Motor Mounting

Finally got the motor, so how do I mount it?

After what has felt like a lifetime the motor has finally arrived. It's hard to imagine that the small package that I can just about lift on my own will give 350HP and over 1000nm of Torque. However its easy to forget that unlike a combustion engine where you only need a small amount of fuel to get that 350HP, with an EV I need the whole 350Kg pack charged at 400VDC to get that power. So weight wise its role reversal, 350Kg IC engine and an 80Kg fuel tank, or a 80Kg electric motor and a 350Kg battery pack. 

The motor mounting its self isn't the difficult part. There are good locations on the motor. There is just enough space in the standard GD euro chassis to shoehorn it in. However if you ever needed to perform any maintenance, you would loose most of your knuckles. The option I think I've settled for is to have a cradle that the engine will sit in, this in turn bolted into the chassis. 

First step was to reverse engineer the GD chassis, I laser scanned a freshly welded GD Euro Chassis and got a mesh of the scan. Although a mesh looks good, other than for looking at clearances its not much use so the whole chassis has to be reverse engineered from the scan. 

Reverse engineering isn't a one click solution unfortunately, it's a long laborious process of working out what should the nominal dimension be, if I measure a length as 374.967mm you can make a good guess that should be 375.00mm. This is a bespoke hand fabricated chassis, its not perfectly symmetrical, its within a few mm. But again you have to look at the scan and work out what should the prefect chassis measure. You can imagine every dimension has to be looked at to work out what should it actually be, it's not a fun process but well worth it. 

A good few hours of CAD work later and we have our reverse engineered chassis. This will be the basis for a good portion of the EV work from the motor and battery box so it was worth while getting it done properly. 

Now I have the actual GD Euro Chassis in CAD I can start work on figuring out how do I actually mount the motor and what modifications of any need to be made to the chassis. 

I've designed 3 mounts that will be CNC'd out of aluminium, these will be bolted to the cradle so the motor can be easily removed. The rear of the chassis will also need to be extended into what was the fuel tank area, thankfully this is no longer needed.

This system keeps all the suspension mounting points in the original locations, so the handling of the GD shouldn't be too effected, only weight distribution differences. The cradle its self will the tie in the lower portion of the chassis so this should then retain the stiffness in those locations. All in all I'm fairly excited now to be able to get this off to GD for manufacture. The plan currently is for me to make up the battery box to make sure I am happy with that, then empty the battery box and give it to GD so it can be used during the chassis welding so clearances can be checked. More on the battery box in the next post.