Random Thoughts on FLCA

[SoSideways]

Ok, so I have an S13.

After learning some suspension dynamics and such, it's pretty apparent that there comes a point in which the front MacPhereson struts goes out of whack. Namely due to if the car was super slammed, the angle formed by the strut and the FLCA will be more than 90 degrees, thus throwing the camber curve way out the back windows.

So I was thinking, well, what about the guys that run a S14 FLCA on their S13s? They said that the S14 FLCA is like 10mm longer than the S13 units, so that there's more room to adjust for ridiculous camber.

So that gave me an idea. If the FLCA pushes the spindle out by like 10mm, wouldnt' that change the "triangle" formed by the strut, FLCA, and I guess the wheel well a little bit?

With the S14 FLCA, if the car has coilovers, wouldn't just switching to them give the effect of slightly lowering the car and more negative camber due to the lower part of the triangle being pushed more up and out?

That would mean that the angle formed by the strut/coilover and the FLCA would be reduced somewhat as well, so couldn't you just raise the car a little bit and gain the camber curve back a little as well?

I'm sure there's a fallacy or major mistake that I cannot see in my theory, since it was, afterall, some late night random thoughts that popped into my head.

Please school me on this one suspension massas!

[EchoOfSilence]

Ok, so I have an S13.

After learning some suspension dynamics and such, it's pretty apparent that there comes a point in which the front MacPhereson struts goes out of whack. Namely due to if the car was super slammed, the angle formed by the strut and the FLCA will be more than 90 degrees, thus throwing the camber curve way out the back windows.

So I was thinking, well, what about the guys that run a S14 FLCA on their S13s? They said that the S14 FLCA is like 10mm longer than the S13 units, so that there's more room to adjust for ridiculous camber.

So that gave me an idea. If the FLCA pushes the spindle out by like 10mm, wouldnt' that change the "triangle" formed by the strut, FLCA, and I guess the wheel well a little bit?

With the S14 FLCA, if the car has coilovers, wouldn't just switching to them give the effect of slightly lowering the car and more negative camber due to the lower part of the triangle being pushed more up and out?

That would mean that the angle formed by the strut/coilover and the FLCA would be reduced somewhat as well, so couldn't you just raise the car a little bit and gain the camber curve back a little as well?

I'm sure there's a fallacy or major mistake that I cannot see in my theory, since it was, afterall, some late night random thoughts that popped into my head.

Please school me on this one suspension massas!
to my understanding, the angle made by super slammed cars would be less than 90 degrees, with respect to the strut. more than 90 would mean the end of the LCA is pointing down, which means the car is being pushed up.

'adding' 10mm to the LCA doesn't necessarily lower the car more, it depends on how the lca was oriented in the first place. If the LCA wasn't parallel with the ground, say, actually pointing down (towards stock ride height), the car would actually be lifted. if the lca is actually pointing up somehow, then the car would be lowered a little. It depends. Then again I might be coming at this wrong;
I think you just need to take a look at either a picture or your own front end and think about what would happen. You may even be thinking too much into this

[SoSideways]

to my understanding, the angle made by super slammed cars would be less than 90 degrees, with respect to the strut. more than 90 would mean the end of the LCA is pointing down, which means the car is being pushed up.



Well, I think we're thinking in the opposite directions from the way you're describing what you're thinking.

I found this picture on google image search, and it should help illustrate what I'm trying to say here.

http://www.rqriley.com/images/fig-14.gif

In that picture, it's pretty close to when our S-chasis is at around stock right height. See how the LCA points downwards, and the angle formed between the LCA and the strut itself is less than 90 degrees in an acute angle (IIRC that's what it's called... been too many years since I've taken geometry class in high school lol).

If you severly lower your car, that angle changes to something like this:

http://i42.photobucket.com/albums/e346/SoSideways/slammed_geometry.gif



'adding' 10mm to the LCA doesn't necessarily lower the car more, it depends on how the lca was oriented in the first place. If the LCA wasn't parallel with the ground, say, actually pointing down (towards stock ride height), the car would actually be lifted. if the lca is actually pointing up somehow, then the car would be lowered a little. It depends. Then again I might be coming at this wrong;
I think you just need to take a look at either a picture or your own front end and think about what would happen. You may even be thinking too much into this

See, from the 2nd picture above, you can see how, if you added 10mm to the length of the LCA, it would push the wheel out some, push the strut out some along with the wheel due to those two being connected at the spindle, and thus creating a slightly lower appearance. Also, the angle between the strut and LCA, where I put the pink text, should be reduced slightly due to the change in geometry.

From there, if you raised the car up some to cancel out the effect of the "lowering" due to the longer LCA, then you would also reduce the angle between the strut and the LCA that I highlighted with pink text.

I dunno, this stuff makes sense to me, but I'm not sure I am conveying what I'm trying to say too well?

[$D$]

your making me think about putting the s14 front lca's on my s13...

[theicecreamdan]

wider is better, s14FLCAFTW

[SoSideways]

So I am right?

Sweet! hahahaha

[Wiisass]

Alright, well I think you're right, but it's not going to be anywhere near the effect that you think it will be. Depending on the angle of the LCA the 10mm extension will be less the greater the angle from horizontal. So the amount your moving the wheel probably wouldn't change the angle between the strut and the lca more than a degree.

There are several ways to think about this. First of all if you consider that with a super slammed car, you're going to be running pretty stiff springs. This means that there isn't much suspension travel when driving. You can now factor in your static camber into the gain in positive camber with roll. So if you run slightly greater than normal camber statically, during roll even with the positive gain, you should still have negative camber on the outside wheel. So if you use this logic, then you really don't have anything to worry about. You can still use the s14 lca for the additional track and camber range.

If you really want to fix this problem, you're going to be dealing with a lot more than most people want to get involved in. But to simply answer your original question, I think that with or without the s14 lca, you're going to be raising the ride height the same either way, or at least not to a really noticeable difference. I'm assuming less than an extra 0.1" max, but probably much lower of a difference.

[SoSideways]

Wiisass, thanks for the input.

My thoughts on the S14 FLCA came about when I was reading a member's comment on how he was ordering parts to cure his bump steer problems in another thread, and that made me think back to the ziptied thread where Scott (Panda, Scooter, RBS14 on here) was wondering how he could improve his car's handling characteristics even at his super crazy ride height.

Obviously I won't be as low as he is, but I'm just kinda thinking ahead.

Am seriously considering lowering as much as I can with 225/45/17 and Stance coilovers by summer. Just wondering how I could help the front bump steer situation other than getting something like the SPL parts FLCA.

Which brings up another question. Since all it really is, is an boxed aluminum arm with a helm joint where it bolts to the front crossmember, and a long ball joint where it bolts up to the spindle.

Are there ball joints out there that could perhaps work with a stock S14 FLCA that could give us a cheaper alternative? Cheap is not the most important issue, it's the issue of if it ever got bent/fucked, you can go anywhere and pick up another set of S14 FLCA, get the special ball joints re-pressed into the new arms (if they weren't damaged), get the BV helm joint/box in kit and get that stuff welded on, and throw them into the car within the week (not months).

[HyperTek]

super slammed is retarded lol.. fucking jdm tyte drifter status i cant drive anywhere yo! lol.. yet i like how it looks lol.

But when you have camber plates, You can correct the pivot point of the coilover by pushing the strut outwards itself which also corrects some of the camber,.

[SoSideways]

I didn't say anything about having my personal car slammed to the ground like Scott or Brian. My car's a daily driver and I'm not as hardcore as they are.

But I do want to retain as much of the good handling as I can even when I'm aggressively lowered.

Thing is, as long as the angle between the strut and the LCA is less than 90 degrees, while that side of the suspension is under compression, wouldn't you still at least retain, if not gain, negative camber? It shouldn't turn into positive camber until the angle between the strut and LCA becomes more than 90 degrees right?

[Wiisass]

It won't turn into positive camber even with the strut and lca angle greater than 90 unless you're running 0 camber. The camber effects of the strut and lca angle is just a gain. So the angle is 100, you could gain 0.5* per inch of wheel travel. If it's 80*, you could be gaining -0.5 per inch. These numbers are just an example, but that's the way things work.

But using those numbers, if you assume that you only have 1" of wheel travel from static in the compression direction. And run only 0.5 degrees of camber, with the strut angle at 100, you'll have 0 degrees of camber at full compression. This is all in terms of the body, this stuff is a little different once you consider the roll angle of the car and how that affects things.

I remember scooter's thread on ZT about all of this. I know I posted a ton of shit in there, but I don't know if it's what you're looking for. I guess we won't find out until the site gets back running.

[kazuo]

Search under username "Var"

He tried installing a S14 FLCA onto his S13 for mo camba.

All it did was give him mo toe.

[SoSideways]

Var did indeed have problems with his S14 FLCA mod.

However, he did say that, for S13 it needs the wider track up front, so it would be good to do this mod.

And also, in his big thread about the whole mod, someone mentioned using S14 knuckle aka spindle for the tie rod to clear.

Well, if S14 FLCAs are made with the S14 tie rods in mind, and S14 steering rack and S13 steering racks are interchangable, can't you just use Z32 or S14 tie rods + to get it so you don't have like 20 degrees toe out?