# Porsche 924 / 944 conversion: which motor adapter / coupler?



## BlackForest (Dec 9, 2016)

Hi,

I want to transfer a Porsche 924 or 944 into a sporty EV.

Please, can someone tell me, where I can buy a good motor coupler and also a good engine mount? I dont have the possibilty to create one of my own... so buying from someone who has done it serveral times would be great.

I want to use a Warp9 or Warp11 and am not quite shure at the moment if I should keep the clutch or not.

Thanks in advance!

I read a few blogs and they named for example evcouplerconnection.com - but this site doesnt exist anymore...


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## oudevolvo (Mar 10, 2015)

Where are you located?
I can recommend the guy that designed and machined the coupler plate to mount my Siemens motor to the Volvo B20 bellhouse.
He also designed and build the motor mount based on a prototype that I created myself.
See also my blogposts
- Picked up and test fitted the Siemens motor and controller (where you can see the adapter plate)
- Designing the motor mount by Mischa of Garage71
He does not have specific experience with motor adapters and mounts for the Warp motor in a 924/944 but he does have a lot of experience in custom car building. He is (like me) based in The Netherlands.
Hope this helps.


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## bchaffin72 (Jan 4, 2017)

As far as I know(and I'm still fairly new to the learning) there is no actual NEED to retain the clutch. It's primary purpose is to disconnect power when you bring the car to a stop or to shift gears(since the engine is always turning). When you've got an electric car at a stop and foot off the accelerator, your motor is not turning, so there's no power to disconnect. And since there is generally little(if any) up and down shifting of the car in motion, you don't really need it there either. You can do away with it and never really notice.

You can take it or leave it, really A possible downside is that it is extra weight you don't really need.


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## Duncan (Dec 8, 2008)

Hi
You are in Germany and may have problems with EMC regulations - may I suggest an alternative?
How about grafting a complete Nissan Leaf motor/transmission instead of the existing one?


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## BlackForest (Dec 9, 2016)

@oudevolvo
I am living in Germany (near the black forest). Thanks for your link. I hope to get either a standard adapter send from someone (if motor and car are well known) or I must find a specialist not to far from me, who can create one.

So far so good - but every day I have new input into this project and getting more confused which way to choose. Fortunately, I got time to decide... 

@bchaffin72
Thanks a lot! I read a few posts and also watched videos (some guys driving in an ev and changing gears), I think I dont need a clutch, too.

@Duncan
Thanks! In my other thread you mentioned to take a battery out of a wrecked Stock-EV. The EMC regulations sounds serious, so your suggest to take a complete stock-EV as a donor sounds more and more as the perfect choice. 

Meanwhile, I watched this video:
https://www.youtube.com/watch?v=U0If_6Z59Xo

The idea is very sexy - just buy a wrecked Nissan Leaf (I looked at ebay.com >> there are working models for 7k Dollars), then strip it down and take motor, controller, charger and batteries. 

As the VW bus shown in the video above - I have similar equirement:
- simple technic (no airbags, no power steering etc.)
- light car (1.100 kg)

Is there someone who can explain my please some questions:

1.) Battery wont fit easily, so I have to strip it an arrange it - I think in the trunk like this:

2.) What components do I need (except motor, controller and battery of course, charger) and does it simply work (or is the system "confused" to be in a different environment without most of the features, that there were in the Nissan)?

3.) How can I tune it beside the fact, that my car will be much lighter?

4.) Pot-Box (pedal to accelerate), display to show capacity of battery and status of charging?

5.) What motor and what system (DC or AC) is in the nissan? Is it strong?

6.) Does a Chevrolet Volt work as well? It is a little bit pricier as I have seen - why?


In my other thread about batteries I wrote my desired profile:
- fast (<5s 0-60 mph)
- 40-50 miles range
- "easy" to setup


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## oudevolvo (Mar 10, 2015)

Why would you want to remove the clutch? It's just a pressure plate, clutch disc and a cable. Removing it does not save that much weight. A little less maintenance perhaps?
On the other hand it does add some safety. You can always decouple the motor.
Assuming that you will be keeping the original gearbox to get to the proper reduction. Assuming that your rear axle has a reduction of approx 4:1.
In direct drive you will need quite a heavy motor to get a fast car I guess.
Being able to switch gears gives you room to play around.
First gear = burn rubber
Second gear = fast
Third gear = normal driving
Fourth gear = highway cruising
Plus you can influence RPM and thus motor efficiency.


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## Duncan (Dec 8, 2008)

Hi Blackforest
Using the complete Leaf - great idea 

The motor is an AC motor - as it is about 120hp - but it can be tuned - you would need a new "brain" for it's controller

No real problem re-organising the batteries

As to "which bits do I need" - safest is to get EVERYTHING then see what you can disconnect and throw away (sell)

The volt is a more difficult one as it is a hybrid


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## BlackForest (Dec 9, 2016)

Thanks!

@oudevolvo
Have you read this? http://www.diyelectriccar.com/forums/showthread.php?t=14163

@Duncan
Sounds more and more interesting...  Thanks for your input.
I want to keep the project as simple as possible. I dont need a 10 inch display to visualize the car and evey detail of it. And I also want to keep the "youngtimer-feeling" of the car by keeping the old instruments (speed, rpm etc.). So I need to create an interface to the original devices...

Unfortunately, the video above doesnt give much information about details of the conversion. Are there other conversion - from a nissan leaf as donor car?


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## Duncan (Dec 8, 2008)

Hi Forest
This guy is putting the Leaf bits in a Saab Sonnet

http://www.diyelectriccar.com/forums/showthread.php?t=151458&highlight=leaf


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## electro wrks (Mar 5, 2012)

BlackForest said:


> Thanks!
> 
> @oudevolvo
> Have you read this? http://www.diyelectriccar.com/forums/showthread.php?t=14163
> ...


In post #one of the thread you site it says:

"When you want to change gear it is made possible by the fact that an electric motor has virtually no mass(compared to an ICE motor). This allows the syncro's in the gearbox to match the internal gear speeds reasonably quickly, which allows the gear to be selected. To change gear you just take your foot off the gas and slip the leaver into neutral. You then GENTLY & SLOWLY introduce the gear leaver to the gear you want to select. The syncro's will match the gear speeds and you will "FEEL" the gears mesh and the leaver will sort of "fall" into place. Then you put your foot back on the gas. 

This may sound complicated but it can be done easily with practice and it only takes only a second or two longer than changing with a clutch. The important thing is to remember NOT TO RUSH IT!!" 

I don't think this is correct. In a clutchless vs. clutch set-up, the rotating masses that need to be compared are the heavier electric motor rotor vs. the much lighter clutch disk. Not the electric motor  rotor vs. the moving parts of the ICE. When the clutch pedal is depressed, and the clutch disengaged, only the light rotating mass of the clutch disc (and in a very small way, the transmission input shaft, bearings, and gears) needs to be sped-up or slowed down by the syncros. This would be the same for a ICE set-up or an electric conversion with a clutch.

This is why it usually takes so long to shift gears in a clutchless electric conversion. The syncros have to deal with the relatively heavy mass of the electric motor rotor vs. only the relatively light mass of the clutch disk in a conversion with a clutch.


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## oudevolvo (Mar 10, 2015)

BlackForest said:


> @oudevolvo
> Have you read this? http://www.diyelectriccar.com/forums/showthread.php?t=14163


Thanks! Had not read that topic yet.
Interesting stuff. 
And thanks @electro wrks for the addition.
As mentioned in that topic:


> You have to consider your preferences


I guess my preference is that I want a car that can be driven normally without much additional instructions. Plus the safety aspect plus perhaps the fact that I am somewhat conservative about it.
However it is good to know that it does not mean you cannot switch gears while driving. In my case, only switching to higher gears gently would work. The gearbox cannot handle switching back.


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## Duncan (Dec 8, 2008)

Hi Electroworks
_rotating masses that need to be compared are the heavier electric motor rotor vs. the much lighter clutch disk. Not the electric motor rotor vs. the moving parts of the ICE. _

It's not the mass that is important its the rotational inertia 
The IC engine flywheel is the "heavy" bit - that is probably 10 times the inertia of the rest of the engine

Once you take that out of the equation the syncros should be able to cope without difficulty


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## rwaudio (May 22, 2008)

BlackForest said:


> Hi,
> 
> I want to transfer a Porsche 924 or 944 into a sporty EV.
> 
> ...


Excellent choice of donor car!
I have an '86 944 that has had a few different electric drive systems installed. First was a warp 11HV, Soliton1, A123 pack. All together an insanely powerful and fun combination. 0-60 in 4.8 seconds (2nd gear, no shifting, and traction problems, wish suspension work it would go faster!).

I miss this system very much, but brushes have difficulty at these power levels for any more than a 1/4 mile drag race. The A123's didn't sag much and I beat a viper to 40mph from a standing start (I'm sure I surprised him). The Soliton is also full of problems and has a finite life span before it needs repair.

Because of this and the need for reliable daily transportation, I ended up with a CALB CA pack, a Siemens AC induction motor and an Azure Dynamics DMOC645 Inverter. This is half the power of the old system, but it has worked flawlessly for what's coming up on 2 years of daily driving.

Do I miss the power? Absolutely! Do I miss the break downs and expense of repairing/replacing parts? Definitely not!

If you could find a 200kw AC system and use leaf/volt/tesla cells you'd have an amazing car. At 200kw you could ditch the clutch. Anything less than 200kw and I would keep it as you will be going through the gears to get the performance you are looking for.

PS. Although I'm in Canada I have an adapter plate that bolts on the torque tube of a 944 that I used with the warp motor. I have the coupler too, but unless you have access to a machine shop that could true it, I'd recommend finding a different solution. I had drive line vibration at 4000rpm that was most likely the coupler.


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## electro wrks (Mar 5, 2012)

Duncan:

You're right about the inertia-I was just trying to keep it simple. If you take a close look at the mechanism, the only inertia the syncros normally have to deal with is that of the relativly lightweight, low intertia, clutch disk when the clutch pedal is depressed. Not the flywheel, pressure plate, ICE parts, or electric motor rotor, turbine, steam engine, etc. With the a clutchless e-conversion, the syncros have to match the RPMs of the much higher mass (assuming higher inertia, too- I know, even though it has a smaller diameter) of the electric motor rotor to the rest of the drive line in order to quickly shift gears. The rotor might weigh 30-40 lbs (~14-18 kg) vs. 3-4lbs (~1.4-1.8kg) for the clutch disk.

Think of it this way: If you've ever had a vehicle with a warped clutch disk, flywheel, or pressure plate, it can be very difficult to shift. In this case, some of the inertia of the warped flywheel or pressure plate is imparted, by friction, through the draging clutch disk. This makes it more difficult for the syncros to overcome the increased inertia and match the RPMs for smooth, quick shifting. It's a similar case with a high inertia electric motor rotor.

It seems that some clutchless set-ups shift easier than others. It might be, in those cases, the transmissions have heavier duty syncros.


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## BlackForest (Dec 9, 2016)

@rwaudio
Of course I know your car, history of DC >> AC etc. Great job and thanks a lot for sharing your experience in your blog! Also, you have a great car choice (a 944 was my first Porsche btw).

I know someone who made the same progress: First an DC system with much amps and power - but had to change the brushes in extreme case after 4.000 km. Then a DC system with same setup as you: Siemens motor and DMOC645 controller. He is very happy, but I am afraid of the costs - because I cant do it myself. 

So, the thought of buying an existing and working system like a Nissan Leaf sounds very good. And it is possible to give the system more power by changing the conroller setup / parameters - as told by an user here.

Or cant I get power from the Nissan Leaf system to have fun in a 2.400 lbs car??

Btw - Duncan proposed to also take out the transaxle and original gear of the 924. And to put motor and gear of the Nissan Leaf instead. Then I only need then is to adapt the 924-driveshafts... Motor and gear is one unit at the early Leafs: http://www.moibbk.com/images/nissan-leaf-engine-3.jpg


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## Duncan (Dec 8, 2008)

Hi Forrest

The 944 had from 120Kw to 180Kw
The Leaf in standard trim has 80Kw
At first look that sounds like a lot less -
In actual driving I suspect that 80Kw available immediately will feel better than 120kw and possibly better than 180kw

180Kw at 6000rpm is ok but you need to drop two gears to use it - if the IC guy is in top gear at 100kph and he floors it he probably has only about 60Kw available
The Leaf driver will have his 80Kw available all the time

Then you can think about tuning it


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