sway bar conversion

[Al.Peffers]

I have a 97 Civic CX hatchback, which has no sway bars... so talking to different people and taking in their advice lots have said they were happier with just adding sway bars than doing full coilovers(cost vs. benefit)

so since my car has none, i know i need the bars(duh) and LCAs, and new bushings(might as well), but which car years work(ie 96-00 civics si/ex work) but what about integras. also is there any other parts which I am forgetting/need?

Thanks!

PS. first official post, but been trolling for a while.

[rc2002]

Depending on how thick the sway bar you choose, you might want to add a subframe brace for insurance.

[Dj_Stylz]

ASR

http://www.weaksauceparts.com/store/search.php?mode=search&page=1

[EM1FTW]

Originally posted by Dj_Stylz
ASR

http://www.weaksauceparts.com/store/search.php?mode=search&page=1
QFT

buy it from weaksauce too :poosie:

[Al.Peffers]

looked at their info, says they use ups, which as I recall charge extra for doing cross border shipping, anyone know how much that would end up being approx?

and their free shipping deals don't work if you send em to these guys (http://www.farrow.com/sparcel2.htm)?

would call them, cept when I'm at work I cannot use company phones for international calls, and only have a 15 min window for cell use/food intake :(

anyways thanks so far.

[Dj_Stylz]

Speedtech sells ASR aswell

[R154]

Fuck speedtech

[GQBalla]

why??

[R154]

Because they over charge for everything. Fucking rip off.

Only kind of people going to speedtech are building NA honda's.

[PremiumRSX]

lol everybody's posts is useless.. nobody answered the threadstarter's question.

Hey Al, if you find out what parts you need to make it work, I can help you with car setup.

Especially if i stumble upon critical information such as motion ratio and spring rates for your Civic...

Then we can do some number crunching with a pen and paper to properly set up your car.

We can calculate your wheel rate and suspension frequency.

If you stumble upon spring rates for your swaybars (I doubt you will) keep that information, we can use it later. If not, we can make accurate estimates or just calculate the spring rate ourselves.

Unfortunately, Beyond is one of the last places I'd look for to find good information like that. :angel:

[H4LFY2nR]

According to Beaks the SiR endlinks and ITR bar will work, but I'd double check about the LCAs. I'm sure if you fire an email off to beaks they will answer your question no problem.

http://www.beaksproducts.com/EK_Quick_Swap.htm

While sway bars will greatly reduce the roll when using the your stock springs, the same bar diameters will be even more effective if you lower your car. What do you plan on doing with your car? (autoX, track, spirited driving, etc)

[PremiumRSX]

Originally posted by H4LFY2nR the same bar diameters will be even more effective if you lower your car. [/B]

Care to explain this?

I am by no means an expert on suspension but many people in more "technical" forums consider me to be a suspension guru and this is the first time I've heard of this.

It's news to me so I'd like to hear your explanation.

I personally cannot see how ride height would affect a swaybar's effectiveness.

Are you trying to say that when you lower your car you increase the distance between your roll center and center of gravity?

If that's the case, then yes you would need more roll resistence to achieve the same amount of body roll as a car with a shorter distance between the roll center and center of gravity.

However, if you're using swaybars for that purpose, you are putting a bandaid on an actual problem.. that being a screwed up roll center and instantaneous roll center.

One thing to keep in mind also is when the roll center and center of gravity are closer, we are looking at a more geometric resistence to body roll. If the roll center and center of gravity are farther apart we are looking at a more elastic roll resistence.

If there are any mechanical or automotive engineers on the board here.. please correct me.

[98brg2d]

However, if you're using swaybars for that purpose, you are putting a bandaid on an actual problem.. that being a screwed up roll center and instantaneous roll center.

One thing to keep in mind also is when the roll center and center of gravity are closer, we are looking at a more geometric resistence to body roll. If the roll center and center of gravity are farther apart we are looking at a more elastic roll resistence.

If there are any mechanical or automotive engineers on the board here.. please correct me.

That is correct. When static roll center and center of gravity are the same height off the ground body roll is at the transition point from downward on the outside tires to upward on the outside tires. Roll center above COG leads to "reverse" body roll and can be very dangerous. A high roll center also increases a tendency for snap oversteer as there is no indication of reaching the limits until the tires let loose due to being overloaded.

[PremiumRSX]

Originally posted by 98brg2d


That is correct. When static roll center and center of gravity are the same height off the ground body roll is at the transition point from downward on the outside tires to upward on the outside tires. Roll center above COG leads to "reverse" body roll and can be very dangerous. A high roll center also increases a tendency for snap oversteer as there is no indication of reaching the limits until the tires let loose due to being overloaded.

Correct! However I kindof disagree with the last sentence. =P
I mean.. we'd have to have a pretty rediculously high roll center for that. Won't be a problem with most cars that people have..

Another thing with roll center is.. typically the higher above ground your roll center is, the greater the jacking effect.

What this means is when you corner, the car actually gets higher. We want to minimize this so technically the closer to ground level the roll center is, the better.

Roll center under ground has reverse effect.

I'm glad I came across somebody that know's some stuff about cars on Beyond.. there is some hope..

[Al.Peffers]

yay smrt(intended) people!


Originally posted by 98brg2d


A high roll center also increases a tendency for snap oversteer as there is no indication of reaching the limits until the tires let loose due to being overloaded.

I mostly agree with, as I have done that... i think it was either my first or second autocross day, going too fast, and cornered too strong, and away I went.... was kinda scary as I could feel the weight pushing onto the side of the car, felt like it was going to roll :thumbsdow


but back on topic, I'm using my car for Autox, spirited driving, and if I'm able to get a decent job in Calgary(or even in Leth) I may consider track days(will eventually hit them, just not sure when)

doing research into stock bar sizes, I've come to find out that the SIR(99-00) used a 26mm bar while the GSR used a 24mm which kinda confused me, but means that if I'm able to either find a used(don't wanna go OEM from cost) SIR front LCA it should be able to handle upto that size fine(I have found ppl with SI fronts which is either 22 or 24).
however that being said when I lower my car, if my reasoning is working fine, I shouldn't need as strong of sway bar, because the suspension travel will not be as great(correct me if I'm wrong). :confused:

also one guy I talked to suggested that i should not bother with a rear sway bar(I call :bullshit: ) as it would greatly mess up my handling.
Which again if my mechanical reasoning is correct I would understeer greatly with just a front sway on, vs both, and as well during strong cornering one of my fronts may lift(if I forgo the rear sway).

btw future plans involve a dropping in a b18c1(or if I get garage and funds a franken B20vtec), coilovers, driver restraint(either by harness or seat or both), and a few other things.

If this mesage sounds jumbled up I appologize, its nearing 5am, and I got home not too long ago, stupid work, so thanks for any and all help!

[H4LFY2nR]

Originally posted by PremiumRSX


Care to explain this?

I am by no means an expert on suspension but many people in more "technical" forums consider me to be a suspension guru and this is the first time I've heard of this.

It's news to me so I'd like to hear your explanation.

I personally cannot see how ride height would affect a swaybar's effectiveness.

Are you trying to say that when you lower your car you increase the distance between your roll center and center of gravity?

If that's the case, then yes you would need more roll resistence to achieve the same amount of body roll as a car with a shorter distance between the roll center and center of gravity.

However, if you're using swaybars for that purpose, you are putting a bandaid on an actual problem.. that being a screwed up roll center and instantaneous roll center.

One thing to keep in mind also is when the roll center and center of gravity are closer, we are looking at a more geometric resistence to body roll. If the roll center and center of gravity are farther apart we are looking at a more elastic roll resistence.

If there are any mechanical or automotive engineers on the board here.. please correct me.


Let's begin by looking at the car as system, before breaking it into elastic and inelastic weight transfer.

When we lower the car and therefore the overall CG, for a given lateral acceleration the lower car will have a smaller roll moment. Therefore, when using the same anti-roll bar and ride springs on both cars, the lowered car's anti-roll bar will contribute proportionally more roll stiffness to counteract the overturning roll moment. This is the simple case of how ride height will affect a given sway bar's effectiveness.

For this discussion I am referring to double unequal length a-arm (double wishbone)/5-link independent suspensions, nothing silly like mac struts lol ;)

Now to discuss roll center locations and therefore elastic vs inelastic weight transfer. I never said that lowering a car would increase the distance between the CG and the kinematic roll center, I was assuming the opposite. Production cars in OEM configuration generally try to minimize bump camber changes while sacrificing the roll camber curves by using very close to parallel a-arms, resulting in very long front view VSAL(virtual swing arm lengths). When a OEM suspension is lowered, the a-arms are put in a state of perpetual bump, and one would assume that the instant centers converge sooner, resulting in a lower RC. However, this would most likely be incorrect, since to keep the geometric (instantaneous, in-elastic) weight transfer as constant as possible so as not to disturb the tires during a turn, the suspension would be designed to have the RC height stay fixed relative to the ground.

Therefore, when the sprung mass CG is lowered, it's relative distance to the kinematic RC is actually reduced (for simplicity we will use the CG to kinematic RC height to be the roll moment arm, not the CG to Force Based Roll Center height). This results in increased geometric weight transfer and decreased elastic weight transfer. So our original sway bar now has even less roll moment to resist as we have the combined effect of a lower CG (lower total roll moment) as well a decreased portion of that total roll moment that has to be reacted elastically by the ride springs and anti-roll bar. As an added side effect, the car's increase in the geometric proportion of the weight transfer will increase the response of the car, however too much geometric transfer and it may load the tires to quick resulting in an unstable car.

So far I have not mentioned lateral RC movement which contributes significantly to jacking effects. You are correct in that a high RC will increase jacking forces, and that jacking can raise and lower a corner of suspension but that is not necessarily a bad thing. When the RC moves laterally towards one side, the kinematics limit the movement resulting in effectively a stiffer spring on that corner. Since the total roll movement remains the same (it is only a product of the CG height from the ground, and the car's lateral acceleration), this effective change in spring rate can alter the suspension displacement and therefore the car's height (or you can look at the force vectors from the laden and unladen tires to the force based roll center). Anyways, you can use lateral movement of the RC towards inside wheel to create anti-jacking forces, therefore reducing the overall jacking created by our above ground RC.

You have to be careful saying that the closer the RC gets to the ground, the better. This is can be very detrimental because the lateral movement of the RC increases exponentially as it gets closer to the ground. Think of the ground plane as an asymptote of the RC height in that at a height of zero, the RC moves wildly in the lateral direction.

Given a constant CG height, a lower RC height (between the CG and ground) will increase the elastic load transfer allowing for springs (ride/anti-roll) and dampers to control the rate at which these forces change at the contact patch during transients.


To Al.P: A rear sway bar will not mess up your handling if you balance it properly with your front sway bar. The relative difference in the roll rates between your front and rear axles will determine your car's roll rate and yaw rate. FYI on a front wheel drive car you will want the rear axle reacting the it's maximum amount of the total overturning moment to maximize the grip on the front drive wheels, meaning you want the rear sway bar so stiff that it actually lifts the rear inside wheel. However that's may sacrifice too much lateral grip in the rear and make the car yaw so fast that it is uncontrollable.

+1 for actually discussing vehicle dynamics on beyond :thumbsup:

-Richard
Active SAE member
Mechanical/Race Car Engineer

[Al.Peffers]

so basically what your saying is that even with the car dropped because how the car was designed and engineered, that the size of sway bar used should remain the same :dunno:

and that going too stiff(spring rate, and sway bar) will mean that physics will win over you trying to control the car, ie you'll either understeer or oversteer into a slide each time you take a corner?

now, back on topic(well slightly off it) I was aware/under the impression that I should get the rear inner tire lifting off on corners(done it and have a pic to boot), my only concern is that in doing this change I was warned by one tuning shop(granted its a drifting shop really, and so FWD to them is a bit foreign) that putting in a rear sway that was too stiff may be excellent for the track, but makes it too much of a handful for basic street driving. I personally believe that is just a case for RWD. This would be the equivalent to me putting on such a stiff front sway that I understeer everywhere/anywhere I turned.
So basically I am right in thinking that they were on the right track but wrong bar, and that putting in a rear bar that is stiffer than the front in a FWD car could potentially make the car oversteer more frequently(track use), but do not a whole lot for city/highway driving, or am I out to lunch :nut:

[H4LFY2nR]

^I was saying that if you select a sway bar diameter before you lower your car, it's effective anti-roll rate may be different/stronger once you lower it. You can always purchase/fabricate an adjustible anti-roll bar to tune the roll rate, since the ideal balance will change with many factors, such as tire pressure, temp, tarmac roughness, fuel load, etc.

Only going too stiff on one end of the car relative to the other end will change the under/oversteer balance. You are correct that you will most likely want to lift the rear inside wheel on the track, meaning that the rear axle is reacting the maximum amount of the roll overturning moment possible, helping leave the maximum grip on the front inside for driving out of a turn.

Usually on the street that means that speed bumps and driveways will tripod your car. If you're planing on running a bar that stiff I would recommend using a beefy subframe brace. The under/oversteer balance that we are talking about is for limit handling (upper limit of the tires grip), so street driving shouldn't be an issue, except for in the snow. But we all drive carefully on the street anyways...

[PremiumRSX]

Cool, thanks for the very informative post Richard.

Most of the things you mentioned I knew already but did not have as clear of an understanding until reading your post.

I also had some misconceptions that you cleared up!

:thumbsup:

First Active SAE member/race car engineer I know.
I will me pm'ing you about my suspension questions. :D

[Al.Peffers]

Originally posted by H4LFY2nR
^I was saying that if you select a sway bar diameter before you lower your car, it's effective anti-roll rate may be different/stronger once you lower it.

I already had that inclination just after reading your post it got me questioning it...

Thanks for the help and input so far, now back to figuring out which exact parts I need on my day off... whenever that will end up being. :nut:

[RedRocketDX]

Ok so I didn't have time to read all the replys but here's the answer to your original question:

I too had a civic with no sway-bars (98 DX) adding a front, and rear made a huge difference in the handling for very little money.

For the front you will need from a 96-00 civic Si(EX-US):
Front lower control arms
End-links
Sway bar (it's 22mm for future ref)
Sway bar bushings
Bushing brackets and bolts


These parts should cost you about $100-$150

For the rear your LCAs already have the holes to accept end-links.
So, you can go the after market route (If you go any bigger than 17mm I would suggest some kind of sub-frame reinforcement)
Or from a 99-00 civic SiR (Si-US) you need:
End-links
Sway bar (13mm)
Bushings
Bushing brackets and bolts
D-brackets and bolts (don't know if they are called this but basically they mount to your sub-frame and hold the swaybar assembly)

These parts should cost about $50-$100

Now some people say that the sub-frame is pre-threaded to accept the D-bracket bolts. Well mine wasn't so I just used nuts with lock washers.

[CK4500]

Originally posted by RedRocketDX

Now some people say that the sub-frame is pre-threaded to accept the D-bracket bolts. Well mine wasn't so I just used nuts with lock washers.

Agreed with his entire post ^^^^^

to explain the part quoted above: The sub-frame is pre-threaded ONLY on vehicles which came from the facory with a rear sway bar. Not only is it prethreaded, but it is also re-enforced. The threads are actually on a separate plate that fits up in the subframe just inside between the LCA mounts.

I have a 2000 DX SE hatch. I did a SiR front sway bar with the SiR LCAs. For the rear, I bought an ITR rear bar (22mm) and the ASR rear brace from Pit Crew Motorsports. (Pit Crew goes out of their way to mail stuff to Canada, very helpful in avoiding BS UPS fees)

http://i16.photobucket.com/albums/b5/CK4500/01.jpg


If you aren't looking for something this dramatic, I still have a SiR rear sway bar d-brackets, and one endlink. They are forsale on here somewhere.