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DIY long arm kit!

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DoctorTim

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2002 WJ 4.7, 6" LA Lift, ECGS Axles, Locked F/R
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Discussion starter · #1 ·
Im getting used to the fact that everything is freaking expensive. College student with not a lot of money.. Ive already build my own bumpers and a dashboard so i thought i would take my fabrication skills to the next level. just got done designing this. will work on the rest tomorow. let me know on your thoughts. Should I beef up the crossmember? everything is 1/4" but the tubing is 1.5x1.5x0.125. As for the linkage, im using either 1.75" or 2" DOM with 1/4" walls, johnny joints at the frame, and eurathane double sheer at the axle.

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#2 ·
Looks good but you should probably plate or grate that open space off the center, would hate for a rock to use that space to wedge in there and hit the tranny or tcase.
 
#4 ·
To my novice fabricator(at best) eye, that design looks good. Ive got a 3 link Rockkrawler with Johnnys at the axle and frame... iv been thinking of switching the frame side to bushngs because the tide is LOUD when the suspension moves. Is there a reason you are putting bushings of the axle? I'm not questioning your design... just wondering if your idea will work better for me than my idea!
 
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#5 ·
XJ-Tim said:
just got done designing this. will work on the rest tomorow. let me know on your thoughts. Should I beef up the crossmember? everything is 1/4" but the tubing is 1.5x1.5x0.125. As for the linkage, im using either 1.75" or 2" DOM with 1/4" walls, johnny joints at the frame, and eurathane double sheer at the axle.

Image
Click to expand...
Since you're going this far with your build and doing it yourself, do yourself a favor: do a bit more research on front 3- link + panhard designs, go to pirate and search for 3-link calculator (excel- based thingy that allows you to design a proeprly working TRUE 3- link). Although radius arms are easier to do than 3-link, 3-link system works a lot better than radius arms. It isn't rocket science, and there are plenty of readily available designs if you browse through the Cherokee section on Pirate.

Other than that, IMO that crossmemeber looks pretty good. As mentioned, plate the area between the tubes, don't leave it open. Make it as level as possible with the uniframe rails, and fab/ buy frame stiffeners. Your XJ unibody will love 'em :D :thumbsup:
 
Discussion starter · #6 ·
MGDWJ said:
I would also make it a 3 piece design kinda like Clayton's
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it is, you see the 3 holes one each side? thats where center bolts onto the brackets

haloperformance said:
To my novice fabricator(at best) eye, that design looks good. Ive got a 3 link Rockkrawler with Johnnys at the axle and frame... iv been thinking of switching the frame side to bushngs because the tide is LOUD when the suspension moves. Is there a reason you are putting bushings of the axle? I'm not questioning your design... just wondering if your idea will work better for me than my idea!
Click to expand...
not sure why, i looked at my neighbors setup from rubicon express on his JK. thats how they made it.

Timo_90xj said:
Since you're going this far with your build and doing it yourself, do yourself a favor: do a bit more research on front 3- link + panhard designs, go to pirate and search for 3-link calculator (excel- based thingy that allows you to design a proeprly working TRUE 3- link). Although radius arms are easier to do than 3-link, 3-link system works a lot better than radius arms. It isn't rocket science, and there are plenty of readily available designs if you browse through the Cherokee section on Pirate.

Other than that, IMO that crossmemeber looks pretty good. As mentioned, plate the area between the tubes, don't leave it open. Make it as level as possible with the uniframe rails, and fab/ buy frame stiffeners. Your XJ unibody will love 'em :D :thumbsup:
Click to expand...
its just dificult for me to see how a third link could fit in there. on ones side i have the driveshaft in the way, and the other side i have the exhaust in the way...?

as for frame stiffeners, i want to make my own, should i get tubing, or plate it? i've seen some kits which are made out of tubing. or should i just plate it with 1/8", 3/16", 1/4"? This is my daily driver, want to keep the weight a bit lower for some precious MPG.
 
#7 ·
XJ-Tim said:
its just dificult for me to see how a third link could fit in there. on ones side i have the driveshaft in the way, and the other side i have the exhaust in the way...?
Click to expand...
Exhaust can be rerouted ;) Running true 3-link usually does involve a bit more work, and you normally need to cut through the floor on the passenger side for the frame-end link mount to fit high enough. It's not a big cut and can be covered with sheetmetal. Even though your XJ is your DD, the upper link notch on the floor can be cut & covered so it looks good and doesn't really eat away passenger legroom.

Radius arms are definitely easier to fab and can be made to work ok with good shocks, but it'll always have the known issues no matter what - brake dive and front unloading on steep climbs. A lot of off-road vehicles are built this way (all coil- sprung live axle Toyotas, Land Rover Defender/ Discovery, Range Rover, G- class Merc, etc...), and it works. But it binds more than 3- link, and is not the ideal way to build a front suspension. Jeep came pretty damn close on building the perfect front suspension (4-link + panhard bar), but they cheaped out on running too short arms built from thin sheetmetal :D Check for 3-link on Pirate4x4 Cherokee section, and then diceide which way you wanna go... 3-link design ain't that hard, but expect spending a couple of days studying/ researching on 3-link/ 4-link theory and getting the link setup right. If you're not ready for that, fab radius arms ;) :D

as for frame stiffeners, i want to make my own, should i get tubing, or plate it? i've seen some kits which are made out of tubing. or should i just plate it with 1/8", 3/16", 1/4"? This is my daily driver, want to keep the weight a bit lower for some precious MPG.
Click to expand...
Frame stiffeners aren't actually that expensive, and IMO the amount of work you do fabbing your own (cutting, bending, drilling a lot of rosette- weld holes, making everything fit) it's probably worth it to buy a set from a known good manufacturer. 1/8" works if done right (= enough rosette welds, stich- welding the upper seam, wrapping the stiffeners all around the uniframe rails), 3/16" is bulletproof, 1/4" is overkill if you ask me.
 
Discussion starter · #12 ·
well solidworks doesn't have an option for something that would recreate a rubber bushing so it doesn't allow me to move the axle up and down like it normally would as you can see.. rubber bushings are made te squish in different directions a bit, which is why a radius arm doesn't work on solidworks, but it works in hte real world.
 
#13 ·
If you are set on a radius arm, at least put the lower mounts even with the frame rails. No sense in having them hang down that low if you are making this thing from scratch.


Are these mounts going to be welded or bolted on?
 
#14 ·
I would go a little deeper on the overlap of that three piece design. Also, those bent up tabs where those horizontal bolts would go arent really doing much because those flanges dont extend over the links. Also a t case skid.

You mentioned the exhaust, be careful moving it too close to the floor, you will melt the carpet lol. When I made my crossmember I lifted the exhaust system 2 inches, that started melting the carpet. I ended up cutting out the passenger side floor and raising it an 1 1/2 and made an aluminum heat shield. But damn do i have clearance.

Also def plate the frame, I used some kit from online it was like 175, way worth the cost vs. time.
 
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Discussion starter · #15 ·
Starboard M said:
If you are set on a radius arm, at least put the lower mounts even with the frame rails. No sense in having them hang down that low if you are making this thing from scratch.

Are these mounts going to be welded or bolted on?
Click to expand...
well im considering a 3-link+panhard seeing how it may actually be easier to make, i did some more research and found that if you make all arms somewhat parallel you get really nice travel. before i commit i need to find out how to re-route my exhaust, thats my only barrier. and i will be welding on new axle mounts. and repositioning the frame mounts more inward. Eventually took Timo's advice haha!
 
Discussion starter · #16 ·
Hussler said:
I would go a little deeper on the overlap of that three piece design. Also, those bent up tabs where those horizontal bolts would go arent really doing much because those flanges dont extend over the links. Also a t case skid.

You mentioned the exhaust, be careful moving it too close to the floor, you will melt the carpet lol. When I made my crossmember I lifted the exhaust system 2 inches, that started melting the carpet. I ended up cutting out the passenger side floor and raising it an 1 1/2 and made an aluminum heat shield. But damn do i have clearance.

Also def plate the frame, I used some kit from online it was like 175, way worth the cost vs. time.
Click to expand...
which one did you get? im probably only going to do a 1/8" stiffener. 3/16" is too much weight for me.
 
#17 ·
Looks really nice Tim.

However, I would elongate the sub-frame brackets forward and back of the two bolts. All the stresses from the LCA will be focused on the two bolts for the trans cross member. I just finished installing the Rusty's Radius Long-arm upgrade. Their sub-frame brakets are about 18" long and have considerably more strength from two 6" bolts running horizontally thru the sub-frame and three bolts on the bottom, the two stock from the trans cross member and an additional one forward of those.
Drilling the 1/2" and 1" holes for the bracketry was a pain, but a nice strong upgrade.

Your design looks great but could be stronger.
 
#18 ·
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DoctorTim
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