Quote:
Originally Posted by GuidoK
Beta is just trying to silence me (I can't interpret his repeating remarks about 'reading the thread' without clarification any other way) and that is plain rude on a forum.
|
If you say you went over the thread, then I apologize and will go into. It just looked like you hadn't read the thread as your first comment was about upgrading the transmission mounts to stiffer rubber, which as explained below, does not work (and is talked about earlier in the thread).
1. The "issue" is really two issues.
The first is the 3->2 rejection during off-canter or high speed cornering. This is not common and is only reported by track junkies. This appears to be fixed by using the stiffer engine mounts.
The second issue is the 1->2 grind which you can work around by doing a heartbeat pause. You will probably not run into this as it's only reported by M owners on the forum so far.
Seeing as the 1->2 shift can be made faster with better engine mounts, this would point that the issue is either:
a. The twisting of the engine in relation to the gearbox is changing the geometry of engine -> gearbox causing the linkages to not match up properly.
b. A combination a. and a mechanical issue with the gearbox.
If it was purely a mechanical issue with the synchros, then stiffer engine mounts wouldn't have made any difference. It also wouldn't make a difference if people pulled the shifter hard down and to the left (which is another solution people use). It would also be reported by all owners, not just M owners as the same 6 speed transmission is used on all Z4s.
2. Stiffer transmission mounts does not solve the issue. There are lots of threads detailing upgrading the transmission mounts, and most of them report less of a change than the engine mounts made with greater increases in NVH.
I always take info from vendors with a grain of salt. However, the info from vibra explains why upgrading the mounts with stiffer mounts on the existing mounting geometry doesn't make much of a difference on the transmission movement, but increases NVH. This explanation coincides perfectly with people's experiences. I also ran it by a friend of mine who is an excellent mechanical engineer in the automotive industry, and he agreed with it. Seeing as the theory matches up with practice, and that they delivered excellent engine mounts (that completely transform the car) with almost no increase in NVH, there's no reason not to believe that they know exactly what they're talking about.