Double triangulated rear 80

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nukegoat

nukegoat

Should have bought a Jeep
10 Year
Joined
Apr 10, 2013
Threads
122
Messages
6,683
Location
San Jose, CA
ibhaters, people bringing random criticism, defending toyota design, blah blah blah

Here's the before. 13 degrees of roll oversteer, low roll center height, tons of flex steer... this is w/ a 5" lift. Horrible. Still flexed ok but didn't work right on-road and was too wobbedy for my tastes. If you're running stock suspension, this is you:
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I designed this so the only things that have to be welded on are two frame plates that a lower link crossmember bolts to and a couple of tabs on the axle to bring the axle lower links up (they weld to the oem lower plates for alignment. Oh, and a couple of triangulation gussets here and there for the heck of it.

That said, the truss could be fabbed on the bench, the wishbone could be fabbed on the bench, the links and frame crossmember are fabbed on the bench, and then it just bolts in all win-like.

Sleeve off-road
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For you geometry weiners out there

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How does it drive? Hopefully good. I don't have exhaust as you can see in the pics so I'll be taking it to a shop to replace the oem water heater with something that doesn't hang below the frame rails.
 
half k cruiser said:
:popcorn: eagerly awaiting the report on this. I can't remember, did you have a custom 3 link up front ?
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Semi-parallel 4-link. I like it but I tried to constrain myself to a design that allowed retaining of the factory sway bar and no relocation of the tie rod. It flexes more than my shocks can deal with but I'll probably just relocate the tie rod and raise the axle lower mounts at some point.
 
Thats not technically a double triangulated design. It's a wishbone three link. The wishbone keeps the housing centered and is also the hard point on roll center. Not saying anything is wrong with the design, but a true double triangulated 4 link would mean all four links are independent of each other, and the top links converge at the top of the center point on the axle and the bottoms converge at a center point on the cross member. The axle is located simply by the double triangulation.

I ran the double triangulated design on my old CJ7 crawler on the front and rear axles. It worked very well but the steering was full hydraulic with a double ended ram mounted on the front housing. The lack of a pan hard means you can't have a frame mounted steering box because you will end up with crazy bump steer.
 
rockrod said:
Thats not technically a double triangulated design.
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It's a double triangulated design, just not a double triangulated 4-link. It's equivalent but instead of a virtual convergence point, it's got a literal convergence point with one giant spherical bearing instead of two.
It's a wishbone three link. The wishbone keeps the housing centered and is also the hard point on roll center. Not saying anything is wrong with the design, but a true double triangulated 4 link would mean all four links are independent of each other, and the top links converge at the top of the center point on the axle and the bottoms converge at a center point on the cross member. The axle is located simply by the double triangulation.
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It's the same thing geometrically.
I ran the double triangulated design on my old CJ7 crawler on the front and rear axles. It worked very well but the steering was full hydraulic with a double ended ram mounted on the front housing. The lack of a pan hard means you can't have a frame mounted steering box because you will end up with crazy bump steer.
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Correct
 
maxamillion2345 said:
Might flip your joints so you don't break off the zerks.
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I thought about that. I may but I'd never be able to grease the driver frame lower then. It's very tight to the gas tank
 
13 degrees of bump steer? Was that the prototype or the current design?
 
ChiTown said:
13 degrees of bump steer? Was that the prototype or the current design?
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That's the roll axis under extreme droop. Pinion looks good still.
 
That's really cool dude!

Go beat on it, but keep a sharp eye on the entire wishbone mounting points/setup. That whole piece has to do the work 3 separate 'links' shared previously and fails all the time on many rigs. Not questioning your work, just the factory stuff you attached to.
 
Booger weldz said:
That's really cool dude!

Go beat on it, but keep a sharp eye on the entire wishbone mounting points/setup. That whole piece has to do the work 3 separate 'links' shared previously and fails all the time on many rigs. Not questioning your work, just the factory stuff you attached to.
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The upper frame mounts are beefy. If you think about the loads on them, I highly doubt they'll ever detach or peel off. The axle upper mounts need gussetting to take axial load. Yep - at the exhaust shop now.
 
Got the new exhaust on. Quite a PITA for the guy but it's done and it was cheap. The thing is *much* better on the road. I think I may need to play with the alignment a bit still, but I'm a happy camper.
 
Nice work. Any pics of the upper link setup?
 
You could do it for around $6-700. I had my exhaust guy tuck the cats and go over the frame and so on, but really the only critical thing is that the muffler doesn't dangle as low as the factory one (no lower than the gas tank sits, ideally).

Metal (I ordered from onlinemetals like a lazy SOB, which is sort of fleecy but convenient) - $200
Barnes4WD enduro joints, tube inserts, and jam nuts - $220
Poly Performance uniball & urethane bushings - $110
New muffler - $70
Bolts and such - $50 (pointe products for the win)
 
I should update my first post. This thing drives *way* better now. Like, ridiculously more stable. I was texting and doing 75 down 101 - even with mediocre front geometry and no front sway bar, it was planted and tracked like it should. I'm not trying to convince anyone of anything in particular, but the numbers don't lie - the rear roll axis is not good with the OEM links once lifted and more than likely a major cause of people's complaints with the rig once lifted (though I think they spend more time than necessary chasing down irrelevant problems.)

Would do again, A++, much win, wow
 
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