A question for suspension boffins

When setting the front ride height using coilovers I dropped the leg through the upright/hub and tightened the pinch bolt. Job done. Is there any change to suspension geometry doing it this way OR lowering spring platform using the two locking rings? Do the two methods have exactly the same effect? Or is one way better than the other? Thanks.

Hi You want them fully seated in the hub. Change the ride height via the platform. Berni

They could drop through the hub all the way to the threads on the tube leaving no ride height at all. Fully seated is not really a thing if you know what I mean I was wondering more if there was a geometric change depending on the method of lowering?

Any change to the suspension will upset previous settings. It will affect camber, caster and probably toe-in, other factors could contribute are tyre width and wider track. The axle needs to be identical. Do you have the original strut to take measurements - I would baseline everthing from that. You need to have 4 wheel alignment and I would use a specialist such as center gravity. The finest part of any Porsche is the suspension.

My mistake I'm obviously not being clear. I'm fully aware of all the points you mention. The question was, and I'll try and word it differently. If you.lower 2" for example by dropping the strut through the hub, or 2" by dropping the spring platform, will there be a difference in geometry between these two methods Hope that makes more sense.

As mentioned the strut should be fixed and not used to adjust height, as this should be achieved by the spring perch. However, both will affect camber.

Well the manufacturer say the strut can be lowered in the hub for more adjustment so not sure where that puts things. What will the difference be in camber/castor between the two methods? That's the question.

All else being equal, none. But by adjusting ride height on the spring perch as opposed to the pinch bolt) you will also be adjusting preload and travel which will affect dynamics (as opposed to static ride height). I'd adjust the perches so the springs are just compressed with the wheel off the ground (MOT fail if not), then set the ride height a little higher than you want via the pinch bolt, then fine tune the ride height with the perches. Then I'd go and get a professional set up ASAP. Like others I am concerned/surprised there is not 'stop" for the strut in the hub assembly.

Any change to rideheight, regardless of how its achieved, will change the camber. Oh and if your struts have no seat, i would suggest there is something wrong with them. The Porsche hub is not designed to clamp the strut in place and with the wheel forces, any unseated strut is likely to slip.

I don't think there is any difference between methods of charging ride height via the suspension strut as far as geo is concerned, as long as it's acting between the same 2 points, then a change to wishbone angles causes the same change to your geo. Edit, actually thinking about it a bit more, there might be a small charge in static camber or camber gain but I'm not sure on that.

Cheers. I had come to a similar conclusion.

I wasn't going to contribute to this thread as I thought the answer to your question was so obvious that someone would quickly post it, but it took until Grifter's post for it to be addressed. If you think of your strut and upright as a single unit, that telescopes linger or shorter depending on perch height and how far up the upright is clamped on, you'll realise it can't affect geometry. What it can effect is preload and available stroke length, which you need to maximise in bump without leaving too little rebound. Roughly 2/3 bump and 1/3 rebound on the shock travel at the ride height you want to achieve is about right. Then set the spring perch height to fine tune and give you the slight preload at full droop already mentioned. A lot of people on here also go on about professional geo setting, ('take it to CG or you'll crash and burn at the next corner!!!'). It's perfectly reasonable and sensible to learn how to do it yourself, (I do my own geo and it's accurate to within 2/60ths of a degree) or if that sounds like hard work, just learn about set up and then go to a local trusted geo place and pay £60 for a four wheel alignment done to your own spec. I've no doubt CG are awesome at what they do, but not all of us buy our bog roll at Fortnums.

Hi I am surprised there is no "seat" or locating hole for the strut to prevent it slipping in the hub. I do not like the sound of that. Personally I would not use them if you are relying on the single pinch bolt to stop them moving. I took my 993 to CG and they did a great job, but that car is a bit trickier to set up than a 986, and I drive it a lot more aggressively than my 986. I have just changed all the struts on my 986 will be doing my geometry at home using my axle stands, string, camber gauge and trackrite. I have done quite a few cars that way and its good enough if you take your time. I'm looking forwards to the process actually. All the best Berni

BTCC cars are set up in the paddock with string boxes. A friend of mine sells laser alignment kits and he sponsored a BTCC team (Welch Motorsport). They compared lasers with string and they were just as accurate and repeatable as each other. The only uncertainty seemed to stem from the skills of the mechanic, I.e. the guy who is good with string is just as accurate as the guy who is good with the lasers.

The perches were/are adjusted so the springs have slight pre load. Leaving springs flapping around at full extension is just retarded. I asked a very specific question. The question was regarding Geo changes using two different methods of lowering. That it. That's all I asked. Some people understood that and some people start running wide and spouting all sorts of info that has no bearing on the question I asked. My bog roll comes from tesco so I suppose I'll have to slum it and do the alignment myself lol. Thanks for the reply mate. :thumb: