bj

Hi All

What is your opinion/experience on the life of a suspension - particularly shocks and coils. I have a 1990 C2 with just over a 100,000 miles which to my knowledge has never been tracked or driven too hard. The right rear Boge (i.e. I assume is original) has leaked probably all of its' oil - since it's not leaking anymore. Do I just replace the bad shock absorber or all of them or replace all coils and shock absorbers with the progressive type coils (i.e. H&R / Bilstien)? I've heard I'll get a better ride compared to the stock setup when going over minor imperfections in the road surface as well as being stiffer when cornering aggressively. Also, cosmetically lowering the car an 1" is appealing.

Your opinions are appreciated
Bill
90C2

Adrian

Dear Bill,
Circa 100,000 - 125,000 miles. With your mileage you must replace all. As for choice of replacement you should check the archives. Opinions vary of course. I do not like progressives on the front. The 1990 model year reduces your options a little but due to the rear shock absorbers which are different from the 1991 and up versions.
Ciao,
Adrian
964C4

bj

Dear Adrian

Are suggesting mixing progressive in the rear with standard coils in the front? If so have you or anyone experienced this setup? How difficult is it to adapt 91 and up systems to a 1990?

Thank you in advance
Bill
90C2

Adrian

Dear Bill,
Works for Porsche. RS America and the Carrera RS both use this mixed system. No Porsche in the 964 series was delivered with progressive fronts. A lot of people like them. I do not .
As for the rest you really need to check the archives or the tech section of rennlist for more details. There are heaps of threads on this subject. I will say that I would not personally consider adapting the revised rear system to the original rear system. Right part for the right job.
Bilstein make systems for your C2. H&R also. You need to check out what you want. We can really get technical and specific to solve certain problems but your question is general and you need to select your poison before further advice can really be given. Look around and check around companies like RUF, FVD etc.
Ciao,
Adrian
964C4

Ade - C4 91

Hi Bill

You should be made aware that if you change to lowered springs on your 964 you will be changing the handling and ride of the car quite a bit.

If you drive a 964 with new factory springs and shocks you will notice that the ride is very smooth and has excellent shock absorption over most surfaces. This had a tendency to make the car quieter and more accommodating over longer journeys.

When you lower the car (even on progressive springs) the ride will be quite different. It will be harsher and noisier, perhaps even feel more unstable as it has less dampening effect at speed. The positive side is that the handling is sharper, more direct and the car can be more throwable.

Lowering is not for everyone, so perhaps if you can, try a few 964's with lowered suspension and see if you like them.

If you do decide to lower the car, I have to agree with Adrian, progressives on the front tend to be a bit bouncy and make the car feel a little weird and unpredictable over rough surfaces.

BTW does anyone have suggestions for good linear front lowering springs are available for fitting to Bilstein HD's?

Ade.

warmfuzzies

Surely it would be of benefit to find someone who can let you feel how their cars handle with different setups, just trawling the archives for info might help, but it's all very subjective.
Ask for someone local who's made the change, at $1000 or so a time it's a big thing to find out later you don't like the new system.

Kevin

bj

Good feedback Adrian / Ade

I make a 200 mile round trip every weekend on what I consider very smooth highways and I rather enjoy the ride I get now with the original system which as I mentioned is tired (i.e. at least one rear shock has lost its oil). I was under the impression reading other threads on this subject from people who have gone with progressive springs that this part of the ride should get better (i.e. better over small road imperfections - road expansion joints). I'm prepared to expect a harsher ride when the roads are rough. Are the above 2 assumptions correct? I've looked at the Shox website and they offer a number of packages including the original Sachs/Boge setup. For 50% more I can get into systems from Koni-Bilstein - Eibach, B&G, H&R. Can I assume these are progressive (i.e both front and rear) or do these companies also make linear systems? Also, I was under the impression that Koni shocks were not available for my year (i.e. 1990) - yet they list a Koni system.

Thank you again
Bill
90C2

delhi

hey BJ,
where do you bring your car for service in Toronto? an OPC or an independant dealer? I'm currently searching for a 964. Perhaps I can leverage some of your experience. heheehhe. Are you with PCA Upper Canada Region?

bj

delhi

I've owned it just over 2 years and have done most of the service myself other than having the Hammer done on it at an independent in the city and having a hub nut lossened at a corner garage that had a good impact wrench. I'm not a member of PCA. I'd be happy to help you.

Bill
90C2

Ade - C4 91

Hi Bill

I can't tell you how your current system compares to a lowered system because I don't know how damaged yours is and how harsh the ride currently is. The rear shocks tend to go first, usually on the LH side (as they are close to the heat from the cat and exhaust), so your front suspension may actually be ok, if a little worn. On the other hand if the rear is stuffed then the ride can be rock solid and very uncomfortable, in which case just about anything will be better.

But generally, comparing a stock system to a lowered system, both new, the lowered will be harsher.

I find my lowered suspension a little annoying over London's really bad roads as the front progressive springs tend to cause bounce and crabbing through corners (especially when the tank is nearing empty), it has its moments though on windy open roads, but actually, looks aside, I think that standard suspension is difficult to beat.

Ade

delhi

well alignment will come into play as well. Aggresive negative camber settings will lead to tramlining. Here in Toronto roads, it might be a a pain.
Hey Bill, how long did it take you to find 'the 964' for you? I'm not sure if I'm too picky or what, but I am having a hard time finding the right one. I'm almost tempted to go for 3.2s.

bj

Ade

I've owned my C2 for almost 3 years and the left rear shock lost its' oil after about 2 years. So I drove it two years with a relatively intacked system - just a little tired due to the 100,000 miles on it. Initially after it leaked the oil out I never seen much difference in the ride compared to when the shock was holding its' oil. Now after a few months I'm feeling something different (i.e. it feels wishy washy in corners) especially when I take a corner at speed and when I bounce that corner of the car from the bumper it oscillates a few times. The ride on smooth highways is the same - fairly smooth with some road noise from the tires. I also plan on upgradeing to Cup1's with lower / wider profile tires which will add to the harshness of the ride. I can understand your statement on bounce in the corners but not crabbing (i.e. or did you mean grabbing). What happens on windy roads? I had mismatched tires for a short period of time and the tramlining was scary - if that is what happens when I go to a suspension like yours - I'll stick with the standard suspension. What are you actually running?

Delhi

I had an alignment due to the PPI discovering it was pulling to one side. I hope to use this same shop hopping they will know how to align it if I lower it - in fact since you mentioned it I'll contact them before I purchase and see if they are comfortable aligning a lowered car. I may have to use someone else though. I have a scrap book of Autotrader clippings when I started looking for a Porsche dating back to 1985. At that time I was even considering 928's and 924/944's. I tried out a lot of 3.2's before I tried this one 964 and purchased it.

Bill
90C2

Ade - C4 91

Bill,

I did mean crabbing, but perhaps that's a term not used much outside NZ. What I mean is a kind of unbalanced wallow as you enter a corner causing the car to take bites out of the corner and feel like it's twisting laterally. I think most people used to progressive springs will tell you that the springs are just settling into the harder zone, which is fine if the corner is consistent and not bumpy (IE. circuit), not so great on bad roads.

I'm running Roock coilovers (H&R over Bilstein HDs), 21mm rear Antirollbar, all new rubber and wishbones. Suspension alignment is RS Euro settings. 17" Factory wheels with N rated Continental Contact2 tyres.

Perhaps the best approach for the front end would be to use lowering perches and normal length linear front springs on uprated shocks, that way you get the full suspension travel, and at the rear - progressive lowered springs on uprated shocks. I think this is close to what RUF do.

I'm not trying to put you off lowered suspension, just be aware that it's not going to be a standard feeling suspension with less height. I would take your time, do lots of research, ask lots of people and make a choice that suits your needs.



Ade

joey bagadonuts

Ade,

I'm not trying to dismiss your opinion but I am having trouble following your description. I agree with some of your observations but not all of them.

In my experience, the switch from linear to progressive springs up front while retaining Factory dampers resulted in a more compliant ride. Small rode imperfections were more easily absorbed by the lowering springs--the ride did not become more harsh. I'm fairly certain that most people on this board who carried out a similar mod would tend to agree.

But you mentioned that turn in is not as precise, that progressive springs exhibit an unbalanced wallow. Agreed! Progressive springs need a split second to "set" before responding to inputs--they're not as immediate.

The bouncy tendancy of your setup, though, suggests another matter. Since you changed both springs and dampers at the same time, I'm wondering if the resulting ride is due to more than just the spring choice; new dampers should not exhibit so much travel. Is it possible that they're not well-matched to the springs?

Bill,

Your assumption is correct. Progressive lowering springs will provide a smoother ride over road imperfections than the Factory linear springs.

bj

Hi Guys

I'm getting a little caught up on the terms, correct me if I'm wrong on the following:

Roock coilovers or more particularly coilovers is a term which includes both the coil and the shock absorber in Ade's case a Roock coilover just happens to be made up of the particular brands he mentioned?

Dampers are another name for shock absorber?

Uprated shock is a stiffer shock absorber - in other words it is more resistant to change.

I was under the impression that the greater stiffness in one of these upgraded spring / shock absorber combinations was due primarily to the spring only. Now it appears the suspension gets its' greater stiffness not only from the spring or coil but also the shock absorber. It makes sense that each coil should be matched to a specific shock absorber? Wouldn't I run into problems trying to put a shock absorber ment for a progessive spring onto one that is linear? Are all shock absorbers damping characteristics linear they only differ in the degree of dampening?

Joey

Your comment that I'll obtain a smoother ride from lowered progressive coils compared to the standard system has nothing to do with the fact that it is lowered but more to do with the fact that the coil is progressive. Correct? I understand that because the coil has both tightly wound sections in the coil and not so tightly wound, it is the not so tightly wound part that compresses first and travels more until a limit is reached and pressure is then put on the more tightly wound section which is more resistant to compressing. Is my undestanding correct?

Thanks again
Bill
90C2