Business Case For E39 M5 SMG II Retrofit Kit - The Unofficial BMW M5 Messageboard (m5board.com)

INVICTO · 5th January 2003, 08:30

Hey everybody,

I am going put the SMG II controller, Hydraulic Unit, Actuators, plumbing, steering wheel and gearshift and into my '01 M5.

While the parts cost are not prohibitive, the software integration and necessary adaptation layer for interfacing with the M5 DME is an unknown.

I am not aware of any absolute non-starter issues with this backfit - we've already got the same transmission as the M3 and an electronic throttle.

Here is my question for the possible clientele of retrofit kit that I would likely offer to defray the non-recurring engineering tab.

If you are interested, how much would you pay for backifitting SMG II to your Beast? $5K? $10K?

Also, please tell me if you've driven the SMG II M3 to be able determine those responses from people speculating on whether they would like it. I had an ’02 M3 SMG Cab and I loved it (till Stuttgart seduced me)

My background is engineering with emphasis on control systems. I currently consult for the Chief Engineer of the Assistant Secretary of the Navy, Research, Development and Acquisitions, on Strategic Acquisitions Planning and Large Scale Family of Systems Engineering.

Thanks for the feedback.

Steve

BostonRocket · 5th January 2003, 09:52

Wow! Now that is a project! I personally am not interested in the retrofit, but I would be willing to pay $5-7k if i was.

Best of luck!

'Rocket

MIB · 5th January 2003, 14:15

SMG 1 Sucked butt. SMG II is better, perhaps SMG III will be the business.

I would be interested butt only at aroung $5,000 AUD,

Which is only $2,500. USD.

I guess that means I'm not that interested.

MEnthusiast · 5th January 2003, 14:49

I think the correct point is that point at which people would turn away from it as an option on the M3. my guess is its in the 5k range. its also obvious that the real cost is in reverse engineering the engine software- Dinan has apparantly spent years trying to get the S2 mod working properly beause of this. Im sure its doable though........ good luck

chunpng · 5th January 2003, 17:26

Invitco,

Wow, what a background!

Does your cost referred to INCLUDING all the parts? if that's the case, $5k-$7k seems really reasonable.

On the other hand, wouldn't it be easier to shoehorn the M5 engine into the M3 with SMG II already? I know it's cost more as the engine is like $40k, but you would have less software/control issues.

Just a thought. Oh, to answer your question, I like the M5 stock.

CP

dNA3D · 5th January 2003, 18:25

I'd worry if I were to do that transplant. Mainly, the M3 tranny was probably designed not to tolerate any more torque than the small 3.2 litre engine could produce, not a lot when compared to the torque the M5 produces. If you were to pull it off and have you car actually work for more than 2 miles, I'd really suggest strengthening some parts of the tranny.

INVICTO · 5th January 2003, 20:07

The transmission wouldn't need to be changed.

The SMG II replaces the clutch pedal and mechanical gear shift linkage with hydraulic actuators powered by a hydraulic pump and distribution manifold controlled by the SMG controller.

Our clutch is a manual pedal operating on a master cylinder that transmitts hydraulic pressure and flow to operate the slave cylinder that actually disengages the clutch.

SMG replaces the pedal and master cylinder with a hydraulic source and solenoid valves to meter the pressure and flow to the existing slave cylinder.

Similary, the push , pull and angle selection on the gear selector rod physically connected to our gear shift would now controlled by a hydraulic actuator, with no physical connection to the SMG gear selector "stick shift" which is actually an electronic switch.

For More Info

Steve

Richard in NC · 5th January 2003, 22:06

INVICTO, (very impressive credentials BTW),
I hate to be a nay sayer but.....
What dNA3D is refering to is the torque difference between the M3 & M5. Even though the transmissions are apparently the same, the M5 produces far more torque than the M3 and consequently can easily fry clutches when abused. As quick as the SMG II can shift, I'd be suprised if an M5 clutch would last more than a few hard launches. Even with the M3, I hear US customers are limited to so many "launch control" starts or they void their warrenty.

I would guess that BMW never offered SMG II in the e39 M5 for 3 reasons (end of product cycle, more limited market, and I'd bet potential clutch life). With a manual transmission, BMW can blame the owner and not pay for it. WIth SMG II, it would be BMW who pays (hence the launch control limit).

I would also bet that the hardest part in doing it yourself would be software adaptation. Besides programming the SMG control module for the M5's power curve, there is no doubt that the engine control module is re-programmed in SMG-II models to deal with its differences. It might even be completely different due to extra sensors and so on. This could take years for a small team to reverse engineer and perfect. I haven't even heard any of the big aftermarket companies trying this.

Lastly, for my personal opinion, I would have considered SMG-II if it was available up front but probably wouldn't consider it after-market unless it is proven to be done right and adds to the car.

It would be an impressive project but I doubt there'd be any ROI for 1-2 years even if people are interested. By then the e60 M5 should be out with a factory SMG.

SC E38 M7 · 5th January 2003, 22:40

I do concur that the clutch would take a beating on an SMGII M5. For this reason maybe an alternative would be a hi performance clutch. Also If there is an SMG in the E60 M5 it will be just as hard to retrofit due to the number of cylinders. A rumored 10 cylinder engine on the future M5 and a 6 cylinder on the current M3 are what makes it difficult. You need the SMGII ECU to communicate with the engine DME. Since the current M5 DME is programmed for 8 cylinders you are either +2 or -2 as far as new or current SMG applications are concerned. Therein lies the challenge of the retrofit. I believe it communicates to the engine DME via the CAN BUS line. I admire your project and look forward to hearing its progress.

StahlGrauM3 · 6th January 2003, 08:11

Quote:

Originally posted by Richard in NC
Even with the M3, I hear US customers are limited to so many "launch control" starts or they void their warrenty.

Richard, no truth to this rumor as it regards US cars. The launch control in the US is detuned...launches at approx 1800 rpm and therefore there is no limit to its use.

In fact, according to BMWNA, launch control doesn't officially exist in the US

Yupkwondo · 6th January 2003, 08:41

I e-mailed Hartge a long time ago about doing an H50 with SMGII and they said it was not possible. Just as everyone has been saying, it was because SMG can not deal with the touque of the M5 motor, the clamping pressure of the clutch is not even close enough they say to accomidate for the speed of SMGII. Hartge said that if it was done, you would have to drive in A1-A2 or S1-S2 to not fry the clutch. Now, if you were to over develop the clutch and have one that could take it...I think that you would have a reasonable project. I would pay around 5-7k for it. Good Luck, if it works I'll be the first one to donate my car to have it done to it.

~ Jason
2001 Lemans/Lemans