Atgani

Low preload seals on an otherwise stock car with rubber suspension bushes and top mounts would be a pointless exercise. In a fully rose jointed car, it may pay dividends, but not on an otherwise stock car with the stiction the many rubber bushes create.

And as you’ve rightly said, they weep, which attracts dirt/grit and leads to decreased service life. Not what I was looking for (though fine if you’re a trackhound who inspects their car before and after every trackday outing.

KW’s are, just like Ohlins R&T’s, supplied with similarly high spring rates for use on our roads in the UK. Added to which here in the UK, the main service department has a less than stellar reputation when it comes to accommodating individuals like me who want to go “off piste”.

hardtailer

That is a misconception. the rubber bushes exhibit no stiction, as there is no relative movement between parts (like there is with ball joints or polyurethane bushes). The rubber is vulcanised to the inner and outer metal sleeves which in turn are solidly attached to the respective parts that rotate relatively to each other.
Any force or torque, no matter how little, exerted onto the bush will lead to a deflection, as small as it may be. As such, by definition of stick-slip/stiction, there is none of that.
There is, however, hysteresis, i.e. after taking away the force, a tiny bit of deflection remains. Ball joint show the same behaviour, though.

I think what you are hinting at is the additional spring rate that rubber bushes in a suspension add when compared to the same suspension fitted with ball joints throughout. However, that is a non-issue as it is (un)knowingly compensated for by the stiffness chosen for the main spring.

The sole use-case of a ball joint over a rubber bush is the much greater radial stiffness of the former. It leads to much reduced toe and camber change under varying drive, brake and cornering forces thereby allowing optimum control over the tyre contact patch.

Turning attention to the shock absorbers: the lower gas pressure in a twin-tube design compared to that in a monotube allows the use of seals that will create less drag and therefore stiction thereby improving responsiveness of the shock absorber. This is felt as reduced harshness, although it is not the main (if I'm informed correctly) reason for improved comfort of a twin-tube over a monotube damper.

To conclude the above, low drag seals would be beneficial more to a vehicle fitted with rubber bushes than to one 'fully rose-jointed".

I agree that for a given seal, a low-drag version will generally compromise the service life.

Atgani

You are correct Stiction was not the correct term, I meant hysteresis in the OE top mount, along with the torsional force twisting the rubber in a metalastic bush.

dougn

[QUOTE=Atgani;19186077]You are of course right, Ohlins cut it’s teeth developing MotoX dampers, but the requirements for MotoX and road biased suspension on a car are very different...

I don't agree. Road going suspension needs to be able to deal with a wider range of shaft speed (like offroad M/C suspension). Track suspension mostly deals with lower shaft speeds

ivansskoro

Would you consider KW v3 with 4kg/mm front and 9kg/mm rear a good solution for roads that are better than UK roads, but worse than Germany? (case in my country)

Atgani

[QUOTE=dougn;19191345]You don’t consider those to be fast shaft speeds in the video I posted earlier in this thread then ? That’s an interesting perspective ... and one which begs the question, why then did Ohlins specifically develop the DFV system for the BTCC cars ?

dougn

[QUOTE=Atgani;19191457]can you point me to the video? There are many links. As far as the DFV valve....I don't know that they did develop it for a specific track use. However, it would help when running over those corrugated things ive seen. It's a high speed relief valve I assume. I seems to me anyone who could make an effective high speed relief would be able to use higher spring rates and retain the nice stiff chassis control and a track worthy suspension that works on the street.....

Atgani

Here you go :

zbomb

Not if you want to go fast.

circuit.heart

Lmao yes. Granted there are exceptions like huge aero downforce - most lap records at Buttonwillow don't launch off curbs. But shaft speeds at Buttonwillow if you DO hit the curbs go way over 10in/sec.

acf321

Just been reading this thread comprehensively and I wanted to throw in my two cents worth as owner of a 10.97 build 3.4 Carrera RHD 6MT.

Like most owners of these cars, mine has tired standard suspension with 124,000klms. Top Mounts and drop links appear to have been replaced recently with new OEM items, and it is running the standard anti sway bars F&R.

Condition is immaculate, and I have added 993 RS engine mounts, transmission mount inserts, and a GT3 short shifter. Wheels are 18" BBS Sport Design 7.5" & 10", however it was delivered new with 18" Turbo 1 (hollow spoke) 7.5 & 10" wheels, which I am having restored at present. Tyres are currently Pirelli P Zero, however I have ordered a set of Michelin Pilot Sport 4S 225/40 and 265/35.

Regarding the Ohlins R&T, this is the choice I have made to use for my fast road application. I considered KWV3, and even a M030 factory set up. Like most, I have been reading a LOT on this topic and had felt very comfortable with the Ohlins choice, until I read this thread. Aside from the OP's fantastic experience with a totally stock set-up, and the Ohlins, there appears to be multiple people here that think they are over sprung for road use.

When I look at reviews from prominent owners, mechanics and journalists (and the OP of this thread), I just hear and read phenomenal comments about how forgiving the R&T are on bumpy commuter roads in the US and the UK (more than factory stock suspension) and then how incredible they are on the track or fast roads. Amongst these owners / professionals, I am looking at Magnus Walker's red 3.4 Carrera on Ohlins (he says they are great), Matt Vlog's CarWOW own car (he is amazed by the compliance on B roads and fast roads) on youtube (also independently reviewed by a Porsche Factory mechanic who rated it materially better than stock, even with Poly bushes and Tarret hollow ARB's), Luke at 'Friends Green Porsche' who also said the same of the Ohlins R&T when comparing to KWV3's, and multiple other owners on this thread and others that just can't speak more highly of them.

Whilst I am not an suspension expert, i have read and watched interviews with Ohlins engineers that state the rationale for their much harder spring rates is to force the wheels onto the roads, so as to increase grip (materially over stock). This is incidentally what this thread and others suggest from those that use Ohlins R&T, that is materially improved grip in corners.

I called two top suspension specialists and race team managers here in Sydney Australia, and both highly recommended the R&T for my application.

Still, I am reading this thread and just seeing many complaints that don't really explain the problem with the R&T, other than (in my observation) to suggest that the same outcome can be had with softer springs.

Have I missed anything here? Failing that, I have my money ready and do plan to buy a Ohlins R&T for my 1998 MY 3.4 Carrera 6MT.

DeanClevername

Sounds to me like you're on a quest for absolute clarity before purchase. And that is impossible to achieve. Impossible because subjectivity is at the core of this being the right fit or not.

Tangible variables are use case, preferences, the specific type of roughness of the roads (or local tracks) you will use them on, amount of camber, etc. Spring rate of course, but that's is just part of the equation. When it comes to ride quality on the street, damping is probably tied with tires as the most important influencing factors.

My old Ohlins + fresh RE71R would ride like a Lexus despite sidewalls massively more stiff than something like PS4S. But by the time the compound had a lot of heat cycles and was worn close the wear bars, the ride would be loud and harsh over small surface imperfections. Same tire, same suspension, totally different experience. Same can be said for any tire really. And lots of cheaper alternatives to good road tires like PS4S have poor ride quality because they are chasing the performance of the PS4S without adding sophistication (dev $$) that allows them to be good in all respects and not punishing in terms of ride quality.

And people opinions might also be colored by the type of "bad road" they drive each day with their car. Big undulations are very different than small surface imperfections like you might get on expansion points or driving over brick roads or the rumble strips that warn you're at the edge of the road surface. Undulations allow the springs to compress and get the quality damping engaged, while the small high frequency imperfections do not. Therefore those small surface imperfections they really allow you to feel the stiffness of sidewalls and springs, shocks can't mitigate it.

A car with softer springs but lower quality damping (or just old shocks) like the M030 or X73 will often feel even worse/stiffer over poor pavement than the Ohlins, while also being much softer and worse performing when you're actually in a corner. This is the underlying reason why so many people say their ride quality in general improves when jumping to coilovers with high quality dampers.

Having driven a lot of Porsche from this era at this point, I can say pretty confidently that if you're not bothered by daily ride quality of m030 with shocks that are a bit aged, or even a fresh x73 with shocks working as well as they can, then you'll be fine with the Ohlins. They'll be no worse in the places where those suspensions feel the worst (probably better) and will absolutely be better once you're having fun and leaning on the car.

But again, all this comes down to one key thing: Know thy self.

Only you know your preferences and your real world use case and the compromise between ride quality as unobtrusive as a sport sedan and vs performance that is acceptable to you.

SealG996

I'm often in the Inner West of Sydney if you want to see how Feals 441+ Swift Springs, plus some harsh pillow ball arms work or don't work...I tend to think Ohlins plus a soft spring, made by Atgani had a good case made in this forum. My 996 is on Michelin pilots. My Holden (Chevy SS)
due to potholes and supply chains ended up on Bridgestones. Michelin Pilots are a quality tire - pity I punctured 3 in 2 weeks after a big rain event.

acf321

Thank you Dean and Seal.
these are both very insightful responses, and Seal I appreciate your offer to have a feel of the Feal’s (pardon the pun).

Have just re-read your response Dean, and given you are the original poster, and its been many years since you started this thread, it means a lot to me to have your comprehensive reply.
Whilst the temptation to go with KWV3 and even the PSS10's, it's the Ohlins that I feel most at ease with.

To your point, putting my driving into context, my car is really just a Sunday toy to effectively drive early and fast. Usually, my prior cars (930, 2.7 MFI Carrera, 914.6 GT, 71T, 70 240Z) were all put back into the shed by 730am after a drive, breakfast and a coffee. So, I target fast twisties and freeways. The idea of commuting is not something I intend to use the car for, and all of my cars tend to be kept to a very high standard, so old and worn out tyres will typically not be an issue.

If I use the RS mounts as an example, I have read here and elsewhere that these are 'too harsh', 'stiff', 'jarring' and materially increase NVH. My experience is anything but that, and that they are exactly what the car should have had from the factory. Similarly with my 71T. I installed sway bars, had the Koni's re-valved to 'Sport' setting, and installed all new rubber (Elephant Racing) bushes. That car was not rock hard, but 'firm' with a genuine sport purpose / sunday smile maker. I intend (and expect) the same for my 996, and so based on yours and other experiences (plus the experiences from Magnus (who incidentally complains on his video abt the rubbish tyres on the car while testing), Matt Watson Car 'Did I ruin my 996 with Mods', Friends Green Porsche and many others, the choice to use the Ohlins appears sound, and rational.

Have a look at this youtube vid on a B road in the UK (Mat Watson), on Ohlins R&T, Powerflex poly bushes throughout and Tarret updated ARB's, and even semi-solid engine mounts. Hard to mount a negative argument from what i can see - from 9:54....
I must say, of all the cars i've owned, the 996 Carrera is by far the most capable and best handling car out of the box (even on standard suspension, no LSD and the less desirable / worn Pirelli P-Zeros). It seems to me to have so much potential, hence my quest to properly understand the best suspension application for my requirement.

Again, this has been super helpful, Thank you!