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Originally Posted by Bolt Upright,Jun 29 2006, 12:04 PM
Guys,
I've been an aircraft structural engineer for 28 years now, so I feel somewhat qualified to comment on this. First off, the benefit of adding an x-brace to the S2K are minimal. The chassis is already mondo-stiff. However, IMO a well designed x-brace can increase the relative stiffness between the front suspension attachment points. These are the three things (stiffness-wise) to look for in a good x-brace:
1) The x-brace should hang down as little as possible from the attachment points. This is done to minimize any offset loading (eccentricity) so as to minimize any out-of-plane bending of the brace. (reduces stiffness quickly)
2) The brace should remain in the horizontal plane without any bends which again will induce bending of the brace and reduce stiffness.
3) *** MOST IMPORTANTLY ***
The attachment bolts must be in tight fitting holes. This is everything. If the attachment holes in the brace are sloppy, then most or all benefit to adding the brace is lost. Think of what we're trying to do here. We want to increase stiffness between the suspension attachment points. If the brace has loose fitting holes, then the x-brace contributes no stiffness until the chassis deflects enough to "close" those sloppy holes. Only at that point does the x-brace start to contribute stiffness. Basically if the holes are sloppy, it's just an oil pan guard (and of course ballast).
This is the x-brace I chose.
I got it from Science of Speed. If you are into under-car bling , this thing is pure sex. Looking at the lower control arms, it seemed apparent that adding stiffness between the fwd attachments would do the most good. Besides, Honda already has a brace at the rear.
One thing that finally sold me on the benefits of the x-brace was the grief I had installing it. I found that the attachment points on the car moved just enough to make installation impossible with the front wheels off the ground. However, once I put the front wheels down on ramps, evrything lined up nicely. This told me that the chassis does flex enough to benefit from an x-brace.
Sorry to be so long winded.
Very nice explanation...
I completely agree with you on how you said the Brace should be all in one plane or else there will be bending... that's so true.
Is it possible that you have the link to that brace at hand because that thing is really a nice piece of work.
Originally Posted by 8kGoodENuff,Jun 29 2006, 02:20 PM
Is it possible that you have the link to that brace at hand because that thing is really a nice piece of work.
Andre
Thanks Andre
I checked their site Science of Speed and they don't appear to offer it anymore. But if I remember correctly, the brace has marking on it which indicate that it may actually be manufactured by another company. I gotta change my tranny fluid soon, so I'll take a look at it then and let you know what I find. In the meantime, contact these guys at their site. They were real helpful with me.
Originally Posted by Kremlin,Jun 29 2006, 02:07 PM
Thanks for the explanation! I didn't even know SoS made one... Can you change oil without removing it?
I'm also an engineer, but didn't feel qualified to make bold statements because I ended up working in software, heh...
I'm just glad it was understandable. Once you've been a stress guy for a while, you start to talk a lot of "techno-babble." My wife has just learned to turn up the TV.
I have no problems changing the oil, but I have the futomo valve with a piece of vinyl tubing which fits nicely thru the x-brace. No need to jack the car up.
BTW, I recently moved to our IT department myself. Plenty of time to surf the forum now.
Originally Posted by Bolt Upright,Jun 29 2006, 12:33 PM
Thanks Andre
I checked their site Science of Speed and they don't appear to offer it anymore. But if I remember correctly, the brace has marking on it which indicate that it may actually be manufactured by another company. I gotta change my tranny fluid soon, so I'll take a look at it then and let you know what I find. In the meantime, contact these guys at their site. They were real helpful with me.
Awesome... I appreciate it. When you get an update from changing your tranny fluid... just let me know.
I don't know of any that require you to remove the x-brace just to change the oil. I think some do dribble oil on the brace if you don't remove it, but a rag can take care of that. Removing the whole brace is overkill, IMO.
I have the Rick's aluminum brace. I wasn't expecting much of a difference, but noticed much sharper initial bite on turn-in right after putting it on. It's definitely a very high quality piece and doesn't have any oil leakage when changing the oil.
here's what I wrote a while back when I bought my x-brace (Muz). I'm not a structural engineer, but I honestly feel that the differences between all the various x-braces (except the Cusco "U") are so negligible that the money spent becomes a more significant factor to assess.
you engineer types like to focus on % differences between braces, angles and dangles ... but I'm a bottom-line bang-for-the-buck kind of guy, and if the very best x-brace is only going to feel at the steering wheel .01% more firm than the "median" brace, but my wallet is going to feel a hell of a lot thinner, I start thinking more about the thinness of my wallet rather than the .01% more awesome my x-brace is engineered.
and I'm not saying whether the Muz or any other x-brace is amongst the cheaper or more expensive, or if it is a superior or inferior design... just a bottom-line assessment of the $ factor for ALL x-braces. (I bought my Muz in a group buy, and at the time the US$ was weak compared to the AUS$, so I probably "overpaid" a bit anyway)
I have the Muz x-brace and where I notice the improvement best is on bumpy roads, particularly in turns. so I am happy. it does nothing for you on flat roads, so it's a waste of $ IMO if you live in TX, FL or the like.
that said, all x-braces* are overbuilt to be extra strong and reduce chassis flex. IMO the cheapest one is just as good as the most expensive one. I have NEVER ever heard of an x-brace breaking... or even bending out of shape... (unless it takes an impact of course, which makes it a worthwhile sacrifice to save one's oil pan)
* when I say x-braces, I mean true x-designs and the Muz one-- I haven't used the Cusco U-shape, but I can't imagine it'd work as well as the x-designs or the Muz.
think about it: the Spoon, the Neuspeed, the Rick's/digrappa, the Muz... at their 4-points of contact with the car-- where they do their work-- their job is to minimize the dynamic movement of those 4 points in space. they do this by being essentially stiff chunks of metal (with some geometric aspects thrown in). IMO, whether one may allow .001" more movement cannot be known and really would never be noticable-- they all do the same job within 99.99% of each other. so get the cheapest one. heck, get a used one since it's not like they ever wear out. just make sure the bolts are new or in excellent shape...
which brings up an important reminder-- you absolutely, positively DO NOT want to strip the teeth where these bolts go in to the frame. make sure they are perfectly straight and go in smoothly. if you ruin the threading in those holes, you are screwed bigtime.
I agree with what you say Tritium. The differences are probably negligible for almost all driving conditions. Although I do believe it helps with steering transients though. I just felt compelled to clarify what the thing is supposed to do, and how it does it. There seemed to be some confusion when I read the previous posts.
For what it's worth, I bought mine to be as much an oil pan shield as anything else. The SOS brace could stop a tank!
, this thing is pure sex. Looking at the lower control arms, it seemed apparent that adding stiffness between the fwd attachments would do the most good. Besides, Honda already has a brace at the rear. 
... but I'm a bottom-line bang-for-the-buck kind of guy, and if the very best x-brace is only going to feel at the steering wheel .01% more firm than the "median" brace, but my wallet is going to feel a hell of a lot thinner, I start thinking more about the thinness of my wallet rather than the .01% more awesome my x-brace is engineered.
