Dexter@tirerack

Today's impression:

Something I realized that I should mention - the valve block. The clicks made by the valves are noticeable. When you're stopped and hit the switch, you hear about 5-8 clicks as the system adjusts. This all happens within about 8 seconds. It takes about 3 seconds more with the struts tightened because they move slower. Then the clicks stop and not heard again until you make another adjustment. This is my experience.

When you make the adjustment while driving, there's about a dozen clicks and they largely stop in about 11-13 seconds, depending on the roughness of the road. Here's the thing though - on a rough road, there's about a 3 minute window that you will hear some clicks (three is the most i've noticed so far) as the system finalizes the settings.

When I asked if the valves could be made silent the engineer showed me the two 2" openings between the rear seats and the trunk. The valve block won't change, but the noise will be heard less in the sedan with "virgin" seats. However, on the wagon, the noise will be of the same volume I'm hearing now. It doesn't bother me at all, it sounds like someone in the back seat hitting two pinballs together.

This isn't a bad thing in my opinion, but nonetheless should be mentioned.

Overall, still enjoying the system to its fullest. I'll take some pictures of the car at the ride heights and try to post them for you so you can understand the "autocross look" that I speak of.

Dexter@tirerack

I'm having a little trouble linking full size photos from my Yahoo account. Here's the link to my Yahoo photos which are a little small, but should give you a good look. I'd be glad to email ~800x600 size photos of your favorites if you pm me your email address.

I'll put together a "final thoughts" post in a bit...

Dexter@tirerack

The controller isn't too bad - it doesn't fit flush like the cruise/fogs do. it hangs above and below about 3-4mm but doesn't look bad at all. It can either be mounted in the blank next to cruise or the one to the right of that.

Space? Well, the tank is about the size of a 6 1/2" bazooka subwoofer - that's the only think you have to worry about space for. Everything else is hidden behind body panels (even in the wagon). All mounts and brackets are specifically designed for the Imprezas - which makes for a real "bolt on" installation.

I'll try to bring in my camera tomorrow and take a picture of the control switch and post it tomorrow night on the Yahoo photo link.

Wingless Wonder

iTrader: (7)

Originally posted by Dexter@tirerack
I'm having a little trouble linking full size photos from my Yahoo account. Here's the link to my Yahoo photos which are a little small, but should give you a good look.
Missing the final 'slash' in your link... try this:

Dexter@tirerack's Praxis Suspension System photos.

--
0==WW==0
"…axles of evil…" - george w. bush

Dexter@tirerack

Update: Drove two Praxis equipped cars on the street and on the track yesterday.

I didn’t learn much new in the road rides, but this was my first “on track” experience with the system. We did a comparo between one of the cars in Sport mode and the other in Track mode. Other than the modes, the cars were identically equipped and in stock condition, other than the Praxis system and 225/45-17 Bridgestone S-03s.

The first car, in sport mode, felt pretty good on the track. Understeer was controlled (unlike my wagon with stock suspension), but still subtly present. After finding the limits of the car on the first lap, I felt I could control the car well for the second and third. Sidenote: It’s amazing how AWD helps on a track during weight shifts, especially noticed after spending so much time testing on RWD cars.

The main difference between the Sport mode car and my wagon on the track was the reduced sway and understeer with the Praxis car. My car exhibits “howling” understeer and occasional oversteer when coaxed, which looks great but costs time. The sport car felt much more controlled. Less need to let off the power as well as correct oversteer during major weight shifts was a welcome feeling.

Then came the car in Track mode. Here’s where things got fun. With an additional quarter turn of the damper adjuster and 25mm of button induced lowering came a well balanced autocrosser. I quickly adjusted to the lessened understeer and threw the car around the track in a controlled manor. Skid pad was great – on lap two and three I was stuck to the cones thanks to the predictability and easily correctable understeer. I carried much more speed in the weight shifts as well with no oversteer at all – and really asked the brakes to work hard after the short straight.

All in all, I shaved just under a second off my time from Sport to Track mode. Not bad for a ~30 second layout. If only I had more laps…

Next issue: the rebuild interval question. I spoke to my contact at H&R recently, and got a good inside scoop on the “guts” of the struts. First off, I respect this gentleman because of his vast experience in the industry and his knowledge of how dampers have evolved over the years – he builds his own dampers and turns his own springs to suit his needs, so he knows his stuff.

He said that upon examination of the damping mechanism and the adjustable components, there is no inherent weakness in the system that would require rebuild during its service life – which includes aggressive driving and track use. I was a bit skeptical, so I just asked “where’s this thing going to fail, when it does?” After a giggle, he indicated that the only wearable part in the system would have to be the o ring seals between the shaft and the strut body. Then we moved into the discussion about the spring angle and side loading. The result of the angle of the spring brings side loading to near zero during the vast majority of driving situations. Well, comparatively speaking, the o-ring seal integrity in a system with no compensation for side loading has been accepted as the industry standard for high performance suspension systems. That inherent weakness is overcome with the synergy of the Praxis spring/damper combination. I never got a mileage estimate – which, in my opinion, was good. I got the impression that the internals were designed and built to last significantly longer than traditionally expected from high performance and racing suspensions.

Also - I'll post the picture of the dash-mounted switch tomorrow evening.

Dexter@tirerack

The picture of the switch is now included in the "Praxis" album HERE. Also we have a brief write up on the system HERE.

Dexter@tirerack

Well, what's best depends on who you are and what you do. Here's me: Aggressive street driver, occasional autocrosser, possible rally experimentation, 120 miles/day driver for work, possible heavy snow, family guy (not a lot of time to fiddle anymore). I truly see the need for a "hybrid" type car, but consider stock suspension an unacceptable compromise.

My drive to/from work is essentially straight, with about 6 places that I corner hard enough to hear the tires. I can't deal with the beating the whole way home because I usually drive with my head on the headrest - but I want to be able to fling the car around specific corners quickly, then smooth things back out.

I would like to actually compete in my class at autocrosses rather than being there just for fun and driving experience. I also need to drive my wife and kid (s(this November)) to the track with me.

The guys at Rally Cabal are too friendly to keep ignoring. I am dying to try rallycrossing.

So, considering these things, the Praxis is for me. Is it for you? It's a big investment so I understand (and once shared) any skepticism, but after getting to know the system, I'm a believer. I will always be straightforward with my impressions as well as answers to your questions; so please ask.

Yes, I benefit when you buy the Praxis from me. But, on the other hand, I miss many opportunities if time is spent dealing with product problems or unhappy customers.

Dexter@tirerack

The Track damping setting is okay on the highway, but it will wear on you a bit. I originally said that was where I'd keep it, but after another round trip, I think I'd stick with the Sport mode for best all around results. The set price from us is indeed $3450. The ETA is still August 5th, but may jump back a couple of days but I expect it to stay in the first half of the month.

EWThompson13

This system sounds incredible. I can't imagine staging for my next auto-x run, having someone ask for a passenger ride, and then being able to re-set the corner weights instantly!!! My question is, will these struts work with aftermarket camber / castor plates??

Thanks for all of you insightful info Dexter.

DarriiffftaaHuy

iTrader: (1)

hey derek, if the "stock" setting is in fact similar to stock, then be careful of rallyX's with bad ruts and such if you value your car. the last event my friends and I attended, my friend with stock suspension came home with a tire that lost its bead, and 3 exhaust leaks from when he bottomed out and smacked his exhaust. we witnessed a blown rally tire and at least 4 blown street tires. and I even bottomed out with my 2" lift! (but it did no damage cuz it was minimal)

But I am curious to see how it performs in the dirt, so just stock up on wheels and tires, go tear it up, and let me know how it does... & enjoy cleaning out dirt from the car for the rest of your life.

Dexter@tirerack

The corner weighting is neat. The car actually levels, then corner weights. The leveling is changed a minute (mine-yoot) amount to facilitate the corner weighting but it brings the cross weight difference to under 21 lbs. compared to stock between 90 and 100 lbs.

Camber plates have not been tested on the system yet. Fronts that fit stock should fit with the Praxis - as long as the hole is big enough to accept the Praxis H&R damper rods. The H&R's are 14mm in diameter - OE WRX has a 14mm shank, which reduces to a 12mm thread. As long as the camber plate is designed to accomodate the 14mm shank, it should fit.

On the rear, you will need to check how the camber plate locates the top of the air spring (what would be the upper spring perch on a coil spring installation). The OE mount positioned the upper spring perch down from the car's sheet metal. The re-engineered Praxis mount positions the upper spring perch much closer to the car's sheet metal - about where you would expect a camber plate to position it. If the air spring cap (the part similar to the upper spring perch) is lowered, the air spring rate will change. If this happens on only one end of the car, the ride and handling will change.

Here's the thing though: You may not need them for your application. The Praxis struts are engineered to accomodate up to 3 degrees negative camber on the front axle. Please note that Praxis can only recommend -1.6 degrees camber, as tire wear degrades significantly with high static camber angles. The recommended settings at the Touring level are:

-1.6 deg, .060 in. toe in Front
-.5 deg, .040 in. toe out Rear

When lowered to Track mode (-50mm), the resultant numbers obtained from the above settings are:

-2.3 deg, .12 toe out Front
-1.4 deg, 0 toe Rear

These settings provide great balance, as I experienced on the track.

Also, using the stock, rubber isolated mounts keeps things much quieter. So, upon consideration of the above specs, if you desire the use of camber plates, tell me which ones and I'll check it with the Praxis engineers.