ok, so my car is slowly turning into a 4th gen, i'll wait until you're done laughing at me for wanting to use a 4th gen rear axle, but hear me out and see if you can give me some feedback. i posted this on a minitruck website to see if i could get some answers, but nothing really, so i figured i would open it up here to the likes of jeff, matt, mike, and anyone else who is suspension geometry savvy.
in the process of slamming the max i ran into a problem. problem is the camber and toe change is extreme from lifted to dropped.(like 2 inches of toe movement along with the wheel moving in towards the car like 2 inches when fully dropped) i decided i should just use a 4th gen solid rear axle, which comes with a lateral link, but i dont want to have problems with it pulling. can i just beef up the 2 link and not run the lateral link? using a 3 or 4 link isnt an option because the tank is in the way and i dont want to run a reverse 4 link.should i use a parallel 4 link instead? i think it woud do the same thing as a 2 link. bounce some ideas off me. thanks, juan

 

the lateral link is to keep the axle from swining side to side.
My concern would be how long are the links going to be?
I think that will affect the arc that the wheels go in when full up to full down.
unless I'm wrong they travel in an arc like this : ( which may cause other interesting problems.

 

Maybe you could make parallel links (you might call them diagonal links) like this / \. The top of / \ would be the spindle side and the bottom would be the crossmember side. Just have the two links per side without having the lateral link. I don't know if this would work but, it's just an idea.

 

What about something like a Mustang 2 front A-arm suspension?

Brian

 

Solid rear axle would be the easiest. You would have to compare the two to see if the mounting points etc are anywhere the same

 

mounting points are no biggie, i can always modify that, like i've done so far( i made new strut towers out of 3/16 metal, modified the transverse link's mount on the strut, i had actually shortened the parallel links etc,but no matter what i do there is one more problem around the corner, so i just want to do it as simple as possible. i have to calculate how much movement there will be with the lateral link. i'll make it as long as possible so the change wont be as drastic.

internet, you're right, the wheels will move towards the car when lifted, but it does that now anyways, along with tremendous camber and toe changes, so if i eliminate camber and toe movement i'm good. i actually want to make my own 2 link banrs to weld onto the axle so i can put an adjustable end on it. this way if my calculations are slightly off and the thrust angle is off i can always adjust it .

it sucks, im going to cut away 3 months worth of work and agravation and start over again, not to mention that i welded my brand new cylinders into the disc brake struts. oh well, live and learn. ill post some pics when i get the rear

 

you still end up needing some sort of link to minimize side to side, ie a tie rod or an upper a arm, thought of both but it just complicates things, in fact i had even thought of trying to get a 300z rear and use the crossmember and and spindles from that, but it complicates things too much. same goes with any type of front suspension system, like the mustang 2, it has to have something to hold the wheels straight, whick when it moves up and down changes toe. 4th gen rear just seems the simplest way to go

 

since you already have hydros installed on the OE struts, try making your own solid axle.
just use some 1x1 square tubing to connect them.
Can you triangulate the parallel links IE \| instead of just | ?
that should help the side to side part of the equation.
you've got pics of your current setup on car-domain right? I'll check there in a bit and see what else hits me.

 

sorry about the red, i just want anyone else that reads it to know that i have hydraulics not bags like everyone thinks


thought about that but i dont want the toe or caster to be off when i weld them together and then the car never goes straight, u know? i can measure it, but a centermeter off here or there will be several centimeters from one end of the tire to the other. besides having to correctly set toe and caster if i weld it myself the camber could be off too.if it were'nt for the gas tank i would just 4 link it, but i can't use a fuel cell since the gas filler is so low.ill take a look at it sometime this week, i was just out there cleaning leaves off around it, hopefully i'll have it enclosed by next week and i can work inside.

 

a couple months ago i noticed that the Infiniti Q45 has its fuel tank in the trunk, those are pretty easy to find in the junkyard, if you have space in the same location you might be advised to try that to free up some space underneath the car.

Brian

 

on that note, check out a j30.

I was looking through my catalog and the only solid rear axles I could find that lacked either a 4 link or lateral arm were the cavaliers and it's derivatives. from what I could see it used a VERY short triangulated arm to locate the axle.
I definately understand your concern on making your own. how wide is the 4th gen solid vs our IRS?

You may want to check out a program from Performance Trends called "Suspension analyzer" I'll let you guess what it does

 

put a gas filler in the c pillar and have it come down to a cell inside the trunk. Then you can do your 4 link.

seriously I think I would do a 4 link and put a cell in the trunk before I did a 4th gen suspension. You could always figure a cool idea to keep from opening the trunk but even if you have to open it then it still wouldnt be that bad since you dont drive it daily like you used to.

 

taking it back to the old school...
i'm assuming you're referring to the rear suspension since the front is a big mess w/ the axles and etc.

go to the junk yard and look at the rear suspension of a mid/late 80s (85-88ish) olds ciera, buick century, chevy celebrity, pontiac 6000, etc etc...you'll notice that body style.

they are FWD cars w/ extremely simple rear suspension. i assume ride quality is not a major concern for you.

basically the axles runs right across with coil springs sitting on your axle and the shock bolted behind it.

2 links that connect to the body of the car and that's pretty much it...very old tech.

very poor drawing...(looking from above the car)

..!..........!
0->-----<-0


the 0 are the tires and the --- is the actual axle. the 2 ! are the parts that connect the axle to the body...the > and < are the locations of the spring...(i'm sure you can mount the actuator there). i don't think there's a cross beam (like the 4th gens)...but good to double check. ignore the periods since the forum software won't space out correctly.

so this axle set up will put both the wheels in a pivot w/o changing the camber/toe of the rear wheels since it just swings up and down..make sure you have enough pivot room and it should be ok. down part is that the swing goes on an arc...so you'll need to probably make the wheel well bigger (if you haven't already done so).

good luck.

 

Danny, the celebrity and its derivatives used a trailing arm also. that's why I suggested the J-body it was the only setup I saw that only used 2 arms.

 

really? for some reason i don't remember it being there..oops.

 

sh|t happens

 

Juan, what about taking the parallel link system you've got now and making the arms LONGER?
Making them shorter will cause the camber and toe changes to be worse as you change the ride height- as you see now.. they travel on a smaller arc.

if you go to longer ones, there will be slightly more unsprung weight, but that's a non-issue for you at this point I'm sure. But that should help solve the camber and toe changes with ride height.. try to put the inside ends as close to the center (vertically speaking) of your suspension travel as possible though- that way you can set the alignment when the car is at ride height, and it will change the same when you go to highest and lowest points.
I'm drawing up a graph in autoCAD now to try to illustrate some things here... it's only 2D and you'll have to redo it to factor in the radius rod, but basically if you can work out the camber change, your toe change should stop as well.

 

here ya go.. hope this makes sense...



I made a BUNCH of assumptions here on dimensions, but you can see where I'm going with this..

the horizontal red lines are set 5" below and above the center... that would be your highest and lowest ride heights, respectively.

the black circle in the bottom right is your spindle- the central point in all of this mess.
I then used parallel links of different lengths and set the ride height all the way down, as if the car was sitting on the ground or whatever.
Since you said you shortened them some already, I stuck in 8" for the blue parts.
the factory links are about 10.5" long, and they're in light blue.
green was an arbitrary 12" length I chose, as well as the red in 18" length.

I also moved the upper strut mounting point inward 3" since you said you'd moved it as well. I just chose a 3" number at random to throw in there.

Basically the goal is to produce as little change as possible from the black lines, since that's the angle where the strut stays. if the strut doesn't change angles, then your camber won't change.

Now look at the pic... in the outward position of the strut, your closest to perfect would be the red lines- 18" links. The worst one is the shortened 8" links.

move the strut towers in a few inches, and now the 18" red links are the WORST option and the better option is the shorter blue ones!


So obviously there needs to be some accurate measurement done here, but you can work with this suspension- it just takes a bit of calculation and some custom rear links.

 

dam thats alot of thinking i've had you guys do.

internetand danny, isnt the j30 a rwd car? i actually had a century, it pretty much has the same suspension as the 4th gen,and the cavalier, except it has a long lateral link instead of that s shaped contraption nissan made. i would even use a century rear axle, but the bolt pattern on them is 5x5(almost 100% sure) so it wouldnt work, plus the one i had had drums, dunno if they ever came with discs. plus it's easier to stick to all nissan parts in case they interchange. space in the wheel wells isnt an issue either since they are completely gutted so the 20's can go down lower, as well as the door frames, ill try to get some pics, they may actually be on cardomain though. the length of the trailing link(front to back) is just short of 2 feet. the suspension travel would be 8 inches, over 12 inches( did it on my tile floor) it only moves 1/4 " out from the top position to center(6 inches on the tile floor) and then back in 1/4" at 12 inches, so thats minimal.
awsm66, cant believe you're getting rid of the 93!, but oh well, at least you have 5 or 6 other maximas. i thought about sticking a fuel cell in the spare tire hump area as far back as possible, but i think it would still be an issue getting gas there, as it is now, sometimes i even have to lift the back end just to get the gas to flow into the tank(dunno why either, one day it's fine, the next it doesnt want to go down)
even if i did a 4 link i would need a solid rear axle for it to go to, so i think that may just complicate things. the only great part about a 4 link is more side to side articulation with less stress on the bushings, but i dont plan on playing with the hydraulics like i used to, itll just go up and down now, so the only side movement itll have is from turns, very minimal.

and matt......................
that drawing actualy kicks a$$. i had shortened the parallel links 1 inch and moved the top of the strut an inch. i did that to clear the wheel opening on the 1/4 because it would just touch slightly when it was all the way down. after i cut up all four adjustable links(yep i bought 2 more so i could have toe and camber adjustments) and welded them back up and reinforced them, i realized that one inch there meant 3 when it was all the way down or up, mind you i hadnt done anything with the trailing link because it would hit the tire when all the way down(suspension moved closer to the car 3 inches) i decided to put the non adjustable link in and strecth out the shortened link(like 3/4 of an inch, so it was 1/4 inch shorter than stock)plus i moved the top of the strut back out. and i had no rubbing, but since the parallel links move up so much(vertical being 90 degees, they are at maybe 140) the length is still so short than it moves the suspension in 2 inches, and the 1/4 inch short adjustable link makes the toe go nuts, as does the trailing link because it makes the wheel pivot where it bolts in.

now.................. if i make the links longer and have them mount closer to the center of the car, it will hit the rails( i already notched them so the parallel links would move past them).

i figure if i cut out the botched up rails, make my own out of 2x3 box tubing, so i get some strength back, bridge them together to prevent flexing and have the hydraulic cylinder mount on them, it will simplify the entire equation. stock 4th gens do have slight camber in the rear, so as it moves up or down, the camber will actually turn into toe movement, but one degree isnt as much as one inch
we ther to use a lateral link or not is very mixed up. some guys say it defies suspesnion geometry if you dont use it and ot works. others people have told me they've had a 2 link for years with no lateral link and no problems. i may try to not use one, and if i have to weld one in.

 

http://memimage.cardomain.net/member...210618_199.jpg
notched rails

http://memimage.cardomain.net/member...210618_201.jpg
wheel in 3 inches

http://memimage.cardomain.net/member...210618_205.jpg
rear door
http://memimage.cardomain.net/member...8_208_full.jpg
see how much those links move in?

i tried to post pics from cardomain, but its only showing nice red x's, , just copy and paste or go to my front page

 

Okay, redneck solution.
stop using straight links.
stop using rubber bushings in them.
go to heim joints, and use curved links.
that will give you the clearance under the rails, and it will still allow you to adjust them as needed for toe and camber.

I'll PM you some info on it...

 

the j30 is RWD (same basic setup as the Z)
I was at the shop today and under a jetta which I happened to notice doean't use a lateral rod either.
it used a setup where the very short arms were in fornt of the beam and the arms going to the wheels were longer and behond the beam rather than in line with it
did that make sense?

 

i took a look at a 98 jetta myself, just the axle, so it should be fine to use. i bought a parts 97 maxima so im gonna see if that fits. thanks for everyone that gave some feedback, especially matt, i actually think the graph is what made me think dooing the solid axle was the best way to go(too many variables in the length of the arms) ill keep you guys posted on what happens