Fitting the Kostov K9HV into Corolla's gearbox

I had to build a new flange to mount the K9HV into the gearbox. The flange should be at least 30mm thick to prevent the motor axle from touching the gearbox axle. I had some 8mm thick aluminium scrap sheets available for the job, so I decided to attach two such sheets together forming a 16mm thick sheet. The flange would be constructed from two plates, one 16mm plate would be mounted to the motor and an other 16mm plate into the gearbox allowing me to adjust their alignment. I started by making a model from cardboard for the gearbox plate.

Using the cardboard models I cut the gearbox plate using a jigsaw.

Locating the holes to drill was a challenge. I decided to try pressing the plate against the gearbox with some Blu-Tack in between so the hole locations would get visible. This actually worked out well. I started by making two alignment pins that the original motor had as well. After the locating pins were made it was simple to locate one hole at the time to be drilled.

Once all holes were drilled, the gearbox plate could be mounted into its final location. Now the challenge was to get the gearbox axle aligned with the motor. I decided to build a special divider tool that allowed me to draw an accurate circle matching the K9HV motor's diarmeter. This would help me to make a first rough alignment.

Next I decided to build the motor's plate. I used countersunk bolts to mount the plate on motor allowing the motor plate to be pressed directly on the gearbox plate.

The motor plate was built with the same width as the motor's diameter so I was able to locate the motor plate mounting holes quite accurately on the gearbox plate using the circle drawn earlier with the divider. I made the motor plate's holes 2mm bigger than its bolts allowing me to fine tune the alignment of the motor and gearbox axles. The fine tuning would be completed by adjusting three stop screws forcing the location of the motor plate from its bottom, left and right sides.

The motor plate's mounting bolts threads were reinforced using helicoils. These four bolts will need to carry the motor and its torque so I did not trust bare aluminium threads.

Now I had all the components ready for finishing the assembly!

First the motor plate was mounted into the motor securely using plenty of thread lock.

Then the gearbox plate was mounted roughly on its place to be aligned later.

Next I assembled the flywheel and clutch. I used a torque wrench and thread lock in all places applicable.

Finally I got to fit the motor in its place and bolt the gearbox plate securely. Then it was time to adjust the motor and gearbox axle's alignment. I had no idea how I could confirm a good enough alignment so there was a lot of trial and erroring to do. Pretty soon I noticed that when I rotated the motor by hand I could hear a quiet creak as the clutch disk was forced to move due to misalignment of the two axle's. I then adjusted the motor plates location in respect to the gearbox plate until there was no creaking sound at all. I figured this alignment is as good as I would get and lock screwed the plates together so they would not move anymore.

To make sure the motor was properly mounted, I connected the motor into its controller and gave it a spin. I was really happy with the result, there is clearly less alignment and balancing error than I had with the former ME1003 motor's mount:) This motor will drive the Corolla smoothly!
  

Placed the original shields on the motor and now it's ready to be lifted in the car:)

Preparing the Kostov K9HV motor

The K9HV was purchased pre used so I inspected it through before mounting it. The picture above shows my first setup that was able to spin the motor. The controller in the picture was the first prototype of Motoc - SR250V500A that will be developed to feed Corolla's motor. This setup got the motor to spin nicely.

A closer look to the bearings revealed a worn bearing housing. The smaller diameter axle side of the motor had about 0.5mm play between the bearing and the bearing housing. This was going to be fixed.

The motor's rear flange was removed so that the bearing housing could be repaired. The ball bearing seemed ok, but it got replaced with a new one just in case.

Cleaning the bearing housing revealed clear signs of wearing. Reviewing different methods to fix the worn bearing housing, I decided to purchase a bottle of Loctite 660 from eBay and give it a try. First I punched some marks in the worn bearing housing to help aligning the new bearing better in the center. Then I applied plenty of  Loctite 660 into the bearing housing before mounting a new ball bearing into its place. Carefully removed the excess Loctite so it wont get in the bearing, I think I got it fixed :) After a couple of days I checked the result and there is now a new bearing installed without any play on its bearing housing, success!

My next challenge was to mount Corolla's old flywheel into the motor shaft. That turned out to be easy as I only had to purchase a 1210 taper lock bush with a suitable bore to K9HV's shaft. www.bearingboys.co.uk had just what I needed once again!

With a new taper lock bush I got my old flywheel mounted and I decided to check how it was aligned. Measuring from the clutch plate surface I got nearly 0,3mm difference on one full rotation. I concidered this as too much so I gently sanded the taper lock bush so that it would compensate the alignment error. After a few trial and errors I settled with and error of 0,06mm. This step is done:)

Last but not least it was time to balance the motor with its flywheel on the shaft. With first rotations it became clear that there was some imbalance that could provide uncomfortable vibrations. As this motor will be rotated close to 2x higher speeds that its predecessor I was ready to offer some time to get the flywheel balanced.

The balancing method used was very simple trial and error, using neodymium magnets on the flywheel and determining where to drill off some material to improve the balance. Having drilled four quite big holes I could no longer determine any improvement so I considered the balancing step done. While balancing with this method I had some flying magnets in my garage when I rotated the motor too high. Although handy to use, I would not recommend using magnets this way for balancing flywheels due to safety.

Now the motor was rotating nicely up to very high speeds, so I am ready to start fitting the motor into Corolla's gearbox :)