Torsion Bars vs Struts

[FloydPink]

I’ve been thinking I might want to go with a stiffer suspension setup in my stock ‘86 3.2. I’m wondering if there’s a difference in handling between larger torsion bars and heavier duty struts. What would upgrading either torsion bars or struts individually do to the ride?

Disclaimer: I’d upgrade both struts and torsion bars at the same time, but I’m just posing this as more of a suspension engineering question to understand the “seat of the pants” differences between struts and torsion bars.

[Tremelune]

Dampers/struts should be matched to the spring rate of the torsion bars/springs, to a degree. Dampers with modern valving can provide you with reduced roll without compromising ride quality over a standard set of dampers (Sports, HDs, etc).

What are you goals?

[FloydPink]

I don’t have a specific goal in mind, but I drive the car mainly on mountain roads so I don’t really need comfortable suspension for daily driving. I’m thinking of this as a speculative conversation so I can understand what’s possible and what are the pros/cons for my spirited weekend driving.

[David 23]

[QUOTE=Tremelune;11442604]Dampers/struts should be matched to the spring rate of the torsion bars/springs, to a degree. Dampers with modern valving can provide you with reduced roll without compromising ride quality over a standard set of dampers (Sports, HDs, etc).

Specifically what dampers do you suggest to replace Sports, HDs, with larger torsion bars? Curious about the upgrade.

[GH85Carrera]

There are millions of options for the suspension setup for you car. Figuring out what is best for your needs and wants is the hardest part. Well maybe paying for it all is the hard part.

Go visit the Elephant Racing web site. He has a lot of options from pure stock to full race.

I completely rebuilt and replaced all the rubber bushings. New turbo tie rods, ball joints and replaced the Boge stock shocks with Bilstien HD shocks, 27MM rear 21 front torsion bars. Rebuild the steering rack and a full corner balance and alignment. It made a huge improvement.

I will never forget walking into my garage and seeing my car on jack stands with no suspension and thinking "What have I done!" It was an gut punch. It all went back together and all is well.

I wanted to keep mine comfortable enough to take road trips, with my wife in the passenger seat. I think it is the perfect compromise of performance and comfort.

Expect to spend a few grand at a minimum, and all the way to big bucks for major upgrades. The sky is the limit with Porsche G body suspension upgrades.

[Tremelune]

Originally Posted by David 23

Specifically what dampers do you suggest to replace Sports, HDs, with larger torsion bars? Curious about the upgrade.

I would recommend a set of Bilsteins that were re-valved to a digressive curve. If you already have Bilsteins, the cost is about the same (though you have to ship them around and wait with your car in the air).

This is where calling up Elephant Racing to determine what valving would be appropriate for your spring rate, weight, and goals, and have them handle it. "Digressive" is the magic term.

You can also get super spendy with those KWs and the like...

[sus911]

My '84 is running stock TB's, which I believe are slightly smaller diameter than your '86.
Mods I have done include adjustable Koni dampers, turbo tie rod ends with bump steer kit & slightly heavier sway bars.
Other than that, I've completely refreshed the rear with new bushings but the front is original. Lowered, alignment & corner balanced.
The car handles superbly, is quite comfortable, doesn't rub front or rear (7/8") and does very well on the track also.
I had big plans to upgrade everything- hollow TB's etc. etc. I'm glad I left it alone and refreshed everything as its up to whatever I ask of it.
Just my 2c.
***EDIT***
Forgot to mention I also added a front strut brace.

[Bill Verburg]

Originally Posted by FloydPink

I’ve been thinking I might want to go with a stiffer suspension setup in my stock ‘86 3.2. I’m wondering if there’s a difference in handling between larger torsion bars and heavier duty struts. What would upgrading either torsion bars or struts individually do to the ride?

Disclaimer: I’d upgrade both struts and torsion bars at the same time, but I’m just posing this as more of a suspension engineering question to understand the “seat of the pants” differences between struts and torsion bars.

The reason the factory used coil helpers and later full coil suspension was that they had reached the limit wrt to T-bar size.

For a street car you are not at all likely to want to put that large a T-bar in your car,

an '86 911 has 18.8/26m5 mm t-bars and 22/21mm underbody sways

20/26 21/26 21/27 22/27 are the first few options to stiffen the suspension w/o making it too stiff for street use w/o altering handling too much, though each does color the handling a bit, I find 22/27 to be too stiff but to each his own

shocks add their own tint to the net result, friendliest is a digressive valve stack matched to the springs and weight and intended use, to get the exact specs it's best to work w/ a knowledgeable Pro

[FloydPink]

Thanks for the input all, I’ll have to give it some thought. I *think* I’d like a bit more of an aggressive setup, but I’ll have to sit on it for a while before I commit to spending a few grand (plus a bit for my local pro’s advice and labor).

[GH85Carrera]

Originally Posted by FloydPink

Thanks for the input all, I’ll have to give it some thought. I *think* I’d like a bit more of an aggressive setup, but I’ll have to sit on it for a while before I commit to spending a few grand (plus a bit for my local pro’s advice and labor).

Good choice is to learn more. Do a search of the hundreds of suspension threads and read them all. Learn from other people's mistakes and successes.

For me, and even my wife the 21/27 torsion bars are perfect. Still comfortable enough for long trips or short trips. But that is my seat of the pants feel.

One thing for certain, ride in a 911 with the hard plastic bushings. Most of them squeak or will squeak and have a very harsh feel. I was able to experience a friends 911 with the hard bushings and that made up my mind on the spot, I went with Elephant racing rubber bushings.

Just my opinions. You need to make the choices that fit your goals.

[Bill Verburg]

Definitely stay w/ rubber bushes for street use, sport rubber is better for sporting use

this data set is also informational

either wheel rate columns or ride frequency columns indicate the effects on handling

I used a '77 Carrera as a base(o) larger than 0 imparts more understeer, smaller than 0 imparts less understeer. Additionally the ride frequencies are a measure of comfort, passenger cars are generally <1, street sports cars <1.4, dual purpose race/street 1.5 -2.0, dedicated race cars w/ aero 2.5-3.5, when you get above 1.5 the car is uncomfortable on anything not glass smooth

[GH85Carrera]

My 85 is a fat pig with carpets and all options. 2,700 pounds. A lighter car would be better with smaller bars.

[Bill Verburg]

Originally Posted by GH85Carrera

My 85 is a fat pig with carpets and all options. 2,700 pounds. A lighter car would be better with smaller bars.

That's true, all the data in the above table is based on my 2646# C3 w/ split weight 1046/1600