Bumpstop Issues With PSS9's

Last question b4 i buy them. under what circumstances will i hit the bumpstops. Bearing in mind that i'm not going for the "lowridah" look, just a bit of lowering, maybe to factory X73 spec plus minus/depending on road condition.

I would stick with factory stuff, m030, x73/74, can't go wrong.

i haven't heard of any bumpstop problems with NA996s. i think you can go with gt3 ride height and be OK. i've heard of the problems on 996TT that have been lowered to gt2 specs. the problems arose during extreme cornering and the strut was compressed to the bumpstops resulting in zero suspension travel thereby destabilizing the car.

ROW m030 not much bang for the buck IMHO.. too much like stock. US m030 is kinda a waste of money. can't do x74 on pre '02 cars. pss9s are great cause you can fine tune the shock settings for the street and the track.

Actually, except for steady-state cruising, you are usually on the bumpstops in the stock configuration. With the RoW 030, I think you are on the front bumpstops all the time. Technically, they are not bumpstops but foam rubber "additional springs" as Porsche calls them. They are a part of modern OE suspension design. The factory springs are about 200lbs/in, so you cannot obviously have 3" of suspension travel when you slam on the brakes. I don't recall the exact numbers, but PSS9s are in the 400 to 500 range. I really don't know what happens to the bumpstops on PSS9s. It would depend on the height of the shock housing vs. the ride height--a fairly complex and interactive arrangement to make generalizations about.

1. You are not on the bumpstops all the time 2. Pss9's have internal bumpstops. Ride height does limit your overall travel range of course.

I run my C4 about 10mm below GT3 ride height... can't say I've ever had any strange handling problems. This includes the odd trackday and many autox. My biggest problem is transversing driveways! t

1. Under what conditions do you say "not...all the time"? If you say stock, then that's not what I claimed. If your claim is "essentially never", then I challenge you to take out the additional springs (bumpstops) and see how it affects your handling. With the US/030/ RoW stock-type suspensions, they are an integral part of the suspension function. 2. What "internal bumpstops" are you referring to? Do you mean internal to the shock? I think not.

I think you would see big bump in handling in going with the row 030, some guys who have done that can chime in, Doug help me out here. Chris

The PSS9 has internal bump-stops. The PSS9 isn't a full race suspension, its a middle-of-the-road solution that gives you pretty good track performance and a great street ride (better than OEM IMO). In my setup, with my car lowered 1" or so front and rear, I have never hit the bump stops on the track or on the street that I could notice. If you are lowering the car more than that, either you are being too aggressive than necessary for DE or you really should be buying an all-out race setup.

The smaller tender springs are helper springs and are not bumpstops they make sure that the main spring stays seated on the collar at all times of extension-

Yes, normally at cruise you are riding on the helper spring, which is considerably less stiff than the main spring. This is why the PSS9 rides so nice. At the track, that helper quickly bottoms out and then the main spring takes over. You can't even barely feel the transition, but in a full race setup you wouldn't have the helper.

If you look at the helper springs they are actually completely compressed at static ride- They really perform no progressive function other than maybe rebounding and holding the main spring on the collar- I was surprised when I saw but by reading the material it denotes just that function

You can't infer static ride from the car standing still. Even so, my car doesn't completely compress the helper springs while standing still. If the purpose was solely to keep the springs on their perches, then the strut shaft would be shorter, or the main spring would be longer. If the helper is fully compressed, then it does nothing, and there would be no reason for Bilstein to put a spring there -- they could make the main spring longer. Helper springs are characteristic of hybrid/compromise struts. An informed friend taught me "if the factory put it there, then it serves a purpose". They are certainly not in the business of making extra parts.

I am considering lowering my 997 1.25" all around with the PSS9 kit. Is that too aggressive?

Its a little annoying when I have to go up the street by my house diagonal so I don't bottom out. And some friends' driveways are barely navigable. If that doesn't bother you then 1.25" lower is probably fine. It depends on the bodywork on the car to some degree -- ZBlue996Kam's car has a front chin spoiler and now we can't get his car onto his trailer. Before you lower the car, check out any trailers you might use, frequently used driveways, etc... to make sure you don't spend the money on an alignment and then find out its too low, and have to do it again.

Yup.