rear stabilizer bar: yes or no?

[JFENG]

(from the parts forum)

But, you have to look at the total sum of ALL your bits....

as you said, it all depends. If you have tons of grip at the back, a rear bar might make you quicker if it allows you to get it rotated more easily and back on throttle sooner. In the rain, yes softer in roll and more rear brake bias. For a car driven on the street, I struggle to believe it will make a significant difference because you shouldn't be driving 10/10ths (or even 8/10ths) on public roads. For you guys with staggered 16's, do you feel like the wider rear tires increase understeer (E9's understeer most of the time)? If yes, a rear bar might make the handling more balanced and fun to drive.

"These cars are faster without the rear sway bar."
Fine, if you are racing and you need another second per lap to get on the podium, do whatever makes the car go faster. Gutting the interior, replacing glass with plexi, nixing the A/C, welding in a skin in place of the sunroof, using a lightweight race seat, and running without an alternator and cooling fan will also make an E9 go faster around a track. What does that have to do with a classic car that's used on the street?

All said and done. I run a fat rear bar on my E9 and I like it for how I use the car because it makes the car respond quicker to my driving inputs. Since I'm not racing, I have not noticed that the car is actually slower.

with all due respect to the amazing people on this forum,
John

 

[rsporsche]

i say yes. i agree with what John has said. i am not racing either. i like the predictability in sweeping turns with the rear sway bar.

 

[teahead]

I vote yes. These cars understeer plenty, which for novice drivers and racers, makes it somewhat safer

Adding a rear bar is not going to automatically induce a ton of oversteer where you'll suddenly slide your rear end around like a porsche 911

 

[deQuincey]

my experience,

with original suspension my coupe sat in her track when cornering, but the front of the car was balancing horribly, it worked as the old cars did, you can see a ceylon coupe in a bmw test track video driven hard
esentially this was correct in terms of suspension but not nice as to perceived safety

so i changed to CN setup, springs and bilsteins, font axle worked fantasic, but rear started to drift

to fix this i had to increase front bar from stock to 23

now i have a correct suspension

someone told me that extra thickness front bar was equivalent to remove rear bar, but i did not try that

 

[JFENG]

someone told me that extra thickness front bar was equivalent to remove rear bar, but i did not try that

We should ask Al Taylor, a very experience racer. Here is my novice reasoning...

A generalization, which by definition is wrong in specific cases: “adding roll stiffness at one end of the car reduces grip at that same end.”

If your car oversteers (back end is unstable or front end loses grip last) you can balance by either adding roll stiffness in the front or reducing it in the rear. CW says reduce stiffness at the rear first.

If your car understeers/plows (eg stock E9 below 9/10ths), your front loses grip before the rear. You can balance it by reducing roll stiffness up front or adding stiffness in the rear. If you don’t care about transient response soften the front first. Old Alfa’s ( duetto, Berlina spiders in the 1970’s) rolled like crazy in corners but stuck to the road well. Ditto 2002’s. But I want a crisp/fast response to steering inputs so I chose to up rear stiffness.

Common ways to change roll stiffness are:

(1) Springs - which change both static and dynamic roll stiffness as well as overall IP/down stiffness. But changes here usually require matching changes shock damping to avoid a bouncy and uncontrolled ride.

(2) shocks -which provide transient but not static stiffness. Going too far can overdamp the springs, leading to terribly sharp/harsh transient response

(3) anti-sway bars - which are like springs but generally don’t affect overall p/down stiffness and within reason don’t require A change in shock damping

And there are uncommon ways (common on race cars), like changing the whole suspension geometry. Not applicable for most of us.

Sincerely
John

 

[Peter Coomaraswamy]

Great information and we need more discussions like this. I joined the forum in 2011 and since that time there have been lots of changes in the general focus of the discussions (I feel). The restoration tips and how to's are super valuable and every new post is interesting and appreciated but I'm seeing more members with solid cars who want to enhance their rides without going totally radical (although radical can be really cool too). So, suspension and steering modifications seem to be getting more attention and for me that is really helpful.

I have a little to add but it may not be of interest or of any help to anyone; on my e9 I have the CN standard suspension with very large sway bars front and rear plus a strut brace and fixed camber plates up front. I had an open diff and a pretty weak engine, (compression was between 125 and 90 psi cold). My first total screw-up was putting the front strut washers in wrong... ouch, once that was fixed I noticed my left rear would dip excessively taking sharp right hand corners. The thicker rear sway bar helped as did welding in IE's rear camber and toe plates but I still could not get the feel I wanted. Some of this may be that I'm used to driving a Shelby Mustang or Porsche Turbo but I am aiming for the ride I want in the car I think is more beautiful than most of the women I've dated (certainly much less trouble), but I digress... I have a pretty beefy engine in there now, 3.5 with forged pistons, 10:1 compression and megasquirt going in courtesy of SF Don, a new 5-speed and a 3.25 LSD from a CSL, I also added a differential brace and a rear shock brace/battery relocation piece and I hope to have her on the road in a month or two as I also have to put in a new dashboard and all that stuff.

I will post all my screw-ups and any triumphs under the 3.5 megasquirt thread I started a while back but please keep this post going with any handling tips and tricks as it's really useful- thanks!!