SMG >> 6 Speed Conversion ... To do, or not to do.

[Andratch]

Hey folks,

I have a '05 M3 Comp with 50k Miles and the SMG gearbox and CSL software. I was on the edge of selling it to buy a Facelift Aston DB9 (with money from another car I sold), but I just don't think I'm ready to part with it yet. So, I would like to take a little bit of recent fleet-thinning money and invest to make The M3 perfect-er.

I've already done the CSL intake, new suspension, new brakes, blah blah...the only thing that's really still on my mind is the SMG > 6 Speed conversion. I'm weighing if I should.

PROS of SMG:

I actually don't mind the SMG (with CSL software) much at all. I'm not good at heel-toeing, and so its little rev matched downshifts and whatnot are actually cool and something I'd struggle to produce with my own feet.
I bought upgraded Storm paddles that make it pretty cool to shift
I hear that the E46 M3 manual is a bit clunky, but I'm also cognizant that that's "internet feedback" that may just be a bunch of telephone game from folks who don't have one. I would do it with a short shifter and ZHP knob.
I also think it's a neat technology, and if I swap it, I'm no longer matching my build sheet (if that matters).

CONS of SMG:

While mine is in really good shape, I'd probably have to change it out when it starts failing anyway, because it's not worth the repair.
The "clunk" from the rear that the SMG delivers is annoying. I have all new bushings and still get clunk. I haven't driven a M3 6 Speed, but I understand the clunk isn't there with the 6 speed (is that right? because this is an important decision factor).
Debatable whether the SMG is better in traffic, because I find myself going like 3-4 mph a lot and it can't really figure out whether to stay in gear or not at that speed.
My daily is an old Tesla, so a 6 speed gives me nice polarity for the weekend car.

So, there's my stances on both sides. From those that have done it, do you regret it at all? Any cons? Does the diff clunk go away?

How much does it cost these days (and any recommendations of a shop to do it in Texas / Houston)?

[samthejam]

Just wanted to say Howdy, as a fellow Houstonian. I converted mine to a 6 speed for reliability reasons on long road trips, as peace of mind. I do not regret it all, and I did like the SMG quite a bit. I DIY'd the swap and can't afford to take my car to a shop so unsure of local pricing for something like that. I got lucky and used a lot of used parts and was able to do the swap for $1500 in parts.

I still have a clunk in slow moving traffic, going from neutral to first or vice versa while rolling at really slow speeds or sometimes from a stop. Not sure if that is the "M-clunk" or not you are describing.

If you are happy with the SMG, I would leave it alone and just save the cash for an issue with the SMG. If the cost to repair is too much, you can manual swap.

[M3llowM3]

Just wanted to say Howdy, as a fellow Houstonian. I converted mine to a 6 speed for reliability reasons on long road trips, as peace of mind. I do not regret it all, and I did like the SMG quite a bit. I DIY'd the swap and can't afford to take my car to a shop so unsure of local pricing for something like that. I got lucky and used a lot of used parts and was able to do the swap for $1500 in parts.

I still have a clunk in slow moving traffic, going from neutral to first or vice versa while rolling at really slow speeds or sometimes from a stop. Not sure if that is the "M-clunk" or not you are describing.

If you are happy with the SMG, I would leave it alone and just save the cash for an issue with the SMG. If the cost to repair is too much, you can manual swap.

this is good advice. I am in a similar position, i swapped years ago as a preventative measure, but had no real gripes with the SMG, as it all was working well, i just wanted the more direct feeling of a third pedal, and do not regret it at all.

[sapote]

The "clunk" from the rear that the SMG delivers is annoying. I have all new bushings and still get clunk. I haven't driven a M3 6 Speed, but I understand the clunk isn't there with the 6 speed (is that right? because this is an important decision factor).

The clunk is from the Diff, not the SMG as it works exactly same as 6sp manual.

To fix the clunk, open up the diff and shim the side-gears to reduce the plays with the spiders gears, and don't use spring cup washer to zero out the plays completely.

[Andratch]

The clunk is from the Diff, not the SMG as it works exactly same as 6sp manual.

To fix the clunk, open up the diff and shim the side-gears to reduce the plays with the spiders gears, and don't use spring cup washer to zero out the plays completely.

I think I read your other post on this - just want to make sure we're talking about the same clunk......Mine happens between gears while moving. For example, a shift from 1-2 or 2-3 leads to a *CLUNK* right before power re-engages. The more I'm on the throttle, the louder the clunk. So, light shifts are silent. Is that the same issue you mention with gaps that need shimming around the spider gears?