What else compares to KWs???

[Peter Empson]

ORIGINAL: AndrewS

Hi,

With respect to road suspernsion, there are limited options and I don't know of another solution that provides such a good road/track set-up without being much of a compromise in either application.

With respect to KW, it feels very similar in compliance to the original suspension. However, the improvement (partly becuase its new) are significant and very noticeable.

On the track I would run 600+ lb spring rates with very firm damping using race developed suspension (in my case it was ProTrak on my Porsche Cup 2000 944 Turbo). You simply would not want this on the road. Even 200lb springs would be extremely hard. The KW spring rates are probably lower than that, but possibly not more than M030.

Regards,
Andrew

I find it fascinating how different our tolerance of things like this varies from person to person. Even if I was using my car only on the road I would still have a very stiff setup compared to the factory options, I just love the feel and feedback that it gives me. I suppose I want a sportscar/racer and less grand tourer (I did have a ride in a proper 968 race car yesterday (still grinning[]) and have realised how close my car is in terms of feel to that).

I'm surprised at how soft you think the KW springs are Andrew, I wish they'd give some figures but I've yet to see them anywhere [&:] Out of curiosity, as a vendor do you think you can see if you can get the details out of them or do they consider it a trade secret?

 

[AndrewS]

Hi Peter,

You must have a tougher spine than me. [] I remember driving my '98 924S Cup car with 400lb front springs and 31mm hollow torsion bars - it was very, very painful (with firm Koni suspension).

I have never seen the actual specifications and properties of KW published. When ordering a bespoke system, they ask for very specific data on the car and then come up with a system to suit. The off the shelf Variant 3 is quite soft compared to your car. My car does run a bit lower with the KW suspension fitted.

I have some favouriate bends where tail out action was always easily provoked with my old suspension - but trying to unstick the back end with KW (even when it's damp) is much more difficult. Only way to experience what I am talking about is to ride in or drive a car with it fitted - it really is that impressive.

When's your next track day?

Regards,
Andrew

 

[Peter Empson]

ORIGINAL: AndrewS

When's your next track day?

Nothing booked just yet [] I'd love to do the the Silverstone evening in May, but it's very unlikely my car will be finished by then, so June and onwards is probably a bit more likely.

It would be very interesting to compare the suspension back to back, even just from the passenger seat.

best regards,
Peter

 

[Big Dave]

Hi Pete.
The rates for the KW springs are as follows.Fitted on V3 ...
These are the STANDARD fittment to a 944/968 car...

Fronts.helper spring,,,20N/mm or 120lbs.
Main spring,,,60N/mm OR 340lbs.

Rears. Helper 10N/mm OR 57lbs,,
Main,,50N/mm OR 285lbs...

I have fitted stiffer springs to my car,
These ARE a stiff as you CAN go , After talking to KW technical about....

Front,,,,Helpers , the same as above,,,
Main,,, 80N/mm OR 447lbs.

Rears.,,,,,,Helpers as above,,
Main,,, 70N/mm OR 391lbs..

I find this a FAB set up.. Just right for my use...Although i wouldnt want to use it as a daily driver....I like my comfort....[][]

PS. The car you went in yesterday had 600lbs springs up front + 350 rears..... Just for your info....

 

[Peter Empson]

Thanks Dave, that's a great help.

Don't know if you saw some of the pics I took yesterday? The tango 968 is on the last page []

Silverstone pics

 

[Big Dave]

Hi Pete.
Yes i had seen your pics.....[][][][]

 

[333pg333]

How do you guys formulate the effective rear spring rate with Torsion bars? I have posted before on various sites an email that Karl from Racers Edge sent me to figure out my rates. It's a bit complex for me, but I'm interested in what method you guys have been using. As most of you know I have the KW 2-way race which is the bespoke system Andrew mentions above. Yes they ask a bunch of questions and come up with a complete setup for your individual car. I told them it was a track focussed car but was still used on the road and they sent me 110N fronts and 50N rears to go in conjunction with the 25.5mm t-bar, plus they made some adj camber mounts too that they didn't have for the 951 back then. Karl said that these were 616lb/in front and 708lb/in rear effective. I assume by 'effective' he means in tandem with t-bar. Also I have removed most of the rubber bushings and gone with solids and ride mostly on Toyo R888s so by rights I should have an awful car on the street, but it is still more comfortable than the old MO30 stuff (when set up stiffly).
Now we are going to build a track car I wonder what brand, adj, valving, spring rates etc we should have for this? Perhaps I should just go with KW again as it seems to be great so far. Also it seems that there is no hard and fast rule as to front v's rear rates. ie some people have more on the one end, others the opposite. I have read about a 'Super 951' in the US that has spring rates 1500lb f &1300lb r for example!!By super I mean one of those tube frame bewinged monsters.
What would you guys suggest? All opinions are welcome.

 

[Big Dave]

Hi Pat.
The rates i posted were the factory rates. They worked out the poundage...
Aparently its the same for a 944S2/Turbo as it is for a 968..
Which is somewhat supprising as the 944S2/turbo,s have slightly thinner torsion bars..
There is a "calculator" to check the "effective" rates, but i like you have never used it...[8|][8|][8|]

 

[AndrewS]

"Also it seems that there is no hard and fast rule as to front v's rear rates. ie some people have more on the one end, others the opposite. I have read about a 'Super 951' in the US that has spring rates 1500lb f &1300lb r for example!!By super I mean one of those tube frame bewinged monsters.
What would you guys suggest? All opinions are welcome. "

Hi Patrick,

My 951 Porsche Cup 2000 car ran 600lb rear springs (ProTrak coil overs - no torsion bars) and 700lb front springs. I tried using firmer springs on the rear, but the car became very nervous and more prone to unexpected oversteer. Ride height is very critical on the 951 - especially the difference front to rear and the best results I had were with the car pretty much as low as it could go, but with the trailing edge of the sill 10mm higher than the leading edge. Again, when experimenting with it lower at the back, the car would oversteer sooner. Braking stability was also better with that set-up as well.

Hence, a ratio of 7:6 front to rear worked well for me and a 10mm ride height lift when measured at the trailing edge of the sill. Car was then corner weighted with me in it and was then very neutral. I ran on ultra light 16", 3 piece split rim billet aluminum wheels (8" and 9" widths as dictated by the regulations). Overall weight was 1160kg (w/out driver).

Regards,
Andrew

 

[frogisland]

I have the Bilsteins with 600# front, 400# rear (still have torsions) - before removing all the rubber from the suspension the car was at its limit for road use, ok on good a roads and motorways, but a handfull at times on poor a/b roads. The Billy's can take much more if required...but for most of us we are just playing at it with trackdays and any half decent aftermarket suspension set-up will be a substantial improvement on old and standard setup.

Don't get too hung up with spring rates though - it is very important that whatever suspension setup you go for the dampers/spring rates are matched, otherwise they will not work as they should and you will end up in a worse situation.

I wanted my car focused more towards the track, it has limited use on the road, i find the Bilsteins very robust, simple (no adjustment) and capable of handling alot of abuse and a hard suspension setup (all of my suspension is rose jointed, solid alloy etc etc except for the arb's which are polybushed for compliancy).

If i was going down the road/ocaasional track route, i would choose KW - adjustability for both environments, sensible price, good KW support/reputation. Bottom line is, on track there was very little between myself and BigDave, the chosen suspension setup was to a degree academic, and that spending money on driver training is better value and would be the differentiating factor (as opposed a middle of the road Vs costly setup).

What about Gaz - most of the PCGB championship cars now have it, looked very good quality at the motorsport show, is reasonably priced, and i am sure you would get a personalised service for your particular need (i'm not associated with any supplier/manufacturer)

I think i may have used a 'broad' 0.6 factor for the rear springs - as Andrew may have touched on, there is alot more to a suspension set-up than which supplier you go for, there is simply so many variables. The state of your bushing will have a dramtic effect for example, camber/castor/toe, height front to rear, overall height, weight distribution and so on. I personnaly like my car circa 5mm lower at the rear compared to the front (taking relative heights from standard measured to castor mounts/centre of torsion). My car with a full tank is a smidgen off 50/50 weight distribution.

JP

 

[Neil Haughey]

ORIGINAL: AndrewS

My 951 Porsche Cup 2000 car ran 600lb rear springs (ProTrak coil overs - no torsion bars) and 700lb front springs. I tried using firmer springs on the rear, but the car became very nervous and more prone to unexpected oversteer. Ride height is very critical on the 951 - especially the difference front to rear and the best results I had were with the car pretty much as low as it could go, but with the trailing edge of the sill 10mm higher than the leading edge. Again, when experimenting with it lower at the back, the car would oversteer sooner.

Sounds like the slightly nose down stance was creating a small amount of anti-squat in the geometry between the rear suspension arms and the chassis. Likewise the nose down stance meant the car had less geometry changes to go through under dive ? (under braking) and hence was more stable under braking as well.

I had heard before maybe from Jon M or someone else that there was a limit to how hard you can go on the back before traction problems really start to bite, this might be the sudden oversteer effect you mention. Perhaps more then anything this would tend towards stopping at that limit and then making the front harder instead (and lower to counter the understeer from making the front harder). ISTR that on road car using Koni this was 250 Lb/inch but maybe much higher with better shocks.

 

[333pg333]

Well my questions are for a track only car or with very minimal road time. It will be stripped out and caged and perhaps be built in stages to a degree. The first stage is happening in that the motor is being built. This is a very special motor and it's construction has been going on since last year and will perhaps be finished in the mid to latter part of this year. So this gives me some time up my sleeve but not a lot.There are tons of things to consider and suspension is one of the main cantidates. Of course you need to have the system setup as a whole, but choosing that system is the hard part. To order the correct spring rates you must first assess the valving. Having many different ideas on rates is concerning as it makes it hard to start the decision process.
Then there is the tranny and driveline. How much do you strengthen one part to weaken another. I have heard some people say leave the axles and CVs as they are because you would rather have them as the 'fuse' instead of the Ring and Pinion or LSD or other more expensive and more difficult to repair parts could be. Some others say to bolster these parts to a degree, keep constant vigil on the parts and of course drive sensibly. The difficulty lies in perhaps using a 968 6 speed box in the hope that it will be ok but what happens if it doesn't handle the massive tq expected? The G50 box is a consideration as we know that it can handle big hp/tq applications but which one. Some customisation will be needed to do that but it's not too difficult with a car that you can basically cut up without fear or favour.
Did I mention brakes....???[]