Please Help Me Put Together a Suspension Package
#61
Upper and lower control arm angles primarily alter the camber, as they travel to their relative extremes....virtually no affect on the caster. And the arrangement of the 928 control arms make for much smaller camber changes than say a lowered 911, that we don't have to fight this battle as much as we have had to do on prior vehicles I am very familiar with. Toe change is a very interesting "study", on a 928. There isn't very much, until extremes occur, so under "normal suspension' travel "bump steer alterations are not really necessary. However, on this particular vehicle, with the suspension travel we have available, we do utilize a custom hand made bump steer system, with custom tie rods and monoballs to keep toe changes to a minimum.
Like on any track car I've ever worked on, I set camber completely from what I see on the tires...temperature readings are almost completely worthless unless they are "live, in real time", from sensors (which we do not have, on this car).
Checking tire temperatures, once the car slows and returns into the pits tells more about how hard the brakes are being used, rather than very much about the tires (You learn stuff, like this, very quickly, when you are sponsored by a tire company, like we were for several years when running the air cooled RSR's.) We had multiple "private test days" at Willow Springs, where the tire company would bring an entire trailer filled with a dozen different compound/construction tires and we just "turn" endless laps, doing tire testing.
Tire temperatures can be valuable to select the proper compound of rubber hardness, but this, too, is generally very obvious thing, visually.
Alignment turns out to be of tremendous importance, especially at Thermal, which has a very "wicked" right turn, which is infamous for chewing up the right front tire. And this corner is present on every different track configuration they will ever set-up (there are several.)
We do have a "mystery" phenomena in our extreme GTS, at Thermal. As of yet, we are not having the same issue with destroying this front tire, as all the other cars do...this is leaving the "people in the know", at Thermal, scratching their heads.
Last edited by GregBBRD; 11-19-2023 at 05:21 PM.
#62
I'll tell you...I learned more about camber and toe (through the entire range of suspension travel), after I bought my own $80,000 alignment rack, than I think I learned the entire rest of my life. Plus, this data is incredibly accurate and fairly quick to gather, versus the other methods I have used, most of my life.
Upper and lower control arm angles primarily alter the camber, as they travel to their relative extremes....virtually no affect on the caster. And the arrangement of the 928 control arms make for much smaller camber changes than say a lowered 911, that we don't have to fight this battle as much as we have had to do on prior vehicles I am very familiar with. Toe change is a very interesting "study", on a 928. There isn't very much, until extremes occur, so under "normal suspension' travel "bump steer alterations are not really necessary. However, on this particular vehicle, with the suspension travel we have available, we do utilize a custom hand made bump steer system, with custom tie rods and monoballs to keep toe changes to a minimum.
Like on any track car I've ever worked on, I set camber completely from what I see on the tires...temperature readings are almost completely worthless unless they are "live, in real time", from sensors (which we do not have, on this car).
Checking tire temperatures, once the car slows and returns into the pits tells more about how hard the brakes are being used, rather than very much about the tires (You learn stuff, like this, very quickly, when you are sponsored by a tire company, like we were for several years when running the air cooled RSR's.) We had multiple "private test days" at Willow Springs, where the tire company would bring an entire trailer filled with a dozen different compound/construction tires and we just "turn" endless laps, doing tire testing.
Tire temperatures can be valuable to select the proper compound of rubber hardness, but this, too, is generally very obvious thing, visually.
Alignment turns out to be of tremendous importance, especially at Thermal, which has a very "wicked" right turn, which is infamous for chewing up the right front tire. And this corner is present on every different track configuration they will ever set-up (there are several.)
We do have a "mystery" phenomena in our extreme GTS, at Thermal. As of yet, we are not having the same issue with destroying this front tire, as all the other cars do...this is leaving the "people in the know", at Thermal, scratching their heads.
Upper and lower control arm angles primarily alter the camber, as they travel to their relative extremes....virtually no affect on the caster. And the arrangement of the 928 control arms make for much smaller camber changes than say a lowered 911, that we don't have to fight this battle as much as we have had to do on prior vehicles I am very familiar with. Toe change is a very interesting "study", on a 928. There isn't very much, until extremes occur, so under "normal suspension' travel "bump steer alterations are not really necessary. However, on this particular vehicle, with the suspension travel we have available, we do utilize a custom hand made bump steer system, with custom tie rods and monoballs to keep toe changes to a minimum.
Like on any track car I've ever worked on, I set camber completely from what I see on the tires...temperature readings are almost completely worthless unless they are "live, in real time", from sensors (which we do not have, on this car).
Checking tire temperatures, once the car slows and returns into the pits tells more about how hard the brakes are being used, rather than very much about the tires (You learn stuff, like this, very quickly, when you are sponsored by a tire company, like we were for several years when running the air cooled RSR's.) We had multiple "private test days" at Willow Springs, where the tire company would bring an entire trailer filled with a dozen different compound/construction tires and we just "turn" endless laps, doing tire testing.
Tire temperatures can be valuable to select the proper compound of rubber hardness, but this, too, is generally very obvious thing, visually.
Alignment turns out to be of tremendous importance, especially at Thermal, which has a very "wicked" right turn, which is infamous for chewing up the right front tire. And this corner is present on every different track configuration they will ever set-up (there are several.)
We do have a "mystery" phenomena in our extreme GTS, at Thermal. As of yet, we are not having the same issue with destroying this front tire, as all the other cars do...this is leaving the "people in the know", at Thermal, scratching their heads.
Got it, and final question, I KNOW I will be surrendering my Devek front bar with this, what about my 'red' "i forget who makes it" rear bar?
And..waiting for Kyle to text me to drive down.
#63
Got it, and final question, I KNOW I will be surrendering my Devek front bar with this, what about my 'red' "i forget who makes it" rear bar?
And..waiting for Kyle to text me to drive down. If you paid any attention to my schedule, you should not be holding your breath....we will figure this out and probably coordinate this, when you are coming down here, anyway. You do really need to go out with the test car and experience it (It has "Version 2" of street suspension in it), before we move onward to the next level of suspension, on that car (after the first of the year.) One of the significant "hang-ups" in moving on to "Version 3" is that the owner of the "test car" is so absolutely thrilled with the handling that we are hesitant to move "forward", knowing that we will likely go "backwards" for a certain percentage of the initial development.
And..waiting for Kyle to text me to drive down. If you paid any attention to my schedule, you should not be holding your breath....we will figure this out and probably coordinate this, when you are coming down here, anyway. You do really need to go out with the test car and experience it (It has "Version 2" of street suspension in it), before we move onward to the next level of suspension, on that car (after the first of the year.) One of the significant "hang-ups" in moving on to "Version 3" is that the owner of the "test car" is so absolutely thrilled with the handling that we are hesitant to move "forward", knowing that we will likely go "backwards" for a certain percentage of the initial development.
Truthfully, I brutally learned this lesson at the 12 hours of Sebring, years ago, as the BMW's just drove away from us, smoothly going through the corners (with all four tires on the ground), while we "pogo sticked" our RSR's through the same corners (with 3 tires on and off the ground.) In some corners, the BMW's would "pull" an entire car length, on us. Simply beautiful to watch the BMW's and very painful to watch all of the RSR's.
A very "enlightening" moment, for me, as the chief car set-up guy....I had a complete lack of pieces, that would help me with this issue....and I had a stack of shocks and other pieces.
(Worth noting, I'm running stock sway bars, in the Extreme GTS.)
Not discussed here (nor anywhere else) my test driver also has a 951 (originally equipped with the "insane" Koni M030 suspension package), which is also undergoing a large suspension development program. I think we/he has bought every single sway bar, from the absolutely absurd "Weltmeister" sway bars down to what came on a 924.
And, as development has continued, we keep "going down" in sway bar size....
Last edited by GregBBRD; 11-19-2023 at 06:54 PM.
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Darklands (11-19-2023)
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icsamerica (11-20-2023)
#65
Surely this breaks down into two categories.
1) How can I replace my stock 928 shock & spring setup without breaking the bank?
2) How can I transform my stock 928 shock & spring set up to a truly up to date supercar technology.
Most of my customers want #1
Generally price is a prime consideration.
1) How can I replace my stock 928 shock & spring setup without breaking the bank?
2) How can I transform my stock 928 shock & spring set up to a truly up to date supercar technology.
Most of my customers want #1
Generally price is a prime consideration.
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission? George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
#66
Surely this breaks down into two categories.
1) How can I replace my stock 928 shock & spring setup without breaking the bank?
2) How can I transform my stock 928 shock & spring set up to a truly up to date supercar technology.
Most of my customers want #1
Generally price is a prime consideration.
1) How can I replace my stock 928 shock & spring setup without breaking the bank?
2) How can I transform my stock 928 shock & spring set up to a truly up to date supercar technology.
Most of my customers want #1
Generally price is a prime consideration.
I'm in the #1 category.
I'd like to get my car as close as I can to "factory new" suspension without "breaking the bank".
Can you email me a list of what you'd recommend?
Cheers,.
#68
Surely this breaks down into two categories.
1) How can I replace my stock 928 shock & spring setup without breaking the bank?
2) How can I transform my stock 928 shock & spring set up to a truly up to date supercar technology.
Most of my customers want #1
Generally price is a prime consideration.
1) How can I replace my stock 928 shock & spring setup without breaking the bank?
2) How can I transform my stock 928 shock & spring set up to a truly up to date supercar technology.
Most of my customers want #1
Generally price is a prime consideration.
#69
#70
https://docs.google.com/spreadsheets...it?usp=sharing
Note, this was HALF this price when I did this...3yrs ago?? DO it while you can, and while the parts are available...
#71
Surely this breaks down into two categories.
1) How can I replace my stock 928 shock & spring setup without breaking the bank?
2) How can I transform my stock 928 shock & spring set up to a truly up to date supercar technology.
Most of my customers want #1
Generally price is a prime consideration.
1) How can I replace my stock 928 shock & spring setup without breaking the bank?
2) How can I transform my stock 928 shock & spring set up to a truly up to date supercar technology.
Most of my customers want #1
Generally price is a prime consideration.
It's actually a bit more involved, for us, that just the two options, currently:
1. Stock suspension rebuild. This can vary from a simple shock change to a complete overhaul of all of the rubber parts, depending on client and budget (most 928's desperately need the rubber parts replaced.) Optimum ride height in the 160mm range....somewhat dependent on what shock absorber is chosen.
2. Fairly straight forward modifications, to improve the handling and improve the NVH. Allows the car to be lowered into the 150mm range. Reduced understeer because of modified pieces which allows the car to be properly lowered and still have front suspension travel without riding on the bump stops (This is what I'm proposing for the OP, in this thread.)
3a. Street/canyon racer suspension, with greatly improved NVH. Oversteer characteristics virtually gone. With sticky tires, the grip exceeds most people's desire to go at the speeds required to "make the car" get loose. Wider than stock tires and wheels allowed, although rear wheel/tire widths must be reasonably matched with the front. (Jeff Mohler will be getting this version.)
3b. Same as above, with custom adjustable shocks for both bump and rebound. The shocks have "altered" dimensions to allow lowering the car into the 140mm range. "Tune ability", for the individual driver's ability very high and can be changed, as driver ability increases.
4. Street/track car. Good NVH. Adjustable custom shocks for both bump and rebound. Spring rates increased. All of the suspension mounting and spring parts are changed.to custom pieces. Virtually unlimited suspension travel. Getting this level requires a Non Disclosure Agreement and the vehicle must be modified in our shop, as the pieces and technology is way beyond anything available, from anyone else. Designed for very aggressive and wide "low wear number" tires. Factory sport seats are a minimum requirement, along with 5 point seat belts. Roll bar highly encouraged and it can not be bolted to the weakest part of the car (the floor.) Minor front chassis stiffening required. Roll cage not required. 350+ horsepower very desirable. Highly functional, true 40%, limited slip required.
5. Dedicated track car/possible to drive to the track. Designed for a car with wide slicks. Significantly increased horsepower highly recommended. Shocks have remote canisters and are triple adjustable. All of the pieces used in Version 4, with significant spring rate changes. NDA required and vehicle must be modified in our shop. Roll cage and chassis stiffening highly desirable. A track test day, with the driver, will be required, to set-up shocks/alignment around the driver's ability. Professional, private test driver possible for hire, if desired. (He will explore the limits with the driver, but the set-up will revolve around the owner/driver.)
Last edited by GregBBRD; 11-21-2023 at 01:52 AM.
#73
We could get together, with 6 other highly technical people and debate this part, all night long.
New, it certainly "absorbs" some of the actual spring rate (of the main spring), as it compresses. Old, this is not the case and understeer is increased, since virtually none of the actual spring rate (from the main spring) is absorbed, but simply transferred through the rock hard rubber.
New, makes obtaining lower ride heights more difficult and the car must sit for about a month (or be aggressively pulled down over night), for this part to compress enough to get the correct ride height. While our 928's might have left the factory at 180mm front ride height, they certainly were not this high, once they arrived here, from an ocean's voyage. This part compressed, along with the movement of the lower control arm rubbers.
The really bizarre part about this part is that it has the same part number, throughout all of the different models.
This borders on the absurd, from a suspension technical point of view, when one considers the difference in front corner weights as the vehicles evolved.
Worth mentioning, in both in Version 4 and Version 5 of our current offerings, this piece is completely eliminated and substituted for something much easier to tune the car around...completely dependent on corner weight.
Last edited by GregBBRD; 11-21-2023 at 01:56 AM.
#74
A very, very interesting part.
We could get together, with 6 other highly technical people and debate this part, all night long.
New, it certainly "absorbs" some of the actual spring rate (of the main spring), as it compresses. Old, this is not the case and understeer is increased, since virtually none of the actual spring rate (from the main spring) is absorbed, but simply transferred through the rock hard rubber.
New, makes obtaining lower ride heights more difficult and the car must sit for about a month (or be aggressively pulled down over night), for this part to compress enough to get the correct ride height. While the cars might have left the factor at 180mm front ride height, they certainly were not this high, once they arrived here, from an ocean's voyage. This part compressed.
The really bizarre part about this part is that it has the same part number, throughout all of the different models.
This borders on the absurd, from a suspension technical point of view, when one considers the difference in front corner weights as the vehicles evolved.
We could get together, with 6 other highly technical people and debate this part, all night long.
New, it certainly "absorbs" some of the actual spring rate (of the main spring), as it compresses. Old, this is not the case and understeer is increased, since virtually none of the actual spring rate (from the main spring) is absorbed, but simply transferred through the rock hard rubber.
New, makes obtaining lower ride heights more difficult and the car must sit for about a month (or be aggressively pulled down over night), for this part to compress enough to get the correct ride height. While the cars might have left the factor at 180mm front ride height, they certainly were not this high, once they arrived here, from an ocean's voyage. This part compressed.
The really bizarre part about this part is that it has the same part number, throughout all of the different models.
This borders on the absurd, from a suspension technical point of view, when one considers the difference in front corner weights as the vehicles evolved.
Just when I see people talk about "had to adjust because of sag"...then I saw the ~1/2" difference between an old upper mount, and a new one, and you could take a pen and feel the difference between the two...
#75
I’m preparing for my ‘79 928’s wintery slumber and want to redo the suspension while she’s stuck in the barn. The problem I have, and has been discussed, what combination of springs/shocks is best. Mine will be a street car with at most, a little spirited driving here/there. Looking through all the threads I’m quite confused.
Last edited by icsamerica; 11-21-2023 at 12:07 AM.