Hello,

I am planning to perform some chassis reinforcement/stiffening to my DC2 GSR. Since none of the manufactures can provide hard evidence to the percentage of torsional or lateral rigidity improvement when adding their products, I have to resort to my fellow racers here .

I am looking for experiences and feedback regarding (especially on the track) the following products:

1. Spoon rear lower tie bar - How does this differ in terms of rigidity compared to the OEM ITR rear lower tie bar? I noticed that the two bars mount in two different locations of the subframe and the spoon bar is not fixed like the ITR bar is. Pros and cons of each? Can I add both to the subframe?

2. OEM ITR Rear Strut Bar - Do I need to remove the plastic rear that covers the rear hatch to install this or can I just remove the strut covers?

Any other comments/experiences you can provide would be great. Also, please let me know what the single most beneficial improvement was to stiffening your DC2 chassis (dampers don't count ).

Thanks!

 

Get a rollbar/cage if you really want stiffness.

What form of competition are you competing in?

Not all of the regulations are the same.

 

Sorry to say, neither of those two are going to do jack when there is much more give elsewhere, like soft "street" springs, lightly dampened shocks, rubber busshings, etc.

SPiFF, who's H3 GSR has no strut bars, tie bars, etc.

 

Reid

Currently, the car is my daily driver which sees track days during the summer. So, I don't have plans, or the funds, to competitively race this car.

Spiff,

Actually, its the other way around. You need a solid, rigid chassis as a foundation otherwise any
TEIL, Mugen or any other top line systems will not perform to its full potential.

As of now, she is on ITR dampers, front and rear.

 

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

Spiff,

Actually, its the other way around. You need a solid, rigid chassis as a foundation otherwise any
TEIL, Mugen or any other top line systems will not perform to its full potential.
</TD></TR></TABLE>

I disagree.

The most important part/upgrade on your car is your tires. Before suspension, before chassis stiffening, before a stage 3 turbo, you need some good tires to keep your car on the road.

Let me guess, you're one of those guys who's going to drop 8k into setting up a car and yet still drive it on the track on street tires.

What's this crap about suspensions not working to their full potential? You setup a suspension based on the car and how you want it to handle. If a suspension isn't working to it's full potential it means you have it set up wrong.

In you own words, could you please explain to me why a stiffer chassis car will be faster then a softer chassis? I'm just curious.

 

you'll prolly get a better result by putting in a rollbar/cage

the DC2 chassis is already pretty friggin' stiff

 

Strut bars and similar products are pimped by the retailers because they are (a) cheap to make, (b) easy to see on the car, (c) easy to install (aka hard to screw up, no PO'd customers), and (d) don't require any real technical knowledge to sell/install/use.

The spring rate of the chassis is WAY higher than the suspension in this case, so ANY improvement that you feel is the result of the placebo effect - having spent the dough, you believe it will be better.

Sorry.

Kirk

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Knestis &raquo;</TD></TR><TR><TD CLASS="quote">The spring rate of the chassis is WAY higher than the suspension in this case</TD></TR></TABLE>

In reference to this,

what kind of spring rates can the DC2 chassis withstand?

 

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

I disagree.

The most important part/upgrade on your car is your tires. Before suspension, before chassis stiffening, before a stage 3 turbo, you need some good tires to keep your car on the road.

Let me guess, you're one of those guys who's going to drop 8k into setting up a car and yet still drive it on the track on street tires.
</TD></TR></TABLE>

I agree with you on the tires. And, no, your wrong, Iam not one of those guys Thats like the guy who buys a NSX for getting groceries.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">
What's this crap about suspensions not working to their full potential? You setup a suspension based on the car and how you want it to handle. If a suspension isn't working to it's full potential it means you have it set up wrong.

In you own words, could you please explain to me why a stiffer chassis car will be faster then a softer chassis? I'm just curious.</TD></TR></TABLE>

Iam glad you asked. Iam by no means an expert, but I'll do my best to explain.

Let me start with an analogy. Take a shoebox with no top. Twist the shoebox. Notice it is faily easy to twist the box. Now, add the cover back on and try to twist the box. Notice it is much harder to twist the box. Think convertiables.

Apply this logic to cars now. Imagine a chassis that is weak/flexes that contains a stiff suspension setup. Now, all that stiff suspension load will be directed to the chassis since the chassis is absorbing much of that load, which is now exaggerated greatly due to the stiff setup. The chassis will twist like a lemon resulting in a transformed suspension geometry(not good). Do you agree that you want to maintain your suspension geometry (think setup) as much as possible on the track? If not, your car won't be that predictable. So, to counter this, manufactures use soft suspensions as to not make the weak chassis noticeable.

Now, a stiff chassis will not bend and flex with high loads, therefore, your geometry will be maintaned the way it was intended making for a much more balanced, neutral car.

Now, if chassis stiffness it not important, why did the ITR come with so much bracing? Even the rear frame was thickened and bracing was added everywhere to the JDM spec car. Another example is the S. A huge X-Bone frame runs down and braces the middle of the car to prevent the inherent flex of convertibles.


Here are some excellent references regarding suspension dynamics, recognized by SAE:

Chassis Engineering/Chassis Design, Building and Tuning for High Performance Handling - Herb Adams

Race Car Vehicle Dynamics (R146) - William & Douglas Milliken

How to Make Your Car Handle - Fred Puhn

I hope all this made sense.

 

None of what you say is incorrect, NAB, but in the real world of what you describe your car being used for, reinforcement like you describe is not going to return any measurable increase in performance.

IT and WCTC Hondas and Acuras use some ungodly high spring rates - like 1000# or more. In a case like that, the chassis WILL be deflecting before the springs compress, so they run comprehensive cages, welded into all of the pillars of the tub. With streetable spring rates, the springs move all over the place before the chassis flexes enough to care.

The great news is that you can buy whatever parts you want, without anyone's approval.

Kirk

 

If you're running over 600 lb/in springs, then you'll notice a stiffer chassis. I'm talking caged. Bars? Not worth it. You want to tie the chassis together from front to back, and side to side. Adding some goofy *** bar to the back of the chassis means squat.

Besides, that space that you just reinforced in the trunk should be considered expendable. Reinforce from as far front as you can, back to the rear suspension. The rest is just crush zone.

What everyone is saying is to save your money. Cuz most of us have already tried wasting money on things like this at one point or another.

Warren

 

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

Iam not one of those guys

</TD></TR></TABLE>
I'm glad to hear that.

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


Now, if chassis stiffness it not important, why did the ITR come with so much bracing? Even the rear frame was thickened and bracing was added everywhere to the JDM spec car.

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

Be careful, I didn't say chassis stiffening wasn't important, just less important then other issues, i.e. tires and suspension.

After reading your post I still don't see where you explain why a stiffer chassis will be faster then a softer chassis. I assume the goal here is to increase the amount of grip a car has, right? The only thing a stiffer chassis will do is transfer weight faster then a soft chassis. I don't agree that the suspension geometry changes with any changes to the chassis but rather only in changes in the load to that corner.

The whole point to maintaining traction is controlling the loads on each corner and how fast it loads and unloads. To stiff, the tires will get over loaded and lose grip. Too soft, the car will take longer to respond to inputs. This is what suspension design is all about so why try to tackle these issues through the chassis.

Can you tell me where and when you feel that the chassis flex is preventing you from cranking out faster lap times.

Bringing this way back to the original question about strut bars and tie bars, I believe they help in an amount so small that the little bit of confidence that I get from knowing it's there improves my times more then it's actual chassis stiffening characteristics. It's that small of a difference.

Oh and some reference materal:

Seat Time - You

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Warren &raquo;</TD></TR><TR><TD CLASS="quote">Adding some goofy *** bar to the back of the chassis means squat. Besides, that space that you just reinforced in the trunk should be considered expendable. Reinforce from as far front as you can, back to the rear suspension. The rest is just crush zone</TD></TR></TABLE>


I agree with most of what you guys said, especially the cage. But, just trying to learn here. The ITR comes with a rear reinforcement bar that fits between the tail lights. Honda wouldn't put something like that in if it didn't help with chassis stiffening, especially since there is no "bling" effect because you can't even see it.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by carl_aka_carlos &raquo;</TD></TR><TR><TD CLASS="quote">the DC2 chassis is already pretty friggin' stiff </TD></TR></TABLE>

I don't know about that. One time a mechanic raised one rear side of my GSR and I couldn't even close the hatch because the whole chassis had flexed so much and the hatch wouldn't align. It's an old chassis that dates back to the 91 or 92 Civic.

 

The stiffness of a chassis is no mystery.

With some garage tools and mathemagics, the torsional-stiffness can be calculated.

edit.. 'roll-stiffness' changed to 'torsional-stiffness'.. meh, I was tired


Modified by halz at 1:14 AM 6/1/2003

 

I'm sure the ITR came with the bracing for a reason. But adding extra bracing to the GSR shell is going to be a waste of money and you wont notice it.

But hey, its your dollar.

 

Honda had a reason. They also have a bunch of super computers running CAE, CFD, and MDA apps to validate their results.

For us, randomly bolting on a bunch of shinny bars really won't do anything. Even if it did, we have no way to tell. Now, my ***-o-meter may not be as well calibrated as some those people who come in here saying, ``I was driving hard on the street and I felt my chassis flex. What bars can I buy to fix it?''. I have never felt any difference. I am now running w/o a front STB and can't tell any difference.

 

Here you go... it's the only way I know of, and I already I have the trunk brace

 

A chassis is stiff for two reasons

1) So that it doesn't do the job the suspension should be

2) So that it isn't squeaky

I doubt that you have problem #1 with a streetable setup, can't help you with #2

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Warren &raquo;</TD></TR><TR><TD CLASS="quote">If you're running over 600 lb/in springs, then you'll notice a stiffer chassis. I'm talking caged.
Warren</TD></TR></TABLE>

Warren: Im just wondering how you came up with that number. Is that refering to a specific car? Was this already discussed in the past in detail?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by halz &raquo;</TD></TR><TR><TD CLASS="quote">The stiffness of a chassis is no mystery.

With some garage tools and mathemagics, the torsional-stiffness can be calculated.

edit.. 'roll-stiffness' changed to 'torsional-stiffness'.. meh, I was tired


Modified by halz at 1:14 AM 6/1/2003</TD></TR></TABLE>

I would love to hear how this can be done, accurately. Care to share? Without statistical analysis done by some pricey software, I doubt your average backyard mechanic can do this.

Sa04,

Now that is the definition of 'bracing' (Y). Who did you have fabricate that setup? You running in Honda-Challenge?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by NAB &raquo;</TD></TR><TR><TD CLASS="quote">
Now that is the definition of 'bracing' (Y). Who did you have fabricate that setup? You running in Honda-Challenge?
</TD></TR></TABLE>

The cage was done by a shop here in Chicago that specializes in tube frame GT cars. I hope to run a couple HC events in the midwest this year, but my schedule is pretty full with Midwestern Council and CenDiv SCCA.

 

Could someone here tell me what measures Honda took to improve the rigidity of the Integra's chassis for the ITR, and specifically why? Even a link to a non-marketing-oriented explanation would be appreciated.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by wakaru &raquo;</TD></TR><TR><TD CLASS="quote">Could someone here tell me what measures Honda took to improve the rigidity of the Integra's chassis for the ITR, and specifically why? Even a link to a non-marketing-oriented explanation would be appreciated.</TD></TR></TABLE>

The ITR chassis was reinforced to accommodate the bigger rear sway bar and stiffer springs.

http://autopedia.com/Acura/97_TypeRunitbody.html

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SPiFF &raquo;</TD></TR><TR><TD CLASS="quote">...http://autopedia.com/Acura/97_TypeRunitbody.html</TD></TR></TABLE>

Thanks very much!

Something that hasn't yet been mentioned is the relationship of chassis rigidity to "ease of use", which for many would result in a faster lap time.

For some time now I've believed any particular chassis, when made stiffer, results in a vehicle that has more consistent and predictable handling dynamics, all other factors being equal. Although I think the talent level some drivers have can certainly accommodate a less-stiff chassis, I think a vehicle that is consistent in its behavior would be easier to drive at its limit, regardless of the talent level of the person driving.

I'm not a wheel to wheel racer though, and I haven't consistently autocrossed for some time now, so I could be wrong here.

edit: spelling


Modified by wakaru at 9:26 AM 6/3/2003

 

NAB, the consensus is that you won't be able to feel the difference on a street car, and it won't result in measureable lap time decrease. That said, they don't cost a lot of money, and they won't hurt the situation, and its up to you how to mod your car.

There are situations where something simple, like subframe connectors on a mustang, can have a huge difference in the feel and performance, due to a horribly flexible chassis design. But on the DC2 the bandaids are within the noise of the experiment.