daily driver by any means, so rolly poly shouldn't be an issue, unless the spring rates have not been changed to factor in weight changes. A 3-link will allow you to run stiffer springs and lesson the body roll that way. One of the bigest problems with 3-link implementation is that people don't pay attention to changes in the dampening needed to offset the increase in quickness of the flexibility.

Also by going to a centered 3-link you will also be able to adjust pinion angle at will.

By putting the front links/radius arms at the 3 o'clock position you will not have clearance issues, although 5 o'clock would be ideal. Then place a ball jointed or heim jointed mount at the top of the axle, at 12 o'clock relative to the front links.

Very simple. Very clean. and very adjustable

j

Originally posted by BillaVista
How would doing this relieve the frame bushing? If anything, wouldn't it increase the load, effectively to the sum of the force fro both upper and lower parts now?
With separated links like you now have, when the axle tries to twist, it pulls on one and pushes on the other. This is in addition to forces due to the axle trying to move relative to the frame due to tire run out. So, one link is in compression, the other is in tension, which puts a load on the radius arm bushing parallel to the frame rail. Those bushings apparently can't take that much force in that orientation.

If you connect the upper and lower links forming a Y, then the rotational forces from the axle wrap are directed into the link joint and transferred perpendicular to the frame, across the bushing mount. The only remaining forces that are parallel are simply those due to tire run out, which is what the bushings are designed to deal with. You just have to make sure the link can take those forces at the joint without bending…

He's right. Make the left control arm a Y and make them as long as you reasonably can. Get the upper mount a couple inches higher up, and you should be good to go as long as the lower links are beefy enough.

YOu can only use it if you keep the :rainbow: color scheme:

http://people.memphis.edu/~ecmills/buggy_suspension.jpg

Originally posted by redrangie
Someone said bushings are "too soft" for a 3-link. I disagree. This is not a daily driver by any means, so rolly poly shouldn't be an issue, unless the spring rates have not been changed to factor in weight changes. A 3-link will allow you to run stiffer springs and lesson the body roll that way. One of the bigest problems with 3-link implementation is that people don't pay attention to changes in the dampening needed to offset the increase in quickness of the flexibility. j [/B]

That would be me. If you look at the original question, one of the big complaints was that the front wasn't as precise as he wanted, and the front axle moved around too much. Personally, I hate bushings. I started out with heims on everything, got tired of the noise, used bushings... couldn't believe the loss in precision and handling, now I swear by heims. As long as you use good ones and replace them periodically, they aren't that bad to use... Hell... I even replaced the control arms on my daily driver with heim jointed ones :-) I think bushings could work well... but it really throws a whole new wild card into the mix... Bushing crush. It has drastic effects on many aspects of handling... and linkages have to be designed to take this into account when using bushings, meanwhile if your using heims, you can pretty much ignore it. In the case of a three link like what Bill is running, when you hit the brakes, all three bushings will deflect a given amount... They are all holding the axle at different locations, so the axle will, in this case, want to twist a little more on the passenger side than on the drivers side... it will probably result in the truck pulling badly on hard braking. Once you try to make a bushing setup try to work well... you really start getting into some advanced engineering theory... Using Heim joints kinda lets you get around that. Especially when you are running a suspension linkage that isn't perfectly symetrical. I really feel that bushings just shouldn't be used on the axle side of a setup like this... It can definately be made to work... but it will require a lot more thought and luck than just using heims.

Originally posted by redrangie
Also by going to a centered 3-link you will also be able to adjust pinion angle at will. j [/B]

If the linkage is symetrical it will be a lot easier to make it work using bushings.

Here it goes Bill. I DID NOT read any of the other post's just so you can get MY idea's and not some bastardized version of someone else's. So if I bring up stuff that you have already responded to Please forgive.

First Panhard Bar- You need to make that bracket so it mounts in a double shear. Your single right now. Not a big deal really just some time with a welder, cutter and 1/4 plate.

Front Coil Buckets- You need to move the the upper and lower perches to a better relationship. Time, Time, Time.

Left side arm- Dump that upper link and put a Johnny Joint in place of the Radius Rubber. Time and about 50 bucks for the JJ.

Right Side arms- Made a TRUE radius arm the the upper link mounted ON TOP of the pumpkin. If you don't want to make all that bracketry then buy Rubicon Exress's UCA mount and make it work. I would use a RE superflex UCA for the pumpkin to lower arm Link but you can make it if you want. Also dump the radius rubber on this side and replace it with a Johny joint.

Are you sure your tubes did not twist a little? Might account for the difference in coil buckets.

Also Do not put the Radius arm in place of the current LCA and UCA combo. There is a lot of metal that is twisting and distorting along with rubber and I believe this is causing your axle wrap.

If you do a Radius arm with the upper Y link on top of the pumpkin I will bet you a dollar to dognuts that your wrap will go away.

Have Fun. Ain't Wheelin Great.

EDIT- I just looked at TNT Toy's post and You need to put that Radius arm on the pumpkin side. That and switching to a Johnny Joint (or Rod end) in place of the raidius arm bushings will fix you up.

Oh and are you sure your tubes did not rotate? The lower control arm mounts are way offset.. That and the coil buckets being all farked up leads me to believe that the tubes might has spun a touch....JMO

Seems to me that the issue isn't that there isn't enough separation vertically. The problem lies in that the axle's rotational axis is so far removed from the suspension's rotational axis. lemme try some ascii
o <--> Upper link
|
O axle tube
|
o <--> lower link

In the above pic (hopefully) the axle is centered between the two link ends. When you accelerate or decelerate, it puts the rotational force 90* to the link, putting one link in compression and the other in tension. You have:

o <--> Upper link
| ^
O__o Axle tube and lower link
v
In this example, the upper link gets the compression/tension loads, the lower link moves primarily vertically with a little bit of compression/tension, but at much higher loads. I think this small movement at great torque (for lack of better words) is what's killing your bushing, and the vertical movement is what's causing your axlewrap. Move the lower link more directly under the axle to move the rotational axes back in line, and/or connect the upper link to the lower link so that the compressive/tensive forces are moved from the frame bushing to the arm itself.
whodat

Originally posted by whodat
In this example, the upper link gets the compression/tension loads, the lower link moves primarily vertically with a little bit of compression/tension, but at much higher loads. I think this small movement at great torque (for lack of better words) is what's killing your bushing, and the vertical movement is what's causing your axlewrap. Move the lower link more directly under the axle to move the rotational axes back in line, and/or connect the upper link to the lower link so that the compressive/tensive forces are moved from the frame bushing to the arm itself.
whodat

Not to shoot your theory down, but while you are correct in that by running the lower control arms at axle centerline, and the upper control arm a distance above the centerline, the lower control arms see more loading, this isn't really a problem. There are many suspensions running with the lower control arms at axle centerline. Granted, most of these are heim jointed, and can take the extra loading in stride, but still, it can be made to work. This actually brings up a question I have about Portal axles. It seems that when using Mog Portals, with the linkages going to the axle tubes, all of the axle side mounting points are much higher than axle centerline. I was wondering what side effects people with portals have seen from this... Avalanche gets around this by welding the LCA mounts on their portals to the bottom of their gear-drive portal... But Mog axles don't have this ability... Probably not as big of a deal using the stock Mog suspension... but I could see this exposing weak points in home fabbed link suspensions...

BadDog.

Ah-ha! I now se exactly what you mean. It's the same principle that allows the common "Sam's Offroad Style" rear anti-wrap bars to work with a shackle at the frame mount - because when the 2 bars, upper and lower, are joined as one in a Y, the frame end would have to move in an arc for there to be rotation of the axle.

I was out fiddling today - I think I am going to try the Y on the left arm, with about 8" seperation at the axle. If I do this and lose the single upper arm, it just may give me room to place the tie-rod behind the axle. Because I'm poor and never have enuff time (kids) I may try this with my last set of radius arm bushings at the frame - but shim them up tighter.

Now - the question is - do I joint the upper to the lower by welding the bars together, or with a Heim ir bushing?

Pig, Goat, and farmer Gordon...please chime in on this plan. You too XJGPN2

Bill

TNToy,

Great pic, thanks for drawing that. I do believe that I will end up doing something very like that. Can I colour it with my kids crayons, or should I powdercoat it in rainbow :flipoff2:

AlaskaZJ

Great input, many thanks.

In response - Panhard bar - that's exactly what I want to do - move it back between the bracket, in double, where the black spacer is. Problem is, I have to lift a bit, and put a bend in the bar to do it, so that it doesn;t contact the crank pulley under compression.

Coil buckets - look pretty good to me in the driveway shots - there way out in the first couple of pics because they were snapped when I was hard on the gas in reverse in lo / lo and the axle wrapped a lot - look at the pinion.

Radius arm on the right - why top of the pumpkin? This would cause the upper arm to angle in quite a lot from the lower, cause all sorts of fancy bracketry required (I am NOT welding a suspension link to cast), and still leaves me with clearance woes under the oil pan, exhaust, starter, driveshat etc. What are the advantages that make all the grief worthwhile?

Tubes aren't spun - lower mounts were intentionally offset. Left lower for vert. seperation, right in the only place it could fit.

Great input - much appreciated.

Originally posted by BillaVista
BadDog.
Now - the question is - do I joint the upper to the lower by welding the bars together, or with a Heim ir bushing?

Pig, Goat, and farmer Gordon...please chime in on this plan. You too XJGPN2

Bill

I'd definately say weld. Keep in mind that the suspensions that join them with a bushing (RE specifically) run the Y on both sides... the extra bushing is to gain a little more bushing crush since a radius arm suspension naturally has bind in it. Since you will only be doing it on one side, I'd weld the Y as one piece. A heim joint would be a bad idea over there because it would act much like Rusty's steering on an XJ... The LCA portion could rotate allowing for the axle to rotate slightly.... granted the axle side LCA bushing would prevent this... but no reason to add an unnecessary joint.

Originally posted by BillaVista
Now - the question is - do I joint the upper to the lower by welding the bars together, or with a Heim ir bushing?


either way will work. the only reason to use heims would be the adjustability they would proveide. they would allow you to change your pinion and castor angle if it were needed.

Originally posted by High5


either way will work. the only reason to use heims would be the adjustability they would proveide. they would allow you to change your pinion and castor angle if it were needed.

What he said.

But one question for all.

Why would you NOT want a symmetrical link design? Is this just my sports car days coming back to haunt me?

j

BV, F radius arms, what you have is better and will work just fine, all you need to do is replace the bushings with some good rod ends like the ones pig has. Yeah, the upper and lower mounts on the axle are close together vertically and overloading your bushings but I wouldn't bother changing your mounts, good rod ends will fix it. I have a set up similar to yours but I have johnny joints on the frame joints and 1" rod ends on the axle mounts, and it works fine.

Originally posted by XJGPN2


Not to shoot your theory down, but while you are correct in that by running the lower control arms at axle centerline, and the upper control arm a distance above the centerline, the lower control arms see more loading, this isn't really a problem. There are many suspensions running with the lower control arms at axle centerline. Granted, most of these are heim jointed,

Exactly. Heims can take many thousands of pounds of pressure, with no deformation or loss of articulation. The poly bushing, however, can't.
whodat

Originally posted by redrangie
Why would you NOT want a symmetrical link design? Is this just my sports car days coming back to haunt me?

j
Because if you had radius arms on both sides, it would effectively use the axle as a giant swaybar. As one side compressed and the other drooped... it'd bind REALLY bad.

Originally posted by TNToy

Because if you had radius arms on both sides, it would effectively use the axle as a giant swaybar. As one side compressed and the other drooped... it'd bind REALLY bad.


That´s why you gotta wrist one of the radius arms.........

Originally posted by TNToy

Because if you had radius arms on both sides, it would effectively use the axle as a giant swaybar. As one side compressed and the other drooped... it'd bind REALLY bad.

Uh, ok. So, you offset and lengthen them so that there is still an angle of deflection at rest of about 30 degrees, while they sit level in the frame mount. That cures your bind.

Giant sway bar? I thought you should set a system for controlled flex. In the suspension that we are looking at, there is NOTHING to slow down the action. The springs are not retained, and unless the loaded (under flex) spring has the proper amount of compression resistance, you get a real tippy set up.

(not arguing, just discussing)

Originally posted by billj



That´s why you gotta wrist one of the radius arms.........


That works to. I have debated wristing one of mine, but it still sees too many road miles with the famdamily in it.
j

Originally posted by redrangie


That works to. I have debated wristing one of mine, but it still sees too many road miles with the famdamily in it.
j



Go ahead and wrist one, leaving provisions for a removeable cross pin. On the trail pull the pin to let it flex. On the road, slide in the pin to lock the arm.......

In the suspension that we are looking at, there is NOTHING to slow down the action. The springs are not retained, and unless the loaded (under flex) spring has the proper amount of compression resistance, you get a real tippy set up.

As can be plainly seen - I'm no genius with the theories, but I can tell you this...there is absoloutely nothing tippy at all about my suspension...have a look at the action pics in the link in my first post. Real world - it works incredibly well...less the wrap and bushing destruction.

Just FYI

One other thing...the front coils are actually retained - though not perhaps as you mean.

The upper bump stop - the metal cup is larger than the ID of the topmost coil loop - so the coil can drop away at the top but not over the bump stop cup.

On the bottom - the bump stop pad inside the coil, is also larger than the smallest bottom loop - retaining the coil on the bottom. It slips out of its sleeve on the coil pad by removing 2 grub screws, then it comes out by fitting between a couple of the coils when they are opened up.

It's really quite clever - in case anyone cares.