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Discussion Starter #1
While talking to a reputable performance parts supplier today he mentioned that one of his clients recently had the 6 speed transmission from the current M3 installed in his M Roadster and it apparently fit with NO problem at all. I have never hear of this before but I have heard a lot of people wishing the Z had a 6 speed.

Is this possible and what would it cost (clearly the transmission isn't cheap)? How much performance benefit would be realized?

MZNorth
 

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I've been quoted US$2.5k-3k for a used 6-speed.

Was told that it bolts in, no other parts required except you have to have the drive shaft shortened (i.e., by a machinist).

Total job inc. labour to do it all would likely end up in the US$4k ballpark (CDN$6.5k to you and me:tsk: ).

Also you may as well factor in another ~US$2k for a new or re-built rear-end. There's not much point putting an overdrive 6th gear in an existing 3.15 final drive setup.

Note also that the 1st 5 gear ratios on both the 6-speed and 5-speed are basically identical (within 0.0x). You're only gaining the overdrive of the 6th gear.

I've been driving with 3.46 final-drive for a few weeks now and while the RPMs cruising at 140+km are starting to get high - and perhaps an overdrive would be nice at that point - the lack of overdrive is not awful and IMO would not warrant a CDN$6.5k outlay. If I drove long distances daily at speed with a 3.46 final drive then I would strongly consider the 6-speed.

In short, it's not going to add any performance to the car, just a more relaxed RPM at higher-speed cruising.

Cheers, Karl
 

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Discussion Starter #3
If the 1st 5 gear ratios are the same I see no point, at all. What RPM are you running @ 140 kph with the 3.46? I don't drive above that all too often but I have been known to periodically use 5th gear at higher RPM's. i.e. Queensway debauchery. ;)
 
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