05-17-2016, 05:40 AM | #1 |
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GTS has a wider front track?
Reading through the GTS Technical Training doc, I noticed a table that specifies that the GTS has a wider front track by 17mm compared to the the base M4. Further, it is also specified that the GTS wheels have the same offset as the base M4 (ET29 front and ET40 rear), meaning that the wider track would not come from the wheels. Before anyone jumps in about the 0.5" wider wheels from the GTS, note that they do not contribute to a wider track since track is measured from the tire center line. The GTS does seem to have a "flusher" look than the base car IMO. A wider track by 17mm plus the 0.5" wider wheels would push the front wheel face out by ~15mm.
If all this info is correct, that would mean that the GTS' front suspension has been modified extensively enough to provide that wider track. Interesting.
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05-17-2016, 07:27 AM | #3 |
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I know. So many typos and unclear info in BMW documentation, it is sometimes difficult to figure what is correct. That is why I did not formulate my post as an absolute certainty. But I believe it is something worthwhile exploring...
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05-18-2016, 08:57 AM | #4 |
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Hmmmmm. The official press release that is available on BMW's press website states that the track width is indeed different.
Civic M4 Track, front/rear: (mm) 1579/1603 M4 GTS Track, front/rear: (mm) 1596/1604 Had a brief look at ETK and I see no changes (... all I see is racist faces. *2Pac's voice* ) in any suspension components. Everything has the same part number. *DUN-DUN-DUUUN* This has nothing to do with the front track, but der ETK says that the rear GTS wheel has an ET42 offset...
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05-18-2016, 09:02 AM | #5 | |
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A 2mm increase in rear wheel offset would reduce the rear track by 4mm. All the more confusing... Albeit we are talking very small numbers here. Could the increased factory camber be the source of the increase the track?
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05-18-2016, 03:49 PM | #6 | |
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On a 17" rim, a camber increase of 1 degree equals roughly a 10mm increase at the bottom of the rim, or a 10mm decrease at the top of the rim (if that makes sense). Ie, to increase camber by ca 1 degree you have to either tilt the top of the rim inward by 10mm (which is what a camber plate at the top srut mount does). Or extend the bottom of the rim outward by 10mm (which is what an adjustable lower control arm does). I have just played with camber settings on my old Ford Sierra RS Cosworth with 17" rims, which is why I have these measurements at hand Here the camber change is less than 1 degree (?) and the increase in track by 17mm seems very plausible to be explained by the increase in negative camber. Especially since the top strut mount probably is similar and the increased camber comes from a changed hub which basically tilts the wheel more inwards at the top and extends it further outward at the bottom. I feel my English is a bit lacking in trying to explain my thoughts here, but I hope it makes some sense... PS. Is the rear camber also increased compared with the std M4? If it's a small change in camber, that could also explain the combination of a higher offset and similar track. |
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05-18-2016, 04:31 PM | #7 | |
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The GTS front camber spec is the same as the base car at -1.45 deg. So the camber does not really explain the wider front track IMO. In the rear, the camber is 0.2deg more at -2.0deg for the GTS instead of -1.8deg for the base car. So I believe the camber could explain the 1mm wider track despite the offsets that should make the track 4mm narrower. PS: Your English is perfectly fine
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06-17-2016, 12:12 PM | #11 | |
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FTFY:
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06-18-2016, 01:11 PM | #13 |
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Dream Car = my M3 with M4 GTS suspension geometry.
I'm guessing a decreased front wheel offset won't be able produce the same handling benefits that the GTS-specific front carrier is able to produce...... Probably would screw up how the camber angle changes when corning as well as the scrub radius. If some third party (like Vorshlag) replicated the GTS front carriers, I would buy them. Last edited by Celestion; 06-18-2016 at 01:19 PM.. |
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