Front Coilovers with Rear T-bars

[hoss4659]

I want to tame the T-bars harshness in the front of the car ('88 911). One solution is to go to coilovers in front. Any problems for a street car in keeping the rear T-bars? This assumes the spring rates are compatible.

Chuck at ER tells me that the sway bars on the G50 cars are probably the stiffest ever put on a car by the factory. Since these are part of the total suspension, any recommendations for less stiff bars?

[T77911S]

if coil overs have the same spring rate as Tbars, how will it be softer/less harsh?

I would think a smaller Tbar and/or softer shocks would do the trick, then put on a bigger sway bar.

[hoss4659]

Came across something on a website called "The Engineers Edge" that cited something called the "coil end effect". To paraphrase, The center 60% of a coil spring works at the designed spring rate but the bottom 20% will function at a significantly lower rate and the top 20% will function at a higher rate. Since the ride height adjustment will compress the bottom coils, the lower rate effect
will be "eaten up" to some extent. The Eibach "tender-main" 2 coil stack looks like a way to get a progressive rate to substitute for the initial harshness experienced with T-bars.

[T77911S]

ah, your getting progressive springs.
I just think of race type springs when it comes to the Porsche.

[masraum]

It's my understanding that the shock towers of 911s with torsion bars, structurally aren't really designed to support the weight of the car the way they have to when going to a coilover setup. I believe there is a way to gusset them in a few places to add the stiffness in. Then I would think you would also want at least a strut tower brace.

Wouldn't it be much cheaper and easier to just "upgrade" to smaller torsion bars and/OR a smaller anti-roll bar, and if not already, stock oil charged shocks.

Hell, I think you could get someone that has upgraded to practically give you their old stuff, or if you can find someone with an earlier car, you could probably swap, they get your thicker units and you get their thinner units.

[dad911]

Originally Posted by hoss4659

I want to tame the T-bars harshness in the front of the car ('88 911). One solution is to go to coilovers in front. Any problems for a street car in keeping the rear T-bars? This assumes the spring rates are compatible.

Chuck at ER tells me that the sway bars on the G50 cars are probably the stiffest ever put on a car by the factory. Since these are part of the total suspension, any recommendations for less stiff bars?

Are you sure that's the problem?

If it's lowered, or worn components, you may be hitting the bump stops.. etc.

[masraum]

Originally Posted by dad911

Are you sure that's the problem?

If it's lowered, or worn components, you may be hitting the bump stops.. etc.

Good point. My old '88 when I had it certainly wasn't harsh at all.

[Tremelune]

It's probably not the springs, unless they're larger than stock. How big are they? Sways? What about when they're disconnected? Ride height? Are any other components worn or not stock? Tire size?

Many variables. Try and isolate before throwing money.

[hoss4659]

Thanks for the comments guys. All of the suspensions bushings have been replaced with stock items. Same torsion bars front and rear that it came with from the factory. Have installed ER's adjustable spring plates, other wise all stock. Running 205s and 225s on 7 and 8 by 16 wheels. Ride height at 25 and 25.5. tire pressures at 26 and 32. Boge struts with adjustable Konis F & R set at one notch above full soft. Just fine on smooth surfaces but unpleasant on rougher roads of which we have an abundance This is a touring car not a track runner. Most of the harshness seems to come front of the car.
What diameter T-bars would you suggest I consider F & R? If I go to coilovers I would like to use the Eibach "tender-main" two stack to get the initial progressive rate.

[OffCamber00]

This is not making sense to me. Unless you are after luxo-barge ride quality, your car should feel pretty darn good. The stock suspension should not be harsh whatsoever. Are you sure there isn't a larger problem?

[Cory M]

What you are proposing is unusual and I'm not sure coils are going to fix your problem. Sounds like you have a lot of new parts in the suspension already. Instead of just throwing more expensive parts at it you may be better off finding a respected Porsche shop and doing a ride along. Maybe something is broken or installed incorrectly. A good shop should have some cars around they can give you a ride in so you can get a better understanding of what it should ride like..

[No Sweat]

What shocks are you using ?? My 87 changed dramatically when I had my org shocks that had almost frozen from age to Bilstein HD shocks. My mechanic recommended them for my Targa instead of Bilsteins Sport for a better ride.

Or you could have some custom made Bilsteinn's made to your specs.

[Tremelune]

I always thought shocks got softer with wear?

[Driven97]

Underdamped and overdamped are both uncomfortable.