Long arm DIY build questions

[JonnyCat63]

To your logic tho, why not do the same? Comment in your lane and ignore our banter/ what you dont like?

Fair enough. However, you mentioned getting flamed on Pirate, and I don't understand the need for all those dickheads that want to flame everyone over comments they don't like. That's the main reason I stay away from sites like that. My time is valuable and I don't want to waste it on asshole keyboard warriors like on Pirate.

I just think it's better to try to be civil than waste time on flaming internet strangers. Just food for thought and I think you may have taken RCP's comments the wrong way. I think he was just trying to be helpful. I would prefer to encourage respectful and helpful banter on whenever possible.

JMHO

 

[ShoeterMcgav]

Heard.

I think rcp and I and Evan and others have am interesting dynamic so maybe I'm quick to my guns. I still see no problem with Clayton's kits nor square diy arms. Anything can bend... and anything can be sleeved. Weight cost and strength.... try to fit your needs to meet your wallet is alls I'm doin

I agree about pirate. I read and seldom post there. Haven't been as active here in a while so maybe it sounded like a noob challenging a vet... he's had a multitude of builds and I do respect him, just not always agree. This is only my 4th jeep so I won't claim to know it all... only what I've experienced first hand and in my offroad groups.

No harm no foul. He didn't seem to take anything I said as a put down. If so... well ya know. ¼" walled steel is plenty strong for my reinforced unibodied rig.


Cheers

 

[75SV1]

Ironman uses square tubing on his longarms. I have both front and rear kits. Getting close to having that build started.

Edit: I looked at the Ironman parts last night. The bottom ones were 'U' shaped. Capped on the bottom, and had rectangle slots along the length. Those were filled iwth retangle tubes.

 

[4x4JeePmaNthINg]

I used the clayton crossmember and built square 2x2 lowers and upper link with .120 dom, jjs on all body side mounts, barnes weld on flex joints on the under axle mount side (they arent great, they arent terrible either). Square tube is fine, I've been over plenty with it going on 3 years and this is my DD. A few notes to aid your decisions.

I had read that you do not need flex joints at all ends of all arms, I choose to do so, though ill likely be putting fixed ends on my axle side lowers, this will save you some money. Im not welding anything onto the axle otherwise a fixed upper would be nice to. I also have thoughts to make the passenger arm a wishbone just for extra insurance.

Square tubes have square bungs, I found most of that hardware at barnes, you could use round, but why bother when there is a better fitting option. one consideration to this would be a non jam nut style bung, one that clamps. I have not seen these in square, they might be nicer to use for adjustments idk.

Upper axle mount is an IRO 1/2" bolt iirc. It is suitable for my needs, I'm usually on high alpine areas and wheel whatever comes on said trails( with in reason, I need to drive home to hahaha). Its not a rock crawler, but it has impressed me thus far.

As far as the upper arm goes and if your welding the upper body side mount on yourself, just decide if you want the upper arm to be longer or shorter and know the driving characteristics this will give your vehicle.


An upper arm will more than likely come into contact with the floor. I made all arms out of PVC first and got a rough idea of where I wanted everything, then I bent the upper with a torch and made the bends to clearance the driveshaft and floor pan.

Test your shocks lengths comp/ext to, this might change how far your axle will be traveling!

 

[xcm]

He's just wrong. And so are you if you think Clayton's long arms aren't a normal sight to see on the trails.

Reading apprehension: you should try it.

 

[denverd1]

The Toyota boys run square driveshafts because they are cheap to make but that doesn't make it right! If you want to use square at least use square bungs, 20 yrs ago when I built mine Clayton was one of the few that even offered long arms.

right? Right for you?

I too get tired of the post padding google search type responses.

flame suit; don't give a shit

 

[denverd1]

Reading apprehension: you should try it.

apprehensive about reading? internet forum is an odd place to hang out

perhaps you meant comprehension?

whats with all the uptight bullshit around here?? yall need to take your jeep out more

 

[RCP Phx]

right? Right for you?

I too get tired of the post padding google search type responses.

flame suit; don't give a shit

Me and most users on here! I've run a square driveshaft before on "trail" only rigs and they are ok, but I have driven over a thousand miles just to get to the trail along with towing a trailer. If you want one, do it!

As for my post that started all the pain, I should have said this!
"Un-sprung weight is the enemy and round tube arms built to about the same strength as square tube are lighter!"

 

[denverd1]

:doh:

thankfully, nobody is taking a poll of what mall crawlers do. Should I ever care how "you and most people" do things, i'll know how to reach out to.

 

[Evan03]

Square works a dinasaurs get old . Everything can bend and break I tend to bend and break more than most.

My arms are 32" ish. I run heims on frame end poly at axle. I think with that Center youl be closer to 36.

Buy bungs for the shape tube you decide to go with dont plug a round hole with a square bung or the othere way

Longer arms has been a great upgrade and a project I learned alot on. Lots of weld together cut apart change it. Setting link seperation . I now got smart and well smarter and have built in link seperation tuning if I happen to change tire size or just want to change things up.

Ive kinda switched to Barnes 4wd for my suspension stuff. Bungs, brackets, steering,

Have fun with it learn lots.

Even rcp has good Info at times heck hes one reason ive got one of the best chicken coops around. He said I couldn't do it I know only did it I actually built it. Pretty proud its not just a rig bolted together.

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[XJ_ranger]

I can't tell if you're planning radius arms or a full traction style long arm with 4 independent links.


If you're doing radius arms, the frame side of the lower arm is where the instant center of the suspension is - and where all acceleration and braking forces will go through. So, you probably want that having minimal slope from the axle to the chassis at ride height and near ride height.



I'd let the arm length be dictated by the desired suspension geometry and not the other way around. The longer the arm, the less change with respect to travel - braking weight transfer, etc.


As for square or round, I've personally bent 2"x.250 wall round a few times, and have bent 2x2x.25 square links in my shop too. I do think square is stronger in bending for the same OD size, but it is also higher weight. The longer the link, the greater the span, the easier it is to bend. If you get links with threaded joints (like the Johnny joints you talk of in your first post), then you can replace them with 7075 aluminum or heat treated chromoly later if the need arises. I've had good luck with my 2" 7075 aluminum lowers from Wide Open Design so far on my comp buggy - which replaced banana shaped 2"x.250 DOM versions.



In an XJ chassis, a mix between ideal suspension geometry and strong locations for mounts with significant re-enforcement usually provides the answer all by its self after staring at the car and the scrap metal you have on hand for frame plating. The transmission crossmember provides a barrier that you can't really go aft of. Plenty of companies have made combination cross members with link mounts and transmission support - I'd wager that's a good place to start.


Happy wheeling.

 

[Evan03]

Pretty damn badass response

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[ShoeterMcgav]

Thanks for all the replies!

Some peeps are funny... internet tho, what ya gonna do?
Luckily there is many ways to achieve the same result. Square vs round was never my intention in this thread. And there are too many variables to compare fairly. Both can be strong long arms (or drive shafts) period.

I initially hd some rock crawler brand bs mid arms that were SOLID tube! ****ers weigh a ton. Over kill. Replaced with chromally DOM but need to push my axle fwd further than the adjustability of the arms so decided to go full long arms with a Dirtbound offroad center piece at the same time I burn on my frame stiffeners. Then mini boat sides and tube flares can be permanently burnt in, all projects for the winter.

The DB offroad xmember is a 3/4 link mount, beefy, well designed, with drop out center almost identical to the Clayton's crossmember I put on my ZJ.

I definitely will be running a 3 link. Don't see the need to add the pass side arm, don't even have an axle side mount anymore, but if I did.. I think exhuast and other stuffs would have to be adjusted and I don't see what could be gained, maybe a little more adjustability for caster?

So ya, 3 long arms not radius.

Square vs dom will be decided when the accountant (wife) gives me the thumbs up and what ever the better deal is at the metal shop for 2 40" pieces. As I said initially, it's not a pound for pound comparison because the square will be heavier at same length.. the Clayton's was a little cumbersome to dial in because you had to do full rotations, due to the radius arm mount. I'd prefer flat edge down on Square, and like that circle can be fine tuned without any side being different. Again, budget and supply will dictate the final material used.

Sounds like 2 40" pieces will get my lowers done.. the upper I'm liking smaller diameter. I have yet to find a threaded axleside mount to pair with a JJ tho. When I redid the rock crawler link I burnt on an IRO upper link (fork?) And kept the arm and frame side heim. So with the only adjustability on the joint side, you have to disco one side to adjust. Id like to be able to keep it in place like the lowers with 1 rh thread 1 lh thread and be able to adjust it. Haven't found 1 though

 

[maxbraketorque]

...

So ya, 3 long arms not radius.

...

One thing I've wondered for a while is whether there is any significant suspension geometry advantage to a long 3/4 link over a long radius arm on an XJ. The situation is that there really isn't any room to have a vertical spacing between the frame side mount points on an XJ long 3/4 links, so should act a lot like a long radius arm.

I'm curious if anyone has any solid numbers on the difference in behavior.

 

[ShoeterMcgav]

The radius arms cause binding in my experience with the Clayton's long arm radius links on my ZJ. As far as geometry I think it's hard to beat triangulated 4 link in the rear, and with the pan hard, 3 link up front.

That said, you can improve any setup. I've wheeled with some CJs and 80s tacos with leafs all around that pull of some impressive flex. As much as I'd like tons and 40s and aluminum double triangulated 4 link front and rear... its not in the cards. For my dollar I think the 3 link will net the best return for my goals/ level of difficulty trails.

Definitely easier to get the separation you speak of in the rear tho. Not quite ready to ditch the leafs and add hoops in the cargo area for shocks/ coilovers tho

 

[maxbraketorque]

Removing the radius arm upper link on the passenger side gets rid of all the binding in a radius arm setup. Will flex as good or better than a traditional 3-link front with the third arm going back to the frame. I'm more curious about whether a traditional XJ 3/4-link front can offer a better geometry for braking, acceleration, and weight transfer.

 

[ShoeterMcgav]

Simple answer is yes. 4 link is king, but 3 link is almost as good with one less built in redundancy. Good joints and brackets is key. Most radius arms come with bushings axle side and that handles a lot of the deflection so wear out fast. 3/4 link puts less stress on each joint. Also, having 3/4 body mounts for the arms is better than 2 with the radius arm imo

I don't think removing the passenger arm of a radius is quite as good as you are describing. But I've seen people have success with doing so.

There may well be a good better best here, but at the end of the day it's what ever is best for you. All 3 options can have design flaws and ways to overcome them. I loved my Clayton's radius arm set up at the time... I've since learned to prefer a 3/4 link... ironically so has Clayton's long arm kits

 

[XJ_ranger]

Sounds like youre anning a true 3 link front. solid plan.



Opinions - 3 link front makes sense if you have packaging constraintsoor if you are keeping the steering box and not going fully hydraulic.



The advantage of a true 3 link is you have significantly more control over the instant center of the suspension and the roll axis angle of the suspension. A radius arm style puts the instant center where the frame side lowers are. With a true 3 link, the imaginary line where the upper link and lower links intersect (if you continued them out toward the rear of the car) is where the instant center is. This can help control weight transfer when braking and unloading when climbing.



As for vertical separation in an XJ chassis for the upper link - as long as strong enough mounts are made, and you get big enough joints, then you can run low amounts of vertical separation. 4" at the frame is achievable and acceptable if you have big enough heims.



Play around with the 3 link calculator a bit and decide what you want from the car.


This book - targeted at low riders on air bags has really good descriptions of the suspension terms and how they effect the car. It's more a book on suspension linkage than air bags. I've found it to be well worth the $45 I spent on it.


https://www.airsuspensionbook.com/

 

[Evan03]

Seperation at the axle is tied into factory brackets I found alittle more helps control dive and lift.

Like mentioned 4" works well on the frame end is also about all that can be acheived without going through the floor.

Some well alot of Rock bouncers have no Seperation at the frame side

I dont think it matters how many bars are on it. I have 3 bars I think just shy of 10" Seperation on axle 4 frame side. Ive also raised brackets on axle lower is 2" below frame .

I think radius arm also works and is easy to build. Though I have not tested a radius arm

My arms are 32" upper is slightly shorter than lower 31"ish

40" is more than enough. Your arms with joints will be 36"ish minus


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[maxbraketorque]

Seperation at the axle is tied into factory brackets I found alittle more helps control dive and lift.

Like mentioned 4" works well on the frame end is also about all that can be acheived without going through the floor.

Some well alot of Rock bouncers have no Seperation at the frame side

...

Good info. I didn't think that 4" of vertical separation was commonly done, but in looking at the IRO and Dirt Bound images again, those do look to be in the 3-4" range.