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Okay... Here's a link to a YouTube video that does work... I think Sean Flynn's -- "socks" on here I believe -- DCT conversion is one of the most innovative things I've seen in many years for the FD. Not sure what work he did on the rest of the car, but suspect its pretty good stuff. I'll check it out. Doesn't matter. On a track, this thing should be really capable. I hope Peter Hahn and Fritz Flynn and other track monsters comment.
I blew my transmission up (snapped the main shaft) and its back now with a Liberty Chromoly shaft, and temp monitoring through Haltech (with provision for a cooling pump). We'll see how it holds up, but ever since I got the short 5th for the track, I've wished for the old 5th ratio as a 6th overdrive gear for the street. I still run a 4:10 rear gear and there's no way I'd go 4:3 unless I had another gear the equivalent of the .709/4:10 OE overdrive ratio on top of it.
My only misgiving with this setup is, the weight. I understand that trans is very heavy. My future plans (once somebody like IRP has it in kit form) is the 370Z trans/diff combo. If I'm wrong about the weight, somebody let me know.
I can think of a few corners, Oak Tree at VIR, final corner WGI, where trying to get a down shift done while braking and turning makes you look like you're in a fist fight in a phone booth. A quick paddle flick might help you focus on smoothly carrying speed instead.
...trying to get a down shift done while braking and turning makes you look like you're in a fist fight in a phone booth.
Hahaha... That really made me laugh, Peter. Helluva turn of phrase. I suspected you would appreciate what he and Neal Adderly had done. I suppose weight could be an issue, but not sure the benefits do not outweigh the weight. Even if there is, say, 100 pounds added, could you turn up the boost just a little bit to get to the same hp/lb ratio? Anyway, they've done something very innovative and has to be a direction several people will go. I remember when sticking a 20b in an FD was innovative. Now, they're all over the place. While I doubt I will ever need or want a DCT style tranny, I think this is very cool and really admire what they've done.
Gordon, I think its an amazing innovation. My hats off to Neal and his collaborators.
Having had the pleasure of driving your car, the multiple gears and quick shifting might really suit it... I recall it feeling very much like a (more powerful) S2000 in its character, the way it revved and made power. But, I suspect that "3 or 4 rotor turbo street car" with big HP is the user profile for this swap.
I'm always trying to figure out where I can shave 5-10 lbs!
Hahaha... That really made me laugh, Peter. Helluva turn of phrase. I suspected you would appreciate what he and Neal Adderly had done. I suppose weight could be an issue, but not sure the benefits do not outweigh the weight. Even if there is, say, 100 pounds added, could you turn up the boost just a little bit to get to the same hp/lb ratio? Anyway, they've done something very innovative and has to be a direction several people will go. I remember when sticking a 20b in an FD was innovative. Now, they're all over the place. While I doubt I will ever need or want a DCT style tranny, I think this is very cool and really admire what they've done.
Box to box it should only be 65-70 lbs difference if interwebs info can be trusted on the BMW box.
the two BMW DCT versions being discussed weigh approx 175 lbs
I’m looking at a weight limited competition class that I can easily get below that additional amount (offset some by the PPF delete too), so it’d just be fairly close to CG height and centered in the chassis rather than me mounting metal weights on the floorboard
I do t see the need of wasting a good aluminum flywheel on it when you are just using an automatic starter that’s supposed to be used with an automatic transmission flex plate.
I would use the automatic flex plate instead and save some more weight MOI from it.
I can't confirm actual weights. But I did just lift the DCT out of my truck bed. I'm not as spry as I used to be, but I remember the stock trans being much lighter.
F80/82 version is listed as 83.2 kg (183 lbs) dry according to the BMW dealer tech training info, but what’s a few kgs among friends
Have a similar BMW document for the E9X V8 M-version and it stated 77 kg (169 lbs) dry compared to the 85 kg listing above, so some variance even within BMWs own literature, but basically around the 175 lb. range. There’s the oil cooler and lines too; factory fill is also 9 Liters of oil.
Also highly recommended not to go too light on a flywheel as supposedly it won’t work out well based on everything I’ve seen so far. Just the standard steel type around 13 - 14 lbs. is what Neal recommended to me, which then gets the AT CW plus the splined adapter that bolts on with the flywheel to the CW and mates the input to the engine (small diameter though). The only purpose for the FW is to provide the starter ring gear and suitable MOI. I didn’t ask/confirm, but assume the AT flex plate works as well. Can’t recall ever seeing a weight for one of those?
Another thing to consider for an older vehicle like an RX7 (no offence) is a DBW TB, which in addition to blip shift etc opens up a whole range of other ecu control strategies that can be advantageous for various scenarios.
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I'd be curious on the specifics of why the suggestion is to with the a somewhat heavy flywheel (relative to the work it will be doing). I'd kind of assume that some of the shifting logic/PID setup is somewhat baked in even underneath whatever controller is used.
well the input adapter is a small diameter and aluminum, so it’s not likely adding much MOI
but more importantly, there’s no clutch assembly any more, i.e. that MOI is now gone and maybe you weren’t considering this? Unless you were using a Tilton carbon-carbon mini clutch then there’s likely going to be less MOI than an aluminum flywheel with a more conventional clutch assembly. If you’re talking about using the mini-clutch type of racing aluminum flywheel, which is only 4 or 5 lbs total and extremely low MOI by itself, imo that’t be really, really pushing it. That type with a mini-clutch is not an easy launch unless it’s a Tilton carbon that can be slipped and it’s still tricky. With only the adaptor it’d be trickier still.
I suppose it depends on whether it’s a pure track car or potential street use vehicle and how smooth you want it to take off from a standing start. Even though the DCT clutch packs are automated, excessive slippage is likely to end up being an expensive repair in the long run. The clutch pedal can be setup with a 0 - 5 volt sensor for manually launching it the conventional way.
They sell lightened versions for the BMW, but the weight we’re discussing (12 - 14 lbs) are what they call lightweight since they have a much heavier dual-mass type from the factory. More low rpm torque too. It might be best to get it all working first and then try to see what you can get away with.
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I understand how the assembly installs, and yes I am speaking of using very light Tilton style flywheels as I have a stack sitting upstairs. What I'm saying is that I'm curious why I keep hearing kind of lame and nebulous statements such as 'it wont work well' since it seems like I either get different answers or speculation. If its a firmware/prediction issue for shifting strategies that cannot be worked around for the time being (or ever) thats one thing, if its a bit of drivability and longevity issue, thats another.
Also as soon as I get back in I'll take a photo of a dry FD trans on a scale, my ~65 lbs weight differential was based on old info I pulled from memory but I believe its right.
Last edited by TeamRX8; May 25, 2021 at 09:11 PM.
Reason: too verbose, poorly worded, reply copied below so need to be twice as distracting from the topic
well my previous comment is incorrect, because obviously it does have a clutch; two of them actually, and they obviously do have some MOI contribution. Otherwise I’d expect that someone of your experience and caliber understands that it’s not a torque converter and also how a flywheel stores and releases energy along with the rest of it.
A certain amount of energy is required to get over a ton of weight moving forward smoothly and an electronic clutch controller isn’t going to overcome the law of physics. If I understand your posts correctly, it almost seems like you have that expectation. Not really trying to be snarky or a wise guy, just not sure where you’re coming from in some of your own reply.
Because my perception is that maybe you’re criticizing other people for not having the definitive answer you don’t have yourself? One of the first things I did after speaking to Neal was search for that answer. There wasn’t much to be found seeing the entire thing is fairly new and still developing in the aftermarket. If you understand the basic principles involved then it seems obvious there will be some limit, but no; I don’t have a specific “absolutely know beyond a reasonable doubt” answer to provide on that.
As I alluded to, my first inclination would be to get it up and running first and bring the potential additional complications in after clearing that hurdle. It weighs around 30 lbs. on a BMW street use production vehicle. I don’t think it’s an unreasonable speculation to think that dropping it to 4 or 5 lbs. might be asking a lot or add what should be considered by any knowledgable person as potentially foreseeable complications. I suppose you disagree. No problem.
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Wat. I'm not criticizing anyone I'm asking if anybody has a solid answer based on information that is of merit rather than the typical conjecture or 'it wont work well' seeing as I'm now designing my drivetrain around Neal's gear.
I'm completely open to and aware of the fact that a flywheel/drivetrain with a higher moment of inertia than what I'd like to run may be a requirement, what I'm asking about is quite literally a reasonable 'why', I cannot believe it to solely be an issue of requiring a higher MOI to impart enough kinetic energy to move the vehicle as I do it all the time with my twin disks and the 5 1/2" disks and pressure plate would most likely be of a similar weight to the very stout looking piece of billet in the input shaft coupler. So is there real information to this past rule of thumb or SWAG? Is there some sort of PID that is set up in the TCU that relies on a defined weight of rotational mass? Anyway, I think somehow you started taking something personal that has nothing to do with you I'm just on a fact finding mission before I (more than 98% likely) pick one up.
On that note, here's the actual weight of a dry FD trans:
Context Closeup
As you can see, my memory of ~110 lbs was off, I'd trust the scale to within a few pounds so lets say an even 95 lbs for a dry FD trans.
well it’s always like playing Russian roulette replying on a public forum, but words like “maybe, seems, but I’m not really sure where you’re coming from” might have some contextual purpose. At least my intent was to provide more leeway than the reply above *seems to imply*. What one person may perceive to be personal might vary with how someone else interprets their own written words as well.
I don’t really know you, but again my impression is that you’re highly experienced, knowledgeable, and a caliber above the average forum member. That’s part of why I was a bit confused about what you were getting at. Anyway, I’m hopeful that you’ll agree that we should try not to detract from the subject with the usual forum posturing and just agree to peacefully move on.
Regarding the HTG developed controller, there's at least one very unsatisfied customer over here (non-rotary). I think he was on the verge of removing the whole shebang, suggesting the developers were entirely out of their depth, at least for something intended for street use.
The issue I see, is that literally nobody in the realm is "expert" or "experienced".
HTG is in my opinion doing an excellent job for having been around the short amount of time they have. They are likely experiencing some growing pains. With their recent release of the tuning suite and new firmwares, most of my concerns about the control unit are gone.
The TPS take-up strategy makes sens, and is easy to get set up.
Shift tuning takes time to wrap your head around,, but once you do, it's not hard to navigate. Like anything, takes a few iterations to get right.
I've seen people pull the plug on the project, and in my brief time recently, can understand why, but it was just a bit too soon as they have made alot of progress on it here in the last month. Previous to that, I may have said it's still too undeveloped, but that opinion has changed as of late.
Alot of the issue is the wiring modifications required. myself and Neal had this work outsourced, and both of them had wiring issues (5v short to ground on the mechatronic), so getting started was tough as nothing worked, and it seemed like it just should have. I pulled the trans to inspect it, was fine, reinstalled, still not working, pulled it to install Neal's to test, also didn't work, ended up sending both out to be reworked/repaired, and then it just worked as it should. There was one or two times in there that almost got the plug pulled, but at this point, I'm so so glad I kept at it. In my opinion, there is nothing even close to describe the feeling.
I read through the wiring instructions on the mechatronic. It does seem daunting.
Did you end up using the Domiworks PCB? Seems like that removes a lot of uncertainty assuming it is soldered correctly by a pro.
Definitely not something I will DIY. Even if it works, I am not an automotive grade solderer, and being in a transmission, you don't anything coming lose of course. Reliability is key on that component, definitely would not be fun troubleshooting the issue you experienced.
My parts from Neal arrived today. To dguy’s point, I have to correct myself and report that the engine-input shaft adapter is steel and has some heft to it; just over 5 lbs. So probably close to the weight of a 5.5” metallic race clutch, though a bit smaller radius.
The aluminum engine-trans adapter is just under 7.75 lbs. Both seem well made. There’s also a bag of black oxide 12.9 allen-hex alloy fasteners along with two thin-wall locating dowels that appear to be for the user to install on the DCT mating side of the engine adapter flange.
No instructions or literature that I see. They’re sort of running this on a social media platform or two. So that might pose an issue for people who are not on social media. I knew and expected this already myself.
Came in a rugged heavy-wall cardboard box suitable for the weight with very good packing material inside, parts wrapped & taped, input adapter-fasteners-locating dowels were packed together in a smaller box, and the main box ends stapled and taped shut. Not something that was slopped together from the Walmart mail & shipping supply aisle.
The issue I see, is that literally nobody in the realm is "expert" or "experienced".
HTG is in my opinion doing an excellent job for having been around the short amount of time they have. They are likely experiencing some growing pains. With their recent release of the tuning suite and new firmwares, most of my concerns about the control unit are gone.
The TPS take-up strategy makes sens, and is easy to get set up.
Shift tuning takes time to wrap your head around,, but once you do, it's not hard to navigate. Like anything, takes a few iterations to get right.
I've seen people pull the plug on the project, and in my brief time recently, can understand why, but it was just a bit too soon as they have made alot of progress on it here in the last month. Previous to that, I may have said it's still too undeveloped, but that opinion has changed as of late.
Alot of the issue is the wiring modifications required. myself and Neal had this work outsourced, and both of them had wiring issues (5v short to ground on the mechatronic), so getting started was tough as nothing worked, and it seemed like it just should have. I pulled the trans to inspect it, was fine, reinstalled, still not working, pulled it to install Neal's to test, also didn't work, ended up sending both out to be reworked/repaired, and then it just worked as it should. There was one or two times in there that almost got the plug pulled, but at this point, I'm so so glad I kept at it. In my opinion, there is nothing even close to describe the feeling.
Latest news, he got a remote tune from them, apparently much improved, but still lacking full manners for street duties. Were you running this, thought someone mentioned maxxecu or haltech control before? I understand there's a few electronically savvy guys locally developing stuff to run the trans, which might help on time zone, language, etc.
Originally Posted by dguy
As you can see, my memory of ~110 lbs was off, I'd trust the scale to within a few pounds so lets say an even 95 lbs for a dry FD trans]
On corner weight scales years ago, 44.5kg, so pretty close.
I have the HTG GCU with a haltech ecu. Sanjay is the one running the maxxecu.
I did end up with the DomiWorks pcb option, and I did send the mechatronic to him for the small soldering. It left me with 25 solder points to make, all on large pads for comfortable soldering.
The domiworks board (when you send him your mechatronic), will come back looking like the bottom half of this top picture (I've already soldered the sensor harness in place in the first picture).
The bottom picture is after I completed both harnesses.
Not really trying to be snarky or a wise guy, just not sure where you’re coming from in some of your own reply.
