heliolps2

Hey fellow Porsche enthusiasts,

I could really use some advice on selecting the right springs for my 1987 951, which I primarily use for street driving. Currently, I have Koni Escort cup double adjustable coilovers installed both front and rear. However, they seem a bit too track-focused for my liking. I've already made some adjustments by swapping out the overly stiff 700-pound front springs for 220-pound ones at 8 inches in length, and the rear 900-pound springs for 425-pound ones, also at 8 inches.

However, the ride is still too low and too firm for my taste. Currently, the front sits at the maximum ride height of 25 inches to the lip with zero preload, and the rear is at 25.5 inches with 1.5 inches of preload. I've just received my new KW V3's, and my car has had the torsion bar deleted. It weighs around 3000 pounds ( Stock) and runs on 225/17 front and 255/17 rear tires. I'm aiming for a street ride height of 26 inches at the fender lip.

After some research, I've decided on 250-pound springs (235 rate) for the front and 425-pound springs (238 rate) for the rear. Now, I'm debating the spring lengths. For the front, I'm considering 10 inches, and for the rear, either 8 or 9 inches. My rough estimation is that they should compress about 3 inches, plus the ride height preload of about 1 inch. Can somebody help me figure out what spring length to use for front 8-9-10-12 inch springs and rear 7-8-9 inch springs?

However, I'm unsure about the exact rod travel lengths for the front and rear. Does anyone have this information or can offer guidance on what spring lengths would be appropriate for my setup?

Any help would be greatly appreciated!
Helio

blade7

Use the springs that KW supplied. And put the torsion bars back in.

walfreyydo

Unfortunately I dont think the KW v3 are compatible with a torsion bar delete. I would recommend reading up on what additional hardware is needed for this type of setup (ie: solid spherical bushings top and bottom of rear shock, reinforced lower shock mount bolt). I am only aware of a few coil-over kits which are suitable, those mainly being the ground control kit and the kit offered by Paragon Products (very very similar to the GC kit). There may be others.

The key clue is the upper and lower mounts on the rear shocks and the lower shock bolt (the one that mounts to the lca). If the bushings are rubber and/or you are lacking the reinforced lower shock bolt, then you are headed for a very bad situation where the lower bolt will likely snap, very likely when you are travelling at high speed... A cursory look at the KW v3s seem to show these are rubber mounts...(https://www.pelicanparts.com/More_In...xoCWhoQAvD_BwE)

Re: spring lengths. Its very possible the PO replaced the original springs with shorter ones for their race application or because of the extremely high (see: waaay too high) spring rates not being available in the longer size. For instance, my coilovers from Paragon (tb deleted) are 8 x 2.5 inch springs (Im running #400/#600 on a track/autox car for reference). Normally you should have plenty of adjustment to raise the car as needed, even beyond stock height, assuming the correct length springs are being used. Putting in the wrong length springs (too short) is likely not allowing you to raise the car as high as you would like. I would recommend researching what spring length your existing coilover kit was supposed to have originally and compare with the existing springs which are installed - consider longer springs at the desired rate you want, using your existing coilovers designed for TB delete.

And lastly, and like blade7 mentions, unless you plan to re-install a torsion bar, I would highly recommend returning the KW V3s, unless for some reason they have the upgraded features as noted above. If your kit looks like the one in the above posted link, those are not going suitable for a torsion bar delete and will be an accident waiting to happen. Lots of posts about folks doing the same only to have their lower bolt snap...

heliolps2

Thank you for the advise. This car has had the T Bar Delete running the Koni Escort coil overs, which the same as the KW's system with the rubber bushings for 10 year on the track and now the street. With no issues that i can tell. I'll be using the my old hardware just in-case.

blade7

Why did you ask for help, if you're not prepared to accept it?

walfreyydo

Run it at your own risk mate...


Examples:
https://rennlist.com/forums/924-931-...t-failure.html
https://rennlist.com/forums/968-foru...sion-bars.html
https://rennlist.com/forums/944-turb...downsides.html
https://rennlist.com/forums/944-turb...sterday-2.html

More info from Paragon (showing the reinforced shoulder of the upgraded lower bolt needed to take the entire weight of the car):
https://www.paragon-products.com/Rac.../re_mc7000.htm

heliolps2

Hey everyone, apologies for the confusion. I was seeking advice on the appropriate spring length for the setup I mentioned earlier. Just got my hands on the KWs today. It seems like the 8-inch rear with a 425-pound spring and the 10-inch front with a 250-pound spring should do the trick. I'll circle back once I've got it all set up. By the way, the factory setup has a 150-pound spring up front, but the KWs come with a hefty 343-pound spring, which seems a bit much for street use in my opinion.

I decide with Hypercoils , Now I need to decide if I should powder coat the springs in KW Yellow or keep them blue. Your thoughts?

blade7

Your 944 doesn't look much like a race car, yet you're attempting to mess with one of the best out of the box road set ups, for the last 15 years.

heliolps2

I've been immersed in the Porsche/911 scene for 35 years now. You may have come across my discussions on the 964 turbo forums and the 930 Forum on Pelican. I always try to lend a hand where I can. However, the 951/944 world is relatively new territory for me. I handle all my own repairs and recently got a 944 base for my 16-year-old son. We've been gradually restoring it over the past couple of years, creating some lasting memories together.

Regarding the springs, it seems like a 12-inch spring could work for the front KW setup with about 1 inch of threads still visible. The front and rear bodies provide approximately 5.5 inches of thread for adjustments, along with 7.5 inches and 4.5 inches of rod travel respectively. Since I'm opting for softer springs than KW, I anticipate a drop of around 2.25 inches, hopefully putting me in the optimal seating position. KW, like other manufacturers, incorporates a 2.5-inch "Helper spring," which compresses onto the 6.5-inch spring, totaling 10 inches for the front and 8 inches for the rear. I've decided to forgo the helper spring in my setup. I'm feeling positive about how everything will come together, especially with the spring rates I've chosen. It should offer a noticeable improvement over the M030 sport suspension, coupled with superior KW valving and todays high tech tire technology, it should do wonders for the 951 already great handling chassis. I'll be sure to share my findings with everyone. Also, given my proximity to Summit Point Raceway, I might even partake in the occasional DE event.

I'll attach a couple of links to some threads I've initiated for your reference.

Best regards,
Helio


https://rennlist.com/forums/944-turb...got-there.html

https://rennlist.com/forums/964-turb...-92-965-a.html

blade7

Little interest in the 965 TBH, other than just buying a new set of big red calipers and 965 discs. Unless you're fitting something like Ohlins or Nitrons, for a lot more money. I don't see the point in buying the KW package that works very well. And then chucking the matching springs out.

333pg333

Just use the springs they supply. Don't worry about the rates, it will work very well. I had their '2 way' race setup in my car with over 600lbs on the front. The rears were over 700lbs in tandem with the t/bar. I also ran on 18" wheels with low profile DOT tyres, and had swapped pretty much all the OEM rubber bushings/bearings out for monoballs or metal. The car was daily driven. It was fine on the street. A lot of people have bought their V3 product and used the springs supplied and all they did was compliment the ride and handling improvements. Try it first and then decide.