S130 Suspension Tech

[Heathhh]

Alright sounds great then. I was not aware of it being a misleading statement from the suspension companies so it was better for me to ask than to ignore their "does not fit 2+2" statements. Thanks for the help on the side topic of the main topic.

[260DET]

haha lets hope he does or uses springs of a Baja racer

 

 

But guys lets keep focussed on suspension tech.. i dont want to be an ass but lets keep it a topic that could be a sticky if valueble enough.........................

 

Rear camber adjustment

-move/adapt pick up points, jet i havent seen any pics for it on a s130

 

Looks like you are going to be the forum pioneer on this Frank Recall hearing that the Z31 had a modified sweep angle, never seen anything specific on that though.

[bluezx]

Here's some progress pics of adjustable rear camber on my S130.

I'm using Z31 rear toe adjuster bolts with slotted plates welded to the sides

of the original crossmember brackets that are also slotted to match.

I plan on doing the same to the inside pivot points but slot them horizontaly

to set the toe-in. I found a write up on this in the Z31 section.

Also, the bushings are solid aluminum.

[frank280zx]

Here's some progress pics of adjustable rear camber on my S130.

I'm using Z31 rear toe adjuster bolts with slotted plates welded to the sides

of the original crossmember brackets that are also slotted to match.

I plan on doing the same to the inside pivot points but slot them horizontaly

to set the toe-in. I found a write up on this in the Z31 section.

Also, the bushings are solid aluminum.

 

Like it!! though i want to do it with heim joints. Are all the bushing aluminum ? and did you have those made or ?

 

My idea is more to what the m3 dtm cars did

 

 

 

 

My set up will be like this. it is like they did on a group A e30.

These 'barrels' are for sale at e30 specialty shops, aand should be welded to the ouside of the trailing arm giving control over the camber aswel.

Im ordering these in the next few months .. then lets see what it brings!

 

 

 

 

This set up gives you all the control over 'toe in and out' aswel as making up for dropping the car.

Your set up just makes up for the drop of the car leaving the rest fairly unaltered. I want full control as the stock set up has a fairly high 'toe-in. So for a slighty dropped street driven car with i.e. tockiko's this is teh way the go.. if you go lower with coilovers orso this still doesnt cut the cake!

Edited March 22, 2010 by frank280zx

[260DET]

Great post Frank, that should be a sticky. Do those mods alter the sweep angle of the arms though? I was under the impression that BMW reduced the sweep angle for motorsport purposes.

[bluezx]

Hey man that looks like a great set up. I think I'll go with hemi joints on the front control arms. That way my adjustable t.c. rods will change caster without binding them.

 

All four trailing arm bushings are solid. I turned and pressfit them at a friend's machine shop. Got to thank Jeff P. for his drawing of the subframe mounts. Turned those in aluminum to his dimensions and they pressed in real nice. I do have rear coil-overs and have them set at about 2"drop. When the fronts are done I'll go to 3" drop I think. It's a street car, can't go to low.

 

Do you think this will give me enough camber adjustment to compensate for the drop? I want to keep

a good contact patch on the road and not eat tires up. Without any examples of our specific car's rear

suspension being modified it's trial and error for me. If I get it wrong I can start over but would rather not.

For the toe I might slot the holes forward to reduce the factory toe-in some.

What's a good rear toe setting for good handling without excessive tire wear?

 

Thanks for any advice you can give.

[frank280zx]

Great post Frank, that should be a sticky. Do those mods alter the sweep angle of the arms though? I was under the impression that BMW reduced the sweep angle for motorsport purposes.

 

They did! The stock (non m3) E30 trailing arm angle is 15 deg ("sweep" angle) BMW Motorsport offered a special Gruppe A subframe and trailing arm combination which employed a 12 deg. trailing arm angle.

Thus altering the camber curve for the trailing arm over the entire motion. In other words, from 0 deg. through 90 deg.

 

And there is an intresting site on this in German so i translated the outcome of it, here you see the graph of a stock and 12 degree angle through its motion (see negative camber gain graph)

 

The attached graph shows the obvious, the rear wheel on a trailing arm gains negative camber as the suspension compresses. Two curves are shown, one for the standard 15 degree trailing arm angle, and one for the Gruppe A 12 degree trailing arm angle.

 

In terms of the effect on chassis, the primary difference between the 15 degree and the 12 degree trailing arm angles is that the 15 degree setup gains more negative camber as the trailing arm moves up in compression.

 

The same goes for the changes in toe in and out during travel of the suspension, the rear suspension gains toe-in as it compresses past the horizontal position of the trailing arms. (when moved [ast the horizontal position of the trailing arm the inverted wil happen)

 

As with the camber curves, the toe curves show that when the rear trailing arm is rotated through 90 degrees, the toe angle becomes equal to the "sweep" angle of the trailing arm.

The other thing is that the 15 degree trailing arm sweep angle causes the rear suspension to gain additional toe-in as the suspension compresses (vs. a 12 degree trailing arm angle). Thus the net effect of going from the standard 15 degree sweep angle to the optional Gruppe A 12 degree sweep angle is that the rear suspension experiences less camber and toe change as the wheels move up and down.

 

But also note that this is not necessarily desirable. You do want some gain in negative camber as the suspension compresses to compensate for chassis roll in cornering. (It would be nice if it did not change during acceleration and braking but try figuring that out!!) A small amount of toe-in as the outside rear wheel compresses in cornering is also nice, as it adds a bit of rear-end stability.

 

Hope this helps.

 

So what I basically want to do by adapting the trailing arm is making sure i can alter the angle and mak sure i start out horizontally.

Edited March 23, 2010 by frank280zx

[260DET]

Good stuff Frank

 

Another thing to think about is making the whole rear suspension assembly adjustable up and down, starting with mods to raise the assembly up. Without trying to think it all through my first thought is that this would make rear roll center adjustment more practical. Roll center adjustment, witout altering the ride height at the same time, is a very handy thing to have.

[PurePontiacKid]

^Or adapt an S13/S14/Z32 rear subframe in and get rid of the semi-trailing arm design lol

[Sonethirty]

SERIALNINE DIY Weld-On Strut Tubes

Check em here.

 

Cheers.

[frank280zx]

also see this link

 

http://forums.hybridz.org/index.php?/topic/90044-my-new-coil-overs/

[PurePontiacKid]

Hey now, don't be jealous of my ghetto skills lol

 

at least now I fixed the problem, and yes I did drive the car DAILY with that much suspension travel (the car basically sat on those springs they're so stiff). it's what I had to do to get down low, and this is the reason that I had my strut tubes sectioned, so I could be really low, and still have suspension travel

 

I'm surprised you guys haven't ripped into me for not using bumpsteer spacers lol

[frank280zx]

Hey now, don't be jealous of my ghetto skills lol

 

at least now I fixed the problem, and yes I did drive the car DAILY with that much suspension travel (the car basically sat on those springs they're so stiff). it's what I had to do to get down low, and this is the reason that I had my strut tubes sectioned, so I could be really low, and still have suspension travel

 

I'm surprised you guys haven't ripped into me for not using bumpsteer spacers lol

 

Its just that a exhaust tube is down right dangerously thin.. and well might get you cought in situation where you dont want to be! At least you seem to understand this is the case...

[JMortensen]

at least now I fixed the problem, and yes I did drive the car DAILY with that much suspension travel (the car basically sat on those springs they're so stiff). it's what I had to do to get down low, and this is the reason that I had my strut tubes sectioned, so I could be really low, and still have suspension travel

 

I'm surprised you guys haven't ripped into me for not using bumpsteer spacers lol

You drove daily on that? Not smart. How stiff are the springs? I have some 600 lb springs and the wire is A LOT thicker than what you have there. 600 in/lb springs would probably give you 1 1/8" of droop, which puts you right on the verge of bottoming. I bet you were running with next to no travel. If you had installed bumpstops, I have no doubt that you would have been on them the whole time, in fact they probably would have lifted the car.

 

Bumpsteer spacers don't fix bumpsteer, they adjust roll center. If you were running that low you need to actually fix the bumpsteer. See the FAQ post on bumpsteer for more detail. The roll center issue is much less of a concern as it relates to safety. Might be a handling issue, but pretty minor in comparison. Really, there are a bunch of other problems with running that low, not the least of which is bottoming the top hat into the strut. As you've discovered it makes a lot of unpleasant noise as the metal pieces smack into each other. What you probably fail to realize is that the suspension and the chassis aren't meant to take that kind of abuse. If you really want the car that low you need to do some pretty major modifications to make it usable. If you aren't willing to do the modifications, you're really doing something pretty ill-advised by running the car that low. I don't see how you could look at that and manage to convince yourself that you still have adequate suspension travel. Your denial-fu is strong.

 

I had a friend who used to deal with lowered Hondas and Acuras in the early 90's. He used to comment that they would buy lowering springs, cut the usable part of the spring off and throw it in the trash, and install the unusably short part of the spring and then drive around. Pretty soon they would come to his shop for a noise in the suspension, and he would find that the one or two coils that they had installed as the spring had fallen out when they had gone over a bump in the road. Perversely you have a usable spring length but you've chosen to install threaded coilovers and lower the perch to the point of unusability. I guess you went the expensive route to having no suspension.

[frank280zx]

You drove daily on that? Not smart. How stiff are the springs? I have some 600 lb springs and the wire is A LOT thicker than what you have there. 600 in/lb springs would probably give you 1 1/8" of droop, which puts you right on the verge of bottoming. I bet you were running with next to no travel. If you had installed bumpstops, I have no doubt that you would have been on them the whole time, in fact they probably would have lifted the car.

 

Bumpsteer spacers don't fix bumpsteer, they adjust roll center. If you were running that low you need to actually fix the bumpsteer. See the FAQ post on bumpsteer for more detail. The roll center issue is much less of a concern as it relates to safety. Might be a handling issue, but pretty minor in comparison. Really, there are a bunch of other problems with running that low, not the least of which is bottoming the top hat into the strut. As you've discovered it makes a lot of unpleasant noise as the metal pieces smack into each other. What you probably fail to realize is that the suspension and the chassis aren't meant to take that kind of abuse. If you really want the car that low you need to do some pretty major modifications to make it usable. If you aren't willing to do the modifications, you're really doing something pretty ill-advised by running the car that low. I don't see how you could look at that and manage to convince yourself that you still have adequate suspension travel. Your denial-fu is strong.

 

I had a friend who used to deal with lowered Hondas and Acuras in the early 90's. He used to comment that they would buy lowering springs, cut the usable part of the spring off and throw it in the trash, and install the unusably short part of the spring and then drive around. Pretty soon they would come to his shop for a noise in the suspension, and he would find that the one or two coils that they had installed as the spring had fallen out when they had gone over a bump in the road. Perversely you have a usable spring length but you've chosen to install threaded coilovers and lower the perch to the point of unusability. I guess you went the expensive route to having no suspension.

 

100% agreed.

If you want low how about airride? It doenst seem like your goal is peformance oriented but more 'Busoku' style.. I think that is worth two thumbs up. For that air ride might be the ticket! Plus you can pump the car up to get over speed bumbs etc.

If you want to drop it with conventional springs, you might want to look itno changing the pivot points up higher (hence bump-steer like JMortsen says) wich can only be done about 1" on a ZX front suspenion like i did on my ZXR.

For the rear you need to alter the pick up points to be mouted higher on the sub frame (though the camber on the rear wheels does suit the 'Busoku' style!!!)

 

The sectioned struts seem to be a move in the right direction.

Edited April 6, 2010 by frank280zx

[PurePontiacKid]

I understand that, I guess what I was saying wasn't coming across clear, I'll try to re-word it:

 

I drove on my car daily for a few months with my suspension set at that height. When I set my ride-height, I made sure that I still had some suspension travel with the springs seated, which I did. Those springs are ungodly stiff, and only droop 1/4" to 1/2" with the full weight of the car on them. When I drove them, the only side-effect was that the car bounced alot when on bumpy roads, but rode just fine on a smooth surface. I never tracked or autoX'd it in that condition, but on the curvy roads that I took the car through, she handled them just fine for my needs, didn't understeer, didn't oversteer, just went through the corner. (I think there was more in it, but I'm still a n00b when it comes to corners).

 

And I realize that the exhaust tubing wasn't the most brilliant idea, but it held up just fine, the only "damage" was at the very top where the threaded tube sat, it got slightly "mushed" down, but looked just fine when I took everything apart. Just a fyi, Yasin did used exhaust tubing as well, but he just used a small piece and welded it to the tube

 

I know that they're waaaaaaaay too stiff, but I haven't gotten around to getting new ground control springs just yet, but they are on my list. I know my bumpsteer and everything else will be way off on my car, but with my n00b skills and 195/65-14 tires, I don't personally think I'll need anything more specialized than a set of bumpsteer spacers.

[JMortensen]

Those springs are ungodly stiff, and only droop 1/4" to 1/2" with the full weight of the car on them.

Bullshit. Try typing some other stuff that isn't true and you find that your computer can't magically make that happen either. 1/2" droop on a stock ZX would require approximately 1400 lb springs. Those are not 700 in/lb springs, let alone 1400 in/lb springs. 1/4" droop = 2800 lb springs. No way in hell. They're probably 350 in/lb guessing based on a picture via the internet, translation, you're driving around with the suspension bottomed. Here's an idea for you to recoup some of your losses on the suspension you paid for but are not using. Get a steel top hat, weld a 5/8" bolt in it so that you have a stud sticking out the top, then weld the top hat directly to the strut housing. Now you can sell your Koni shocks which don't actually do anything 99% of the time, and your coilover kit. Now you don't have to worry about bumpsteer because you have a fixed suspension. PLUS, it will handle like a go kart. Literally. In the rear you could get a tube, weld the 5/8" bolt to the top and a clevis to the bottom to make it similarly unsuspended. Then all you have to worry about is breaking the chassis with the NVH you put into it through the what-would-have-been-suspension.

When I drove them, the only side-effect was that the car bounced alot when on bumpy roads, but rode just fine on a smooth surface. I never tracked or autoX'd it in that condition, but on the curvy roads that I took the car through, she handled them just fine for my needs, didn't understeer, didn't oversteer, just went through the corner. (I think there was more in it, but I'm still a n00b when it comes to corners).

So when you didn't need suspension, you didn't feel the effects of having no suspension? I never would have guessed. A glowing endorsement for what not to do from who not to take advice from.

[PurePontiacKid]

So what poor, un-thoughtful modification did I do? I got the idea to section my strut tubes from these forums, so I could have more suspension travel (apparently I didn't have any before, so this 2.5" should help, am I right?) I had the tubes professionally TIG welded because I am incompetent and couldn't get enough penetration on them with my welder. I got and modified a 1/4" thick 2" diameter exhaust flange and welded that to my strut tube for my collars to sit on using some new methods I learned. And from what I get, isn't most of what I did what some S30 guys do anyways to lower their cars more than they were able to previously?

 

I admit (for the third time now) that my first iteration of my coilover setup was wrong in all ways possible, but it worked for me, I didn't reccomend that anyone do it, it's just how I did it because I didn't have the resources to weld to the strut tubes at the time.

 

So please enlighten me on what is unsafe about my CURRENT configuration, because besides some strut spacers and other various small details, I see nothing wrong or unsafe about it. (and besides being "too low")

[JMortensen]

So what poor, un-thoughtful modification did I do? I got the idea to section my strut tubes from these forums, so I could have more suspension travel (apparently I didn't have any before, so this 2.5" should help, am I right?)

No, you are wrong again. If you section the struts and then lower the perch to the point at which the gland nut hits the strut top when the weight of the vehicle is on the suspension, you still have NO suspension. Common sense would tell you that the spring is going to sag, math would enable you to estimate the sag, but you continue to deny reality and say that your springs only sag 1/4 to 1/2 inch with the full weight of the front end on them. Un-possible.

 

Probably the biggest other issue related to lowering the car that far is suspension bind. Suspension parts can literally smack into the frame leading to catastrophic failure, or they can be twisted past the point where they can move freely, resulting in bent suspension parts or possible catastrophic failure. I found a BUNCH of suspension bind on my S30 when I checked. The rear sway bar was hitting the frame. With the sectioned struts in the rear the lower control arm could hit the frame. The front sway bar was at such an angle that the end links were bound and the end link bolts were bending. The rear sway bar end links were hitting the frame. The TC rods bound in their mounts that I had someone build for me previously, etc. Your car is being run lower than mine was. They're not the same platform, but to think that you can just lower it as far as you want and that there won't be any repercussions and not to bother even checking is not smart and potentially unsafe.

 

Beyond that you have the bumpsteer issue. I don't know what the curve is like on the S130, but I've reported my own car's emergency lane change manuever over one particular bump at the track numerous times, and I would imagine that the S130 has a similar bumpsteer curve and that it gets similarly worse the farther you get from Nissan's intended ride height. Mine was that bad BEFORE sectioning the struts. Your semi-trailing arm rear has similarly bad rear toe changes. You can see from Frank's post #127 that the farther the suspension moves from flat the worse the toe change becomes. Where is your control arm in relation to that graph?

 

I don't think the exhaust tubing is really an issue. It's shoddy workmanship, but I don't believe that it is inherently unsafe. I don't see the tubing folding under the load from the spring, especially when the spring can't compress far if at all before the suspension bottoms.

 

I like the idea of cutting the BS out of this thread. This one WAS going pretty well. Maybe make a new "What PurePontiacKid is Doing Wrong" thread and move all the crap into that one.

Edited April 7, 2010 by JMortensen

[TearingRaven]

How could these modifications be "unthoughtful" if he made them himself? If you ask me, an unthoughtful modification is dumping a V8 into a Z-car, because EVERYONE does it. What I see here is trial and error, research and development of (heaven forbid) new concepts and techniques. Sure, its not perfect, but is anything at the early stages? Rather than giving your hypertension a workout by yelling about his set up, perhaps the critics should relax, take a geritol, sit in their easy chair and watch a lovely episode of Wheel of Fortune while sipping on a can of Ensure.