"The handling is so dead on accurate, so amazingly responsive, so incredibly able, so unmistakably predictable, so pure and so perfect, that the English language is grossly insufficient in its ability to describe the level of improvement realized by what you are about to read!!!"

BACKGROUND

Without question, my latest mod is the best money I have spent on this car to date. What are we talking about here? Suspension, suspension and more suspension! After quickly realizing the factory Turbo suspension was not up to the task, I went with the ubiquitous Bilstein PSS-9’s. I lived with them for some time and slowly realized they were incapable of dealing with what I threw at them. At that time, I did exhaustive research with regard to the 996TT suspension and, more specifically, the Bilstein PSS-9’s. I spoke with many experts in the industry and performed a series of tests on my suspension to identify what the issues were and where they needed improving.

GRATITUDE

I wish to extend my deepest and sincerest thanks to the following people for all of their help in various ways during my long and arduous journey to the pot of gold where I now reside:
Cary Eisenlohr – ERP Parts, California
Cary, above all I want to thank you for the multitude of hours of suspension talk, engineering discussions and general shooting of the bull. Your advice and direction is/was absolutely invaluable. Everything we discussed sunk in and the end result demonstrates that.
Gary Bohrman – Exclusive Motorcars, New Jersey
Gary, your patience and belief in my ability to assess the problem and come to my own conclusions, with your guidance, is greatly appreciated. Your droop tests were wholly instrumental in allowing me to realize the biggest of all of my problems…….lack of travel.
Steve Weiner – Rennsport Systems, Oregon
Steve, your help in assessing my suspension woes and suggestions for the remedy were a great help.
Hershel Zelcer – CargraphicUSA, New Jersey
Hersh, I appreciate your help in assessing my problems and allowing me wheel time in the CargraphicUSA 996TT featuring your Club Sport suspension. This was a very important reference for me. Realizing the potential of the 996TT when properly set up was the catalyst for my quest.
Todd & Mike – AWE Tuning, Pennsylvania
Guys, thanks as always for the advice, support and patience. Above all, thank you for securing all of the necessary components to see this project through to fruition. Todd, I really want to thank you for personally spending the time with me to go over spring rates, travel, droop and generally insure that the whole package would function properly and achieve my objectives. This is a wonderful testament to the customer service your firm provides.
Ron Brown (Vipertestarossa) – Forest Hill Exxon, New Jersey
Ron and Al, thank you again for the help with the donut replacements, toe link and of course the alignment. The drive home after dinner was the best drive I have ever taken in the car since I have owned it!!
Lex Carson – Moton, Georgia
Lex, thank you for being available on BOTH Saturday AND Sunday during the extent of my installation. This speaks VOLUMES for customer service. Your help was greatly appreciated at a most crucial time of the installation. I also wish to thank you for overnighting the additional parts we discussed. That was above and beyond the call of duty.

Well, that last “thank you” let’s the cat out of the bag of what this is all about. Since the cat is out of the bag, I will now say I have just finished the installation of the Moton Club Sport suspension in addition to many other specialized race parts. Read on…

BILSTEINS

This whole journey was undertaken after I realized the Bilstein PSS-9 coilover system in my car was not meeting my needs. I had previously prepared a comprehensive assessment of the PSS-9’s and will refrain from doing so again. I will quickly recap:

• PSS-9’s have a limited lowering potential that should not be exceeded. The lowering limits should be strictly adhered to with additional margin added in to insure adequate travel. As with most coilovers, the more you lower them, the less travel your suspension has. The PSS-9’s seem to be particularly sensitive to this.
• If you install PSS-9’s and lower the car to GT2 ride height, you will be riding on your bump stops. Bilstein’s total travel of 100mm (approximately 4”) is comprised of approximately 50mm of free shock travel + 50mm of bump stop compression. The bump stops have a linear compression rate up to a deflection of 40mm. After that, they stiffen markedly, thus leading to handling irregularities.
• PSS-9’s spring rates are only marginally stiffer than stock. Based upon my research, the front is only about 11% stiffer than stock.

MOTONS

During my research I reviewed the benefits and detriments of the following suspension systems:

• Moton
• JRZ
• Ohlins
• Jic/CROSS

I finally decided on the Motons. That is not the end of it though!! This is where ERP Parts comes into play. And this is where the real differences are realized!!

Let me describe the system and show you some photos of the parts and installation…..

The Moton Club Sport kit is shown below:



The kit includes the front and rear dampers, H&R springs, lower control arm rubber bushing replacements for both front and rear, rear upper control arm replacements, rear toe link replacements, rear GT3 sway bar and, finally, Racer’s Group drop links. The monoball strut top mounts and needle thrust bearings are not shown in this photo but can be seen in later photos.

The front coilovers are shown below:



The rear coilovers are shown below:



The rear upper control arms and toe link are shown below:
These are some beautifully machined pieces!! I almost didn’t want to install them!!!



One of the front drop links is shown below:



The rear sway bar and one of the rear drop links is shown below:



The front coilovers installed:



Another view of the front coilovers installed:



The rear coilovers and upper control arms installed:



Another view of the rear coilovers and upper control arms installed:

 

A view of the needle thrust bearings and the races:



A view of the assembled strut with the monoball mount and needle thrust bearings:



Comparison of factory rear upper control arm and the ERP “Works of Art”!!:



Rear suspension compression adjustment cartridges:



Rear suspension compression adjustment cartridge hydraulic line grommeted through body:



Front suspension compression adjustment cartridge:



Front suspension compression adjustment cartridge:



Finalizing the installation at the KPV996TT cave:
Love those red springs!!



Rear toe link and rubber bushing replacements installed:

 

I collected a lot of spring rate information and settled on 450 pounds/inch for the front and 700 pounds/inch for the rear in addition to 50 pounds/inch tender springs for both the front and rear. I chose these rates due to the fact that I live in New Jersey and use my car on New Jersey roads. They are not always pristine racetrack type roads and have their share of bumps, dips, potholes, etc., etc. Since I am using my car approximately 90% street and 10% track, it is a good compromise for me. If you have generally smoother roads, I would recommend slightly higher rates. The front end of the 996TT tends to exhibit porpoising (or pogo-ing) when pushed hard. Basically, the car is under-sprung. I found that to be that case with the stock suspension and to a slightly lesser amplitude, but higher frequency, with the PSS-9’s. The 450 pound springs in the front essentially eliminate this effect. That was one of my biggest gripes with the stock suspension and also the PSS-9 upgrade. If you are after strictly performance, I would recommend staying away from any spring rates that are less than 400 pounds/inch on the front of this car.

The first three suspensions, in my list above, offer two-way adjustability. That means you can independently adjust the compression and rebound damping. This is a huge help! I am currently experimenting with these.

The toughest part of this suspension installation is the routing and securing of the compression cartridge lines. There are many moving parts in the suspension and you must insure the lines do not get abraded or caught up in anything.

ALIGNMENT

Following are several photos of the alignment process at Ron’s shop:







I decided on a ride height within the GT2 envelope. My final ride height was 112mm in front and 123mm in the rear. The GT2 has a 108-118mm range in front and 133-143mm range in the rear, however, the TT has a 15mm lower rear suspension subframe meaning it is converted to 118-128mm equivalent range for the rear.

I reviewed all of the factory specifications for the USA Turbo, ROW Turbo and GT2. Considering the fact that I eliminated the flex inherent in the factory suspension, I decided on the following specifications as a good compromise between a track oriented setup and better tire wearability setup:
Front:
-0.9 Camber
7.0 Caster (now adjustable with the ERP “Works of Art”)
+0.06 Individual Toe
Rear:
-1.7 Camber
+0.17 Individual Toe

Prior to the ERP Parts installation, I concerned myself with toe change due to thrust on the tires from forward motion as well as other wheel articulations due to flex in all of the rubber isolation joints. These rubber joints have been eliminated so alignment changes mid-corner or under load are a thing of the past!!!!

If you recall, Xico had the rear suspension of his 996TT replaced with that of the 996GT3RS. Although I am unfamiliar with all of his reasons for doing that, I believe I have accomplished the same result at a fraction of the cost. The rubber is gone and the degree of adjustability is greatly enhanced.

So, there it is guys. The last big mod and DAMN was it worth it!!!!

 

WOW!! sick-en-ing!

 

ken u are my hero. You are going to love that set up... Great research and thanks for paving the way man... I might do that one day

 

In a word awesome!!!!!

Great post, great technical information!!! Thanks for sharing... Enjoy the ride!!!

 

Ken, I have to agree (and not just because of all the really nice things you said about me) this is a great tech write up. For those that don’t know, Ken is a structural engineer and a very intelligent guy …. I only wish more magazines could afford to pay for someone like him to write unbiased articles. I really like his pragmatic/analytical approach and it's made me a believer in whatever he’s done to his car. Ken is truly a fanatic!! I can’t wait to read what he’ll have to say about the NEXT bag of goodies I'm gonna try to get him to bolt on!! Ready for STAGE II Ken????

 

Ken, you are the main man. One question, why do you still have the rear seat belts in your car?

So is there any words that the PSS-9's will be re-engineered with greater spring rates and be able to be lowered further without hitting the internal bump stops? Could you say buy H&R springs and install them into the PSS-9's for a stiffer spring rate? And what seem strange to me it why does the PSS-9's have the threaded spring collar larger than what the shock/spring combo can handle? Like you said before, bad job of engineering on Bilstein's part.

 

Glad to see more people using Moton here on 6speed, great write up and thanks for sharing.

 

So this is why I haven't been able to get you on the phone for the last few days?

 

I'll just be ridding on your coat tails. Thanks for balzing the trail. Moton's, here I come!

I really, truly appreciate your efforts. So many people do wonderful things on this board (Ken - Motons, Rockitman - detailed installations, Stephan IA exhaust work, Chad for just about everything, ...). My only way to repay/thank you guys is to do one of my own.

I am going to show the data acquisition system benefits and installation. I have the unit now and will be installing it in two weeks.

Thanks again Ken.

 

Now I really do feel bad for the southern hicks because of the upcoming TOD.

 

Ken..that was an awesome write up!!! i am glad ypur car is the way you want it..by the way..ron is a great guy,and i am sure his work is great also!!!!

 

Damn!! That is some good scoop!! If I had a coupe and was going to race it , I would definitely go with this kind of set up.

 

Hey... Xico was the first one with the Motons so us southern boys deserve a little credit.