Sway bar upgrade without torsion bar upgrade?

[eurocarrera]

Has anyone upgraded their sway bars, and NOT upgraded their torsion bars? I have a 1985 gray market coupe, and the shocks in general seem pretty firm. I tried the acid test of trying to bounce the car up and down, and I was barely able to push the car down half way!!!!!! Either the PO had the Bilsteins done, or it already has upgraded torsion bars. It does indeed have the 18mm stock sway bar up front.

When I drive over 60, sometimes the car feels like it is wandering, so later this year I was going to put on a tubo tie rod kit, new front wheel bearings, ball joints, A arm bushings, and then a 22mm Weltmesiter sway bar in the front and the back. I was hoping that this would get rid of that "floating" feeling, and make the car tighter in the turns.

Oh yeah I am going to lower the car and get it balanced at the same time.

[Early_S_Man]

Bill,

Yes, I installed heavier anti-roll bars and ran them for several years before installing 21/26 torsion bars! Mark Donohue was a proponent of soft springs/stiff anti-roll bars, and that was a factor in my experimentation! I found the experiment worked quite well, and only went to the larger torsion bars when I went to much larger tires and wheels ( 8's & 9's vs 6's all around, before) that tended to decrease spring rates because of their greater positive offset.

[Joeaksa]

Euro,

If you can push the fender down very much at all I would look at the shocks very carefully. My 85 car felt very good in the corners and I could not push the fender down very much. 80k miles on them.

Decided to upgrade to Bilsteins and when I put the stock rear next to the new one, it was unbelieveable. The front units had very little gas left in them and were completely trashed as well. My old ones were worn out and the change to new Bilsteins was the best money I have ever spent on the car.

You might look at the back shocks and see if they are the orginal ones and if so a change is in order. Also, I second what Warren said above. I upgraded to the "turbo" model of sway bars and the ride is excellent but not too harsh.

Joe

[eurocarrera]

Joeaksa, I am used to shocks on american cars where you usually get the car bouncing by pushing it up and down several times, and then let it go to se if the car keeps bouncing - that was usually the key indicator to tell you if you had bad shocks. When I push on the P-car, I can "barely" push it down more than a few inches, and I "really" have to push on it. It returns normally back up to standard ride height after that. That leads me to believe that the shocks are OK. The car does have 146K on it, and I would think after that period of time the shocks would be wasted, so the PO MUST have replaced them.

[eurocarrera]

Forgot to mention - the car does have Bilsteins

[Joeaksa]

Bill,

If the car has Bilsteins now, then I would try to figure out how old they are (hope you have some maintenance records or can contact the old owner) and find out how many miles on them.

Stock shocks are gone after 20-30k... Bilsteins or Koni shocks are guaranteed for life and that means around 100k in my eyes. Another way to check this is to drive another car with the same type of shocks and see if there is any difference.

If you already have Bilsteins then you should be in good shape but they are not good forever!

Joe

[Early_S_Man]

Another thing to be done before installing larger rear anti-roll bars is to reinforce the mounts with gussets! Post-78 mounts are weak, and often crack or break with stock 18 mm bars!

[eurocarrera]

Does anyone know a reliable shop in the SF Bay Area who could weld the rear sway bar support plates on the car? Anyone have this done recently?

Also, what can I really expect by replacing my from ball joints and and tie rods with the Turbo kit (and other mods I mentioned) on a car with 146K miles on it? Thanks for the replies so far!

[911pcars]

One drawback of installing a large sway bar without changing the torsion bars is that you might "tighten up" the settings for better weight transfer control to make up for the lack of heavier torsion bars. This may place more stress on the sway bar mounts than otherwise. Although installing sway bars is a relatively easier upgrade (which prompts many owners to do this first), I would recommend upgrading the torsion bars at about the same time.

Late 911s with the factory undermount front sway bar usually need add'l chassis sheet metal reinforcement when using an aftermarket through-body sway bar. The add'l weight of these cars and a large diameter rear bar may also place more stress on the rear mounts, hence the reinforced mounts.

"....Mark Donohue was a proponent of soft springs/stiff anti-roll bars, ..."

Yes, but not sure what cars he was referring to when he said that. He also drove 3200 lb. TransAm Camaros and a special 917 for Penske (among other cars); not quite the same as a 911.

Sherwood Lee
http://members.rennlist.org/911pcars

[eurocarrera]

What are others opinion on this? Do you have to do the torsion bar upgrade as well? I thought the sway bars were there to only compensate for the roll factor, and not necessarily the up and down motion that would be more inherent to shocks and sway bars. Additionally, it was my understanding that the torsion bars apsorbed and sprung back on harder shocks the car took, wheras the springs took on the smaller bumps in the road.

Has anyone ripped a sway bar mount by just using torsion bars - it sounds like it is just an inherent problem we need to be aware of.

[Early_S_Man]

Sherwood,

Chevrolet Engineering has been using the heavy anti-roll bar philosophy promoted by Donohue ... on production cars for 30 years now on high performance and regular cars as well ... beginning with '72 Monte Carlo's ... '77 Impala's ... '82 Z-28's, etc. So, I guess it is a fairly-well validated concept!

Most of the broken rear mounts on post-77 911s have been on stock suspensions, so I guess it has NOTHING to do with the installation of heavier anti-roll bars! It was just a revision that was badly designed, and fairly-widespread effects in the customer base suffered as the result!

[KNIGHTRACE]

I hope to be of some help, we have spent lots of time with this,
Early S man is correct. If you place the larger swaybar in the rear
you will find the stiffer you make it the better the car handels, the problem is you will quickly rip the antirollbar brackets off.
It compensates for the weak t bars. You can get away with a little but not too much. It needs stiffer bars and revalved Bilsteins.
I sell Sanders bars and sway bars if you ever need anything.
I have NEVER seen a case where 31mm bars were not best.....
There is a lot of confusion on this though. (If the shocks are revalved CORRECTLY to match the 31mm bars, ride quality may be improved) If you put 31mm bars or even 27mm bars and dont revalve the shocks to match, the shocks cant controll the bars and it will hurt ride quality. Hope I helped some.
William Knight
(270) 462-4199
(fax) 462-4099
knightrace911@hotmail.com

[911pcars]

"Chevrolet Engineering has been using the heavy anti-roll bar philosophy promoted by Donohue ... on production cars for 30 years now on high performance and regular cars as well ... beginning with '72 Monte Carlo's ... '77 Impala's ... '82 Z-28's, etc. So, I guess it is a fairly-well validated concept!

Warren,
'72 Monte Carlo's and '77 Impala's? And we know how well these cars handled. They would have handled a lot better with heavier springs; and they did when these cars were equipped with the "police cruiser" package (which also included larger sway bars, btw). Using soft springs and heavy sway bar has been a fairly common concept, but what GM, Ford and Chrylser gave us was primarily for comfortable boulevard cruising and for minimum car control when the steering wheel rotates a little. Remember, these cars are around 4000 lbs.

"Most of the broken rear mounts on post-77 911s have been on stock suspensions, so I guess it has NOTHING to do with the installation of heavier anti-roll bars! It was just a revision that was badly designed, and fairly-widespread effects in the customer base suffered as the result!

As far as I know, the rear sway bar mounts up to '77 were the same all the way up to the late 80's. What happened in '77 to cause the brackets to crack? The torsion bar size didn't change significantly (+1mm). Perhaps a heavier factory sway bar + add'l vehicle weight.

Using heavier sway bars contributes to the overall spring rate. However, unlike torsion bars where the spring forces are concentrated at the torsion bar mounts, sway bars can load the chassis sheet metal in places not designed for the added stress. Here's one related thread:
I thought my car was handling funny

As long as the vehicle doesn't jump over bumps (maintains contact with the road), I think a higher spring rate in conjunction with adjustable sway bars (on our cars at least) is a better combination to control unwanted weight transfer and body roll.

Just MHO,
Sherwood

[jluetjen]

I'm of the opinion that Sway bars are a tuning device and springs(T-Bars) hold up the car. How you put them together is the art and a lot of it depends on the driver -- so I doubt that there is a "best" setting. The "best setting" for a novice driver will be hopelessly soft and pushy for Michael Schumacher. We all hate to admit it, but we're not Michael Schumacher. Most people find Michael Schumacher's settings too hard (read "knife-edge" handling) and difficult to drive at the limit for any length of time - even for one lap. If you doubt this, ask any of Michael Schumacher's ex-team mates: Johnny Herbert and Eddie Irvine to name a couple. They all complianed about just these things when they were teamed with Schumie.

So what to do?

1) What is the skill level of the driver and the intended use of the car? If the driver is a novice or the car is intended to be used on the street a lot, then softer is better. This applies to both springs and T-Bars. Many 911's shipped without any sway bars at all in the back and a lot of people never noticed.

2) If the car is going to be used for auto-cross racing and is using sticky tires, then stiffer settings will be required. Once again it is often better to err on the side of softer since that allows more feedback to the driver and makes it easier to keep the car on the limit without going over the edge. Which T-Bars or Sway-bars? Once again it depends on a lot of things, including suspension geometry, weight, HP, tire stickyness and most likely a few more.

A brief digression regarding Swaybars. Admittedly Chevy's tech folks have been advocates of the stiff bar/soft spring approach and Mark Donahue echo'd this. On the other hand, no less a designer then Gordon Murrey often prefers to omit rear sway bars all together. Hmmmm I've come to the conclusion that sway bars work best as a means to transfer weight from the front of the car to the back during steady state cornering. In the case of the 911, they are used to transfer weight from the back to the front via the use of comparatively stiff front sway bars. (Note that 911's have always had front sway bars. Is my memory correct Warren???) Notice that the front bar is used to relieve the rear end and vice versa. I've already posted a string recently that has an example (look up my name and sway bars).

Springs on the other hand hold the chassis up. If your chassis is rolling or squatting so much that your wheel cambers are going too far positive or negative (the latter in the case of rear squat under hard acceleration), then you most likely need harder springs. If your springs are too stiff, then the car won't handle well over bumps or the suspension will have so little movement that it can't work as designed nor will it transmit any information to the driver about impending loss of traction.

Now springs can be used to affect weight transfer and sway bars used to keep the car off the bump stops. But this should most likely be considered a crutch to make up for some other difficiencies such as geometry. Finally, the shocks also have an impact on all of this stuff since their low speed dampening affects the speed with which the car travels through its suspension movement.

Finally 3) If the car is going to be tracked extensively on slicks or sticky tires, you might need to go stiffer still from the autocross settings. The specific combination will once again depend on the configuration of the car.

Another small detail about springing is that the suspension (especially the sway bars, but to a lesser degree shocks and springs) can be too stiff for the chassis. Accoring to Mark Donahue, the 911's stock chassis stiffness is about 2000 lb-ft/degree. This is pretty good and comparable to many Formula Fords. I haven't confirmed this number, but if it is the case, using very stiff sway bars on top of stiff springs could result in the chassis moving more then the suspension. This is a bad thing since it means that changes to the springs or sway bars may not have any affect since the chassis is bending. Chassis flex is also a bad thing because it is undampened and so it is possible to get the chassis moving in some harmonic. Ugh!

This will never happen - right??? It is not as uncommon as you might think. Have you ever heard of a driver complain that they've changed springs and bars and nothing seems to work. This is often the symptom of a soft chassis.

Anyhow - T-bars and sway-bars. Stiffer or not?

The t-bar recommendations for street, auto-cross and track that you find in many catalogs and on this BBS are most likely a pretty good place to start.

Regarding sway bars, my question would be is the car loose or does it push? If it is pushing, consider a stiffer rear bar or its setting if adjustable, or alternatively a softer front or setting if the front bar is adjustable. The opposite is true if the car is loose. If you can't tell if it is loose or pushing, then I'd suggest leaving the sway bars alone until you reach the point where you can say: "The front/back is always washing out when I go through X corner and preventing me from taking that corner any faster no matter what I do." At that point the change should hopefully resolve the push/loose issue and allow you to travel faster. But be aware that it may make a different corner worse which is a trade-off which you'll need to work out yourself.

I know - you asked for the time and I told you how to build the watch! But that's the fun of playing with a 911!

[jluetjen]

When I drive over 60, sometimes the car feels like it is wandering,

BTW - have you considered adding a front spoiler? If the problem only seems to happen from 60 MPH up, it may not be a chassis issue at all but rather an aerodynamic issue.

Also, you have confirmed that the suspension alignment is correct? If you're toe is a little out it can make a big difference in the way the car feels. Too much toe-out can cause the car to feel like it's wondering and darty. This might be great for auto-cross but annoying on the highway.

[stlrj]

When I drive over 60, sometimes the car feels like it is wandering,

I agree, this is more a function of alignment so I wouldn't be surprised if the same wandering was present after the addition of bars.

Joe

[dtfastbear]

Bill,

Any decent shop in the Bay Area can reinforce your sway bar mounts. I just had this done a couple months ago, as the tech inspector for time trials pointed out that one of the mounts was cracked!

I had S-Car-Go do it up in San Rafael, but there are plenty of shops closer to you. Ken's Sport Tech is a good shop. Denny Keller (over in the East Bay) is also excellent. Rennwerks is a new shop down south but has already built a good reputation. Email me is you need contact info for any of these shops...

Are you going to the time trial at Thunderhill in July?

Take care,

Dean
dtfastbear@yahoo.com

[APKhaos]

Like a lot of us [I guess], I'm looking for a happy medium that will help track performance in DE events, but still be streetable.

The 'definitive' torsion bar setup for perfect track balance seems to be 21f/31r, which is way too stiff for street. Likewise with sway bars, the perfect track setup will be too radical for street.

My humble 85 Carrera is a pleasure on the track, but the suspension is waaaay to soft all round - lots of corner pics showing lots of body roll attest to this. I'm wondering if there IS a happy medium???

[eurocarrera]

WOW. Lots of good advice! Thank you everyone. Since I am primarily using the car for street, and I only do about 10 autocrosses each year (I do plan to do Time Trials, but I need to get the kids through school first !$$!). I am now at kind of a stand still. It sounds like the best thing to do is what Bruce Anderson says "go with 21/28MM" torsion bars, and then move onto 22MM sway bars front and back. However, I was trying to still stay in the "improved" class for Golden Gate region of the PCA, which says that you can upgrade sway bars, BUT not torsion bars (strange). Anyway, it looks like I may bite the bullet, and go with the following then this coming October when I take apart the front end for a few days:

* 21/28 MM torsion bars
* Front Ball joints
* Turbo Tie Rod Kit
* Poly bushings front and rear
* a good alignment

Then maybe next year I will do the sway bars.

Basically, I gather from everyones opinion that even if I don't go with the sway bars right now, I should still see an improvement in cornering with just stiffening things up. And to answer the question about the spoiler: Yes, I have one up front, but I don't have the Carrera tail in the rear.

Thanks again everyone.

[hobieboy]

You may also want to consider replacing your shocks to match the stiffer torsion bars. I'm a firm believer that the suspension works as a system - changing one component without considering others might actually be detrimental to handling.