Help needed - suspension starting point - backdated widebody '77 w/ 3.2

[PcarPhil]

Hey there folks,

I'm continuing with my backdated widebody longhood project and it's maiden voyage will be soon! I'm now on chassis #3, the final chassis that I will finish the project with. For various reasons chassis #1 and #2 didn't work out for me. I now realize it's much much easier to start with an accident free chassis!

So what I've got is a lightweight non sunroof, non A/C, 1977 911 S chassis with widebody bodywork and a 3.2 engine / 915 trans with factory LSD. The hood, front fenders, bumpers, and engine lid are all fiberglass. The rear flares are Dansk metal flares. Wheels are 951 8x16 fronts with 225/45 Hankook Z212 tires and the rears are 9x16 Fuchs with 245/45 Hankook Z212 tires. I'm running 1.5" rear wheel adapters and no adapter/spacers on the front wheels. The front control arms and rear trailings arms are '85 units. The car will be primarily a spirited weekend country road driver on fairly smooth twisty roads.

I've been some research and one setup that I keep coming back to is jpnovak's ST:
The ST on the road: driving impressions - Oh yeah! It runs!! It's fast!!

*Note his comments on the front torsion bar rates*

I'm wondering about the suspension setup for my '77. The whole car is of course lighter than stock - especially the front. I've got Rennline monoballs in the rear trailing arms and have Elephant polybronze bushings on the way to replace all the other bushings. Also I'd like to try and stick with the stock torsion bar size up front (18.8 or 19mm).

What should I use as a starting point for rear torsion bars and front and rear sway bars?

I've got the following parts available that I could install if recommended:

-'85 front and rear factory sway bars.
-H&H fully adjustable front and rear swaybars (don't know what size).
-'77 front sway bar.
-'85 front and rear factory torsion bars (19 and 24.1?).
-22 F and 29 R torsion bars.
-'77 rear factory torsion bars.
-Bilstein HD shocks and struts.
-Koni red shocks and struts.
-911 8x16 Fuchs that could replace the 951 front wheels (wider front track with 911 offsets).

So along with the ploybronze and monoball bushings can I (or should I) use any of the above parts as a starting point for the suspension setup?

I'm not against buying new parts, especially torsion bars, but if I can reuse some of the stuff I already have that would be great.

Thanks for the help!

[Chuck Moreland]

Ride quality and performance is a trade off, and one man's pleasure is another's poison.

That said, for a weekend fun car on fairly smooth roads I assume you want a taught performance ride and not a cushy cruiser.

The 22/29 combination you have in hand should do nicely and will save you some money. On a wide body car this is a very streetable setup.

However I would go with bilstein sport shocks rather than the HD.

[Bobboloo]

I'll kind of re-iterate what Chuck said in that the HDs don't match the 22/29 bars but if your Koni Reds are adjustable then you might be able to use them. I have Koni Reds on the front of my car and was able to adjust them to all the way firm to use with my 22 front bars.

I'm no Guru but here's what I'd do in your shoes.

First off install the all the new bearings.

Next, since you have the luxury of the assortment then why not try out some different setups. Maybe start with the 22/29 setup and the Koni Reds adjusted full firm. See if the ride is acceptable for you in terms of harshness. You might be surprised. The suppleness of the new bearings go a long way to improving the ride. Drive the car over some different kinds of road surfaces to get an idea. You won't be able to test the car handling until you get it aligned and corner balanced but for now you can test ride harshness.

Wait until you make a decision on the T-bars and shocks before you mess with anti-sway bars. They'll be the last step for you to "fine tune" the suspension. Bigger T-bars sway less than smaller ones so your decision on T-bars will affect the sway bar set-up.

If the car is too firm for your liking then you can try a 19/26 or 19/27 T-bar combo with the HDs.

If the roads are indeed smooth like you say I have a feeling you may be going with the 22/29 setup. If you chose 22/29 and the Konis don't offer enough dampening for the T-bars then get your HD's custom valved for your 22/29 set-up.

After you've decided on your cars T-bar/shock set-up get the car aligned and corner balanced and then add the sway bars. You'll be able to fine tune the cars overstear vs. understear character.

[PcarPhil]

Originally Posted by Bobboloo

Wait until you make a decision on the T-bars and shocks before you mess with anti-sway bars. They'll be the last step for you to "fine tune" the suspension. You'll find that the bigger the T-bars the less assist is needed from the sways to keep the car flat in turns.

If the car is too firm for your liking then you can try a 19/26 or 19/27 T-bar combo with the HDs.

If the roads are indeed smooth like you say I have a feeling you'll be going with the 22/29 setup. If you chose 22/29 and the Konis don't offer enough dampening for the T-bars then get your HD's custom valved for your 22/29 set-up.

After you've decided on your cars T-bar/shock set-up get the car corner balanced and then add the sway bars. You'll be able to fine tune the cars overstear vs. understear character.

Bobby,

Are you suggesting initially running the car without any sway bars at all?

Thanks for the reply.

[PcarPhil]

Thanks Chuck.

I'm concerned that with the 22's up front that I'll end up with too much understeer, especially coming out of corners on the throttle.

Yes I'm looking for a performance oriented ride, not a cushy cruiser. On my fiberglass bumpered SC I always felt the rear spring rate was too soft (stock TB's).

Do you think a 19/29 TB combo would promote too much oversteer considering the new weight distribution of my backdated '77?

http://www.instant-g.com/Data/911CoilConv.html

Originally Posted by Chuck Moreland

Ride quality and performance is a trade off, and one man's pleasure is another's poison.

That said, for a weekend fun car on fairly smooth roads I assume you want a taught performance ride and not a cushy cruiser.

The 22/29 combination you have in hand should do nicely and will save you some money. On a wide body car this is a very streetable setup.

However I would go with bilstein sport shocks rather than the HD.

[Bobboloo]

Originally Posted by Kaefer

Bobby,

Are you suggesting initially running the car without any sway bars at all?

Thanks for the reply.

Yes, just to get a feel for the NVH (noise, vibration, harshness) of the ride over different road surfaces in a straight line. Not to test corner handling. Corner handling can't be tested until the car is aligned and balanced anyway.

Keep in mind that the harshness is affected a bit by sway bars so if you think it might be a little to harsh for you with 22/29 then it'll get a little worse when the sways are added.

[aftermath]

If you have a bunch of FG, do you know your corner weights?

[Chuck Moreland]

Originally Posted by Kaefer

Thanks Chuck.

I'm concerned that with the 22's up front that I'll end up with too much understeer, especially coming out of corners on the throttle.

Yes I'm looking for a performance oriented ride, not a cushy cruiser. On my fiberglass bumpered SC I always felt the rear spring rate was too soft (stock TB's).

Do you think a 19/29 TB combo would promote too much oversteer considering the new weight distribution of my backdated '77?

http://www.instant-g.com/Data/911CoilConv.html

There are many things that affect under/oversteer. However 22/29 is not an understeer inducing combo, especially on a widebody. The widebody front lever arm is longer and makes the 22mm behave softer than on a narrow car. Result, more stick in front.

Plus, your 225/245 tire combo is disinclined to understeer.