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Discussion in '80-Series Tech' started by GW Nugget, Jun 8, 2018.
This is the kind of info the world has been waiting to hear.
I suspect my vibes are from the double cardan. I had it built twice and the second shop had to work a little harder to correct the balance from the first round. Makes me wonder what it would be like if done correctly the first time
Not changing it out so will never know for sure
Most likely. With the Slee arms your pinion angle is back to where it was stock which is meant for standard driveshafts. A DC shaft requires the pinion operating angle to be 0º at cruise throttle, +/- 0.5º. Pinion operating angle is the difference between your pinion slope and driveshaft slope. This is a complicated way of saying the pinion needs to be pointed up at the tcase so that the CV joint at the pinion and the driveshaft are straight.
Here's my notes when setting up my DC shaft in the rear:
Yes, the stock radius arms are long enough. A 4” lift introduces very little angle - it’s not harsh over bumps and handles the most critical test of hitting an interstate expansion joint around a turn at 70 mph.
My rig is unflappable on that test - we have a nasty one at the bottom of Floyd Hill on I-70 that has a bunch of pothole patches right as you hit it that about sends my IFS vehicles into the cliff wall and the 80 on 37’s drives through it like it isn’t even there.
The other test is if your arms want to push down on big climbs - my 80 always climbs, because that rigid radius arm design prevents tires from drooping way into holes where they won’t climb back out and the angles are so minimal the arms don’t want to press downwards like short Jeep arms (and overly flexy suspensions) will.
This is my old XJ.
That’s a custom cut and turned D44 front, Currie high pinion 9” rear, and long arm y-link radius arm conversion.
I specifically kept caster on the low end - about 2 degrees - as radius arm designs aren’t spec’d around a lot of caster and you don’t want too much quickness in your steering when lifted.
The 80 with caster plates on a 4” lift outperforms this setup because of the extremely low bushing deflection and durability that doesn’t exist in Jeep rubber bushings.
There is nothing to be gained on an 80 with longer radius arms. You could y-link it or whatever to get rid of the bind, but at what stability cost to a vehicle that is way too big to not be a dual purpose road use vehicle?
My front swaybar has been a lawn ornament for a decade. Quick steering with swaybar snap is a terrible design goal IMO and increases rollover propensity on a lifted rig. It’s the about the last thing I would spend money to achieve.
I’ve had low caster on the Jeep pre-radius arms and custom front axle and it literally drove in a zig zag down the highway. The 80 is straight as an arrow at 90 mph without any weird steering feedback or any wobble of any kind. My only issue right now is I’m due for a front end rebuild.
What problem are we trying to solve outside of meeting a number in a book? The 80 just doesn’t have any of these issues that you spend a mint fixing on other platforms and it is so embarrassingly easy to stay in performance spec on a 4” lift because of the ability to covert the broken back driveshaft to a DC, which requires angling the pinion down with the resulting increase in caster.
Somebody was either genius with that design or we got very lucky, but I can’t begin to rationalize why you’d want to engineer around it. Unless you were converting to a Jeep suspension, in which case you get Jeep problems.
BT. DT. Never again.
There was definitely some genius behind the resulting package we call they 80.
Um excuse me I'd like to have a stern word with Mr. PHH genius and the exhaust guy.
Might have been an afterthought.
"Hey boss, check out this concept for the next generation Land Cruiser. It will be the best Land Cruiser ever built!"
"Hmm. Looks good, what are the specs?"
"You're gonna love it. Solid axles front and rear of course. Fulltime 4WD with center locking diff. Front AND rear locking diffs. All the latest bells and whistles with no shortage of luxury features. It's a vehicle well ahead of it's time and will be extremely capable off-road. We spared no expense. Due to the engine design she may blow a few head gaskets in 15yrs but by then we'll probably be owned by Chrysler."
"Where the f#ck is the exhaust?"
"Well about that. We kinda ran outta room. Not sure where to put it."
"Can you squeeze it through the frame right here and move this piece over a few inches?"
"Um yeahhhh, but Finance and Marketing keep telling us we're way behind schedule and millions over budget. This will set us back even more."
"Okay f#ck it. Run it along the outside here then make it go under the frame and out back. Give it a nice whistling sound too while you're at it."
"Boss, but what about ground clearance? This Land Cruiser is supposed to be[...]"
"UNDER THE F#CKING FRAME!!! God I can't wait to retire. I hate all of you."
Both minor details that can be changed. The PHH lasts as long as any water hose could be expected to last and I don’t have an issue with the exhaust system. Compromises must be made some place.
Installed these beefy b&$ches last night! Tracks so much better on the freeway now. My steering wheel is off center after installing these, however, so I'll try to get it back on the alignment rack soon and adjust the toe and check out the caster readings now. I was at 0 degrees with the bushings and it felt funky on the freeway before.
Wise choice on the Slee arms. I would make that my #2 mod after a lift kit.
For those of us running stock height but considering a minor lift (2.0 to 2.5") are these Slee arms beneficial? I'm one of those guys that researches something to death before committing and have been browsing lift options for over a year now. I think I have it narrowed down to the 2.0" or 2.5" Dobinsons. Waiting to commit until I have a plan for weight (still thinking about doing a winch in the stock bumper vs a front bumper+winch).
I probably don't even really "need" a lift but the original springs are worn out so I figure might as well. The previous owner installed OME shocks so it still handles decently with the worn springs, but loaded down I can tell.
Woah looks like these are for a 6" lift.... probably not what I'll need.
Number 2, lol
I'm going with 3" Slinky springs and from everything I've read, I think the caster will end up at 5 degrees positive. I'm currently at about 3" with OME and spacers using the yellow OME caster bushings and I was at 0 degrees of caster and the truck was darty on the freeway. I'll post up the alignment numbers with the current set up and once again with the Slinkys soon. The truck drives way better already and feels much more composed running down the freeway.
They're like (incredibly expensive) rock sliders for your front axle! I'll be running Rubithon next year, so I'm sure they'll be tested there...
Not needed for a stage 1 lift. I'm at about 4.5 inches and they feel perfect. Very stable and predictable on the road at speed.
But I don't like caster bushings at all, and I would consider some of the land tank caster brackets instead.
Yeah, I was thinking 3" Dobs with Slee arms.
Oh and the PFF what the hell
Considering how many people run 2.5-3" lifts and are looking for a better caster correction option, I am surprised Slee or someone else hasn't made a radius arm option for this height or even 4" height using stock bushings. I am guessing there is a reason for this. Maybe not enough people would buy them but I like the idea of it better than caster plates.