Coilover question (1 Viewer)

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I am just in the process of making some dolleys with wheels for the axle stands so I can set it at ride height and see what I have with everything out of the way.

I have already determined I will be up to about 24" on frame height...

I should have more on the weekend as the rest of my week is shot.
 
updated the link calculator to better represent what I have. AS looks OK but I would like the oversteer to be smaller (some understeer would be nice)
 
Seriously, dont get caught up on all that talk you have to have understeer in the front. 1 or 2*s of over steer is just fine. Besides if you ever link the back end, then most likely you'll be build something that has 2-3*s of understeer in it and then the vehicle total will be -1 or 0. Besides to much understeer can actually cause the vehicle to roll eaiser in tight turns.
 
am I crazy?

Nope, you are not crazy....

I skipped most the replies, sorry. Had a few cold ones this evening. :rolleyes:

40" tires and overland?

yes I think you are a bit off on that. I like the high roof, a lot. I like the 40's. I like the truck. However, 40's + overland is over the top. Sorry man, I am pushing the limits myself with overland in my current build and I think 40's + overland is over the top. 37's to me is the limit if you want to call it an overland truck. Don't want to argue the details of the word or whatever. Been to Panama and back, lived out of my truck the whole way, know what overland is.

You are headed the right direction if you want a "do-it-all" suspension and truck but 40's put it in the class of trailer queen. Been there done that. I say this because to build it right with gear for rock and pavement, power for anything, suspension to handle whatever and so forth and have it sit on 40's is extremely difficult to do and will cost ya' a ton of cash. By the pictures you get 40's and blah blah blah but you still have a long ass on the truck! So what are you gaining really?? If you want to make it super sweet in the rocks extend the wheelbase or better yet chop the body. 105-112"ish WB is what you want for rock crawling. If you want an off road weapon, bob it or extend the WB and get your approach & departure angles where they need to be to be a weapon. Dump a whole bunch of sheet metal, lighten the truck.

How wide do you plan on this being? Have you considered the rear suspension, axle width and suspension geometry. Will it all fit? The front of the frame rails are rather wide really, this can create a lot of dramas unless you go with a really wide axle. Same for the rear in terms of axle width, coilover mounting location and rub. Are you ready to chop the frame if needed to make this work?

The 60-series frame doesn't have a lot of arch where the axles sit under the chassis with a somewhat stock wheelbase. To fit 40's you have to lift or trim or both. If you lift to much, as you are aware it gets to tall. You can't trim all that much on a 4-door, or at least this one without screwing up the rear doors. So what to do? Move the axles and extend wheel base. One of the reasons you can fit 40's under a JK or TJ without a lot of effort is due to the frame design and suspension design. It is a whole different ball game in a 60-series Cruiser, especially when converting the suspension. Are you ready to do a cross bar in your engine bay? Are you willing to move the fuel tank to the bed and have clearance under the body for a linked suspension that flexes well? There is a whole s*** load of stuff on the table if you want to do 40's, and link it, ect ect ect.

If you want it overland, stick to 10-12" coil overs, limit tire size to 37's and don't get crazy with suspension. Realize you will lift a tire once in awhile or have to winch where you wouldn't if it was a trailer queen. Understand you have lot's of classic nice sheet metal and tons of body to destroy and wheel the truck as such. If you care more about running the the hardest rock trails over going to Baja for a month build the truck as such. There is no perfect truck and I just have to say 40's is pushing the limits for on road unless you do all kinds of things that cost all kinds of money. If you are set on 40's and the ability to do hard rock crawling, I strongly suggest building your truck into an overland vehicle, still doing the thing you want but drop it to 35-37" rubber. Then buy a $5000 4Runner or mini-truck and wheel the piss out of it on 40's in the rocks.

Yes the 3" vs the 2.5" has a larger surface for cooling, beyond this you are not gaining much. It also has a large spring on it. A 2.5" c/o has a 3" or so spring on it. Do you have any idea how this is going to fit in terms of axle width vs frame rail width? I am thinking it is not going to fit to well. You can set a c/o up however you want for weight, that is not a problem, just buy the right springs and or play with them until it is dialed in. However, your dramas with fitting this is going to be axle width, frame rail width, c/o width/spring width, axle swing under articulation and so forth. Wheel b/s is even going to come into play. I just don't think you are going to be doing this very easily, without spending some big bucks and with out having to cut a s*** load of sheet metal out of the body plus possibly modifying the frame. To do the same kinds of mods to my 2-door Nissan Patrol, I had to cut the rear wheel wells a shot load and then box them back in with new sheet. This reduced cargo space just to mention one thing that makes it not so overland. Not to mention 2ft was cut off the rear of the frame and a new frame fabricated out of dom. On a 4-door it is going to be more complicated.

I have had the trailer queen on 40's, had the long distance runner overland truck on 33's and now I am building something in between. Been to Panama in my truck, lived out of it on the way, trailered the crawler to Moab, Arizona and whatever. Been there done that. You can't build a 'do-it-all" on 40's without spending big bucks!

I am not trying to shut you down or say you can't do what you want. I have however built a truck on 40's with 16" coilovers. I have also built plus used an overland truck and drove it a long ass ways and lived it out of it for nearly 4 months. I am now building something in between and so I am giving you want I think, my opinions and advice from my expericne. You can do with that as you will! :D

That is my 2 cents! And by all means if you have your mind set on 40's and a truck to travel 1000+ miles down the pavement to the trail plus the cash to build it by all means I say do it! But perhaps a different platform would work better for links, 40's and overland. ;)

:cheers:
 
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All good points RMP&O.

The truck has had 39" tires on it for trips to Alaska and 38" tires on it for trips to the NWT. I didn't think 40" tires where that much of a stretch... IF I can get them to fit. One of our traveling companions ran 39.5" on his BJ74 (a lot easier to do, I know)

I am very prepared to notch/move the frame if need be. Especially in the rear. New fuel tank is in the works already. (I am planning to run air bags in the rear) Cross over in the engine bay is also in the plans. Axle width is already widened 6" (running a 80 series rear and diamond in the front) so I don't think 2.5" CO up front will be a problem. It's the upper link and the panhard that are my current issue.

If I can get it to work, great. If not it's back to springs and life goes on.
 
Seriously, dont get caught up on all that talk you have to have understeer in the front. 1 or 2*s of over steer is just fine. Besides if you ever link the back end, then most likely you'll be build something that has 2-3*s of understeer in it and then the vehicle total will be -1 or 0. Besides to much understeer can actually cause the vehicle to roll eaiser in tight turns.

This is one of the best statements I have heard in a while.

You can over analyze the crap out of suspension design and end up with something that everyone says will be "perfect" according to the numbers. And then, by the time you build it, things change slightly and it is not what you expected.

I know rigs with a TON of antisquat/antidive that perform very well. And I know rigs that on paper look great but do not work well off road. Build it, then make tweaks as necessary to fine tune the suspension. This is one of the reasons that an adjustable suspension is handy.

That being said. I still think you are not going int he right direction with a conventional three link/panhard bar. If you are concerned about street manners you will have some odd braking habits because of the single upper.
 
That being said. I still think you are not going int he right direction with a conventional three link/panhard bar. If you are concerned about street manners you will have some odd braking habits because of the single upper.

Can you explain this? I assume has something to do with you recommending a radius arm instead? Cripes I haven't read a thing about weird braking habits! :mad:
 
By only having a single upper (or lower for that matter) you are freeing the axle to be able to rotate during articulation. Same reason bronco guys put a "wristed" arm in their radius arm suspension.

That ability to rotate during articulation can manifest itself by rotating the axle during panic stops. Which can lift one side of the truck and lower the other side causing some really odd handling during panic stops.

In a rock rig, it's not a big deal, but in a street rig, it can be hairy.

There is a reason that you don't see factory built rigs use a 3 link with a panhard bar front.
 
that makes sense. I really appreciate the info. A guy can get bogged down in it all.

I think I have the room for a 4 link with panhard but was concerned about binding issues. Should I take a harder look at this? Is 6" still the minimum separation I want with two uppers.

If I use the 3 link calc do I just add the fourth link on the other side or do I use the four link calc and add the panhard?
 
You will bind more with a 4 link/panhard. But that is part of the game.

To tell you the truth, I have never understood the 6" separation thing.

And, as I understand it, in the basic form, your link numbers won't change much from the three link calc.

But if you start to use the more advanced portions of the calculator, then you will want to use the correct one.
 
Well, these are from last night at a frame height of 23.5" I have a buddy with a set of 39.5" IROKS that I can borrow for fitment but lots of room for the 37s.

I need to clear some fuel lines of the inside of the frame and move the exhaust up but there should be room for both uppers.

The rear cross member also needs to be redone, but that was the in the plan anyways to lift the back of the drivetrain up accommodate a flatter belly. I might lift the engine an inch as well if I don't start hacking frames.

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How much up travel are you looking for .? coz another way it's Y links .. and yes you will need to sacrifice some binding ( travel ) for on road manners .. ain't gonna be perfect ..
 
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4"-6" I only had 4" up travel on the SOA do to oil pan clearance issues with the 4x4 labs highsteer. I need to go back to regular up front steering so that is no longer an issue.

It's going to be the panhard that limits my up travel.
 
By only having a single upper (or lower for that matter) you are freeing the axle to be able to rotate during articulation. Same reason bronco guys put a "wristed" arm in their radius arm suspension.

That ability to rotate during articulation can manifest itself by rotating the axle during panic stops. Which can lift one side of the truck and lower the other side causing some really odd handling during panic stops.

In a rock rig, it's not a big deal, but in a street rig, it can be hairy.

There is a reason that you don't see factory built rigs use a 3 link with a panhard bar front.

You can combat that effect. If you can set the upper and lower to keep consistant caster throughout the travel. The other way is to really go out of your way to make the panhard as long as the draglink. A panhard that is 12"s shorter then the draglink regarless of being parrallel will cause bump steer during brakeing. You will never get rid of ALL of it, but you can help a lot of it. On the flip side, a 4link with panhard (dont triangluate the uppers) will do alot to reduce strange braking out of the box.

Just in case anyone readying this asks what kind of strange braking, a can get a touch of pull to one side. Or at least thats what I expeirenced. Like I said though it is fixable.
 
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I think I have the room for a 4 link with panhard but was concerned about binding issues. Should I take a harder look at this? Is 6" still the minimum separation I want with two uppers.

If I use the 3 link calc do I just add the fourth link on the other side or do I use the four link calc and add the panhard?

Just use the 3link calc, you dont need the 4link version. The 4link one is for triangulating uppers and lowers. By adding a second upper to your 3link it wont change any of the numbers.

The separation of the links at the axle is to handle the twisting of the axle during acceleration and deceleration. At the frame its to fine tune your brake dive. You put as much in as you want, just remember the less separation the greater the torque loads on the steel and joints.

Please, Please, Please make your upper link adjustable so you can fine tune your anti dive. Dont limit your self to only one option. If you're willing to do it, do it right. I like less AD because the nose lifts less while accending steep hills and obstacles. Not to say I would not have made it up the same obstacle with a higher number but it has made it easier. ASK ME HOW I KNOW. I've only had 5 different version of a 3link on the this vehicle.
 
Thanks 4WU.

All links will be adjustable. I just started placement of the lowers on the axle side as this is where I have the least amount of options. I figure start there and work my way back.

I need to get my new steering arms on order so that I can see where my drag link is going to end up. One thing I have noticed is that having RHD steering is a bit of a PITA with the pumpkin on the same side as the steering box.
 
You will bind more with a 4 link/panhard. But that is part of the game.

Radius arms still bind a lot more. I put 14" coilovers on a Jeep LJ a few years ago that already had a Rubicon Express lift. It bound after 12" of shock movement. Im faily certain that 4 semi parallel links would at the least allow a full 14"s.

To tell you the truth, I have never understood the 6" separation thing.

About 7 years ago Pertersens did one of the first 4link tech articles, the rule of thumb that they used was that you should set your separation distance to 25% of your tire diameter. But thats not really possible when you wheel on 37"s and 40"s. 40"s would net you 10"s of separation and there just isnt enough room for that.
 
Radius arms still bind a lot more. I put 14" coilovers on a Jeep LJ a few years ago that already had a Rubicon Express lift. It bound after 12" of shock movement. Im faily certain that 4 semi parallel links would at the least allow a full 14"s.

All depends on the design really. I've seen parallel 4 links bind pretty quick. 12" shocks on a radius is pretty good!


About 7 years ago Pertersens did one of the first 4link tech articles, the rule of thumb that they used was that you should set your separation distance to 25% of your tire diameter. But thats not really possible when you wheel on 37"s and 40"s. 40"s would net you 10"s of separation and there just isnt enough room for that.


It's been a rule of thumb for longer than that, but it still does not explain why the rule started.
 
It's been a rule of thumb for longer than that, but it still does not explain why the rule started.

My guess is rod end/bushing failure. On my anti wrap for the rear of a SOA I was at about 4" and I went through bushing like crazy. Opened it up to 6"-7" and hadn't replaced one in years??

I think the 2.25" .375 wall DOM and EVO ends can handle the stress of less then 6". There going to have to because I don't have that much room :frown:
 

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