with the springs and sways, the handling for & aft and sideways is awesome...however, u add the upperstrut tie bar to the mix, and u may b doing more harm than good...here's y in my experiences...first off, Ernie (Eclipse23) mentioned this to me, and i was skepticle (boy was i proven wrong)

in case any of u haven't read some recent posts, i, along with Zapata and others, have talked about the purpose of the upperstrut bar and whether it was worth buying or not...i pointed out that the upperstrut bar DOES serve a purpose if forces on the car in a turn are too great on sways alone, and forces creep up the car, causing body-lean (the upperstrut bar helps to absorb residual forces not absorbed by sways)...in the back, however, there really aren't people here who have a rear upperstrut bar...so u have an imbalance, and it is this imbalance that has caused my close calls...i have taken some pretty aggressive turns, and what happens is the back starts to hop a little from it's lightweight rear-end (remember, the weight ratio is 63% front/37% back (62/38 for 6-speed))...the front end is soo rigid and firm, while the back is a bit more loose, u can see where this is going...if the upperstrut bar was not installed, there would b more flex up front, thus canceling out to a degree the potential for breaking loose in the back

last week, i did it taking a turn at about 40 (90 degree turn), and i could feel it no doubt bout it...VSA kicked in, and i recovered immediately.

when i first came home from PAA with my springs and sways, i tested the suspension at my exit ramp (180 degree semi-sharp turn)...by the time i got up to around 45 or so, the back took 1 giant hop to the left...i let go of the wheel immediately, VSA kicked in, and i recovered.

granted, these are a bit on the extreme side in controlled conditions, however i wanted to point out that in case of emergency or if u're racing someone, there is the potential for u to break loose if u're not careful...in fact, it would b worthwhile if u could create your own controlled conditions where there's little to no traffic, and see if u can create the effect...then take the upperstrut bar off and try again...identify how the car handles in each case.

sorry for the long post...i wanted to try and b as thorough as possible to avoid confusion

 

Thanks, you just cleared up the meaning of life ...

 

geeze fotis muh man is trying to edumacate fellow board members and you're ragging on the guy.

Scooter,
Yeah after hearing your experiences and just the physics of the whole thing i don' think i'll be putting the upper strut bar on my car. Having a tight car is great for handeling but also has it's negatives.

 

What if you don't have springs?, Or have stickier tires.

 

Principle is the same. Front will be stiffer than the back.

 

I thought that by making the front more stiffer, you would in theory break loose the front before the rear, since there is flex that is keeping the back end from breaking loose... but you are correct in that the rear would hop when it looses traction, instead of the tires breaking loose in a controlled manner since the rear wants to keep traction because of the flex, but once it does, it would be uncontrolled.....but generally stiffer place looses traction before the other....

 

wat if u got the sways..and lowered suspension

than decide that u can afford to buy both upper/lower struts


is it worth it than?

 

i would agree with u, however since there is such a weight difference between the front and the rear, there's no way the front's breaking loose...63% of 3500 pounds (2205) is on the front vs. 37% (1295) on the back just based on the car alone...your body weight adds more to the front half, further throwing the ratio to extremes...so depending on the tires u got, the weight of the front gives such a heavy footing on the pavement, the tires are not moving...in fact, if anything, your tires will roll underneath the rim a little b/c of the weight...the back tires will never do that

 

I have been noticing a similar “problem” if you want to call it that.
The thing is, I noticed it immediately after the Springs/Sways were installed.
Don’t forget, I went from STOCK setup to new Wheels, Tires, Springs, Sways all in ONE week.
The handling of the FRONT of the car seems to be much more improved then the REAR when the Springs/Sways got installed

When I installed my Neuspeed upper bar two weeks later the handling issue got neither better or worse.
I don’t think the bar has anything to do with it. At least on MY car.

My tires stick pretty good back there so I don’t think it will be a safety issue once I learn the new limits of the car.
The overall package is definitely better then a stock setup, but you are right, the improvements “tighten-up” the front much more then the rear of the car.

Shawn S

 

yes, i noticed it literally on my way back from PAA when i had my springs, sways, tires, and brake lines done...my upperstrut bar has been installed since Sept. '01...in attempts to find the limit of the car's capabilities, i hopped the back, altho the tires do like Wayne himself said when he tested the car out "stick like glue"

since the 6-speed does distribute the weight slightly (1% = ~35 pounds), that may/may not make a difference.

 

I hate to say this but, where ever there is more weight, sometimes the car actually breaks loose on that side even more, hence the understeer on our nose heavy cars...for example porsche is known for their very controlled oversteer compared to other sports cars just because their engine is in the rear of the car...so thats necessarily not always true that more weight in front would mean more traction...from what I have noticed is that even my TL which is probably a bit more heavier than the CL actually understeers quite a bit during a hard turn...this is even in wet and dry conditions, but mine seems to break loose in the front in a pretty controlled manner, btw I dont have the upper strut bar so i cant vouch for that but keep in mind that i have H&R sport springs, tokico blue shocks, and 18 inch wheels with 225/40/18 series tires...and this is from personal experience...

 

You only have the springs. Sways make the situation completely different.

You have to look the car as a geometric plane that goes from front to back for the strut bar discussion it differ for springs. Normally the front and the back of the (car)plane have the same rigidity. Now, the level of rigidity determines the severtiy of the weight transfer from side to side. A car w/ an upper strut bar has greater rigidity in the front and less in the back. The weight transfer from side to side in the front is much much less than it in the back because of the upper strut bar. The rear w/o a bar has more weight transfer than the front so when you go into a hardcorner the back will swing because of the uneven weight transfer between the front and back of the car. So as the car goes through the corner the forces move front to back and since the movement from side to side is greater in the back, the back breaks loose first.

 

just having a bad week :shakehd:

 

so what's the deal yo???

 

Things ok my greek friend??

 

Guess I won't be getting the Neuspeed bar! Thanks for the report, Scooter.

I wonder if one were to install just a rear upper tie bar on a car with sways and springs, if that would produce a more useful stability addition than the front one does. The rear one would be compensating for the weight distr. and whatever. Wouldn't doing the opposite of what hurts make it better?
If too stiff a front hurts, what if you make the back stiffer instead?

 

i think u would b well off if u put a rear upperstrut bar on...there's someone here on the boards, maybe Astro, who put a rear LOWER strut bar on...this bar's effect is marginal at best since the sways superscede the bar...u need an upperstrut bar...u need higher stability...lower stability is covered by a 22mm bar that absorbs hellaforces...upper stability is necessary.

another theory worth considering...the back is just too light...put some heavy weight in the trunk and see what happens...the fact is the rear Comptech sways are solid and thicker than stock and supposed to add stability, right?? solid and thicker = heavier, right?? let's assume for a moment it does...think of how handling would b if u put in the trunk a few Home Depot sized bags of top soil

 

There is a lot of oversimplification going on here.


If one considers a car chassis that is reinforced to have minimal deflection (in all cases), an increase in rear sway bar size will increase oversteer (and decrease understeer) (It's easier to get the back out *and* I don't see too many people complaining about the addition of the Comptech sway bars. They increase the rear roll stiffness more than then increase the front stiffness (I prefer the more neutral balance).

The influence of FRONT strut tower bars is not that simple; they increase rigidity of the cars frame in most cases (up front) and ALSO increase the ability of the suspension to keep the front tires on the ground. (So, the tires grip better, but there is also an increase in weight transfer, and the increased weight transfer generally translates to more understeer!

The increase grip provided by better traction (relative tire contact increase and reduced change in relation of tire angles from side-to-side [toe-in related to Ackerman angles] will have the effect of increasing front grip and reducing understeer. (Think of this like adding wider [or stickier] tires to the front of the car.)

The stiffness increase that is provided by the strut bar to increase weight transfer (similar to a roll bar) will actually increase understeer. (When you increase the size of a rear sway bar, the car’s understeer will decrease [increased oversteer]. When you increase the size of the front sway bar, the car’s understeer will increase [decreased oversteer].


This whole discussion gets over simplified and I’ve been able to get the back end to come out at higher speeds, but the balance is basically neutral 80% of the time.

The car’s velocity (the velocity squared is what will influence front-to-rear list and/or downforce [we don’t have any that I can tell]), the radius of the turn, and other factors can make the addition of the front strut bar change the behavior in completely different ways depending on these very factors.

IMO, the additional upper strut tower is probably most effective in keeping the steering geometry correct in tighter turns (higher loads) at initial turn-in.

For more info on what changes in springs, tires, sways, etc do to a car’s balance, check the table on one of TireRack’s pages.

http://www.tirerack.com/tires/tirete...n/racepres.htm

$0.02

 

Check the weight of most FWD cars -- you will notice that they are heavy in the front and light in the rear. The weight of the rear sways bars has virtually no bearing on the handling of the car.

If you put some heavy weight in the back of the car, it will just increase oversteer!

The increasing stiffness of the Comptech bars -- they increase the roll stiffness in the back MORE than they do in the front, will account for the increase in oversteer (and/or the decrease in understeer that I was looking for). IMO, the front bars impact is minimal.

If you look at the TireRack link you will clearly see that more weight in the back of a car decreases understeer and increases oversteer.

A humble suggestion: Check out the SAE website and grab the 800 number. Ask someone there for a free catalog of publications. They have some very good books on racing suspension, etc and perhaps it will remove the mystery from this. (Amazon could be checked out as well…)

As for the theory meeting the "real world", I had the opportunity to waste tons of money of my Bimmer, and I was surprised at some of the results that occurred with the addition of various sway bars, strut tower braces, shocks, springs, braces, and other goodies (it seemed rather counterintuitive until I started asking racing buddies and getting more books). Check the TireRack link...

 

then perhaps an option u have is to put different, wider, sized tires in the back, like most sports cars, to provide more traction...if more weight in the rear is no good, and if adding sways is "too good" for the back since the rear hops a bit, wider rear tires should cancel the effect.

but Eric, u never went into a REAR upperstrut bar for our cars.

 

As soon as Eric posts, the thread goes supersonic over my head.

I just want to know in yes/no terms if strengthening the upper back of the car would be good or not (for someone with springs/shocks/sways).

 

The "arguments" I pushed regarding the front bracing is somewhat analogous to the rear situation.

1. A decrease in rear flex would INCREASE the weight transfer (more stiffness) and would "probably" result in more oversteer.

2. That same decrease in rear flex would keep the suspension geometry in the back working as "designed" to keep the tires on the ground (there are some exceptions to this, but this is already getting out-of-hand).


Once again, there are two "opposing" functions at work *and* the result and subsequent balance from a REAR upper strut bar and/or other "stiffener" could depend on the size of the tires, the grip of the tires, the size of the swaybars, the spring rate of the springs AND the design of the rear stiffener.

I can comment in a "no doubt" manner about the effects of the front strut, since I have it, and actually removed it to see if I was dreaming about what it "seemed" to be doing. So what I commented on is the result of theory and experience.

IMO, the CLS is a "plow-mobile" as equipped from the factory. The handling on my car is now basically neutral in "most" situations (well, it still plows in really tight turns and it tends to oversteer at higher speeds [aerodynamic forces at play]). I hope nobody interprets this to mean I can just swing the tail out at will; however, getting into a high speed turn and getting off the throttle will generally get the back out.

If someone is really that concerned over getting the "backend" of their car too loose, they can always follow the suggestions in the Tire Rack link regarding spring rates, tire pressures, sway bar sizes, etc. and do all of the changes to DECREASE OVERSTEER.

Kevin M, who sold his car, was racing the sucker and he did a lot of mods to the car. One of his "main" gripes with the car was the inability to "rotate" the car. He was even contemplating a gonzo sized rear sway bar to get some more oversteer...

IMO, a stiffener in the back of the car IS NOT going to turn the car into some over steering monster!

BTW, even a "plow-mobile" can be made to get its tail to swing out when pushed far enough...

So, the result WILL depend on the exact construction of the rear stiffener and the various components and tire pressures. IF the stiffener really helps the rear of our car so much that it now oversteers like crazy, just pull out the Comptech rear sway bar and put the stock one back in...

There is always going to be some "juggling" with parts and mods, why not see how mattg's rear brace effects the handling and go from there.

 

And your question is why there is an even longer answer waiting...


The short answer is -- it depends on what you’re looking for...


See the reply above...