[thrlskr]

Rootus,

I haven't been active here in last few weeks. Why did you get rid of the PSS-9?

[Rootus]

Originally Posted by jaydubya

My only concern about this setup for my own use is the ride height. Prodrive says that it lowers the front 30 mm and the rear 10 mm. In my area 30 mm of lowering at the front will make my car into a snowplow during the winter

I think that's a legitimate concern -- the only setup I've driven in snow was the OEM strut/Pink spring/RCE lowering plate combo, and it was ~20 mm lowering in the front, ~10 mm in the rear. With anything more than a few inches on the ground (the most we ever get here in western Oregon ), it was plowing a little now and then. Another 10 mm and it would have been a sure bet. I definitely can't be using the RCE lowering plates with the RB320 springs .

However, if the front struts are indeed identical to the OEMs, I wonder if I could use my existing Prodrive '05 springs on the front? I guess it is possible that those springs would coil bind before the struts ran out of travel...

It would be easier to tell that if Prodrive would tell us what the spring rates are. I guess it's a deliberate secret, for the same reason that the rear perches are custom.

If you get a chance to test-fit a "regular" front spring to the front struts I would be very interested to hear if they fit ok.

I set the pink spring in the seat on the front and it fit in exactly the same way as on the OEM strut. I could install the top hat and tighten it down, but that's about as far as I think I can test it.

Dave

[twiSTies]

the stance looks great, but isn't that too much lowering in the front for the a-arm geometry?

[jaydubya]

Originally Posted by Rootus

I set the pink spring in the seat on the front and it fit in exactly the same way as on the OEM strut. I could install the top hat and tighten it down, but that's about as far as I think I can test it.

Dave

If the spring fits on the lower perch and in the top hat then that's all I would need to know

Once you haved these installed, if you could get measurements from the hub center to fender lip that would also be helpful, I could compare them to my current setup with OEM struts and Prodrive '05 springs to get an idea how much lower it would be.

Cheers,

Jeff

[Rootus]

Originally Posted by thrlskr

Why did you get rid of the PSS-9?

I decided I didn't want any more noise, even when it just occurs at low speeds in parking lots. Maybe I'm getting old . I realize now that it would be next to impossible to have a set of silent coilovers, at least as long as there are helper springs involved. Perhaps if they came up with a method for locking the springs to the perches...

[holycow]

Originally Posted by jaydubya

In my area 30 mm of lowering at the front will make my car into a snowplow during the winter

30mm is only a tiny bit more than an inch. A single inch makes that much of a difference? It turns your car from totally normal to a complete snow plow?

[jaydubya]

Originally Posted by holycow

30mm is only a tiny bit more than an inch. A single inch makes that much of a difference? It turns your car from totally normal to a complete snow plow?

Yes.

The stock height is really borderline. Nice thing about the Prodrive '05 springs for me is that they lower the car a very small amount (almost none in the rear). We get 400" of snow a year at my house. Often it comes in 12" increments...

[holycow]

Originally Posted by jaydubya

Yes.

The stock height is really borderline. Nice thing about the Prodrive '05 springs for me is that they lower the car a very small amount (almost none in the rear). We get 400" of snow a year at my house. Often it comes in 12" increments...

Sounds like you need a 4WD lifted truck...

[jaydubya]

Originally Posted by holycow

Sounds like you need a 4WD lifted truck...

Naw, Subarus are great in the snow. Throw on some snow tires and you are set. I've never gotten stuck in any of my Subarus, and the STi is my fourth one. However its ride height is a bit lower than the wrx so it requires some planning in the snow.

With the STi and a season pass I'm all set...

[Rootus]

Originally Posted by jaydubya

If the spring fits on the lower perch and in the top hat then that's all I would need to know

Well, the spring fits like a glove in the lower perch. And the top is guaranteed to fit -- because you have to reuse the OE ones.

And it's that second point that I felt like mentioning in this post. I think it's worth pointing out to anyone considering this kit that they should be aware of the OE upper perch and rubber isolator requirement, in case they're converting back to fixed perch from coilover or some other situation that denies them access to the stock struts.

Luckily I have two sets of OE struts, so I have no shortage of hardware. Except for top nuts, for some reason. I'm kinda surprised Prodrive didn't include new ones, since lock nuts are only supposed to be used once. Bilstein included new ones with the PSS9s.

[wrinklefree]

So how does the setup feel??

[stretch]

I hope you guys don't mind the repost from here, but it should be somewhere in the "suspension" forum I think:

===

I think I just spent an hour on the phone with Dan. I'll hit on some points that I think everyone will be interested in hearing:

- Dan doesn't like numbers. However, he's very happy to talk about Prodrive products and concepts without getting into specifics. I thought he was a pleasure to talk to and he extended the same welcome to others should they have questions.

- These DO have more bump travel than the stock struts, but just a little. I don't have an exact number, but I think having just a little over stock would imply ~2.25 inches. For a car lowered this much to have stock-like travel is good, and I was relieved to hear this. I don't know how this compares to the various coilover sets out there, but my guess is many coilovers have a little more. I didn't ask about droop travel.

- The lower spring perch in the rear is a totally different design to keep costs down. Bilstein doesn't have the tooling to match the stock design, thus it would be expensive to make it.

- They're using a much more progressive bump stop than stock, perhaps similar to the one with their lowering springs. (Indeed, that's the secret to the ones with their lowering springs- I run them now and can attest to this.)

- The progressive spring design is there to combat "stiction" issues inherent in any inverted strut design. I don't know how steeply it ramps up or what the rates are, just that the rate goes up just after ride height to allow the strut to start sliding as easily as possible.

- Spring rates are unknown still, however: Dan did make the comment that the most hardcore Ohlins 4-way adjustable tarmac setup (sitting next to him) was running something like 430lb/in front, 360lb/in rear springs (quite low compared to what many sell) and went on to say the concept of "firmer = better" was totally wrong. Speculate!

- Sway bar rates are unknown still. Dan said the arm length on the bar is not the same as stock, so the 22mm bar could act more like a 21mm bar or a 23mm bar. I don't know. The rubber bushings are a smaller diameter so that they are pretensioned once mounted. I wish Dan could be more specific about the rate of the bar, but given that it's adjustable, I guess it'll come down to user preference anyway.

- The aerodynamics (caused by the forward rake in ride height) are a very significant part of the package. Don't quote this, but it sounded like it increased downforce up front while reducing drag at the rear.

- The struts are non-adjustable because that allows Prodrive to be much more specific with the valving. Adjustable PSS9's aren't accurate enough. (Dan made the comment that the new PSS10's are a much improved design.)

- The struts are slotted to add about half a degree of camber over stock.

- I believe Dan was being very sincere when he said he was giddy how well the RB320 setup drives (combining comfort and performance). He hates the stock suspension and mentioned several technical reasons for its shortcomings (all of which we sort of already know but it's good to hear them validated by engineers).

[05_GD7]

Awsome points -

Looks like something I really wanna consider in my choice between RCE Black/Ohlins Fixed vs Prodrive RB320

[SOLUTION]

Originally Posted by stretch

- They're using a much more progressive bump stop than stock, perhaps similar to the one with their lowering springs. (Indeed, that's the secret to the ones with their lowering springs- I run them now and can attest to this.)

I don't see bump stops listed in the parts list for the suspension. Do you think it's considered part of the strut? I don't see the bump stops in any of the picturers either.

[stretch]

All struts have (or at least should have!) bump stops. Since the Bilsteins are an inverted design, the bump stop is inside. You could see it by removing the nut on the bottom and pulling the strut body out, the same thing you have to do on a stock STI strut.