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Finnegan · 04-09-2013, 07:07 PM

So, boiled down, that analysis and math contends that gear selection position can't move much, and there are physical limitations to how much movement the mechanical systems have available in terms of tolerance. Okay fair enough.

But that doesn't get us to a solution. And that is what most of us are after. Here are the data points we have, along with the most reasonable solution to the following issues:

Issue - 3rd to 2nd

3rd to 2nd is an issue. It's not driver error, unless half the forum (and quite a few other forums) don't know how to shift this car or other BMWs.

This issue isn't limited to the Z4M. The E30 and many other BMWs also suffer from the same issues--and the "cure" is the same: stiffer engine/transmission mounts.

Frequency of this issue is reduced with stiffer transmission mounts (that's what folks here report 1, 2)

Shifting is improved and the 3rd to 2nd issue is further reduced (or eliminated) with a stiffer engine/transmission mount combo. (1, 2)

Issue - 1st - 2nd

Pulling down and to the left helps, and in many cases eliminates 1 - 2 grind. Many report this, and it can't be discounted.

Sychros don't self-repair. So why would pulling left help? (I have no idea, but it does, and many report this.)

It's possible that in learning to pull down and to the left folks, have learned to work around a synchro limitation (so the user has modified more than just pulling to the left, maybe waiting a bit and allowing things to "catch up"). That would support your synchro contention.

Solution, in either case, w/o swapping out a transmission, would be to: 1.) pull down and to the left; 2.) upgrade mounts (since it helps with the other issue, and may help here).

Regarding 3rd to 2nd, the aftermarket community says pretty much the same thing across the board. The solution being offered by Turner Motorsports, Vorschlag, UUC, AKG, Rogue (1, 2, 3, 4, 5) all work on the same premise and offer the same solution. (I seriously doubt the customers who bought these products--and report improvements--are all wrong or that they're all in league with vendors.)

If the evidence in front of us shows that the 3rd to 2nd issue can be improved, if not corrected, with improved mounts, and that the same solution may help or improve the 1 -> 2 grind, why not just run with the solution and call it a day?

04-09-2013, 07:07 PM	#249
Finnegan Dog Listener 703 Rep 7,850 Posts Drives: Z4M/. Z3M, E36/46 M3 Join Date: Oct 2008 Location: Teaching the dog to slalom iTrader: (22)	So, boiled down, that analysis and math contends that gear selection position can't move much, and there are physical limitations to how much movement the mechanical systems have available in terms of tolerance. Okay fair enough. But that doesn't get us to a solution. And that is what most of us are after. Here are the data points we have, along with the most reasonable solution to the following issues: Issue - 3rd to 2nd 3rd to 2nd is an issue. It's not driver error, unless half the forum (and quite a few other forums) don't know how to shift this car or other BMWs. This issue isn't limited to the Z4M. The E30 and many other BMWs also suffer from the same issues--and the "cure" is the same: stiffer engine/transmission mounts. Frequency of this issue is reduced with stiffer transmission mounts (that's what folks here report 1, 2) Shifting is improved and the 3rd to 2nd issue is further reduced (or eliminated) with a stiffer engine/transmission mount combo. (1, 2) Issue - 1st - 2nd Pulling down and to the left helps, and in many cases eliminates 1 - 2 grind. Many report this, and it can't be discounted. Sychros don't self-repair. So why would pulling left help? (I have no idea, but it does, and many report this.) It's possible that in learning to pull down and to the left folks, have learned to work around a synchro limitation (so the user has modified more than just pulling to the left, maybe waiting a bit and allowing things to "catch up"). That would support your synchro contention. Solution, in either case, w/o swapping out a transmission, would be to: 1.) pull down and to the left; 2.) upgrade mounts (since it helps with the other issue, and may help here). Regarding 3rd to 2nd, the aftermarket community says pretty much the same thing across the board. The solution being offered by Turner Motorsports, Vorschlag, UUC, AKG, Rogue (1, 2, 3, 4, 5) all work on the same premise and offer the same solution. (I seriously doubt the customers who bought these products--and report improvements--are all wrong or that they're all in league with vendors.) If the evidence in front of us shows that the 3rd to 2nd issue can be improved, if not corrected, with improved mounts, and that the same solution may help or improve the 1 -> 2 grind, why not just run with the solution and call it a day? Last edited by Finnegan; 04-09-2013 at 07:35 PM..
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