Well last week a friend of mine told me that the 1st gen's get better handling without a sway bar since they have solid rear ends. This guy has been autocrossing rx2's, rx3's and rx7's since the late 80's so that's why I took his advice. I did notice a bit more gripping power on the corners. I'm curious as to what other people have to say about this topic?
Your feedback would greatly be appreciated.

 

i feel the grip without the swaybar. on the mtns i can grip a little harder than before, but then agian my tires are no names

 

If you take a look at the "Upgrading a Stock (1st gen) RX-7 thread" (a link to it can be found in the 1st gen FAQ), alot of guys in there say the first thing they do is take out the rear sway bar. Seems to be a standard practice, but I haven't done it yet.

 

What your dealing with is a soft susension, body role, and wieght transfere. on stock susension, our cars are old, the spring are soft and the shocks are weak. When you go into a corner the outside wheels go from handeling 1/2 the weigth to as much as 3/4 of the weight of the car. what the sway bar does, is as one wheel goes up in travel it pushes a little bit on the inside wheel and pushes it down. It's to help keep the weight of the car evenly spred out and gives you more surface area because you have more rubber touching the ground. The problem becomes that on stock 1st gens the suspension is so gone on it that the shocks arn't strong enough to keep the wheel planted on the ground. The results it "hopping" and the rear end slides out and a ton of oversteer. How does removing that sway bar help? Well if you think about it, when you take that corner the wieght will be transfered to the outside wheel. the sway bar isn't there to transfer to the inside wheel. So their is more wieght on the outside wheel and because of it'll take a lot more wieght to spin out or oversteer becuase the surface area of rubber touching the ground is a lot greater now. All your doing is helpping the shocks push the wheel down. The problem becomes then, that your front end is stiffer than your rear and you end up the the under steer problem. understeer is easier to prevent when driving but it harder to correct when it happens too. If you have a strut tower bar too, that just adds to the under steer of the car without the rear swaybar.

Whats the better way to fix the issue? get rid of the body role. everyone knows what body role is. What you do is get new springs, even stock ones will do. then replace the shocks with something stiffer. tokico hps are cheap and good. Leave the swaybar on there and then go for a drive. the body role has almost stopped, the swaybars are working great and won't have the issue with understeer or oversteer.

Something people get confused on a lot is the perpose of the sway bar. The sawybar isn't there to help take corner a lot faster. All they do is reduce under steer and over steer. If you took them off your car with a good suspension all you would do is slide.

After all the long ramble i'm going to bed.

 

"How does removing that sway bar help? Well if you think about it, when you take that corner the wieght will be transfered to the outside wheel. the sway bar isn't there to transfer to the inside wheel."

I hate to be rude, 13B4port, but you need to do some homework. I suggest reading one or more of Carroll Smith's books - "Tune to win", "Design to win", etc. There are also several books by British authors that are references for chassis designers.

If you just get the car up in the air and look at the sway bar and how it is connected to the front (or rear) suspension, you can see that the sway bar must be twisted for the car to lean. The sway bar resists this by putting MORE WEIGHT ON THE OUTSIDE WHEEL in a turn. If it is the front wheel, this causes understeer. If it is the rear, this causes oversteer.

As for springs getting "soft" when they get old, that can happen, but it should be obvious. If the springs change in their characteristics over time in any way, they will sag, and the car will be sitting lower. If the ride height is still normal, the springs have not changed, and a brand new set of STOCK springs will make absolutely no diffference.

Certain years of the 1st gen do tend to have what is called "final oversteer", meaning as the tires reach the limit of their grip, the rear end tends to break loose, a very undesirable characteristic. Some people correct this by removing the rear sway bar. The best solution is to put wider rims and bigger, wider tires in the rear, to increase cornering power on the rear axle. During my autocross days, I developed my Cortina GT over the course of two seasons, step by step, and the single most effective modification I did was going to wider rims, even with the same tires. I was very successful, by the way.

As for removing the front sway bar, that will increase the body roll to the point it will get scary and you may think you are cornering faster!!!! Virtually all modern race cars have adjustable front and rear sway bars to control the handling.

What you need is some very good quality gas shocks, and if the handling feels loose, put some urethane bushings in the front sway bar and sway bar links, so that the sway bar can do its job more precisely.

 

With a solid rear axle these older style vehicles have a built in rear sway bar to some extent (the axle housing), all race car developers will remove the rear bar on a 1st gen FB, this includes G-Force Engineering, probably the premier suspension tuner for FBs. You do need to develop far beyond just removing the rear bar for any real performance advantage. Look at this site www.gforceengineering.net for a guideline on what's available, remember there are numerous sources for parts and or installation. Look into the reputation and experience prior to making ay expensive moves.

 

upgrade the stock suspension to something better..... Don't remove the sway bar...

 

It all depends what the step after removing the bar will be. If you are going to go through the whole suspension, pull the rear bar. The biggest problem these cars have is the rear suspension geometry, as the car leans the upper links bind things up and the whole rearend becomes a "sway-bar".
Since springs and bars work together to provide roll stiffness there are any number of ways you can control body roll. What you are trying to do in the front is control roll to keep the tires planted on the ground at a reasonable angle, in the rear you are trying to balance things out with the front (solid axle after all, no camber change).
So because our cars are so tail happy under power we have to put a front bar on that is as big as your arm. Its bigger than it needs to be because its control the lean as it should but its extra big to make the front slide about the same time as the rear. The end with more effective bar stiffness will break loose first.
The best option has already been mentioned, call GForce Engineering and order Jim's set-up book. It's the best money you can spend if you are just starting out with FBs and suspension in general. It will save you from buying parts multiple times as you learn about the car and car set-up.
So my advice, dump the rear bar and see if your buddy has an old Racing Beat front bar to throw on the car. Until you start thinking about springs etc. this will give you a feel for what the car is capable of. When you get Susko's book you'll learn why you want to have the smallest bars you can that do the job, thats why you want to borrow a front bar not buy, you won't need that particular bar when you set the car up the GForce way.

 

below 45 mph its better. above that the car bounces a lot more! and is way less friendly. it makes it almost feel like driving with an open dif. lol I put mine back on after i got some bushings!

 

Just comments, no attitude.

Traction, or "Grip" is best when the tires share the task.

Sway bars control "over steer" and "under steer" by loading tires (or not) with the "weight" that is generated by body roll while cornering. Body roll is determined by lateral acceleration and the "roll center" of whatever suspesion geometry is used..
Solid axels have high roll centers, high roll centers generate large roll angles. Sway bars (anti roll bars) resist the roll and transfer the "weight" to the outside tire. ( removing "weight from the inside as it does so) The weighted outside tire will (may) operate at greater slip angles due to carrying more load. One tire loaded twice as much can not generate twice the grip. That's a LAW! With Less grip in the back. Presto, over steer! ( at least less under steer) or to the extreme as the back end lets go, Final oversteer.

Family sedans understeer. it's safer.( say some) RWD solid axle cars can have less understeer if a sway bar is added. Over steer takes some of the work out of "spirited" driving. But Pay Attention!

Back tires are often bigger than the fronts because they transmit "drive" as well as lateral forces. A "foot print " adjustment to control overloading the tires contact patch.
RX-7's could benefit by this. Solid axles are the best at keeping the tires flat on the road! That's GOOD.

In performance driving, everything goes through the tires!


There are a lot of good books out there. I like Fred Pun's "Making your sports care handle"

Cal

 

I think you are on the right track but a sway bar is actually trying to lift the inside tire as the body leans. Overall you will end up with a lower total 'grip' number when a sway bar is involved and the loads are sent through it to the other side of the suspension.(Simplified version) And yes Fred Puhn's book is a good place to start learning and then to remind yourself whats going on under the car.

 

jgrewe

Thanks for giving Fred Puhn the "h" he deserves. ;-) I should chek my typing before submitting.
Grip enhancement descriptions are always incomplete. There are just so many systems all coming into play at once.
As a point of clarity regarding "lifting" of the inside wheel. This action "should" increase available relative traction at that wheel right until the point of the wheel leaving the road surface. Only in proportion to the load present at the tire certainly. But this is in the opposite direction (sign) of the overall result, which is the outside wheel becoming overloaded, losing relative grip and then the rear end turns "faster", More oversteer.

A real eye opener regarding suspensions, is any video taken from the cockpit of a formula car over the front wheeels.
Unless a curb is struck, NO MOVEMENT OF THE SUSPENSION can be noticed.
It's all tires!

The Karting crowd have it

Regards

Cal

 

Hahaha, look at what I started
Keep it coming guys, It's really interesting to hear everyones knowledge and info about this subject.

 

In threads like this, I always get a kick out of everybody stating their opinions as fact. I don't see nearly enough "in my opinion" or "I believe that", etc. Far too many "experts" out there, and you end up having to wade through two pages of bullshit sifting for accurate information.

"swaybars push the inside tire down"? lol.

Anyway, just my opinion... If you don't know facts, then present your information as opinion.

 

There are a couple of physical inaccuracies above that have been corrected by others so I won't go into that too much. Suffice it to say that stiffening the rear suspension increases the load on the outside tire during cornering.

Simply put, everyone likes a little different handling feel. The suspension setup you choose should suit you and your driving ability and style. I have found from removing the rear bar that the ultimate grip is improved, but the snap into oversteer is also more dramatic, both make sense if you think about what's going on back there.

The best thing to do is to try it both ways and decide for yourself. It only takes 2 minutes to remove the bar completely.