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3.46 variable lsd installed

4178 Views 7 Replies 5 Participants Last post by  karlblomquist
I received my final drive back from Metric Mechanic yesterday via Fed-Ex (well-packed, no box/packaging damage).

Spent the better part of the evening installing it. It was lot easier getting off than getting back on! Aligning this upper bolts while on a creeper on the ground (car on ramps) was not fun considering the 80 lb block I had to work with. But eventually it went in OK.

Took the opportunity of having the mufflers off to replace them with Supersprint DTMs. Questions about that later.

Re the final drive - I had the following done by Jim Rowe:
- gear change to 3.46
- extra clutch plate
- mod Limited Slip (25%) to Variable Limited Slip (20-100%).

Re the feel - launches are tremendously better. I expect this is mostly because of the variable mod. Jim says that when pushed his mod allows the clutch grab to creep up to 100% lockup. I can launch much more aggressively now and not see a flicker from DSC.

With the new gearing red-line comes up noticably faster in 1st & 2nd gear. I'll need to adjust my timing for enthusiastic shifing. :)

Takeoff might seem a little better (probably more the lockup than anything), but where I really see the difference is around 3rd and 4th at highway/secondary road speed. Downshifting into 3rd at 130 (km/h) and cranking it produces noticably more pull than before - and the pulling is relentless all the way to redline. The car could really use an extra 500rpm of red-line in my opinion.

Similarly, 2nd gear at 70-80 and stepping on it produces tremendous amounts of thrust.

I agree with Ron - 3.46 gearing is such a better mate to this vehicle.

My only remaining concern is that now sharp corning seems to kick the DSC on more often than usual. This could be a function of the increased torque to the wheels causing easier wheel spin on sharp corners, or perhaps the new clutching needs to "break-in". I'll be keeping my eye on this new trait - maybe it just requires adjusting my throttling through corners. Of course, I can always turn DSC off, but I've gotten too used to it saving me from myself. :yikes:

Re the Supersprint install - man those things are hard to get lined up the same. After 2:00am rolled around I said screw it and just tightened them up. They're not well-aligned right now, but I just wanted to drive a bit before tackling that again.

Anyone have any tips on methods to get these mufflers lined up properly? The passenger side one hangs too low and pulls to the driver side. I have the mod'd bracket per Ron's note about passenger side hanging. The driver side is not too bad.

Cheers , Karl
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After some regular and aggressive driving over the past 300km I have to say that the Metric Mechanic modified final drive is great!

Enough has been said about the gearing... the car pulls like a rocket in gears 1-4 and cruises nicely in 5th (not too high rpm).

If anyone is considering doing a 3.46 upgrade you can get gearing only done by Jim Rowe of metric mechanic for $1445 + shipping. This is an alternative to purchasing a 2nd complete final drive. The total prices are close and you can't go wrong either way. Of course, if you want to have the 3.15 as a "backup" then purchasing a 2nd assembly is the only option. However I understand they are not exactly plentiful in supply, plus here in Canada they list for CDN$4000.

Jim states that their failure rate of re/re final drive assemblies is 0% (i.e., no failures).

Realistically any good mechanic with access to a machine shop or machinist can swap gearing in a final drive, but the main problem is sourcing the parts. It's a hunt for a good set of matched r/p gears and it's almost guaranteed that some machining of bearings or shims will be required to get proper fitment... I've been through this twice now (Quaife in E39 540 and now the M Coupe gears).

Anyway, just wanted to give a thumbs up to

Cheers, Karl
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