[Turninconcepts.com]

It is with great pleasure and relief that TiC would like to let you know that the next level in Subaru enjoyment is now available!!

This is the big project that we have been working since last spring, and where a majority of our R&D has been focused. In the end, we have come up with a coilover solution that will prove to be one of the best and most comprehensive setups available.

This is our SST setup. SST stands for Single Adjustable Street and Track. The target customer is guys who daily drive the car, but make it to the occasional track day.

Price is $2200 shipped in the US, and includes the following:

dampers
main springs
helper springs
spring couplers
thrust sheets
adjuster knobs
aerator disks
bump stops
bump spacers (rear)
upper perches (front and rear)
rear adjuster extenders
dust boots

Below are some of the details on this setup. We encourage you to look around. There aren't many on the market that provide this level of information.

The dampers:

Height, and travel:
The dampers are based upon AST's 1-way adjustable setups with the adjustment being to rebound. One thing that makes these a very nice starting platform is the OBSCENE amount of travel on the setups.

For travel here is the numbers that Stretch JUST posted up on IWSTI, where most of the development work has taken place. For those of you who don't know Stretch has picked up a set of these prototypes so that we can collaborate with a real world user with outside influence and feedback (so we can listen to what the people want). The reason I'm posting Stretch's numbers is to make this as third party, and away from as much of the vendor marketing BS as possible.

Originally Posted by Stretch

(Clint)This is at a ride height of 14" front and rear as measured from hub center to fender lip.(/Clint)

So, at that ride height, one would have 3 inches of droop in the front and 2.5" of droop in the rear. You'd have over 3 inches of bump travel remaining up front and over four-and-a-half inches (!!!) of bump travel remaining in the rear.

Valving:
We tried an off the shelf setup, and while it was ok, it could be better. As a result a revalve was needed. The outcome of the revalve was this:

1) Move to the competition style valving to allow for a larger orifice.
2) Evaluate the current shim stack, and make changes to it based upon our need (and spring rates choosen - more on the springs later)

The result of this revalving was, what we feel, is nothing short of amazing.

Below is some charts. The Dyno plots were actually done by Koni USA on their very nice Roehrig shock dyno setup. The settings tested were 3 down, 5 down, 7 down, 9 down, and 11 down. When I say down, I mean down from full stiff (you ALWAYS want to adjust in relation to the needle valve being fully closed. In this case we're talking down from stiff).

Velocities used were:
0.05 m/s
0.13 m/s
0.22 m/s
0.33 m/s

Stroke used was 50mm.

These were the exact same settings we used to dyno plot the Ohlins sportlines, by the way, so we have a direct 1:1 comparison.

Front:


Rear:


Further on valving:

Now, some of you may know about Stretch's suspension worksheet. If you don't I suggest you look into it as it's a great tool for determining all sorts of ideal suspension setups. Granted, it takes a decent amount of reading and understanding to comprehend everything in it, but that's ok. To get comprehension all you need is a good head on your shoulders, the ability to search, and willingness to put in the time to read and understand.

On top of Stretch's worksheet there have been others that have also been working the numbers on all of this fun stuff. One person who really stands out in all of this is 4Banger who has been communicating with us and Stretch in all of this to really put together a very comprehensive mathematical model of the Impreza suspension, and what can be done with it. He also has some really beautifully assembled graphs that are easy to read.

So, 4Banger went to town with his spreadsheet, and understanding of critical damping based upon what we've put together. He put together some really nice charts to see where the TiC setup stands when comparing dyno plots to the given parameters of the car. While a dyno plot is good, this data is even better, and here's what he came up with for each tested setting for the spring rates we've been working with:

[Turninconcepts.com]

Springs:

The springs we chose have the rates of 392lbs front and 280lbs rear. These are the same rates as what comes on the Ohlins, and according to all our calculations, Stretch's calculations, and 4Bangers calculations this puts you at rather aggressive frequencies front and rear, but those frequencies are appropriate for the target market of this setup (remember, aggressive daily driving and light track work).

As for the brand of spring - we went with Swift. There's a few reasons:

1) We already carry Swift springs. The reason we carry them is for the same reason we carry the parts we carry. The quality is good, they do what they say, the support is good, and the prices are realistic.
2) The Swift springs have a larger linear range than others. Swifts are linear from 20% of travel to 80% of travel. Eibachs by comparison are 30% and 70% (as stated by Eibach on their own website).
3) The travel of the Swift springs. The material that Swift uses is very nice in that it not only gets you a longer range in linear rate, but is also allows for fewer coils to get that rate, and the wire is thinner on comparable springs. This means that you have more travel out of the spring before it binds. Given the obscene amount of travel on these dampers this was a BIG thing we had to consider.

For the Swift springs we are using 60mm ID springs both front and rear.

The front springs have a 203mm free length (~8") and have a max stroke of 133mm (~5.2").

The rear springs have a 228mm free length (~9"), and have have a max stroke of 145mm (~5.7").

We are also using helper springs. This is something that we here at TiC feel is fairly important given the amount of droop travel these have.

The helpers we are using are the same for front and rear. They are a 60mm ID spring, have a freelength of 60mm (~2.4") and a stack height of 21mm (~.8"). The rate is 84lbs. Additionally, the helpers include thrust sheets. These are simply thin metal shims that sit on the adapter from helper to mainspring. The purpose is to allow the spring to rotate as it compresses and extends. This will cut down on any kind of "spring motion" binding, and make for a smoother motion from the suspension when compared to a setup that does not have these.

As for straight up tech comparison between the Swift springs we use vs. the Eibach springs that Ohlins uses we are working on getting that. One of the gentlemen we know has access to the equipment to get this data, and we are working hiring him to do this work.

[Turninconcepts.com]

Upper perches:

We weren't happy with the upper spring perches that come with ASTs, so in the usual TiC fashion we decided to make some changes. Changes that we feel are for the better.

Our unhappiness came from the fact that the perches are so long. Take a look at this pic, and you'll see what I mean:


The problem this creates is that the "cup" for the perch is so deep that it creates a concern of hitting the body of the strut on the inside if you bottom out, and are running short bump stops.

There are two solutions to this.
1) Use a bump rubber that's fairly long. While this is great for the rear since you most likely won't ever bottom out the rear, and it makes for a very nice progressive bump in the rear we weren't happy about how long it had to be, and it takes away some strut travel. This we were not happy about when it comes to the front.
2) Redesign the upper perch to be more shallow. This would fix a good bit of the clash problem, and would allow us to run a shorter bump rubber.

We're going to go with option 2 for at least in the front. We're still working with Stretch to determine if we should do the same in the rear (the downside for the rear is that if you're using the stock top hat you have to cut the dustboot holder cup on it).

This allows more travel, safer travel if you bottom out, and allows the safe use of a shorter bump stop.

Now, this was no laughing matter, so here's some more info:

Originally Posted by Turninconcepts.com

Prototype front upper perches are in.

Here's some info:
12.57mm (.495") shorter than perches that ship with the ASTs.

Upon full compression amount of strut shaft left exposed after interference: 8.18mm. This is more than enough given the bumper we'll be using. Lets run the numbers: bumper freelength 2 5/8" ~ 66.675mm. Using the common compression number of 75% for bumpers that leaves 25% left that's considered uncompressable. That comes out to 16.67mm. So basically, you could compress that bumper to 12.5% of original free length before perch clashes with damper body. Something that's just not going to happen.

Heck, even with the shorter AST bumpers are 42mm. 25% of that one is 10.5mm so you could even get away with running the shorter ones, and not worry about rising spring rate for a little bit longer.

Now for some pics:

[Turninconcepts.com]

More on the Upper Perch:

Now, since the upper perch is such an important part we did some further testing to the capabilities we have here.

First we did a FEA on the stock AST part and the TiC part. First load we tried was 6,000 lbs. This showed us that both parts will fail in the same way. That way we at least know we're consistent in failure with the stock part.

Next we ran the FEA with a load of 3,000 lbs. Granted if you ever see one corner with a 3,000 lb load you've got bigger problems than just a perch it gave us a better idea of where things stand. The loads placed on the failure point are well below the capabilities of the material we uses.

Then we had some prototypes made, and I got to break one!

Here's the info on that:

Originally Posted by Turninconcepts.com

Well, that was a fun way to blow some money.

I felt I needed to test the upper perch to make sure it will fail where we expect, and how we expect given a worse case scenario of the spring bottoming out and the entire load being transfered through the perch.

You'll remember from a previous post that we had some FEA run given a load of 3,000 lbs. You'll also remember the predicted failure would be at the top ring where the step is to meet with the tophat. Also remember this is the same place we see the highest loads for the AST stock part.

On a side note - if you ever see vertical forces of 3000 lbs on one corner as a single catastrophic load then you've got bigger problem than just a spring perch.

Now, on to the rig. I felt I couldn't just throw it in a press and go. I needed something to press on the spring seat since that's where the real world loads come into play. Well, I could use a spring, but that would be a waste of a perfectly good spring. So I needed something close. It had to be big, it had to be heavy, and it had to be stronger than what I was testing.

Enter the 2 3/8" Craftsman socket. It's big, it's bad, it's beefy.

A few pics:

[Turninconcepts.com]

Upper perch testing - the result:

Originally Posted by Turninconcepts.com

So I popped this puppy into our 12 ton hydraulic floor press (great for changing wheel bearings by the way).

Donned my protective eyewear, positioned the part, put a steel blast shield in front of it (glad I did), and started cranking away.

Now, I'm not a small guy. 6'3" 250 lbs. All muscle (man, I wish). I was cranking on this puppy. Toward the end I ended hanging from the lever for the press just to get things to move.

I decided it was going to be the perch, the press, or me. Something was going to go pop, and kept pushing it until something did.

With a nice loud explosion followed by the resounding ring of metal flying out of the press we had a failure.

So, after searching around the garage for the parts that went flying I found them. The end result is failure exactly like the FEA predicted.

Now, given the stress on the part, the load put into, the FEA model, and the design that you won't bottom out your springs I gotta say that this one looks good in my opinion.

Oh, and for those of you interested in the pics, here they are:






If you want to see the big, fully detailed images follow these links:
http://turninconcepts.com/forums/ast...est/fail_1.jpg
http://turninconcepts.com/forums/ast...est/fail_2.jpg
http://turninconcepts.com/forums/ast...est/fail_3.jpg
http://turninconcepts.com/forums/ast...est/fail_4.jpg
http://turninconcepts.com/forums/ast...est/fail_5.jpg

[Turninconcepts.com]

Top hats:

We are not planning on including top hats with these. There are so many good ones that people have picked up we don't want you to be stuck with redundant equipment.

For those of you who feel you need adjustable top hats we have been working with Vorshlag on making some for the Subaru. There's another thread on the progress with those bouncing around here somewhere. For those of you who want to stick with your stock top hats - that's fine. Throughout all of this we have used the common denominator of stock equipment. The reason is because that's all we can anticipate will be or can be common across every single car.

Wagon guys - pay close attention to the rear tophats. Even if not for these dampers, but other coilovers you've carried over from the sedan. Since the rear hats will be camber adjustable, and sedans have a deeper knuckle clevis than the wagon setup you'll be able to use these plates to correct your strut angle (something that's been needed for a LONG time for you guys)

Price:
I know everyone is going to ask this. We have ROUGH idea on price for these. Since this is a vendor announcement thread we cannot post up pricing so even if we had an exact number you won't see it here.

When:
Hopefully soon. We are working hard on the last bits and pieces to get these finalized. 4Banger and Stretch have been VERY valuable in this regard, and it warms my heart to see members such as them take such a keen interest in the community that is Subaru ownership.

Closing thoughts:
These are the make it or break it part for TiC. Tony and I have been doing TiC for about three years now. For the past year I have been doing TiC full time just trying to grow the business to the point where it can stand with both of us doing this full time (something we would really like to do). Right now it doesn't even really stand with just me doing it full time (as my badly beaten savings account, and frustrated wife can tell you).

We realized a while ago (last winter actually) that in order to be taken seriously in the world of Impreza suspensions we HAVE to offer something like this. Otherwise, we'll just be another "also ran," and that just doesn't sit right with me. If we're just another "also ran," and not toward the top when it comes to suspension setups then there's no point in doing any of this.

Through all of this exercise I have pretty much kept a log of what's going on over on IWSTI. When I have information and numbers to share I have done so. I have tried to make this as open as possible for a few reasons:

1) So you can see some of the trials, tribulations, frustrations and joys that vendors who develop things go through. Hopefully, this will lead to a better understanding of what is involved in something like this, and will instill a deeper appreciation of what not only us, but others go through to bring you good parts.

2) The information is there for you to start to make an informed decision when it comes to buying a coilover setup for your car. If you don't understand the data then explanation is a short step away in educating yourself. This will help not just in looking at this setup, but in looking at any setup, and achieving a greater understanding of how and why suspensions work.

3) It's fun!

[evilSTi7]

bump for some awesome sounding coilovers!

[WC LATHE WERKS]

ready to purchase

[MKTURBO]

Clint i'll be calling you today to official spend way too much money......put a set aside for me!