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I will also be following this thread! Great info on various suspension set ups so far. I'm having a 40 linked in the next couple of months and really want to know how and why it works well.
 

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well went with ordering parts for the 3 link front. Sounds like I may add a 4th link to share the forces. It will be something close to my last design on the front. That should net me a decent performing suspension. My goals for each are:
30-80% AS/AD by moving upper link mounting
Instant centres a long ways away to aid in wheel recession
Aiming for 0 to -2 understeering roll axis
lots of castor up front to help keep tracking straight 4-6*
3-5* max pinion change through travel
12" shocks
If you can build some adjustment into the upper link frame side mount that will be a good thing.

Long instant center is good....and rather low also. A long instant center also seems to help indicate how AD/AL/AS changes through the suspension travel.

I would shoot more for -2 roll axis rather than 0. It will help with how much steering wheel input you need to give the vehicle....or rather how sensitive the chassis will be to input. I wouldn't be afraid of a little more either.

Lots of positive caster? As tire size increases, in theory, you need less. Running LOTS of caster ( which 4-6* isn't really ) was an old school patch to help with high speed stability and poor suspension geometry.

I wouldn't worry too much about pinion change...other than it's a good indicator of caster change. Both aren't THAT big of a deal. Most of the time the suspension is going to be operating in a pretty small window. We don't really care what happens too much on the edge of the window. It is pretty impossible to have almost no pinion angle change ( driveshaft relative ) while keeping caster change ( wheel relative ) in check.

12" shocks. Good. I don't see the need for more than that on most vehicles. I'd try to make room for 6" of uptravel from ride height if possible. Packaging that in a low ride height is always fun. I would try and get the shocks as close to the tire as possible. Having them mounted slightly wider at the bottom and angling in at the top will help the sway related motion ratio. Packing that will be challenging.
 

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Discussion Starter #24
great tips and comments again from everyone. I'm looking closer into running front coil overs now as and option rather than the 80 series stuff. Mainly for tight packaging and more tunabliity for ride height and frequency. aiming for 300-350 lb coils but will measure corner weights before landing those for sure.
 

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Have you read this by chance?

Suspension Encyclopedia/4Wheel Underground


My FJ40 ran a 175 over 200 which is a 93.3 lb/in primary rate. I know your truck is much heavier overall, but a lot of that is in the rear. I had 6" uptravel on a 14" shock.

Calculators are great for getting an initial plan, but I would get your link kit and start mocking everything up as well.
 

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great tips and comments again from everyone. I'm looking closer into running front coil overs now as and option rather than the 80 series stuff. Mainly for tight packaging and more tunabliity for ride height and frequency. aiming for 300-350 lb coils but will measure corner weights before landing those for sure.
Try and get sprung weight if you can when things are apart. If you go coil overs, try to borrow a set of coils. Use those to get a very close calculation of actual sprung weight by measuring the length in the car.

It depends what you want the vehicle to do in the end, but 300-350lb coils seem WAY too stiff if you end up with a 12" coil-over set close to 50/50. I think stock FJ80 front coils are something like 120#. Do you have any idea what the car weighs now?
 

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Discussion Starter #27
the reading I've done shows 80 series coils range in the 220-300 so I'm likely a little heavy as you say. I'm tipping scales at 7000lbs loaded up for camping now but have a heavy rear bias. I'd bet the front sprung weight is in the 1000-1200 range. so 600 per spring…..in 6 inches…..does that math go around??? then add in the coils being offset and likely angled from the load….that still is likely a much lower rate as you mention….
 

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the reading I've done shows 80 series coils range in the 220-300 so I'm likely a little heavy as you say. I'm tipping scales at 7000lbs loaded up for camping now but have a heavy rear bias. I'd bet the front sprung weight is in the 1000-1200 range. so 600 per spring…..in 6 inches…..does that math go around??? then add in the coils being offset and likely angled from the load….that still is likely a much lower rate as you mention….
I got the front stock 120lb/in number from some info Icon suspension had posted somewhere. They had some stock springs tested when they where developing springs/shocks or something.

The best way to measure sprung weight is with coils on the vehicle when it is DONE. I don't think the front suspension sprung weight is going to be nearly as variable as the rear end. Your idea for using air bags for the primary rear suspension is a good one, especially if your pushing 7K when loaded! Yikes. I am hoping I can squeak the new truck in under 4K.

Getting a decent idea of spring rate for the front should be pretty easy once you know the sprung weight. You don't want the coils to unseat. If your running a 12" shock and you need to compress the springs at least 6" for ride height, you can just divide sprung weight by how many inches of compression you need. If you have 600lbs of sprung weight per corner, and you need to compress the springs at least 6" to sit at ride height....that would be a spring rate of 100lbs/in. Many people these days are even adding 'preload' on coil-overs to allow an even lighter spring rate. If you want a spring rate higher than that you need to run a tender coil of some kind. Generally, that isn't being used too much these days from what I am seeing. Most people are going toward using the lightest spring weight to do the job. With that, you have to deal with sway. This usually means some kind of swaybar for full bodied and/or top heavy rigs. Sometimes you can get around it with proper suspension/chassis design. Proper shock valving can also help, but typically that is a 'rate' fix rather than an actual change in roll resistance like a swaybar is.

I can't wait to see what you come up with on this. I love the look of the thing already.
 

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Discussion Starter #29
thanks I'm especially excited too… Ordered the adapter flanges from high angle today and re confirmed my order for the new rock monster 8 lug wheel set.

Read the home brew sway bar based on toyota torsion bar thread last night. That is rich up my alley so I'll start figuring how and where I can fit that bar with an adjustable arm length of 18-26" to give me some anti sway adjustability. Top heavy is what this thing becomes with the James baroud up top…. not unreasonably so but you know its there….. Last trip to pismo on the interstate clover exit and entry ramps I could stuff the tire into the tub…..that was 6-7" of stuff at the time…
 

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Discussion Starter #30
Well I've lost a little steam but am still slowly making progress..

On a recent run my transmission gave me more trouble but that is now corrected. The land cruiser black box is nice but certainly has some shortcomings that weren't clear originally.

My TMR order arrived and as I unpacked it I was getting pretty darn excited again. I think I have most pieces I need to get the bulk of this suff tacked into position in the next couple weeks.

Couple questions on the steering: My dodge dana 60 currently sits with a missing top cap on the RH side and a push pull arm on the left. My first thought was to run the Y link style steering that the cruiser has now. Angles are tolerable and with the upgrade in components strength should be there as well. Alternatively I could get a high steer arm for the LH and run crossover or arms for both with high steer. Trouble is this will be set up for RHD truck…. steering wheel on the right of vehicle. What say you folks…. If I go with the Y steering I'll need to replace the top cap on the RH side as its missing all together. I'd likely go with a springless style replacement.


Next consideration is front shocks. Thinking ORI's could fit the bill on the front as they will have adjustibility built into them in terms of ride height, spring rate, and anti sway. They aren't much more if any than a coil over, bump combo and will be easier to package. My concerns are the cold weather we live through up here and any risk of leak down in daily driver use. Don't mind topping them up now and then but don't want to carry an N2 bottle if I can avoid it.
 

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On a recent run my transmission gave me more trouble but that is now corrected. The land cruiser black box is nice but certainly has some shortcomings that weren't clear originally.
Unfortunately I don't have any tech to add, but would you care to elaborate on the above statement? A blackbox is on my list of potential future mods.
 

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Discussion Starter #32 (Edited)
I only think there are issues behind the cruiser transmissions. In my opinion there are some design flaws that when left unattended will cause serious issues or failures in my experience. I can elaborate more in a PM if needed. I'd reached out to them in the past on some of the issues but I'm not sure they'd seen them… they never did respond.

Could just be me...
 

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Couple questions on the steering: My dodge dana 60 currently sits with a missing top cap on the RH side and a push pull arm on the left. My first thought was to run the Y link style steering that the cruiser has now. Angles are tolerable and with the upgrade in components strength should be there as well. Alternatively I could get a high steer arm for the LH and run crossover or arms for both with high steer. Trouble is this will be set up for RHD truck…. steering wheel on the right of vehicle. What say you folks…. If I go with the Y steering I'll need to replace the top cap on the RH side as its missing all together. I'd likely go with a springless style replacement.


Next consideration is front shocks. Thinking ORI's could fit the bill on the front as they will have adjustibility built into them in terms of ride height, spring rate, and anti sway. They aren't much more if any than a coil over, bump combo and will be easier to package. My concerns are the cold weather we live through up here and any risk of leak down in daily driver use. Don't mind topping them up now and then but don't want to carry an N2 bottle if I can avoid it.
It shouldn't be hard to make a Dana 60 steering arm for RHD. If its just the steering arm ( not a tie rod ) it doesn't have to have proper acketman. It can just be a simple straight arm.

Side note. I haven't had the best luck with springless caps on my dodge in the long run. I daily drive the thing and I have to adjust/replace the bushing in the top cap at least 2-3 times a year. This truck doesn't see a ton of off road miles, but does get driven every day just about. I would just use springs and replace them every 20 years or whatever.

That said, with as low as this chassis looks to to be sitting, especially with your uptravel goals, I don't think your going to have room for a raised drag-link and tie rod. Packaging the steering along with a panhard is probably going to be enough of a challenge. I would just use a normal t-linkage mounted on the stock knuckle steering arms.

On the front spring/shocks stuff. ORIs are pretty neat, but I would think that for what you look like your do with the vehicle ( longer distance remote travel ) a normal spring/shock, or coilover, might be 'better'. A spring is still a spring even if the shock fails. If the ORI fails your going to have to make the journey to help on the bumpstop. If a shock is leaking, at least the spring will still hold it up. The front suspension weight should not change THAT much as the car is loaded for longer trips. Most of that weight change should be isolated to the rear suspension.
 

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Discussion Starter #34
Finally made a little progress.

AAM 10.5 is now stopped, shaved and bracket removed in prep for links. Tomorrow I hope to get a truss tacked into position with the integrated pinion guard. If all goes well it will be positioned under the rig sometime in the coming 10 days….
 

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You say it is an '81 47, but the Bezel and drip rail says it is a '79 or earlier 45.

Maybe Toyota kept the Troopy in 45 guise post '80 and just ran with the new model number on it.

Do you know where it's fuel tank originally sat from factory ? In Cab, or Under.
Original Handbrake ? Diff mounted, or on Transfer Case.
And Original frontbrakes ? Disc or Drums.
 

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Discussion Starter #38
Well, Its been like 4 year with no progress.... ha... New plan and details to come. Measured for the rear and in order to not cut the heck out of my tub i've ordered trailing arms for it now. This will let me sneak 12" coil overs into the rear with even more wheel travel.... though I'm not sure I need more travel for this rig....

I've been tossing back and forth going with radius arms in the front for east but really wont decide until the axles are under the truck....
 
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