15. Modifications

May, 2010

One of the cells of the original battery set, the ones I had ignorantly stored without keeping them fully charged, failed, and I installed a new set of six batteries. I was very soon pleased to discover that my range had increased to 30 miles, far more than I would need for one of my usual errand-running trips, and about twice the range of that first set of batteries. In fact, I could go 3 days of travel between charges! In my discussions with Bob Batson of Electric Vehicles of America, I began to think of other ways I could improve the efficiency of the drive train.

June, 2010

The original chain drive was noisy. It literally screamed like a turbine at 30 mph and had only one gear ratio, 7.5 to 1. During every acceleration from zero, the motor would draw 300 amps and with start/stop traffic, would get hot to the touch after 5 miles.

I improvised a splash shield to contain the oil from the chain. Another disadvantage to the single gear ratio is having a motor sprocket so small that it supposedly increased the rate of wear on the chain and the sprocket. I learned that belt drives waste less energy, last longer, and of course are much quieter.

I bought this Cushman truckster transmission off e-Bay for $160, thinking I had a good deal compared to the more expensive ones, and then after using it for a few weeks decided to have it rebuilt for about $700. It was designed for rotational thrust on the shaft bearings, not side thrust, so I thought those should be replaced with new, and then the shop discovered that the internal shafts were chewed up, and a new one had to be custom machined. It has reverse (finally, no more pushing out of parking spots!) and three speeds forward at 1:1, 1.66:1, and 2.66:1.

July, 2010

I decided to go with Goodyear toothed belts because another EV builder was using them, and he could sell me a couple of extra sprockets for cheap. However, machining them to fit the hubs and shafts was not cheap and neither were the belts. This whole upgrade was over $2,000, and I've been avoiding adding up all my receipts for fear that it went over $3,000! Pat Blair welded and fabricated a very fine mounting plate, and installed it in the frame. There's a pillow-block bearing on the outside end of the transmission's shaft to take up some of the side-load.

The motor rotation has been reversed because the shaft is now on the other side of the vehicle. The belts have to be extremely tight to avoid slipping, and I would put a small scissors jack between the motor and the transmission to spread them apart before I tightened the mounting bolts. This picture was taken before we decided there needed to be a pillow-block bearing on the outside end of the output shaft of the transmission.

Both sets of sprockets each have a ratio of 2.37 to 1, so the combined ratio in high gear is 5.61 to 1, in middle gear it's 9.31 to 1, and in low it's 14.92 to 1. I'm waiting until next summer to test my maximum range and top speed, and in cold weather (35-40 degrees here in Oregon) I am getting about 17 miles and 40 mph.

The rear-wheel drive sprocket is smaller, but the belt had to go above and below the swing arm pivot, which had to come out in order to install the belt. When I had the swing arm out, it was a good time to replace the rear tire as well.

August, 2010

Things are looking more crowded in the engine compartment now. In the foreground is the outside pillow-block bearing to take up the side load on the tranny shaft, and a splash guard for water. It turns out that the belt carries water forward when it's raining, and then the controller gets wet and stops working. Fortunately, it was OK after it dried out! On the top of the transmission you can see the yokes of control cables that run off to the left and up to the driver's seat. Above the controller is a coil of about 10' of cable inserted between two poles of the motor, to help it run cooler and more efficiently. The tranny has cut the amps needed for acceleration in half, which may extend my range. However, it has to spin down between gears, so there's about a 4-second pause before I can engage each higher gear. It takes practice, and I'm not getting the jack-rabbit acceleration I wanted to keep ahead of the big gasahogs, but I can climb hills that were impossible before, so the little 12-28 HP electric motor is doing very well with a transmission to help it out.

I adapted a motor control for outboard boat motors as my gearshift levers. The knobs are due for an upgrade to some spherical wood ones, which will be more comfortable to push. You can also see along the edge of the floor a stained 1x4 I installed to keep rolling objects from falling out of the vehicle.

I also decided to put in molded bucket seats, new carpeting, and retracting seat belts. That fleecy blanket there on the floor is my "heater," which works really well along with a winter jacket, gloves, and ski hat.

October, 2010

I had to put in heavier, longer shocks in the rear to raise the ride height, since there was an additional crossbar under the frame to hold the motor & tranny and I was hitting the tops of speed bumps.

Partly for fun, partly for unwary pedestrians and cyclists, I installed this small ship's bell, operated by a rope that goes back to the underside of the dashboard. The horn button in the center of the steering column is shorting out, so I'll put a push-button in the dash for that soon.

January, 2011

The VW steering is incredibly sloppy, and I had put in a second used steering box thinking that would tighten things up a bit, but I ran out of adjustment. So I finally discovered a tiny difference in the diameter of the lower shaft into the arm that connects to the tie rods, and shimmed it out with a few layers of heavy duty aluminum foil. It works!

These top lights aren't installed yet, and I hope to get to them soon. I'm so low that I need something for other drivers to see me better. No, the doors still aren't on, but wait 'til this summer! Perhaps one of the reasons I've delayed so long on the doors is my enjoyment of the open air and view of the sky, even when it is raining. (P.S. I finally decided I was not going to have doors!)

August 2014

Suddenly, I lost power. I discovered that a $9 drive-shaft coupling with internal splines failed because it had worn its splines completely smooth. Fortunately, the transmission was OK. After a long talk with a machinist, and a motorcycle mechanic, I decided that the side-pressure from the belt on the drive-shaft had pulled the shaft ever so slightly out of perfect alignment, causing the wear. Not only that, I was actually losing power by going through all those gears. I decided to sell the transmission on e-Bay, and it quickly sold to a golf course in Michigan, who installed it in the vehicle for which it was designed, a Cushman Truckster. 

April 2015

I had borrowed a 49cc scooter for the winter and procrastinated on altering the motor mount so I could re-install it in its original position. It involved cutting through a great deal of steel with a grinder. I bought a reverse switch for the polarity of the motor, operated by a 12v coil that was energized by a small switch on the dashboard.

Subjectively, I can get to 30 mph more quickly and smoothly now. If there's nobody behind me, I hold the amps at 200.

Copyright 2011, David Hazen. You may download, store, or print a single copy of this page for your personal information. No part of this material may be reproduced, stored or transmitted for personal gain.