Forums/Z31P/z31-performance-upgrade-forums suspension-chassis-and-brakes/G-E's crazy rear multilink idea
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G-E: (2007-07-12 19:28:01)
84z31: (2007-07-12 20:15:49)
Re: G-E's crazy rear multilink idea
hows that going to work.
the control arms won't be able to move up and down.
springerc69: (2007-07-12 20:51:31)
Re: G-E's crazy rear multilink idea
Anyone try a rear end like this? A ladder bar system with a track bar to keep it centered? I do recall seeing pics of the z that was back halfed, but I don't remember seeing details shots. Has anyone tried it this way? I don't know what kind of travel you'd get with such short arms. I'm thinking about taking my buddies spare straight axle rear end from a 90's Jeep Cherokee and seeing how it would fit/move in this fashion when I replace my busted rear end. If this worked it looks like a pretty easy way to convert to a solid axle (umm, 9 inch :lol: ), but if it looks this easy it probably won't work well. Any thoughts?
84z31: (2007-07-12 21:12:01)
Re: G-E's crazy rear multilink idea
you don't want a live axle. it would suck for windy stuff.
springerc69: (2007-07-12 21:15:50)
Re: G-E's crazy rear multilink idea
When my z is actually running I pretty much only drive to the drag strip and back with the occasional around town trip, so twisties are not an issue for me.
G-E: (2007-07-13 01:24:48)
Re: G-E's crazy rear multilink idea
correct, they swing..... and if there are three positive attachment pivots then you can control the swing direction, there is actually a fourth however (swaybar)
anyway if you linear thinkers missed it, the idea was to link camber side to side, like the front wheels when turning, the outer one is negative and the inner is positive.... on the front this is controlled by caster and strut orientation, in the rear we have to be more creative
Firehawk: (2007-07-13 04:58:50)
Re: G-E's crazy rear multilink idea
If you are going custom, why not design one with an upper arm and coilover mounting to allow larger wheels.
cheezmonta: (2007-07-13 05:29:07)
Re: G-E's crazy rear multilink idea
My buddy was working on making his 87' N/A into a drag car but he gave up on it in favor of a 76 Celica GT for the project.
This was as far as he got…
His new drag project.
He's got the car turned into a skin and was working on building a tube frame for it before he moved shops. Now it sits collecting dust until he finishes rebuilding his 76' Fairlady Z.
G-E: (2007-07-13 06:01:25)
Re: G-E's crazy rear multilink idea
in theory a cheap-enough weld on kit can be made, some bars and bushings + weld tabs, instructions, the idea was to keep as much of what you already have, you can keep the rear suspension components actually, but coilover is no harder than drilling a new hole already
going all custom would be nice but the precision required and complexity of the rear arms means you'd more than likely have to replace it with something non-z (maybe non-nissan), you'd need to start with an upright like say audi's which has lower/upper/rear attachment points already and rework or create a new hub to our specs to work with the upright… and you'd still need the central point behind the diff to locate the toe-arms which means more body bracketry
my "idea" would only need 3 bars with bushings, a new diff mount with toe arm attachments, a few tabs to weld on.... and a lot of cutting of old shit
Steve88t: (2007-07-13 06:06:11)
Re: G-E's crazy rear multilink idea
WD21 Pathfinders already use a 4 link with panhard bar. Get a later one with lsd and disk brakes if you want a solid axle setup.
G-E: (2007-07-13 07:18:30)
Re: G-E's crazy rear multilink idea
I was expecting some comments on the design.... but all I get is chatter about solid axles
someone familiar with chassic setups chime in with something worth reading [archived image: smile.png]
OK85ZX: (2007-07-13 11:10:22)
Re: G-E's crazy rear multilink idea
would be alot less work just to use a multilink from a 240SX.
NissanEgg: (2007-07-13 11:48:31)
Re: G-E's crazy rear multilink idea
In your pic G-E, the bottom or rear most bar looks like it will kill the whole setup. From my point of view, it looks like a rear tierod assy. Now if the left wheel were to go up over a bump, the "bar" would pull on the right wheel, causing it to toe out badly. Or maybe I am looking at your rendering wrong.
Now if you used your redesigned lower control that is in the pic, and attached a Civic style upper control arm, you could have a double "wishbone" setup very similar to the Hondas. And the upper control arm could be made very simple and could incorporate adjustable camber. I cant find any pics of the Civics rear setup because I don't have time at work to look without getting in trouble.
G-E: (2007-07-13 18:44:34)
Re: G-E's crazy rear multilink idea
the two bent arms would ideally be attached to a common substructure at the back around where the diff is to help locate the trailing arms, any "pull" on one side would almost entirely affect camber and not toe (ok a little but..)
it's hard to see but the bent rods are actually "upper" wishbones in a sense, they are also forward of the halfshaft so as to give it some horizontal triangulation
84z31: (2007-07-13 19:28:13)
Re: G-E's crazy rear multilink idea
wish bone style rear suspension FTW
G-E: (2007-07-13 19:29:49)
Re: G-E's crazy rear multilink idea
or course I could have just drawn a parallel bar system at the back (like half a double wishbone) and a single arm in the front but that won't link camber
NissanEgg: (2007-07-13 19:31:07)
Re: G-E's crazy rear multilink idea
The rear bar going from the left to the right still needs to be attached solidly to the body to prevent shift or inadverdent movement like toe or camber changes.
G-E: (2007-07-13 22:47:24)
Re: G-E's crazy rear multilink idea
one side up one side down would only be the case if you hit a huge bump on the outside wheel while driving in a corner which would increase that wheel's negative camber without changing it's toe
the inner wheel would go positive and maybe toe-in a touch but that wheel would be lightened by the swaybar so there should be minimal change, but it would still grip well… if the car intends to bounce sideways with the outer wheel off the ground, the inner wheel will still maintain some good traction with the outside edge digging down further with the positive camber, and that toe-in might actually help you smooth the back-end's fishtailing transition back into grip...... like hicas
btw the rear mount point for the upper bars should be about level with the front control arm attachment so any lift will pull the top inward
Benedict: (2007-07-17 00:35:49)
Re: G-E's crazy rear multilink idea
so instead of pulling the Z31 shite out and putting in a proven multi-link (S13/14…Z32, whatever) you're going to take the time to design and fab something almost from scratch that "may" work well.
Right…
Butter: (2007-07-17 03:10:04)
Re: G-E's crazy rear multilink idea
You are basically designing a totally new suspension, which will take more work than I think you realize. All that really needs to be done to make a bolt in kit is to modify S-chassis subframes to bolt in. Aside from the coilovers, mine will bolt into any Z31 as it sits.
phxZ31: (2007-07-17 03:45:14)
Re: G-E's crazy rear multilink idea
I'm pretty naive when it comes to suspension stuff.. So forgive me if these questions are pretty basic.
What exactly is wrong with the stock Z31 suspension? I realize if you lower it you will get excessive negative camber. I can easily understand why you wouldn't want this, especially if its a drag car. But, wouldn't correcting the negative camber be much simpler than swapping in a whole new suspension from another car?
G-E: (2007-07-17 07:25:03)
Re: G-E's crazy rear multilink idea
excessive camber and toe changes, not the best thing for a sports car, and unlike a wishbone suspension, limited adjustability and no linearity in the control over the range of motion
Benedict: (2007-07-17 15:35:05)
Re: G-E's crazy rear multilink idea
Get the car to do what you want for the least amount of invested time and money. That's why I would push for the S-chassis' multi-link.
If you pull it off then cool but at what cost and how well will it work.
Just trying to be practical/cost and time effective.
NissanEgg: (2007-07-17 16:52:04)
Re: G-E's crazy rear multilink idea
You have to take into accounts of pivot centers and their angles within the same control arm(bind), instant roll centers, centers of gravity for the car, anti-squat and anti-dive geometries.
Then you have to take into account what angles you have as the movable parts swing thru their arcs (for toe, camber, and caster changes).
Then when you figure all that out, you got to figure out how to dampen the new setup correctly with spring and shocks. Because you will be changing leverage points for the springs and shocks, you will have to do some nerdy math to figure out the correct damping, free height and droop of the springs, etc.
It can be fun designing something as you go along. But fine tuning it to work correctly will make your head hurt, unless you got friends who happen to be chassis engineers.
Butter: (2007-07-17 23:38:51)
Re: G-E's crazy rear multilink idea
+1[archived image: smile.png]
G-E: (2007-07-18 02:58:46)
Re: G-E's crazy rear multilink idea
well mockup would be fairly easy, the bushing orientations/styles/thicknesses can be changed without affecting the overall design and the spring and shock would still be pushing at points beyond the hub … also the pivot point at the rear for the upper bars could be made adjustable, like an engine hoist arm, choose your hole/height to play with settings, and worst case use pivot ball endlinks
since we don't have much choice when it comes to springs, it would be a matter of trying the one you think you want (ie stiff like jason's or weaker alternatives), I know the swaybar will have to be significantly beefy, again there isn't much choice and what choice there is is rather similar
and if I were to do this a camera could be mounted under there to observe it all in motion
edit: I do see one problem, sidepipes would fix it
Butter: (2007-07-19 00:27:53)
Re: G-E's crazy rear multilink idea
please do not try it.
please.