EricSMG
Well-Known Member
Great convo, Rick. It's refreshing to exchange ideas without being rude or dismissive.Well, to be fair, the expressed purpose of a "Performance Pack" model is to emphasize track performance. By definition, that makes it a focused package for the task at hand. But, with that said, some of this is on Ford; they specified the performance criteria they wanted the Torsen to meet, they also were responsible for the chassis controls and suspension integration. That also includes sorting the wheelhop issue (and its cascade effects).
Part of where I think Ford might've fallen short was in scope of imagination - they envisioned a low-volume package that would be purchased by a handful of people autocrossing and doing track days, etc. Not something that would be adopted by the general consumer. In retrospect, that seems kind of silly, because most people buying the performance version of a sport coupe are probably going to opt for the most performance that is practical. The take rate of that option seems to have been a bit higher than was anticipated. That may be why we've seen indication of a PP2 option on the '18MY. It might be to push the overall performance level up, while also making more of the performance content more readily accessible.
In any case, it does remain true that the limitation of a typical helical-gear differential is the one-wheel unloaded situation, but in my 20-year experience using these types of products, I can't say its been a significant concern. I've not come across the wheelhop-induced unloading as described, so I wonder how relevant it is to the typical buyer. Obviously, it must happen if some folks are reporting it, but on the whole how widespread is it? There are certainly ways around the issue, but all have their tradeoffs. The Wavetrac design seems novel, I'd like to get my hands on one at some point to see how it performs...
Calling the PP focused is not taking a jab at it - it's calling it what it is. I bought it for precisely the reason(s) you state - to get the most practical performance. I always buy/drive the 'sportiest' version of what ever it may be.
Is this "issue" really a problem? Not really. Is it something that's both extremely annoying, and, unique (in my experience) to this car? Absolutely, to me. I'm 40 years old and have driven nothing but front engine rwd cars with traditional and viscous LSDs - none behave this way, which is the point - this doesn't happen in my experience and so it jumps out like a sore thumb. I'm sure others don't even notice it.
I like my cars to be precise, effective and well mannered. Something about the Torsen/IRS combo in this car is none of those at very slow speeds while turning and accelerating gently - if it's wet, forgettaboutit - total and complete mess. I can only imagine ice and snow. Is it the Torsen or the IRS or the combo? Not sure, but it's a nasty little characteristic in the S550 GTPP.
Edit - poly diff bushings inserts have helped this about 25% or so in the dry by highly limiting the wind-up/snap-back of the differential (better wheel control, more constant force). Still very bad in the wet.
Although this is entirely not the case, think about what you're saying. The entire point of a good diff is to prevent single wheel spin no matter what the driver does. Inducing spin should always result in both wheels spinning for maximum control and forward push.I think the issue is people trying to induce wheelspin...
In other words, saying that the single-wheel-spin is driver-induced essentially proves that the diff/suspension aren't doing their job(s).
Sponsored
Last edited: