By Rob
Here are a few more answers to some of your recent queries. Thanks again for your thoughtful questions!
Q (Paul): Did you select tires, and how do you measure ride/handling attributes?
A: Interesting questions. Yes, we work closely with the top tire companies in the world. In our case, Michelin is our partner on the CTS. There is a detailed submission process, in which they provide us a wide range of samples and we work back-and-forth to dial in all the attributes. This was very intensive for the CTS, as we now offer a new and unique Michelin Pilot Sport II summer-only tire, in addition to the Pilot Sport All-Season tires.
In terms of ride and handling measurements, it is a blend of subjective “seat of the pants” observation, with objective measurements and data. For ride quality, I’d say it’s 70 percent subjective. This is where our ride trips and millions of miles of seat time are crucial. Lots of repetition and lots of observation of how the car feels. The other 30 percent is more electronic, with ride frequency measurements and instrumentation giving hard data to support what we’re observing. For handling, there is also a blend of the subjective and objective. Measurements like maximum lateral acceleration and an agility test we call “control response” are really important. But a lot of the fine tuning is subjective. Track tests are crucial for feeling how precise and accurate the car is, how “flat” and responsive it is in the corners and “twisties”.
Q (Jake): Did you guys test vibration issues a lot?
A: Yes, vibration is something we test a lot. You might have seen us post a little bit about this a few months ago, in fact. There is a lot of fine tuning of things like engine mounts, differential mounts and other bushings that are the intersections between the driveline and the car itself. This includes very precise measurements using chassis dynos and accelerometers. The results of these “fine tunings” are than captured on the Dyno with data acquisition and than verified on the open road to insure the customer has a pleasing driving experience at all speeds.
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Comments
I still have to pinch myself when I see someone from Cadillac discuss chasis dynamics, flat cornering, seat of the pants feel, and responsiveness. It was just a few short years ago when Cadillac and performance were not even compatable. I remember seeing someone try a 1985 Eldorado slalom test and the front wheels litterally bowed under themselves in the corners as the body leaned, bobbed, and weaved all over the place - and the driver got motion sickness to boot!
It is such a refreshing sight to see that Cadillac gets it now.
Posted by: Joe | October 29, 2007 12:44 PM
Would the special performance Pilots be good for my 04 CTS-V? Is there a special number or description to make sure I get the right version?
Posted by: Bob | October 29, 2007 8:47 PM
On what suspension package were the Pilot Sport A/S tires offered? When I purchased my 08 CTS the Y42 package had lower rated Michelins only while the Y43 package, which I purchased, was only available with the Pilot Sport II tires. I eventually purchased a set of Dunlop Winter Sport M3 tires as I knew I had to do something quickly about replacing the Pilot Sport IIs before cold weather set in here in Chicago. Knowing how finely tuned the suspension is with the Y43 package, I purchased an extra set of OEM alloys to mount the winter tires on so I could retain the same wheel characteristics (especially weight) as with the OEM wheels that came with the Pilot Sport IIs. I have to second your comments about how much tire selection can change the ride and handling characteristics of the car. While the Dunlop winter tires are quite good (as evidenced by the high comparative ratings on the web site I purchased them from), there was a noticeable change in ride/handling when I changed from the Pilot Sport IIs (not necessarily bad, but noticeable none the less).
Posted by: James Hufton | October 29, 2007 9:59 PM