[Darth Vadar]

    [ATTACHMENT NOT FOUND]Okay, getting ready to pop in a Bilstein Escort Cup Coilover Suspension for Auto-X and occassional DE events... some smooth road driving but < 500 miles per year on the highways with J Q Public... They already nailed me once and almost got me a second time in one month! Lucky I was driving old Red, the GMC SUV that takes a lickin' and keeps on truckin'!!! Both times female drivers... one on a cell phone and the other with no headlights and was "Looking for the switch"... Go figure!



Well, back to subject at hand... Photo attached of the Bilstein Coilover setup for my 968 Coupe... And the question of the moment... what is the recommended Spring Rate for both fronts and rears... the package came with 500 + 40 (helpers) in/lb fronts, and 400 in/lb rears, as recommended by a "Shall Remain Nameless To Protect The (maybe) Innocent" noted race shop, but that doesn't mean I have to use 'em! Springs are cheap to try different combos, so give it your best shot! I bet someone has the "Hot Ticket" out there!



Oh, 2.25" Perches front and back, so unless I decide to switch those out, I need to stay with that parameter... And, I don't intend to pull the Torsion Bars, so the rear Coilovers have to "Play Nice" with the bars...

But, there s/b ample Spring choices for the rears... even with the bars still in place...

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[flash]

i don't know the bilsteins to tell whether or not 500 is too much for them, but it would be way too much for the konis - i have 400 up there right now, and the struts can't keep up on the street - ok on the highway, and great throwing it hard into a corner - a total mess in my local grocery store parking lot - same thing for the 600s in the rear on the carreras (no torsions)



so, if it is a track ONLY car, you're probably not far off with both sets, assuming the bilsteins can handle that stiff of a spring

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[Eric_K]

The Bilsteins will work well with those spring rates. The escort cups are the same as the old turbo cups. They were designed to be race shocks and are valved like it. I ran them at 450f/600r w/no torsion bars - which is in the ball park of what you have. You will probably need to reindex the torsion bars for them to work with the coilovers. Keeping the TB's is actually more work than getting rid of them.

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[Darth Vadar]

Hey, thanks very much, Eric!



Yes, keeping the torsion bars is a pain in some ways, but, I read somewhere that Porsche even went back to using them in their Cup Cars, after trying to run with just Coilovers...



I could always soften the front by putting the 400's up there, and buying some 250's for the rear...



Then index the bars, etc.



I have some time and am close to the Tire Rack South Bend, so will ask them if I can do some testing on their skid pad ... watching a customer remove rubber from a set of tires they just sold him should make them smile! Our PCA Region does a lot of Auto-x's at the Tire Rack, so hopefully they will let me do a few laps!!!

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[Jason Judd]

I removed my torsion bars and went with the Bilstein Cup suspension all around...



After trying a few combinations, the one I like best is 650# up front and 750# in the rear.



Jason

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[bob blackwell]

Wow! sounds like a great location you have there Darth, why not host a 968 Get Together sometime and we can wear out some tires together? "Have tires, will travel" Bob Blackwell.

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[Darth Vadar]

Not a bad idea! The Tire Rack is normally very supportive of PCA activities, so they might go for a 968 "Get Together"...



They are literally right on the I-80/90 Indiana Toll Road, halfway between Chicago and the Ohio border... easy to find and lots of motels and restaurants close by...



Tire Rack has a nice skid pad, and also a short track for Auto-X events; they are usually booked most weekends during the summer, but I can see what they have open... I won't be back there until Spring, so everyone sit tight and we will see what develops!

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[orphanowner]

I run the exact same Bilstein struts with 8" 550 lbs springs on my "street" 968. Not exactly a comfortable ride but with 900 miles a year, who cares.



The short 40 lb springs on your setup are called "tender" springs and their sole purpose is to keep the upper spring perches where they belong should the car come unweighed on the road (read full rebound) or when you jack it off the ground. The Turbo Cup springs had the same setup in a single progressive wound 3" or something close to stock diameter. I ran these same struts with a revalve at 1200 lb, see pic.



The rear is a little more complicated. The worst part about going coil over with T bars is indexing the T bars so that the coil over’s and the T bars work together. Otherwise, you can have each spring doing something different. My preference is 30 mm hollow bars rear with 450-550 coil over’s front... but what do I know!

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[Darth Vadar]

Well, sounds like the 500 (+40's) front and the 400's rear will get me "In the Ballpark", and then I will just have to try different rear Spring setups and torsion bar positions to see what the car likes best!



Question: If I run my 8" Eibach 500's + 40 in/lb "Tenders" with my Racers Edge Spring Perches and Camber Plates, how much will that setup lower the front end? One inch? 1.5 inches?



Almost forgot... I am planning on implementing the M030 Sway bars, front and rear... will those work well with the Bilstein Coilovers??? Or....?

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[peartree]

Hi Darth



I'm also interested in the Escort Cup struts. I'm interested to know what your valve settings are. I've also sent you a PM.

Thanks

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[Darth Vadar]

Got it!



Back to you...

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[RS Barn]

Ok I have to chime in here.

I'm a fan of Bilstein Turbo Cup stuff. I have very different spring rate combos. They have been used with lots of PCA club race victories and lap records. Karl from Racers Edge agrees.

I like 600 front 250 rear with t bars in a heavy car 2800 up

I use 550 front 500 rear w/o t bars on light car >2700

I've used these combos up 50 lbs each end as well based on track.

My first couple of events in my 968RS we danced like a Donkey with heavy back springs. I'm now at 568 front and 333 rear w- t bars using Swift springs (very progressive)

I know there is a large community that runs more rear spring than front but I'm not one of them. I've driven too many well set up front engine Cup style cars that haul butt with these combos.

Pete

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[Darth Vadar]

Excellent info!!! I am going to start with 540 front and 350 plus stock T bars rear, and see what the old girl feels like with those...Look Out, Tire Rack...coming your way!!! Warm up the ol' skid pad...



I like your analogy "Danced Like A Donkey"! Somehow, I can sort of imagine that! I assume you reindexed the T bars to get your ride height where you wanted it?



What length Springs? 8 inchers?

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[RS Barn]

I would highly recommend 8" 250-275 rear with your fronts. Yes, rear is reindexed. I can give you some specifics that would help.

BTW you need to cut down bump stops on rear.

Pete

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[333pg333]

Yes it amazes me how many differing spring rates people are running and their various front to rear bias'. I'm certainly no expert, in fact almost diametrically opposed, so I got mine custom made by KW in Germany. When I first found out the proposed spring rates 110N f and 50N r combined with 25.5mm t-bar I got various calculations back into lb/in. Karl at R Edge figured them to be 616 lb/in f and 708 lb/in r effective coilover rate. Many people said this was wrong, wouldn't work, ride way too hard, 'Dance like a Donkey' lol. Anyway I must admit to being nervous when they first went in, but wow, not only were they much better than my recently rebuilt and modified Mo30's with 968cs rear helpers on the track (and I mean MUCH better!), they were more compliant on the street. So much so that I went ahead and installed a bunch of R Edge solids as well. People can't believe how much better they are than they thought, for the street, and on the track I've blasted 5 sec's off lap time in only 3 meets. 1.55 to 1.50. I'm not bragging here, but they are just that good. Anyway my point being, is that I think that the major difference in a lot of the different brands must be all in the valving of the shocks and therefore there's not an absolute BEST spring rate for our cars 944/51/68's.

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[flash]

i thnk you just hit the nail on the head, because in my car the 400/600 setup is just too stiff for street - running around in a parking lot is no fun at all - nice in a hard turn though

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[DCTepper]

What are the advantages of keeping the torsions bars vs removing them? (I understand the difference in necessary spring rates with or without the t bar)

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[Renalicious]

Yeah, there are so many different spring rates that it's tough to figure out what you need =/ I too would like to know how removing the torsion bar affects things. Like, if I bought the Koni yellow suspension (the $900 set), would I need to up the spring rate to well over 250lbs if I removed the torsion bar? I don't want a soggy stock feeling, but I also don't want a bone shattering ride. The Bilstein Escort Cup start at 300lbs, now would that be too soft without a torsion bar? How about the front? Heh, I'm a real noob when it comes to suspension <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />



Since my car isn't a daily driver anymore, I wouldn't mind having a more trackable (non race) setup too.

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[Darth Vadar]

[quote name='RoadRacer' post='30157' date='Jan 24 2007, 02:17 PM']What are the advantages of keeping the torsions bars vs removing them? (I understand the difference in necessary spring rates with or without the t bar)[/quote]



Well, from what I have gathered, Porsche never intended the 968's to run w/o the T bars, and the stock rear shock mounting points are simply not up to the task of supporting the entire suspension load with Coilovers only. Of course, for the full out caged racers, there are complete rear suspension replacement setups, BUT, that is not what most of us are going for... and, in fact, the Porsche factory racers kept the T Bars and just added on the appropriate Coilovers, so that would seem the best way to go for a street / track combo car.



The challenge is to get the right combo of coil springs, shocks and ride height with the T Bars still in place... pull the T Bars, and you only have to deal with 2 variables, vs 3...



That said, there are plenty of folks (like Pete at RSBarn) who have gone thru the process of elimination and sorted the variables sufficiently, that the rest of us can get pretty close to "Right On" out of the box... depending of course on where we are starting from! But that is what keeps it interesting...

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[333pg333]

If I was deleting the t-bars I would be very careful what suspension I got. Having said that the Porsche cup cars ran with t-bars and unless you planned on changing or playing with a bunch of springs then I don't really see the need to delete? My impression of the Bilsteins escort cups is that they are an uncompliant valved shock. I would seriously research the brand and their characteristics, looking for something that offered you an up to date modern designed system. I will harp on about the KW's as they are exactly this, and their use of the bypass valving allows you to ride over irregularities without unsettling the car. Not like the older systems that were either hard or soft so to speak. You can have your cake and eat it, just make sure of the recipe!

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