piscorpio

I thought I would ask this in here, figuring people in here would actually have experience putting these things to use. Does anyone find that it makes a difference running an unhinged strut bar, like Mugen bars versus a hinged bar like Skunk2 or the no-names you might find on e-bay?

I understand why the unhinged should be stiffer, but I am just looking for feedback from those with real world results. Thanks in advance.

JDubya

I was wondering the same thing too. I just sold my ebay hinged rear strut bar to replace it w/an "ITR" one. Hopefully it'll make a difference.

whitney

No real-world results here, but Theory is good, m-kay?

Strut bars are under tension during cornering, so the hinges don't matter:

http://www.e30m3performance.co...y.htm

piscorpio

That article nearly scared me away with all the fancy math and engineer speak, but I stuck with it and got some very interesting info. So the ends of the bar don't actually push in, but stretch out, cool. Thanks whitney!

Mark sans

While I agree that the hinge doesn't matter, that e30 article is based on a car w/ McPhearson struts, not a double wishbone. The force on an MP strut suspension at turn in is much greater. YMMV w/ a honda.

piscorpio

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HippoSleek &raquo;</TD></TR><TR><TD CLASS="quote">While I agree that the hinge doesn't matter, that e30 article is based on a car w/ McPhearson struts, not a double wishbone. The force on an MP strut suspension at turn in is much greater. YMMV w/ a honda.</TD></TR></TABLE>

What do you mean, just that the force on the struts is less on a Honda and therefore the brace may not have as strong an effect as with the MacP strut equipped vehicle? Either way, the hinge issue seems a non-factor from the responses.

whitney

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HippoSleek &raquo;</TD></TR><TR><TD CLASS="quote">While I agree that the hinge doesn't matter, that e30 article is based on a car w/ McPhearson struts, not a double wishbone. The force on an MP strut suspension at turn in is much greater. YMMV w/ a honda.</TD></TR></TABLE>

The upper wishbone mounts at the top of the shock tower, though. So why wouldn't the forces be just as high on a Honda? Looking at the FBD on the E30 site, if you throw an upper wishbone in that diagram, I don't see why the forces would change at all.

I used to buy the "higher forces on a strut car" argument, but lately I have been wondering why.

phat-S

Take the shock tower bar off your car and run a few laps and tell me if you can feel a any difference whatsoever. Not saying you won't, might just be that my asscamberometer is very poorly tuned.

whitney

Hey Phat -

The best reason I have ever heard to run a front brace is to reduce cyclical fatigue on the tub. The bar definitely reduces the loads the tub takes in a corner.

That's why I run one on my DSP BMW and H4 Civic (it's probably holding the Civic together). I use one on my Miata since it reduces cowl shake.

I agree though -- I didn't notice a performance difference before to after. There may be a difference, but it's noise on my internal G meter.

phat-S

What chassis fatigue are you particularly concerned with here? Where would it be flexing that a shock tower bar would remedy?

GSpeedR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by whitney &raquo;</TD></TR><TR><TD CLASS="quote">

The upper wishbone mounts at the top of the shock tower, though. So why wouldn't the forces be just as high on a Honda? Looking at the FBD on the E30 site, if you throw an upper wishbone in that diagram, I don't see why the forces would change at all.</TD></TR></TABLE>

In a car with an independent front suspension, like your Civic, all the lateral forces are transmitted from the UCA to the frame rail, the UCA is connected by a hinge and thus would only move vertically. The upper shock mount (connect to the towers) is simply a locating mount and does not experience significant lateral forces). In a Machpherson strut car, all the lateral forces are transmitted into the shock tower, which as you can imagine, can flex a good deal. The shock tower is the main support in an M3, Sentra etc.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">I used to buy the "higher forces on a strut car" argument, but lately I have been wondering why.</TD></TR></TABLE>

Its because of differing suspension geometries, I was confused about it for awhile as well.

piscorpio

Thanks for the input guys. Seems that the hinge vs. no-hinge issue is resolved, no one seems to argue one is better than the other.

GSpeedR

Well, I do own a $20 front strut bar. The frame around the engine/trasmission is an open bay so it probably will have an effect on the overall chassis stiffness of the car.

Plus you can lean on it when your engine is hot.

phat-S

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSpeedR &raquo;</TD></TR><TR><TD CLASS="quote">1. In a car with an independent front suspension, like your Civic, all the lateral forces are transmitted from the UCA to the frame rail, the UCA is connected by a hinge and thus would only move vertically. The upper shock mount (connect to the towers) is simply a locating mount and does not experience significant lateral forces).
....
2. Well, I do own a $20 front strut bar. The frame around the engine/trasmission is an open bay so it probably will have an effect on the overall chassis stiffness of the car.

Plus you can lean on it when your engine is hot. </TD></TR></TABLE>

How can you say both? If you are saying in the latter one that "probably will have an effect on the overall chassis stiffness of the car but the chassis stiffened is not affected by driving" then I'd understand you but otherwise I am confused. Not trying to start stuff here - I just am not following.

But I do agree with you that it makes a great lean-on piece (and motor hoist too I might add).

Tyson

phat, my take on this is that the strut bar doesnt help maintain so much the suspension geometry, as it would for the non double wishbone suspension, but it does in fact provide greater chassis stiffening, inherent in the design of the engine bay. so while having a strut bar doesnt necessarily aid suspension design, it helps in overal chassis stiffness, which does have its effects in the general ride and feel.

madhatter

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by phat-S &raquo;</TD></TR><TR><TD CLASS="quote">my asscamberometer is very poorly tuned.</TD></TR></TABLE>

Ahhh.. New sig.

piscorpio

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by madhatter &raquo;</TD></TR><TR><TD CLASS="quote">

Ahhh.. New sig.</TD></TR></TABLE>

lol, I liked that one too.

GSpeedR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by phat-S &raquo;</TD></TR><TR><TD CLASS="quote">

How can you say both? If you are saying in the latter one that "probably will have an effect on the overall chassis stiffness of the car but the chassis stiffened is not affected by driving" then I'd understand you but otherwise I am confused. Not trying to start stuff here - I just am not following.</TD></TR></TABLE>

Tyson pretty much answered for me, but what I meant was that for "Strut cars" the bar aids by providing a tension force between the shock towers as they displace outward a very significant amount. That is what the BMW site was discussing, which someone brought up. I was just saying that isn't really relevant for independent suspension cars, where the lateral forces are transmitted to the frame (much much stronger than the shock towers).

The comment I made about "overall chassis stiffness" is that the frame is open at the top of the engine bay and this bar could reduce some overall flex of the chassis, similar to how a cage reduces flex by connecting more points of the frame. A frame to frame "strut bar" would be ideal. Pretty much you can connect any pieces of the cars structure together and it could help, but probably not $50 worth of help.

For my Integra, I think it's probably better than nothing... but not much.

phat-S

Tyson et al, help me get on the same page as you guys here. I am by no means at all qualified to debunk/bunk suspension theory but I do not follow you guys bunks. This piece doesn't affect front suspension movement, you guys seem to acknowledge this. On the rear of our cars, we all agree (don't we) that a shock tower bar does nothing and that the horizontal reinforcement in a cage between left and right shock towers does virtually nothing (locating the rear legs of the cage however onto the rear shock towers does as that is helping diminish vertical movement). So you guys are saying that this shock tower bar up front diminishes chassis flex in particular as flex occurs in the engine bay. And this is felt? This is what I don't follow. The engine bay's dimensions are pretty much reinforced by the motor mounts is it not? I realize these are rubber mounts, so are the front shocks. So you are taking a piece of metal and attaching it from left to right at a rather arbitrary point trying to prevent additional engine bay flex above a point where the suspension moves. If that does indeed work that way, how could it change the way the car feels or drives? Is it any different than having the hood flex? Its not a contributing factor as I see it. My understanding has been that a *strut* tower bar prevents the left and right strut towers from pulling apart under load (not prevents from pushing together) so what effect is there if we prevent metal from pulling apart above the points about which the suspension moves?

Guys, I am not saying you are wrong, I am saying that I have one on my Mac strut 944 (and guarateed it ain't doing much w/out spherical bearing mounts for the top of the strut) and *had* one on the CRX. I was told it wasn't doing anything and it was pulled off - the car felt no different. Now, later, after the fact, I am trying to determine why and the more I talk to folks and think about it - it seems like a nice way to hoist the motor but not much else.

whitney

Interesting discussion guys. Appears we have answered the original poster's question, but this tangent is related.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by GSpeedR &raquo;</TD></TR><TR><TD CLASS="quote">
I was just saying that isn't really relevant for independent suspension cars, where the lateral forces are transmitted to the frame (much much stronger than the shock towers).
</TD></TR></TABLE>

I think I still disagree with what you're trying to say, though. On my Civic, I am pretty sure that the upper wishbone bolts right up to the top of the shock tower. Doesn't it? Or am I confusted?

Regardless of whether the upper mount point of a car's front suspention is the shock/strut tower OR the frame rail (to which the shock tower is attached), there will always be a "spreading force" during cornering, due to the torque on the suspension member (see aforementioned FBD). Thus, a strut bar will always take some load and decrease the strain on the tub welds. How effective is a matter of geometry, but every suspension will do it. Whether it is worth it (money and weight) is up for debate.

whitney

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by phat-S &raquo;</TD></TR><TR><TD CLASS="quote">?</TD></TR></TABLE>

Phat - Why do people want to seam-weld tubs? Or build good cages? Same answer.

Stronger tub means less flex means more consistent suspension geometry and longer lasting tub.

piscorpio

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by whitney &raquo;</TD></TR><TR><TD CLASS="quote"> Appears we have answered the original poster's question, but this tangent is related.

</TD></TR></TABLE>

Definitely, and then some, thanks to all. Now I will just sit back and watch, some good points here.

phat-S

Whit, look at where they make their seam welds - they are in places that affect chassis rigidity from what I have seen. They build good cages to minimize chassis flex where it counts. When possible, they attach cage points to the parts that move - this is why I presume attachment points to the shock towers from the cage are prohibited at club racing levels because there is a distinct advantage (and I see a difference between tying a cage point to a shock tower and using a shock tower brace). I can't argue with you on the longer lasting aspects of it - that's an interesting piece of information. Tell you what, take your hand and put your body weight on your shock tower bar - if it moves a millimeter, tell me what welds you saved a week ago. Not trying to be a smartie-pants, just don't see this the same way or better said, don't see a value attached with this appliance.

illusion

im not about to get involved with this either.. and dont take this as i believe that everything honda does is right.. but honda put one on the ITR. its gotta be for other reasons than the bling factor..

GSpeedR

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by whitney &raquo;</TD></TR><TR><TD CLASS="quote">I think I still disagree with what you're trying to say, though. On my Civic, I am pretty sure that the upper wishbone bolts right up to the top of the shock tower. Doesn't it? Or am I confusted?</TD></TR></TABLE>

I actually just opened my hood to check this out for myself. On my G2 Integra, then UCA doesn't bolt to the top of the strut mount. The bolts do poke through the sheet metal (had me confused) but the frame rail runs right through there. Follow the side engine mounts, which ARE attached to the frame rail. I'm certain that my fellow Hondas are the same.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">Regardless of whether the upper mount point of a car's front suspention is the shock/strut tower OR the frame rail (to which the shock tower is attached), there will always be a "spreading force" during cornering, due to the torque on the suspension member (see aforementioned FBD). Thus, a strut bar will always take some load and decrease the strain on the tub welds. How effective is a matter of geometry, but every suspension will do it. Whether it is worth it (money and weight) is up for debate.</TD></TR></TABLE>

Most people are making one assumption: that the frame absorbs all of the force applied upon it. This isn't perfect, but it's still realistic. The frame is pretty damn strong . Then the frame rail does not displace inward during cornering (like the shock towers do on unbraced Mac Strut cars). You are right that there must be some deflection, but I don't think its measurable.

One thing that people haven't consiedered (in this discussion) is the vibrational forces the frame and the welds/joints experience under shock (say, a bump). This is another reson you can argue to have a STB. Flexual and longitudinal compression waves would cause great stress upon the joints, but that's kinda the realm of acoustic/vibrational engineering which is fun, but gets boring really quick. So, I guess you can file it under general chassis stiffness.