godmars_snakly311 19 Report post Posted August 4, 2021 Hello there, Would like to know for the E46 M3 with SMG II gearbox parking issue. Is that like full manual gear box parking procedure if downhill user reserve gear. If uphill use first gear to parking the car? Or all parking use N is fine for SMG II gear box Thanks Quote Share this post Link to post Share on other sites
M3_Power 636 Report post Posted August 4, 2021 (edited) Park in gear. It’s a manual gearbox. it’s why it chimes when you leave it in Neutral Edited August 4, 2021 by M3_Power Quote Share this post Link to post Share on other sites
jon dee 500 Report post Posted August 5, 2021 Stole this from an M5 forum but I think it answers the question... Quote Re: question about parking my SMG M5 on an up-slope... Leave it in D1 or 1 and shut off the engine... with the engine on it will be in neutral of course to prevent it from stalling. Once you shut your engine off while the instrument cluster says 1 or D1 you'll hear the clutch engage and it'll be locked in gear. Reverse also works... Try it again. Turn off your Engine while in R or 1 or D1 and release the hand brake the car should catch in gear and rest its weight on the transmission and not roll. Test it on a slight incline instead of a hill though Cheers... Quote Share this post Link to post Share on other sites
Palazzo 477 Report post Posted August 5, 2021 Isn’t this the exact opposite of recommendations for parking with an auto trans, so you don’t rest the weight of the car on a small piece of metal not really designed for the task? Quote Share this post Link to post Share on other sites
jon dee 500 Report post Posted August 5, 2021 Here is a picture of the trans brake that is actuated when you put the shift lever in PARK. The lug on the pivoting arm engages with the toothed wheel attached to the trans output shaft and locks the output shaft against turning. This is the standard park brake setup for just about every auto trans with torque converter. The pull-up lever or foot pedal commonly referred to as the hand brake or E-brake operates on the rear wheels of RWD cars and is additional to the trans brake on auto trans cars. A typical automatic car will have a torque converter so at standstill there is no mechanical connection between the engine and the wheels. The engine cannot provide any braking force so the manufacturers provide the trans brake to lock the driveshaft against rotation. It is ALWAYS recommended to put the shifter in PARK when parking. Not only to prevent the car rolling but in most cases to prevent the car from being started in gear. On the other hand, a manual transmission has a mecanical connection between the engine and the wheels when the clutch is engaged and the car is is gear. It is also recommended that the car be put in a low gear when the car is parked on a slope so that the engine can supply some braking force to augment the hand brake. On steep hills it is also recommended that the front wheels be turned into the kerb, as if the hand brake does not hold the car may slowly edge forward as cylinder pressure leaks down. The SMG is a special case of an manual transmission without a torque converter, where the clutch action and gear shifting are achieved with an electro-hydraulic system. Thus to obtain the benefit of engine braking force the car must be parked in gear WITH THE CLUTCH ENGAGED. This is achieved by turning the engine off while the car is in gear as described above. Turning it off while the gearbox is in neutral means that no gear is selected and no engine braking assistance will be available. As for all cars it is recommended that the hand brake be used in conjunction with the engine or trans braking for safety reasons, and it is a good habit to get into Cheers... Quote Share this post Link to post Share on other sites
Palazzo 477 Report post Posted August 5, 2021 Sorry, I wasn’t very clear, I’m sure it says don’t just leave it in park, but always use the parking brake to hold the car, rather than slapping it in park and using the trans as the brake. Quote Share this post Link to post Share on other sites
aja540i 1906 Report post Posted August 5, 2021 SMG doesn't have a Park option, its in a gear, or its out of gear ( neutral) its a manual gearbox. 1 Quote Share this post Link to post Share on other sites
Palazzo 477 Report post Posted August 5, 2021 Yeah, fair point, I guess it’s holding on an actual gear as opposed to the park “lock” shaft in the ZF. Quote Share this post Link to post Share on other sites
isis 16 Report post Posted August 5, 2021 it bings at you if you leave it in Neutral when you kill the engine. so just move it into gear Quote Share this post Link to post Share on other sites
jon dee 500 Report post Posted August 5, 2021 30 minutes ago, isis said: it bings at you if you leave it in Neutral when you kill the engine. so just move it into gear If the clutch is not engaged then putting it in gear won't do anything to hold the car. Cheers... Quote Share this post Link to post Share on other sites
aja540i 1906 Report post Posted August 6, 2021 When you move it into gear you can hear the clutch engaging, its quite a clever piece of kit! Quote Share this post Link to post Share on other sites
jon dee 500 Report post Posted August 6, 2021 31 minutes ago, aja540i said: When you move it into gear you can hear the clutch engaging, its quite a clever piece of kit! I'm going to assume that the engine must be running or at least the ignition turned on to get the clutch to engage ? Cheers... Quote Share this post Link to post Share on other sites
aja540i 1906 Report post Posted August 6, 2021 1 minute ago, jon dee said: I'm going to assume that the engine must be running or at least the ignition turned on to get the clutch to engage ? Cheers... nope, uses hydraulic pressure and the pump is electric, it will engage with the key off. I don't think it will disengage unless the brakes are on if the engine is off, but not 100% sure. Quote Share this post Link to post Share on other sites
KwS 2425 Report post Posted August 6, 2021 Imagine how sort a life span the clutch pressure plate (and the hydraulic system for that matter) would have if the system held the clutch disengaged every time the engine was off 🤣 Quote Share this post Link to post Share on other sites
jon dee 500 Report post Posted August 6, 2021 (edited) 3 hours ago, aja540i said: nope, uses hydraulic pressure and the pump is electric, it will engage with the key off. I don't think it will disengage unless the brakes are on if the engine is off, but not 100% sure. Yeah... I was just having a read up on the SMG II M3 system and I see that you get 10 seconds to knock it into gear after switching the engine off. Kind of like having a certain time to roll the windows up after you switch off... clever stuff Otherwise it will just sit with the clutch engage but not in gear. I guess if you leave it in gear when switching off you don't get bing'ed Now I have to go and see if I can find a pic of the gearbox internals... got me interested now. I know that the SMG seems to get bad mouthed a lot, but it actually sounds like it should be a cracker if it is working correctly. EDIT: Judging by the lack of repair information on the box itself, and the the fact that BM only wanted to supply a complete SMG trans if something went wrong inside, I can see that owning one of these could be problematic when they get into the 100K plus kms bracket. I think that I will just be happy with the standard steptronic box in my E92. With the xHP flash it works pretty good !!! Cheers... Edited August 6, 2021 by jon dee Quote Share this post Link to post Share on other sites
aja540i 1906 Report post Posted August 6, 2021 Most of the stuff that goes wrong is on the outside of the box, pump, accumulator, sensors etc, internals are basically a 7 speed manual (SMG 3) with proper maintenance should outlast the rod bearings easily!! Quote Share this post Link to post Share on other sites
KwS 2425 Report post Posted August 6, 2021 The E46 SMG2 gearbox is more or less identical to the 6spd manual gearbox internally. Its all the stuff on the outside to make it work that is different. There are a few companies that convert the SMG box to manual, although i hear that cannot be done to the SMG3 7 speed box. Quote Share this post Link to post Share on other sites
aja540i 1906 Report post Posted August 6, 2021 Yeah, SMG 2 was a modified manual box, 3 was designed to be SMG from scratch so a different story, manual M5/6 just had a 6 speed box not a manualised SMG 7 speed. Quote Share this post Link to post Share on other sites
jon dee 500 Report post Posted August 6, 2021 Good point.... I saw a couple of videos on SMG to manual conversions. So I guess converting a manual gearbox (if you can find one) to SMG is just a matter of swapping all the accessories over ? I'm doing a bit of learning here I was looking at this car https://www.trademe.co.nz/a/motors/cars/bmw/m3/listing/3198627891?bof=WD5GfN4f and although it is described as automatic, looking at the shifter pic I'm thinking it is actually SMG ... right ? Cheers... Quote Share this post Link to post Share on other sites
aja540i 1906 Report post Posted August 6, 2021 it would be sacrilegious to convert a manual box to an SMG imho! Quote Share this post Link to post Share on other sites
KwS 2425 Report post Posted August 6, 2021 (edited) I feel like i saw in a video about converting the M3 CSL to manual that there was some machining/modifying needed on the box, so if there was i wouldnt think converting to SMG would be easily doable. Even if you wanted to, which you wouldnt. The M3 vert, they werent DCT not SMG werent they? Completely different beast. Edited August 6, 2021 by KwS Quote Share this post Link to post Share on other sites
jon dee 500 Report post Posted August 6, 2021 Yuss... looks like DCT alright. The SMG and DCT seem to operate under much the same control strategy, and so the controls are also similar. Live and learn Cheers... PS: Quite like that colour. Generally I don't like black wheels but they look OK with that red body colour. Quote Share this post Link to post Share on other sites
jon dee 500 Report post Posted August 8, 2021 (edited) Just because BMW call it a Sequential Manual Gearbox does not make it a sequential gearbox. It is a conventional manual synchromesh gearbox with an electro-hydraulic system to change the gears in a Steptronic fashion. A true sequential box (dog box) is a totally different animal, and I am not aware of a dog box ever being sold in a standard production car. As explained in this video, a true sequential gearbox is a specialised tool for racing, and although superior to a synchromesh box in virtually every way, the noise of straight cut gears and the abrupt shifts are not suited to production car use. A dog box does not need the incredibly complex control and operating system of the SMG or DCT, but the latter certainly appears to have achieved a performance level that keeps M car drivers happy I looked long and hard at getting a sequential box for a previous car, but considering the cost and the fact that the car was not a dedicated race car, I gave the idea away. For an average punter such as myself who does not do track days, a Steptronic auto with a flash is plenty good enough !!! Cheers... Edited August 8, 2021 by jon dee Typo... 1 Quote Share this post Link to post Share on other sites
