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I have the stock flywheel to work with, but yeah, machining and balancing is definitely cost to consider. I suspect I will be about even in the end either way. I won't lie though, that Domi adapter is gorgeous.
Any idea what spring rate your friends went with on their Adamat hub on the LS?
Not sure exactly. I think Draysen (TT LS E90) has the stiff springs.
a guy i know has been working on developing a spring hub for the LS as well. He has them for other motors. It'll replace the whole flywheel/flexplate. I can ask if he's ready to sell them yet.
a guy i know has been working on developing a spring hub for the LS as well. He has them for other motors. It'll replace the whole flywheel/flexplate. I can ask if he's ready to sell them yet.
Yes please! Would love to know what other options are out there before I commit.
Yes please! Would love to know what other options are out there before I commit.
i sent him a link to this thread, he will probably chime in or reach out. He's a good person to talk to for tuning and firmware upgrades on the trans as well. I payed him to do mine.
I started this DCT journey before I was aware of any options leaving the mechatronics alone, so I gutted mine a long time ago. Now I'm leaning towards the maxxecu, so I bought another DCT with known bad clutches for dirt cheap, as a mechatronics donor, just to be able to use the maxxecu. I'm leaning towards the "Race" version. Haven't considered the flywheel option.
Thanks for the real world feedback.
I see a need for both a CAN keypad and for a display to show what gear you're in and also for other CAN interfaces. I'd like to combine the need for CAN bus Keypad and a display for letting you know what gear you're in, maybe a shift light, into a custom touchscreen. The custom touch screen I designed in my Vette, controls the transmission and pretty much all the cars operating modes, and is CAN enabled, so I'm leaning towards building one for the BMW.
If anyone is interested, I can share design and software and collaborate on that. If you already know the CAN messages needed, I've got the rest of it pretty much under control. It would look something like this, but customized for the DCT.
I was made aware of another vendor that can control the DCT transmission without having to gut and modify the computer. CANformance Engineering https://www.canformance.net/ can control both E and F series DCT transmissions with a direct plugin. No DCT rewiring needed. It's a standalone trans controller. I've heard good things about this unit. It also supports the MaxxEcu so it can be integrated. I checked out their tech pages and the CAN info is pretty easy to implement.
So far MaxxEcu can plugin support only the e9x M3 V8 trans. The MaxxEcu is a combination of ECU and transmission controller. I'm kinda leaning that way because I like the integration and think they can blip the throttle better than me having to rig some throttle blip feature into a GM ECM. I heard some people having a hard time tuning downshifts, but I think that shouldn't be an issue. I'm going to hold off on pulling the trigger on any of these till I have to.
So when I first bought my DCT, there were no direct plugin options to control it and therefore I gutted the mechatronics (the internal computer) unit in prep for rewiring it. Now that there are direct plug in options, I bought a second DCT, for super cheap (it had burnt out clutches) and will transplant that mechatronics unit into my first trans.
Measured progress over the last few weeks. Elected to re-profile the stock flywheel to both clear the Domi adapter and allow the hub to center on the main, all in, it's about $300 in machine work. I just like the idea of running a flywheel vs just a flex plate.
Also got the engine placed in the engine bay. The DCT transmission will definitely require some significant clearancing of the tunnel. I was hopeful I could do this without a full interior removal, but no dice. The dash needs to come out to properly cut and weld.
Plan is to use the MaxxECU Race since they have cracked the BMW encryption and can run the transmission without any additional modifications to the internal TCU board. In theory, it should be plug and play (tuning excluded).
Domi calls for a flex plate only on the LS to DCT adaptor. I just feel better running some sort of flywheel, so machined down the original LS flywheel to work. I re-profiled the front surface to clear the Domi adaptor and sunk the hub into the center to find the main. Will fit it up this week to see if I have clearance issues, or if the hub extends to far onto the transmission drive spline.
Domi calls for a flex plate only on the LS to DCT adaptor. I just feel better running some sort of flywheel, so machined down the original LS flywheel to work. I re-profiled the front surface to clear the Domi adaptor and sunk the hub into the center to find the main. Will fit it up this week to see if I have clearance issues, or if the hub extends to far onto the transmission drive spline.
I was thinking about this topic. Wouldn't it be better for crisper shifting and clutch life to have less mass to slow down or speed up with each shift?
I was thinking about this topic. Wouldn't it be better for crisper shifting and clutch life to have less mass to slow down or speed up with each shift?
I guess I see it as just the opposite. Definitely interested in other opinions, but my thought was having more rotational inertia would smooth out the shifts through the handoff. In general, flywheels create smoother shifting but come at the expense of rev responsiveness. This is a street car, so I’d rather prioritize smoothness over responsiveness.
I fully accept that I may be totally wrong in my assumption, so feel free to educate me if that’s the case.
I guess I see it as just the opposite. Definitely interested in other opinions, but my thought was having more rotational inertia would smooth out the shifts through the handoff. In general, flywheels create smoother shifting but come at the expense of rev responsiveness. This is a street car, so I’d rather prioritize smoothness over responsiveness.
I fully accept that I may be totally wrong in my assumption, so feel free to educate me if that’s the case.
I don't have any real experience with this trans yet either. If you think about it, regular automatics have the weight of the converter spinning so there is more than just the flexplate. What is in the V8 M3 BMW setup? That's what I'd think was engineered for this trans. I'll call my BMW buddy to find out.
Productive weekend. Managed to get the shaved flywheel fit up and checked for clearance. All seems good. Close, but good. Because the flywheel is obviously thicker than the required flexplate, I elected to take the difference off the end of the hub adaptor rather than cut a deeper pocket into the flywheel. Happy with the results.
I like the amount of engagement between the trans and hub adapter in your setup. Mine doesn't go in as deep.
Did you balance the flywheel after cutting it?
Thanks for posting your pics, I forgot there was an alignment pin between the DCT and the adapter plate. Also, I noticed that your DCT mount bolts appear to protrude quite a ways in. Is there any interference with the flywheel?
I talked to my BMW buddy. He said many BMWs have a viscous coupling plate connecting the DCT. He thinks it's mostly for noise reduction in neutral and lots of folks are removing these because they break. Another experienced BMW guy (high HP BMW engine) successfully runs a light aluminum plate with the steel ring gear attached at the outside. So that's probably closer in mass to a flex plate than a clutch plate. I still haven't heard smoking gun proof that one is better than the other, so please carry on.
If there is enough length on the end of the crank on the lip that centers hub adapter to the crank, I may build a spacer using a spare flex plate center section, so I can get a little more engagement. I used to do this on my high HP setups, where I'd often break the stock flex plate, but here it would only be for spacing.
I like the amount of engagement between the trans and hub adapter in your setup. Mine doesn't go in as deep.
Did you balance the flywheel after cutting it?
Thanks for posting your pics, I forgot there was an alignment pin between the DCT and the adapter plate. Also, I noticed that your DCT mount bolts appear to protrude quite a ways in. Is there any interference with the flywheel?
I talked to my BMW buddy. He said many BMWs have a viscous coupling plate connecting the DCT. He thinks it's mostly for noise reduction in neutral and lots of folks are removing these because they break. Another experienced BMW guy (high HP BMW engine) successfully runs a light aluminum plate with the steel ring gear attached at the outside. So that's probably closer in mass to a flex plate than a clutch plate. I still haven't heard smoking gun proof that one is better than the other, so please carry on.
If there is enough length on the end of the crank on the lip that centers hub adapter to the crank, I may build a spacer using a spare flex plate center section, so I can get a little more engagement. I used to do this on my high HP setups, where I'd often break the stock flex plate, but here it would only be for spacing.
Depth of spline engagement: I put a bore scope in the DCT housing when I mounted it up the first time, and while the engine/adaptor/trans did mount, I could tell the hub was right up to the end of the DCT input shaft. With the added thickness of the flywheel, things were too tight. I took about two millimeters off the end of the hub and put a new chamfer of the end. Repeating the same bore scope after machining, things look perfect. There’s about 1mm of end play on the hub spline.
Regarding the adaptor through bolts, they did kiss the flywheel ring gear, so I trimmed all the bolts back to stand one thread proud of the adaptor thread hole. That resolved any clearance issues.
Have not yet balanced the flywheel. Wanted to confirm I was done machining before I did a final balance.
I believe the original BMW setup for the DCT utilized a dual mass flywheel specifically to quiet things down and absorb some shock in the driveline. Interestingly, many of the DCT adaptors for the 4 cylinder applications come with a custom flywheel. This seems to be much more important on engines with high NVH. The V8 is a pretty smooth engine, so a flex plate only seems to be totally acceptable. In the end, I’m just going with my gut and electing to assume a flywheel will improve drivability. Time will tell if I’m right or wrong.
As for hub engagement on the end of the crank main, after talking to the machinist that shaved the flywheel, we elected to sink the hub into the flywheel about 2.5mm rather that machine a pocket deep enough to get the hub to center in the main. Because the flywheel is as close to a pressed fit as you can get, we indexed the pocket off the center bore for zero play between the flywheel pocket and hub.
10-26-2022, 02:58 PM
