Looks like I need a new slave cylinder…

I found two issues (maybe related). After talking to the go-ev guys, I learned that the shaft on the Warp11 motor is designed to move ~1/8″ when a significant amount of axial load is applied.  It just so happens that my new high pressure clutch presses applies a significant amount of force.  The problem was that I mounted the shaft coupler about 1/16″ away from the motor face.  So, when I pressed the clutch, the shaft coupler would rub on the motor housing.  After I discovered this, I took everything apart and moved the shaft coupler out about 3/16″ away from the motor housing. After assembling all back together, I pressed the clutch and squishhhhh. I heard something spraying inside the bell housing. At that point I called it a night. The next day I took everything apart (AGAIN), and found the bottom of the bell housing full of hydraulic fluid. I pulled the slave cylinder and saw that the bellows were full of fluid and there was a tiny crack where it could spray out. I ordered a new slave cylinder which should arrive early next week.

Fighting with the clutch…

I wanted to test the clutch out.  So, I bolted the motor onto the transmission with the flywheel and clutch installed. I rolled the setup under the car and put it generally in position:


I connected up the clutch line, and proceeded to bleed the system.   I got it bled with a vacuum bleeder, but the clutch petal was acting quite odd.  It started in the up position, but with just slight pressure, it jumped all the way to the floor with significant force.  I had to use my hand to pull it off the floor.  After looking at some Porsche forums, it sounds like this is a common symptom of a bad slave cylinder.   Since the slave cylinder was fine before, and I haven’t really done anything to it, my guess is I have something assembled incorrectly.  Time to take it all apart…


A fancy new clutch

My last EV project had an issue with clutch slippage.  If I got on the throttle too hard from a standstill, I could feel the clutch slip for half a second before it grabbed.  I definitely did not want to repeat that problem.  So, I called up the guys at Kennedy Engineering and asked them to make me a clutch that could handle the torque of my electric motor.  The claim their clutch can handle a 500hp+ engine.  So, I assume my “little” motor will be fine. $800 and three days later I’ve got a new pressure plate and clutch disk.  The springs on this new pressure plate are about three times as thick as the original. I have a feeling this will work quite well.

The new one is on the left…



If you look closely at the photos above, you can see the difference in the thickness of the spring steel fingers.


Before I bolt everything together, I had to make a couple modifications to the aluminum flywheel (which I took from my previous EV). The old pilot bearing was too big for the Porsche input shaft. So, I removed the old bearing, found a thicker walled bearing, and machined the flywheel to make it fit.  I also had to take of a little meat around the dish of the flywheel so it matched the diameter of the Porsche’s dish.  I geeked out a little, getting the everything aligned within +-.001″.

Thanks to my buddy Mose for letting me use his BIG lathe.

One pulley and a plastic “battery”

This has been a hot summer and even though the Boxster is a convertible, I DO want air conditioning.  Plus I didn’t really want to mess with getting the existing air conditioning system professionally discharged.  So, I’ve been working on a scheme that will let me keep the existing compressor and drive it off of the tail shaft of the main drive motor.  In order to do that, I needed a way to mount a pulley to the tail shaft that matches the belt type of the pulley on the compressor.  I tried finding something off the shelf, but didn’t have much luck.  It is a six rib flat belt.  However, I noticed that the water pump (on the engine that I removed) has a nice pulley on it that mounts using a simple three bolt hub. So, I decided to fabricate a hub that would bolt to the pulley and fit my tail shaft.  It’s a simple part, except for the keyway. In order avoid buying a broach to cut the keyway (they are $80, and I would only use it once), I found a steel chain sprocket from McMaster Carr that already has the proper bore size and keyway.  Then I cut off the sprocket teeth and machined it down so that it was thin enough to fit inside the pulley.  I left a little alignment shoulder to make sure it mounted concentric. Drill three holes and it’s ready to bolt together.


I also wanted to start planning my battery placement.  So, in order to visualize the cell placement, I laser cut a plastic box that has the same dimensions as my cells (ThunderSky LPF160’s).  I used this online box maker to make the pattern.  This should let me safely test fit different locations for cells without having to worry about shorting something out.




Motor… meet your new friend


My previous EV used an Audi 5000 transmission.  I pulled this motor (Warp11) and adapter out of that project and hoped that I might be able to salvage some of the pieces.  Turns out that the mounting holes on the bell housing are very similar.  Looks like I just need to enlarge a couple of the holes in the adapter plate and the bell housing will bolt right up.  Then there is the small issue the distance between the bell housing face and the surface of the flywheel.  Looks like I need to push the flywheel out about 5/8″ or shrink the adapter plate.   Looks like it will be easier to add a spacer behind the flywheel and just get some longer bolts.


This is the custom aluminum flywheel I machined for my last EV build.

Remote repair

When I bought the car, the previous owner only had one key and the remote didn’t work.  This wasn’t an issue until the other morning when I accidentally closed the hood while the main battery was disconnected.  Usually this wouldn’t be an issue.  You just put 12v on the little red “pop-out” connector in the fuse box and ground the chassis.  This powered up the car alright, but it also set off the alarm.  Apparently while the alarm is sounding, you can’t activate the hood latch.  Usually the alarm can be disabled by putting the key in the ignition.  Not this time.  Nothing I could do would shut the alarm off.  So, being an electronics guy I opened up the old key fab, replaced the battery and jumpered the alarm button that had been smashed long ago.  Whew, I am sure my neighbors are glad I figured that one out.

Since I had the remote open, I figured I might as well fix it properly.  I ordered up some new buttons from Digikey that were almost perfect replacements. A little soldering and it’s good as new.

I also ordered some replacement plastic housing off of Ebay.  It should be here within a week.

UPDATE:  The new housing arrived (from DSPSTORES.com).  It fits well.  The button covers are a little stiff, but I imagine they will soften a little with use.



The engine is OUT!

It took a bit to wrangle it out, but we finally got the engine pulled.  Many thanks to the info on Pelican Parts.

It took two big floor jacks and a bunch of concrete blocks to get the rear end high enough. We even had to put one set of blocks under the front tires so that the nose wouldn’t hit. We just took everything very slow and methodical.


Now to see if I can sell the engine…

Down but not out…

I’ve been working on my car early in the morning to try and “beat the heat”, since by 10am, it is too hot to work on it.  Because of this, the progress has been a little slow. However, I did get the new boots on and was able (with my Dad’s help) to drop the engine.  It actually came down with out too much of a fight.