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Originally Posted by orthojoe;13394957 I'm curious to hear your thoughts on a post that John Tecce at BGB made several months ago regarding toe deflection:
Joe, my question to you is, now that you know about the problem described by BGB, have you done anything to your rear suspension, other than toe links to dial in more camber?
I'll let Tom handle the technical suspension questions, as that's more his forte.
I feel the insinuation that we don't functionally test units before sending them to customers is a little unfair. It would literally be impossible to keep up with sales and road test EACH unit before sending it out. We do perform random tests, but testing each one individually is just unrealistic.
We've sold well over a thousand DSC units, and this is the first time anything of this nature has occurred. There have been one or two faulty units here and there (for varying reasons, usually related to something on the circuit board during production that is out of our hands).
In this particular case, when making some improvements in the firmware, our software engineer accidentally made a mistake in the coding. It was literally just a typo of one character, but it had quite an effect on the output commands being sent from the DSC to the shocks. It was extremely unfortunate and a little embarrassing for all of us. However, as mentioned, it's the first time something of that nature has occurred. The bad file made it onto a batch of less than 10 DSCs; unfortunately Joe's was one of them. We immediately sent out a recall notice to the customers whose units were potentially affected. Using our diagnostics in the DSC software, we were able to work with each customer and determine who had a faulty unit. We then sent out brand new units overnight to all customers with return labels for them to send their units back to us, completely free of charge for our customers. We also paid duty fees/etc. for our international customers.
It was a very unfortunate circumstance, but it doesn't reflect who we are as a company. What does reflect who we are as a company is how all of our customers who were affected by the bad batch are now more than satisfied with our response time in handling the matter. I'd also like to emphasize that it was localized to a very small sample of customers.
Regarding how they were faulty... As mentioned, there was a typo in the coding for the firmware version. A wrong calibration would be very easy to fix, as customers can go online and download the most recent .pdts file at any time. The fault in the coding affected the output command from the DSC to the shocks in a rather unpredictable manner; not so much so that the car was dangerous to drive, but it certainly affected performance, particularly on track.
The whole situation was certainly a learning experience for us, and we're using it as an opportunity to improve our level of support and quality control and to instances such as this in the future.
Originally Posted by Mech33
Joe, great commentary. So... the DSC units don't get functionally tested prior to sending them to customers? Especially customers that they intend to leverage for reviews to drive sales? Or... did TPC just dial yours up a notch since you didn't feel much of a difference initially?
And if it was a failed part, would a less advanced driver have noticed? Maybe not...
I'd be interested in understanding how the units were faulty in a way that didn't cause problems with the car. Wrong firmware? Wrong calibration stored? Just curious really.
I have a lot of respect for John Tecce and BGB Racing for their development and racing program. John is correct regarding toe deviation at higher lateral g-load(especially when using slick racing tires that generate more grip and lateral-g) caused by the difference of material between the lower control arm bushing and toe link bushing.
The amount of deviation ultimately depends on the amount of flex on the rubber bushing selected and the amount of grip the tire compound has. We have to assumed that OEM selected the stiffness of rubber bushing to pair with OEM tires(or tires of similar grip). Over the years/models OEM offers different control arm bushings; from different stiffness rubbers, to metal reinforced rubber, to full metal. (see image below on examples I have around the shop).
For reference, front & rear rubber control arm bushings were factory quipped on 996 Cup cars with slicks. The 997.1 Cups have rubber front/metal rear. The .2 Cups are metal/metal. The GT4 street car is Porsche's first production mid-engine car with metal toe link bushing. We have to assumed that they did their homework in selecting the ideal rubber bushing for the control arm to pair with the metal toe link bushing. Anyway, this is one cause of toe deviation- caused by difference of material flex rate at higher lateral g than assumed OEM's testing perimeter. For the purpose of this post, lets refer to this cause as LGTD(Lateral-G Toe Deviation).
The other cause of toe deviation, often viewed as the primary cause, is suspension geometry as the suspension travels up/down. Lets refer to this as SGTD(Suspension Geometry Toe Deviation). The GT4 has MacPherson Strut type rear suspension(as oppose to the Multi-link type on the 996/997/991). By design, the MacPherson Strut has more toe deviation since the travel up/down is more of an arch than on Multi-link. When the SGTD is less than ideal to begin with, the LGTD is then added when the bushing material flexes beyond certain lateral g threshold. The TTD(Total Toe Deviation) is SGTD + LGTD. The purpose of the new TPC Racing GT4-specific rear toe links is to improve SGTD. I don't know at what lateral g threshold the OEM GT4 rubber bushing will make the LGTD bad enough to make the car unstable. But reducing the amount SGTD will certainly improve the car's stability.
Summary:
SGTD + LGTD = TTD.
Smaller value of TTD is good.
Hope this is not too confusing.
My position on posting specific SGTD values remains the same. But I am delighted to report that with TPC Racing GT4 rear toe links the peak tested SGTD values is reduced by ~50% compared to using symmetrical toe link bushings. The peak tested values are result of compression(downward movement) of 25mm and rebound(upward movement) of 25mm from stock ride height.
Finally, for those who are in the market for adjustable rear toe links and still skeptical about our new GT4-specific version, we have hundreds of symmetrical stainless steel bushings that we'll be glad to supply.
I'll let Tom handle the technical suspension questions, as that's more his forte.
I feel the insinuation that we don't functionally test units before sending them to customers is a little unfair. It would literally be impossible to keep up with sales and road test EACH unit before sending it out. We do perform random tests, but testing each one individually is just unrealistic.
We've sold well over a thousand DSC units, and this is the first time anything of this nature has occurred. There have been one or two faulty units here and there (for varying reasons, usually related to something on the circuit board during production that is out of our hands).
In this particular case, when making some improvements in the firmware, our software engineer accidentally made a mistake in the coding. It was literally just a typo of one character, but it had quite an effect on the output commands being sent from the DSC to the shocks. It was extremely unfortunate and a little embarrassing for all of us. However, as mentioned, it's the first time something of that nature has occurred. The bad file made it onto a batch of less than 10 DSCs; unfortunately Joe's was one of them. We immediately sent out a recall notice to the customers whose units were potentially affected. Using our diagnostics in the DSC software, we were able to work with each customer and determine who had a faulty unit. We then sent out brand new units overnight to all customers with return labels for them to send their units back to us, completely free of charge for our customers. We also paid duty fees/etc. for our international customers.
It was a very unfortunate circumstance, but it doesn't reflect who we are as a company. What does reflect who we are as a company is how all of our customers who were affected by the bad batch are now more than satisfied with our response time in handling the matter. I'd also like to emphasize that it was localized to a very small sample of customers.
Regarding how they were faulty... As mentioned, there was a typo in the coding for the firmware version. A wrong calibration would be very easy to fix, as customers can go online and download the most recent .pdts file at any time. The fault in the coding affected the output command from the DSC to the shocks in a rather unpredictable manner; not so much so that the car was dangerous to drive, but it certainly affected performance, particularly on track.
The whole situation was certainly a learning experience for us, and we're using it as an opportunity to improve our level of support and quality control and to instances such as this in the future.
Great response to the situation. The product is a legitimate upgrade and is staying in my car. You really don't need to be a pro to feel the difference, it is that big. FYI, anyone in CO is welcome to try my unit at HPR if they like. Swap takes 5 min.
I am chomping at the bit to try the DSC box in my GT4 that Mike and Tom sent. The toe links they sell that are in this thread are top notch and you aren't going to get the alignment correct without adjustable motorsports oriented toe links. I wasn't aware but it looks like they took it a step further to make a link with better bumpsteer, all of which will further improve your car's handling as it goes through the suspension stroke. TPC consists of some sharp dudes, Tom's feedback I read is spot on and like BGB, Mike takes a lot of pride in improving things. My $.02 is that the combination of some of their advanced toe links and Cup style inner monoball control arm flanges would be as good as you can get.
When we ran the Cayman we had a lot less rear tire AND we had a tire with a notoriously soft sidewall. There was deflection in the sidewall during the moment when you wanted to release the brakes and finish your turn-in just prior to apex and then there was toe deflections from the hard mounted toe link overpowering the rubber mounted control arm bushing. Swapping that inner rubber control arm flange for a Cup style monoball one fixed everything for us.
I don't feel a lot of that behavior in the GT4 street car we have but I also have barely modified the suspension because I've been focused on power for the retail business. The Club Sport race car I get to drive now and again has all monoball so it's not there in that config. I think the factory keeps the rubber in the back for the road noise but someone who is in the know can confirm, as that's just conjecture.
I feel the insinuation that we don't functionally test units before sending them to customers is a little unfair. It would literally be impossible to keep up with sales and road test EACH unit before sending it out. We do perform random tests, but testing each one individually is just unrealistic.
I appreciate the response. It would definitely be ridiculous to road test each unit before sending it out. By "functional testing", I meant just that: testing the function of the unit, in a general sense. Sure, one way is by actually plugging it in and tracking the car. Or another way is to plug the unit into a "functional tester" that communicates with the unit and runs it through a set of diagnostic tests to confirm everything is behaving as-expected, including that the firmware is sending the appropriate commands to dampers in response to other car data, etc. You wouldn't need a car for this... you would simply need an appropriate electronic "emulator" that pretended to be a car and gave you a Go / No-Go that the unit was behaving as expected.
Such a tester would be quite handy in identifying firmware bugs that broke functionality, as well.
Originally Posted by DSC Sport
We've sold well over a thousand DSC units, and this is the first time anything of this nature has occurred. There have been one or two faulty units here and there (for varying reasons, usually related to something on the circuit board during production that is out of our hands).
In this particular case, when making some improvements in the firmware, our software engineer accidentally made a mistake in the coding. It was literally just a typo of one character, but it had quite an effect on the output commands being sent from the DSC to the shocks. It was extremely unfortunate and a little embarrassing for all of us. However, as mentioned, it's the first time something of that nature has occurred. The bad file made it onto a batch of less than 10 DSCs; unfortunately Joe's was one of them. We immediately sent out a recall notice to the customers whose units were potentially affected. Using our diagnostics in the DSC software, we were able to work with each customer and determine who had a faulty unit. We then sent out brand new units overnight to all customers with return labels for them to send their units back to us, completely free of charge for our customers. We also paid duty fees/etc. for our international customers.
It was a very unfortunate circumstance, but it doesn't reflect who we are as a company. What does reflect who we are as a company is how all of our customers who were affected by the bad batch are now more than satisfied with our response time in handling the matter. I'd also like to emphasize that it was localized to a very small sample of customers.
Regarding how they were faulty... As mentioned, there was a typo in the coding for the firmware version. A wrong calibration would be very easy to fix, as customers can go online and download the most recent .pdts file at any time. The fault in the coding affected the output command from the DSC to the shocks in a rather unpredictable manner; not so much so that the car was dangerous to drive, but it certainly affected performance, particularly on track.
The whole situation was certainly a learning experience for us, and we're using it as an opportunity to improve our level of support and quality control and to instances such as this in the future.
Makes sense. That seems like one of the worst types of issues to have, since the fault is not obvious to the customer. Great that you guys caught it. Any interest in making the firmware field-upgradeable?
I appreciate the response. It would definitely be ridiculous to road test each unit before sending it out. By "functional testing", I meant just that: testing the function of the unit, in a general sense. Sure, one way is by actually plugging it in and tracking the car. Or another way is to plug the unit into a "functional tester" that communicates with the unit and runs it through a set of diagnostic tests to confirm everything is behaving as-expected, including that the firmware is sending the appropriate commands to dampers in response to other car data, etc. You wouldn't need a car for this... you would simply need an appropriate electronic "emulator" that pretended to be a car and gave you a Go / No-Go that the unit was behaving as expected.
Such a tester would be quite handy in identifying firmware bugs that broke functionality, as well.
We do actually have exactly what you described for the accelerometers, and we test all of these as such before sending out. As a result, we have caught a few faulty ones.
Regarding the controller, it's certainly something worth looking into, but it may get a little complicated because there would be so many things to look for. Unless the "emulator" were very sophisticated and provided a full simulation of shock behavior of sorts, I don't think it would have caught this one in particular.
Fortunately, somebody on the TPC/DSC team is interacting with the software day in and day out, so I think that helps in catching these mistakes when they do arise. Whether it's our software engineer, calibrator, Tom driving and/or tuning his GT3, or myself or Harris who aid in technical support, we typically find any anomalies rather quickly.
Makes sense. That seems like one of the worst types of issues to have, since the fault is not obvious to the customer. Great that you guys caught it. Any interest in making the firmware field-upgradeable?
There is a lot of interest in that, and we've put a lot of work into making it possible. At this point, however, we haven't been able to do it without the risk of crashing some of the hardware components. At the VERY least, we would like to get it set up in the near future so at least dealers can upgrade firmware.
Also, if anyone ever feels - in the slightest - that their DSC isn't behaving as intended, there are a number of diagnostics we can run using the tuning software. And typically, with the amount of positive reviews it has received, people aren't too shy about letting us know if it performs anything short of amazing Fortunately, 9 times out of 10 we can make a few adjustments in their calibration file and they are much happier.
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While I had planned to write a more complete message, this thread seems to be a good opportunity to add another account that echos TPC notes.
Quick bit about me: After years ago being heavily involved with DEs and then moving on to own and play race cars while traveling with a professional team I have taken quite a number of years away from being at the track. Recently I have just gotten to know TPC after they have setup my GT4 this season (street/track alignment, Cantrell roll bar, harnesses, brakes, etc).
This past weekend I was at Watkins Glen and paddocked with Tom. Even though TPC has offered to let me try the DSC before, I had declined as I wanted to first get a sense for the car with making adjustments one step at a time as I got back involved. For the last session of the day I asked Tom if I could take him up on the offer to try the DSC to see what the difference is.
Much like OrthoJoe's notes and true to TPC's description the DSC was certainly noticeable... Nose dive was greatly reduced and the car did feel more stable, specifically under heavy breaking.
Reading the list over time I have seen a number of threads regarding a reduction of some number of seconds that the DSC may help achieve. While I believe that DSC will help in lap times, I think this may be missing some of the point as a lap time itself involves quite a number of factors. The increased stability is noticeable and could certainly contribute to such. In my case, the largest takeaway was a feeling that I could manage the tires grip better, particularly under breaking. For my data logging, I can simply say that in the last session where I used the DSC I did not have enough clear track or time to get what I would believe to be a valuable overlay for comparison but will be looking more closely at this in the coming days. Regarding purely lap times, I can say that my times were very similar between stock controller having open track, and using the DSC while managing to get through quite a bit of traffic. Overall, I do believe that the adjustments that the DSC made did provide increased stability that was valuable.
I hope to get some useful data overlays between my sessions stock and the one I used the DSC to share. However, I can say that the DSC came home in my car
Any concerns about running 19x11 et50 wheels with the toe links?
No problem clearing 19x11 as long as its a "true" 19-inch wheel. I mean I have seen some wheels that have ridges or raised areas inside the wheel barrel that takes up space. Don't know why but some companies make wheels like that.
Adjustment- Yes. Offset inner- No. On the Clubsport race car there's some adjustment on the outter rod end, its similar to 997 Cup, except the conical pin is horizontal instead of vertical. We also make and use the same arrangement for 981 Boxster/Cayman(non-GT4). It looks like this- The gold color shims to adjust bumpsteer. This is not applicable to the GT4 street car because there's insufficient space between the upright and inner wheel barrel. On the Clubsport, I do believe that even with the limited amount of adjustment on the outter, further improvement can be achieved with offset inner. Just by eye balling the angle of the link, even with the outter adjustment at max, it looks to me offsetting the inner some will improve geometry...But the spec series probably prohibit this change.
want me to snap some pics of the ClubSport rear suspension Tom?
06-22-2016, 11:46 AM
Fortunately, 9 times out of 10 we can make a few adjustments in their calibration file and they are much happier.
