Sean, If you want to increase the handling of your car, changing your dampers is the best way to go about it
simply lowering your car and uping the front spring rate will do little but change the balance of your car "for the worse"

SPRINGS are only a very small piece of the equation..SHOCKS/STRUTS are where the science is. When it comes to dampers adjustability is also a very usefull tool.

If you are interested in learning a bit about dampers for your or any car call me.
www.morissdampers.com
586.469.9635

 

i think removing the torsion bars and just using coilovers is the ultimate thing to do, however one reason *not* to remove them (like firestarters machine) is that it forces a change in class, at least for pca time trialing/auto-x anyway. maybe for de, and random track use, but to compete againsyt other pca members, it would probably make the difference between C, CP, CPi class... just a thought. i am trying to fugure out the same thing. (get another one i guess!)

 

If you are interested in suspension upgrades you should read the tech sessions at Paragon Products, they are very good.
Decide what your car is going to be used for and what your budget is. You can buy suspension that is worth more than your car.
You have the option of stiffer springs, and ones that lower the car.
I had a 1983 944 NA like yourself, which was my first Porsche. I bought the 225 lb. lowering springs (Weltmeister) and a set of
bargain basement new strut inserts from some English suspension company, I forget the name. They were adjustable front and rear, and I put the shocks on the rear matching them to turbo 944 torsion bars. I had the rear torsion bars indexed (this was expensive to do, labour intensive).
If you go the M030 helper spring route (about 100 lb effective rate) for the rear, you have to lower the rear by the torsion bars being indexed. One Rennlister had a set for sale a few weeks back, and he avoided this by cutting 2 inches off the upper shock body to allow the perch to sit higher. I doubt that helped because you just lose shock travel and risk bottoming out that poor Koni adjustable!
This set up for my 83 was a very nice balanced set up
and was acceptable for the road. The lowering of the car helps a lot. The car handled awesome and I was VERY happy with the improvement in cornering prowess.

The name of the game is a balanced set up.
You have to decide what your budget is and go from there. You could easily buy a set of sway bars to start. For instance I bought a beefy 27 mm sway bar off eBay for a great price. Buy the M030 19 mm adjustable rear bar from Paragon. These two items alone would tighten up your stock suspension for only about $200.00 and you could install them yourself.
Yes the rear end tends to squat but that's how the suspension works. You probably have 23.5 mm torsion bars, and the turbo S cars only had 25.5 mm bars, so it's not a huge difference.
My car came stock with the 86 sport suspension and was raced like that. I know that some people think "stiff is better" but trust me, it isn't. A balanced approach starting with sway bars (to reduce body roll/lean) will be a good start.
The front coil over kits are better than just a spring upgrade, for the reasons that the other guys posted. But you still have to deal with the torsion bars and put thicker bars on to match the front spring rate.
Personally, the "total approach" that Racers Edge products allow, including bushings, is the way to go.
Consider replacing bushings at the same time you do the torsion bars... it will save you money. The Weltmeister black plastic bushings are cheap (street use - PARAGON) and the Delrin and spherical ones at Racers Edge are best for racing.
Concentrate on the rear suspension, that's where a lot of your handling comes from.
Then match the front to the rear. http://www.davidsims.ukgateway.net/944t/suspension.htm
HERE IS THE BEST SUSPENSION LINK I HAVE EVER SEEN ON THE SUBJECT.
I highly recommend Karl at Racers Edge and Jason at Paragon. They are both knowledgeable and the service is second to none!!!!!!!

 

AMEN!!! Stiffer won't necessarily mean more cornering-power or increased speeds. That has to do more with the laws of physics which dictates that weight-transfer is the same for the same cornering-speed, regardless of the amount of body-roll/lean you have.

Read up on Herb Adams, Fred Puhn, Carroll Smith and other suspension experts out there. They advocate setting up your suspension just stiff enough to not bottom-out on the biggest bump that you'll encounter and no more.

What does improve with stiffness is detrimental camber-changes due to the MacPherson strut front suspension in our cars. When the suspension compresses enough under lean to put the ball-joint above the inner-pivot of the A-arm, all movement after that causes positive camber. Combined with the lean itself and you've got a tire that's rubbing its outside edges. Not good for cornering-grip.

So by stiffening the front-end, you keep the suspension from compressing and dialing in positive camber. But you can go too far in stiffness and end up upsetting the body so much when you hit bumps that you end up launching the tire into the air coming off bumps. Not good for grip, having a tire in the air...

 

what would be a good compliment, for the rear suspension, to front coil overs with 225 lb. springs?

 

Check out the link I gave you, it breaks down a few suspension choices, and various 944 tech data for suspension.
There is also links to other info, including an Excellence article that is quite good.
Depending on your needs and tolerance level for a rough ride, you might explore the aftermarket for options. ($$$$$$$$)
Good luck, read lots, make a game plan and take the balanced approach to a well tuned suspension!!!!!

 

25.5mm factory bars(OE - 951S, 968), or 27mm aftermarket bars (then could move to 250# easily). As was discussed before, you may find the stcok rear T-bars and the 200-250# spring range to be okay for you... especially if you have a good rear stabilizer. It's a matter of how much work you can afford to do.

Skip

 

So what is the stock spring rate on an '87 951? I see a lot of discussion of the merits of 200 or 250 lb, but where does that relate to the stock rate?

Also, Skip, do you sell springs for your coilover kits that are stiffer but do NOT lower the front of the car?

thanks all

Thaddeus

 

Thad, If I'm not mistaken, stock springs for 944, S, and turbo are 1 yellow dot=165lb.,
2 dots=175lb., 3 dots=185lb., I'm unclear if the MO30 option spring follow the same formula.

I did the insert,
("hacksaw" from the "Book of Ribs") upgrade, and am trying out the 200#'s cause they are close to stock, and won't require many other changes.

Koni rear upgrade and corner balance to follow...!

 

[quote]Originally posted by Thaddeus:
<strong>So what is the stock spring rate on an '87 951? I see a lot of discussion of the merits of 200 or 250 lb, but where does that relate to the stock rate?</strong><hr></blockquote>

~160# usually

[quote]<strong>Also, Skip, do you sell springs for your coilover kits that are stiffer but do NOT lower the front of the car?</strong><hr></blockquote>

Yes, but you'd have a wide enough range of adjustment with the standard lengths (8" or 10") to lower AND raise with the same spring... for those who race AND rally with the same car

 

[quote]Originally posted by 951and944S:
<strong>Thad, If I'm not mistaken, stock springs for 944, S, and turbo are 1 yellow dot=165lb.,
2 dots=175lb., 3 dots=185lb.</strong><hr></blockquote>The dots only indicate what tolerance group the springs are in so you can fit springs from the same group. The difference between tolerance groups is small.

Stock springs have a rating of only about 23 N/mm as I recall, or around 130 lb/in. The Turbo S with M030 suspension has 28 N/mm springs, or about 160 lb/in. But the spring rate is non-linear so it may actually be higher depending on compression. In any event, all stock 944s have relatively weak springs... one reason why they have excessive body roll in corners.