Bridgestone/Praxis Suspension System
10-28-2003, 07:16 PM
#77
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Location: Warsaw, Indiana
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Car Info: 02 WRX Wagon White
No - I'm still working on it. I saw a pair of 3 gallon tank at a tool show last weekend that looked like they'd fit fine. Only problem is they were attached to a compressor and cost about $100.
10-28-2003, 08:29 PM
#78
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Car Info: 95 Legacy wagon
would anyone be able to custom fab a tank in the wheelwee that will fit in like a sub box?
contouring to the bottom of the wheelwell and making a flat panel on top...i think that it would make the most of the space.
I wouldnt want to work aroud the tank in a wagon trying to fold the seat... kind of a space hassle i can almost live with...
JAN
contouring to the bottom of the wheelwell and making a flat panel on top...i think that it would make the most of the space.
I wouldnt want to work aroud the tank in a wagon trying to fold the seat... kind of a space hassle i can almost live with...
JAN
10-28-2003, 08:51 PM
#79
wet blanket
I'll be the wet blanket ...
Liability is *the* issue for anything custom. The tank pressures up to ~120 psi.
Also, the size of the tank, 7 gallon, helps keep the air compressor from cycling as much. Though usually infrequent (unless showing off
) the tank is a reservoir that enables quick settling of the system when changing hts. as well as stabilizing the system with varying loads.
Remember, this system is designed to keep the 4 corners of the car at the calibrated heights. Therefore, a light load, heavy load, off balanced load, full to empty tank of gas, no matter what load difference there is from calibration ... those 4 corners will be maintained at the calibrated heights.
Although I suspect that the particular tank that Praxis selected was priced right as it is very common. That and it meets liability issues I suspect as being their primary criteria … but I don’t know for certain. And, like we have found, there are not too many choices.
Liability is *the* issue for anything custom. The tank pressures up to ~120 psi.
Also, the size of the tank, 7 gallon, helps keep the air compressor from cycling as much. Though usually infrequent (unless showing off
) the tank is a reservoir that enables quick settling of the system when changing hts. as well as stabilizing the system with varying loads.Remember, this system is designed to keep the 4 corners of the car at the calibrated heights. Therefore, a light load, heavy load, off balanced load, full to empty tank of gas, no matter what load difference there is from calibration ... those 4 corners will be maintained at the calibrated heights.
Although I suspect that the particular tank that Praxis selected was priced right as it is very common. That and it meets liability issues I suspect as being their primary criteria … but I don’t know for certain. And, like we have found, there are not too many choices.
11-13-2003, 01:52 PM
#80
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Join Date: Mar 2003
Location: Warsaw, Indiana
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Car Info: 02 WRX Wagon White
After an extensive discussion with Doug Gill (solo events, technical manager) at SCCA regarding the legality of the Praxis system in SCCA solo events, I can report that within the current rules structure, Praxis legality is as follows:
Stock Classes (S) - not legal *
Street Prepared classes (SP) - not legal **
Prepared classes (P) - legal
Modified classes (M) - legal
Street Touring classes (ST) - not legal **
Street Modified (SM) - legal
* S classes do not allow spring replacement.
** SP and ST classes require that the spring be replaced by a spring of the same type (coil with coil, torsion-bar with torsion-bar, etc.). Even though the air-spring does not alter the location or direction that the spring force is applied, it would be considered different and, therefore, not legal.
By analogy, it is interesting that other, very common and popular aftermarket products face this same quandary. Upgraded engine computers face the same classification status as Praxis.
Stock Classes (S) - not legal *
Street Prepared classes (SP) - not legal **
Prepared classes (P) - legal
Modified classes (M) - legal
Street Touring classes (ST) - not legal **
Street Modified (SM) - legal
* S classes do not allow spring replacement.
** SP and ST classes require that the spring be replaced by a spring of the same type (coil with coil, torsion-bar with torsion-bar, etc.). Even though the air-spring does not alter the location or direction that the spring force is applied, it would be considered different and, therefore, not legal.
By analogy, it is interesting that other, very common and popular aftermarket products face this same quandary. Upgraded engine computers face the same classification status as Praxis.
Last edited by Dexter@tirerack; 11-14-2003 at 11:47 AM.
11-14-2003, 11:29 AM
#81
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Join Date: Jun 2003
Posts: 5
Hey Dexter,
Was there anything said about use in winter conditions? A friend of mine was told by a rep from Tein, that their struts aren't well suited for winter use, as you will need to wash them off everytime they come in contact with snow. He ended up going with KW since they are stainless steel. I'm from Ottawa so we get our share of snow, -30 C temps, salt, sand, etc. Any info would be greatly appreciated.
Deuce
Was there anything said about use in winter conditions? A friend of mine was told by a rep from Tein, that their struts aren't well suited for winter use, as you will need to wash them off everytime they come in contact with snow. He ended up going with KW since they are stainless steel. I'm from Ottawa so we get our share of snow, -30 C temps, salt, sand, etc. Any info would be greatly appreciated.
Deuce
11-14-2003, 11:46 AM
#82
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Location: Warsaw, Indiana
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Car Info: 02 WRX Wagon White
No problem in the winter. The strut is powder coated, the air spring mounts are aircraft-grade aluminum, and the bags are rubber. They might run a little stiffer in the extreme cold because of rubber and pliability, but that can be corrected by looser (more loose) settings on the dampers.
11-17-2003, 11:43 PM
#85
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Join Date: Nov 2002
Location: Lindsay Lohan's Cleavage
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Car Info: MY02 WRX
Hey Dexter,
Sorry to keep buggin', but I'm still very interested. Any word on the below inquiry? Thanks.
- Logan
Sorry to keep buggin', but I'm still very interested. Any word on the below inquiry? Thanks.
- Logan
Originally posted by Logan
Has the developers done any lateral grip, 700 ft. slalom & track time comparisons versus various well known coilover brands (JIC, DMS, Tein, HKS, APEXi, etc.)? If not, can you find out if it can be done?
I've been searching for something like these since I first got my car. The flexability of the Praxis system sounds amazing. Everyday driveability on rough roads like the stock suspension and tight "rail-like" feel on the twisties like a set of coilovers.
If we can see comparison numbers and even if they're slightly less than the best coliover numbers, I'd get them in an instant. I know others feel the same.
- Logan
Has the developers done any lateral grip, 700 ft. slalom & track time comparisons versus various well known coilover brands (JIC, DMS, Tein, HKS, APEXi, etc.)? If not, can you find out if it can be done?
I've been searching for something like these since I first got my car. The flexability of the Praxis system sounds amazing. Everyday driveability on rough roads like the stock suspension and tight "rail-like" feel on the twisties like a set of coilovers.
If we can see comparison numbers and even if they're slightly less than the best coliover numbers, I'd get them in an instant. I know others feel the same.
- Logan
11-19-2003, 01:47 PM
#86
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Posts: n/a
Dexter,
First - Thank you for all the info you've provided and this is my first post ever so I apologize if any of these questions are stupid.
In your post on 7/8/03 You reported:
"I asked how the system was initially calibrated, and it turns out the user programs the three ride heights with the car up on three jacks and measuring from the ground to the fenders on a flat surface. The recommended touring ride height would be OE, and the sport mode should be set at 25mm lower and then race mode should be set at 50mm lower."
I'm really curious what the possible adjustment options are.
I commute in and around the New York City area and have to deal with roads that range from fairly smooth to Rallycross wanna-bees. It's doubtful I would ever autox but I might want to do a driver's school at a road course one day. I was thinking some people may want to have Touring, Sport & Track for the warmer months and then recalibrate to Rally, Touring & Sport for the colder months. Has any research been done into a setting that would be optimal for the 1/4 mile? It might help aerodynamics to practically scrape the track.
Is it possible to have a non-standard settings such as Higher Than Stock?
Does the height difference between positions have to be 25mm?
Is 50mm the maximum drop from Stock ride height?
I assume you would have to have different initial alignment specs for anything other than the 3 standard settings. If other height settings are possible, does Praxis have alignment recommendations for them?
Thanks,
Neal
First - Thank you for all the info you've provided and this is my first post ever so I apologize if any of these questions are stupid.
In your post on 7/8/03 You reported:
"I asked how the system was initially calibrated, and it turns out the user programs the three ride heights with the car up on three jacks and measuring from the ground to the fenders on a flat surface. The recommended touring ride height would be OE, and the sport mode should be set at 25mm lower and then race mode should be set at 50mm lower."
I'm really curious what the possible adjustment options are.
I commute in and around the New York City area and have to deal with roads that range from fairly smooth to Rallycross wanna-bees. It's doubtful I would ever autox but I might want to do a driver's school at a road course one day. I was thinking some people may want to have Touring, Sport & Track for the warmer months and then recalibrate to Rally, Touring & Sport for the colder months. Has any research been done into a setting that would be optimal for the 1/4 mile? It might help aerodynamics to practically scrape the track.
Is it possible to have a non-standard settings such as Higher Than Stock?
Does the height difference between positions have to be 25mm?
Is 50mm the maximum drop from Stock ride height?
I assume you would have to have different initial alignment specs for anything other than the 3 standard settings. If other height settings are possible, does Praxis have alignment recommendations for them?
Thanks,
Neal
11-19-2003, 02:35 PM
#87
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Location: Warsaw, Indiana
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The system can be indexed at three points anywhere within the suspension travel. Their recommendations are the most common settings possible. However, in certain situations, one might want higher than stock and in other situations sitting on the bump stops might be optimal. That's no problem, but it's your call. "Collateral damage" can occur if you stray too far from normal settings.
11-19-2003, 02:50 PM
#88
My $.02 worth, I have a Praxis system installed.
There is quite a range of travel available in our suspension. I have only had mine set/calibrated to the Praxis suggested settings, but have considered others just as you are thinking. For winter's deep snow, I was thinking about a SUV height. That might be as high as possible & maybe allowing a bit for some travel. That height I do not know, but imagine how high the car is when jacking it up just before the tires leave the ground.
As far as I know, the primary consideration is the change in wheel alignment that occurs from one height setting to another. Their suggested settings are an optimum ... and a place to start. You might want your best for "tire wear alignment" done at the height that you expect to do most of your driving.
The caveat to that, the Praxis alignment suggestions are made at Touring/OEM ht. The alignment that results at their Track height setting does work pretty well at the track. I realize that this is pretty vague ... so maybe Dexter can get all the alignment numbers laid out for us. :banana:
There is no limitation on the "delta" between height settings. The only limitation in that regard is that there are three positions available. Since there is a height sensor at each wheel, they all actually work independantly; so a "drag" height with the front end at a different ht than the rear could easily be set. Again, alignment questions.
I don't know how low the lowest is that the subies can be set. You might try to find someone that has their car "slammed" as the Praxis system would likely allow that ... as an idea of the range of travel available. For track use though, you would lose the benefit of any suspension when riding on the rubber stops. Having been at a few different tracks ... aerodynamics is the least of my problems. Although I am considering getting a lip in front that attaches to the stock bumper ... one that I could remove when conditions require greater clearance
Maybe Dexter knows if Praxis has alignment suggestions for other height settigs.
There is quite a range of travel available in our suspension. I have only had mine set/calibrated to the Praxis suggested settings, but have considered others just as you are thinking. For winter's deep snow, I was thinking about a SUV
height. That might be as high as possible & maybe allowing a bit for some travel. That height I do not know, but imagine how high the car is when jacking it up just before the tires leave the ground. As far as I know, the primary consideration is the change in wheel alignment that occurs from one height setting to another. Their suggested settings are an optimum ... and a place to start. You might want your best for "tire wear alignment" done at the height that you expect to do most of your driving.
The caveat to that, the Praxis alignment suggestions are made at Touring/OEM ht. The alignment that results at their Track height setting does work pretty well at the track. I realize that this is pretty vague ... so maybe Dexter can get all the alignment numbers laid out for us. :banana:
There is no limitation on the "delta" between height settings. The only limitation in that regard is that there are three positions available. Since there is a height sensor at each wheel, they all actually work independantly; so a "drag" height with the front end at a different ht than the rear could easily be set. Again, alignment questions.
I don't know how low the lowest is that the subies can be set. You might try to find someone that has their car "slammed" as the Praxis system would likely allow that ... as an idea of the range of travel available. For track use though, you would lose the benefit of any suspension when riding on the rubber stops. Having been at a few different tracks ... aerodynamics is the least of my problems. Although I am considering getting a lip in front that attaches to the stock bumper ... one that I could remove when conditions require greater clearance
Maybe Dexter knows if Praxis has alignment suggestions for other height settigs.
11-20-2003, 11:11 AM
#90
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Join Date: Mar 2003
Location: Warsaw, Indiana
Posts: 681
Car Info: 02 WRX Wagon White
Psi,
The suspension specs, as supplied by Praxis, are as follows:
Praxis recommended specification (one-time setting done in touring mode)
Touring, Front: -1.6 deg camber, .060 inch toe-in
Touring, Rear: -.5 deg camber, .040 inch toe-out
Alignment changes as ride-height is lowered to 'Track' (these are the resultant numbers as the car is lowered 50mm to the Praxis' recommended touring mode)
Track, Front: -2.3 degree camber, .120 inch toe-out
Track, Rear: -1.4 degree camber, ~0 toe
As far as recommendations for settings if your touring height is different, that's tough. The camber and toe changes aren't perfectly linear throughout suspension travel, so using the above numbers as fuel to create a formula, it would be close but not right on the money.
The suspension specs, as supplied by Praxis, are as follows:
Praxis recommended specification (one-time setting done in touring mode)
Touring, Front: -1.6 deg camber, .060 inch toe-in
Touring, Rear: -.5 deg camber, .040 inch toe-out
Alignment changes as ride-height is lowered to 'Track' (these are the resultant numbers as the car is lowered 50mm to the Praxis' recommended touring mode)
Track, Front: -2.3 degree camber, .120 inch toe-out
Track, Rear: -1.4 degree camber, ~0 toe
As far as recommendations for settings if your touring height is different, that's tough. The camber and toe changes aren't perfectly linear throughout suspension travel, so using the above numbers as fuel to create a formula, it would be close but not right on the money.