The Story of a Complete Suspension Upgrade to My 1989 Carrera 4

by Adrian Streather RO Swiss-European Region TIPEC (SERTIPEC)

So how did I come to decide to completely remove and replace the suspension of my 911C4. Up until November 2000 I was completely happy with the handling and the feel of my C4 what changed all that. The PCA-GR Christmas party. To be totally correct, the return trip changed all. The weather was fine, the road was clear (German autobahn) and I decided to see how fast the C4 would really go. my wife Gail counted out the speed. 200kph, 210kph, 220kph, 230kph, 240kph still felt solid, 250kph started to feel a little light, 260kph and the front end was really up, 262kph and I decided it was time to stop, the front was starting to move, like it was on air, it felt unsafe, really unsafe. As I slowed down past around 250kph a Jaguar XKR went past me, that was it I thought, he looked nice a stable at these speeds, time to fix this problem.

My 911C4 with 16 Inch 993 Cups wheels with the ride height mentioned above

My project was underway and I had no idea what a story this would be.

So where to start my research. I needed to find articles on the issue. My search led me to back issues of the American magazine Excellence. The American need to try and make everything different was going to help me this time because on the Americans had bothered to write anything down. So how to get hold of these back issues of excellence dating back to 1990. By the way I had no idea at the time if these articles would help me but I had to try. My attempts to contact Excellence proved fruitless. I eventually placed a request onto Rennlist. This led to making contact with a fellow lister who had all the magazines I needed and offered them to me for a good price. We struck a deal and six weeks later the magazines arrived.

It was with great excitement I opened the package and got down to some serious reading. The article I was particularly interested in was a three part story called “Wringing out the Carrera 4” by Randy Hubbard in 1992. Part three held exactly what I was looking for. A tested suspension upgrade. After digesting the data, talking with a few other experts on the subject I drew up my modification parts list.

I needed the following parts and nothing else. no substitutes would do,

I ended up with a set of 911 Turbo wheels from my very good friend and fellow club member Denis Zuba. These came with Yokohama Porsche rated N0 A008Ps on the front and AVS Assymetrics on the rear. A perfect combination of performance tyres. Through another very kind Porsche 964 RS owner, Kathy in Geneva who has given me a brand new set of Pirelli P7000s to test and two used sets of Pirelli Zero Cs. There are some very generous people around and I am honoured to know them. The tyre companies have been very unhelpful in my quest to test various tyre combinations.

The upgrade tested in 1992 did not use 17 inch wheels so I did deviate somewhat but I thought who cares.

My 911C4 with 17 inch 911 Turbo wheels but not lowered yet

So now to find the parts I needed. The sway bar was quite easy. I contacted my trusted Porsche parts supplier in Holland, club magazine advertisers Van Zweeden Porsche. I duly ordered the sway bar and obtained it for 183 Euros, brand new Porsche part. As a side issue I also ended up with a full set of second hand RS America sway bars. I got them for aprice I just could not ignore and the package when it arrived included a pair of front links as well. Now to find the KONI parts and this proved just a little bit more difficult. I asked the question on the club mailist and got a response from Phil Wignall that his friend Simon Butterworth from Porschapart had two struts in stock. A RH and a LH. I purchased them for 200UK pounds and Simon threw in a set of what I believe are KONI Lowering springs (for a 944) for an extra 10 pounds. I took the lot. I think I purchased the last set of LH and RH 8741 1216Sports front Struts known to man. I did find two LH only struts in the USA. The rear shocks were proving impossible to find in Europe. The KONI catalogue shows no shocks available for the rear of a 1989 or 1990 C2 or C4. Well I knew that not to be true so my search took me to the USA. I eventually tracked down the last 8241 1104Sport at KONI USA (they do not make them anymore) and I found another one via another company. Both brand new. I was not to know that one company did not supply me a critical part which was to cause me a few headaches later on. I should have checked the package better. They included everything except the top nut. Believe it or not, the threads on the top of this shock absorber was not metric but a SAE thread size. You try finding a SAE thread nut in Switzerland. Well more about this later. So now to the springs. These were obtained via the Rennlist. I purchased an almost brand new set of EIBACH 964 RS Springs and a set of 911 RS America Springs from fellow rennlisters in the USA. I also purchased a set of H&R Lowering Springs from the German eBay but these eventually arrived a week after I had finished the upgrade. Not that I care because the RS springs are PERFECT. So just one part to find. A strut brace. What a saga. Well to cut a long story short, I found a German FVD strut brace in the USA. I purchased it and had it shipped back.

A quick trip down to see Denis, Sandrine and new baby Lea in the Audi and pick up the wheels and tyres completed the mod kit. I was ready to go.

The next thing to do was to go and see my mechanic Martin Inderwildi. Matin has his won company in partnership with a friend. Both are 20 year Porsche Veterans but now sell VWs and Audis and have authority to repair up to 964 series Porsches. So I took all the parts down to Martin and we went through, step by step what I wanted. I provided all the documentation I could find for the struts and the shocks, how to adjust them, the RS specs etc. The only other thing to do was to make an appointment and book the C4 in. April the 4^th and 5^th were the days decided on and all I had to do now was wait.

April the 4^th rolled around and I took the 911C4 into Martin. All I had to do was to wait. I even took these two days off work to ensure if anything was needed I could be ready for it. Glad I did. late afternoon on the 4^th Martin rang me. The nuts on the top of the rear shocks  from the existing set up did not fit the new shocks. One had been supplied with the shocks but the other was missing. I should have checked the package but I didn't. I said well they are metric aren't they. Nope, these new shocks had a SAE top thread. Everything else was okay but for some reason the top thread was SAE. PANIC stations, this is Switzerland, metric land but I did have one option. My work. I had to wait for Gail to get home from work, it was raining but no problem. I waited by the road and when Gail appeared I flagged her down, jumped in and took off for work. I searched our store and found what I needed courtesy of Rheintalflug and Embraer. With the correct nut in my hand I raced off to Martin and gave him the nut. He was impressed on how these things can be corrected. Whilst I was there and my C4 was on the hydraulic lifter I had a look around. The front struts were fully installed. Unfortunately it was too dark to take photos.

So the drama was over, well I hoped it was. I went home and Martin said he would call me when the C4 was ready the next day. it was a nervous wait but the phone call came at around 5pm. Gail gave me a lift down to the workshop and when we got there, Martin and my C4 were nowhere to be seen. Out for a test drive they said. After about five minutes of waiting the familiar growl of C4 greeted us coming into the facility. it stopped and Martin climbed out with the biggest grin on his face I have ever seen. He handed me the keys and he said I gave him a standard Porsche and he has returned me a go-kart. Martin also went onto the explain the alignment and balance procedure and to give me the figures. He explained that the C4 was completely out of balance. He had measured it all before he started work and it was totally out of whack. He showed me how now that all the panel gaps were now even. This is a good point. Uneven panel gaps are often attributed to accidents but it can just as easily be an out of balance and uneven corner height. Anyway, after the explanation and a quick walk around it was time to drive.

My 911C4 Lowered and a photo also showing the strut brace installation

What can I say. Martin was right this was a go-kart. The handling of my newly set up and lowered C4 was 1000% better than it was before. It was a real case of chalk and cheese. It was solid, the understeer was massively reduced, the response time was much quicker it went round corners faster and tighter and stiffer and did not activate the traction control. It was stable, rock solid at speed and when I got home after my extended drive all I could say was, “I´m impressed”. I was so happy and the set-up was perfect. Not too hard not too soft. In the park platz it looked low and mean. For me it was money well spent and a modification adventure completed. The only thing I have yet to do is to get over to Germany and give it a high speed test. the highest I have got up to so far is 220kph and I want to get it up to 260kph plus just like before and really see how fast this 911C4 will really go. One last point is the tyres. I currently have a set of Yokohamas installed as described earlier in this article. I would really have to recommend these tyres. They are really brilliant in the dry, pretty good in the wet and even took me through a little bit of snow. As already mentioned, thanks to a fellow rennlister Kathy Meinen in Geneva who very generously gave me some tyres I will be testing these tyres as well. I intend write an article dedicated to tyres and my testing later when I have more totally subjective and unscientific results which will include some 16 inch wheel and tyre combinations on the 944. I am currently the proud owner of  32 tyres and five sets of wheels.

My 911C4 and one of the sets of Pirelli Tyres the P7000s

Ten days after the job was completed, Easter the snow returned and I was grounded. In the next week we had over a metre of snow.

Next project is to return the 944 I have to roadworthy condition for my daughter. By the time you read this article she will have hopefully passed her driving test (May 22^nd) and will be using the 944, so that will be two more articles you can all look forward to, then there will be our holiday, the Streather family in France or Italy in two Porsches. One driven by myself, the other by my daughter Stephanie, now that should be one heck of a trip,

Ciao,

Adrian