Hey, folks! It’s been a while since I’ve gotten some work done on the Mercedes. After a catastrophic inverter failure, I shelved the project for a while. Now that I’m coming back around to it, I’ve decided to redo a few things. Since I have to take the whole thing apart, I might as well address design issues I discovered during the build process. Chief among those issues are the adapter plate and coupler. While they were functional, I do not believe that they were as good as the should have been. So, up first, the adapter plate redesign!
Newly Designed Adapter Plate
The original adapter plate had several issues, but there were three really big ones: it was not thick enough for the intended bearing, the bore was not large enough for the intended bearing, and there was no locating ring to maintain alignment.
I was unaware of some very important design decisions when making use of bearings and press fit assemblies. I have changed the clearance ever so slightly so that the bearing will not slip fit into the adapter, and it will be held in plate with Loctite Bearing Mount. Here is a link to the product on Amazon: Loctite Bearing Mount Stick – Green. This will make the bearing easier to mount and replace: a hydraulic press is no longer needed! As an additional benefit, the bearing race will not be deformed by an overly tight fit, which leads to premature bearing failure and lots of heat. The adapter plate is also 50mm thick, now, instead of just 20. This will allow the bearing to fit properly with more thread engagement on the mounting holes.
The Loctite Bearing Mount can be broken down with heat from a torch, allowing the bearing to be reasonably replaced in the event of failure.
An additional redesign adds the all-important locating ring to the adapter plate. This ring is present on all of the motors that bolt to the Can EV adapter plates. I neglected to include it in my original design, intending to alight the motor with only the bolts. This is not sufficient! As such, I have added a 10mm locating ring to lock everything into position. Adding this ring required several dimensions to be updated, so the adapter is now much beefier than it was before.
Lastly, I added 3 more sets of transmission-adapter mounting holes for versatility and I clocked them to better align the motor and transmission. They should now be much closer to parallel, which will make mounting them as a unit easier.
Other Details
The adapter plate uses a new bearing. The ER211-55 of the original adapter has been replaced with an ER209-45. This is to accommodate the require dimensional changes that I made to the adapter in order to add the locating ring. The bore of the adapter will fit the 80mm bearing in a tight slip-fit, and the coupler will be made of a 45mm steel rod turned on a lathe. More details on that later…
Pics or it didn’t happen!
OK, OK. Pictures coming up. In addition, the model is available here: New Adapter Plate Model. I’d recommend waiting until I receive the actual plate and report on fitment before you go off and have it milled.
Front view of the adapter plate. The Can EV transmission adapter plate bolts to this face.
Thanks for the update Jeff, I did wonder what happened to your project.
You said ” catastrophic inverter failure” has the invertor failed as well ?
Was it the power output from the leaf motor at destroyed the coupler or just a design failure.
Glad you back !
Hey, thanks! As far as I can tell, all signs point to a failure in the power stage of the inverter. I have to tear the engine bay apart again in order to find out exactly what happened. Since I’m going through all that effort, I’ll address the coupler and adapter plate while I’m there. That being said, they did work and I drove the completed vehicle around the block before the inverter blew. I suspect the regen current somehow surpassed the maximum and blew the IGBTs – that, or it was just too much juice for the power stage to handle. I had it set to 200 or 300 amps regen, and I was off the throttle testing the regen when it suddenly died.
Hi Jeff, Great site! I am working on an MGB conversion myself. Like you, I concluded the transmission was superfluous. After all, at 3000 rpm (the knee of the torque fall off the MGB will be going 55+ mph and at 5000 rpm could potentially be going 101 mph (not with me in it). Where did you upload the cad drawings for the coupler and the Adapter Plate? Also did you lengthen the drive shaft? (I was thinking to do that).
Hey, Jerry. Thanks! The adapter plate is linked in the last section of this post. Here’s a direct link, though: https://blackfamily-my.sharepoint.com/:f:/g/personal/jeff_potkettle_black/Ek-R165L4qBNk1YdINzw-TUB7-eW7PTIZMhoorF6m7cGrA?e=4ZdRBf
I have it hosted in my OneDrive, and that folder has both the CAD drawing and the model export. I just sent it off to be milled last night, but I won’t receive it until late February. You might want to wait until I get it in before you send it off as well, just so that I can be sure it fits. One other thing, this adapter plate is for use with a transmission. Something slightly different will be required if you don’t want to use one. The coupler would have to be suspended inside of the adapter plate, probably on two tapered bearings. You could then put a yoke directly on the coupler to do direct drive. I may design one of those, but this particular adapter won’t do that for you.
The Nissan leaf motor does around 11,000 RPM, so some kind of gearbox is definitely in order. I’m sure it could move an MGB without one… but the performance probably wouldn’t be nearly as stellar.
Food for thought. Thanks