« July 1st, 2005 »
< Why the project took so long... >
As you may have noticed from looking at the dates on this site, the Jeep EV conversion took more than a year to complete. I wasn't expecting a year long project when I began the conversion process in July 2003, as a lot of EV conversions have been and can be done in 4-7 months or less. About now you're probably wondering what added the extra 6 or so months of work to the Jeep project. I will explain the several major set-backs to the project in detail below. The main point to get across here is that while any Electric Vehicle project's completion can get delayed, the Jeep's elongated conversion process is not typical of the way most EV conversions progress.
The first major setback of the Jeep EV conversion occured in the middle of March 2004. By this point in the conversion, the Jeep was basically reassembled and ready for testing on the road. Had everything gone as planned, the Jeep would have been finished and out on the road around this time. The Jeep was taken out on the road for test drives as planned, and it was during those test drives that a nasty problem showed itself: drivetrain vibrations and difficulties shifting gears. The vibrations would begin when the motor was spinning at 1700 RPMs and get worse as the RPMs increased. After more test drives and a lot of thinking among myself, Mark, and Chris, we decided the motor had to be pulled so we could inspect the clutch components for proper operation. After taking out a lot of stuff which we had just spent time installing, we discovered the problem. By design, the new flywheel and motor hub assembly which were machined for the Jeep project omitted a pilot bearing for the transmission pilot shaft.
The lack of a pilot bearing was something which we were concerned about from the beginning. The flywheel/hub design was not made by us but rather by the out-of-state EV parts distributor from which I purchased most of the components. His lack of knowledge about doing an EV conversion which keeps the clutch, and thus failure to provide a well designed flywheel/hub for this application, led to lots of frustration and wasted my time. However, something had to be done if the Jeep was to get on the road. So Mark, Chris, and I had to modify the flywheel/hub assembly ourselves to accomadate a pilot bearing. The process of adding the pilot bearing is discussed in more detail at the Motor/ Clutch 2 page. The end result was a lot of extra time (and some money) unneccesarily wasted on a bearing which should have been designed into the flywheel/hub before it was ever shipped to me. I say this because the flywheel/hub assembly was sold to me as a custom product which was supposed to work correctly for my application, but originally did not.
I wish I could say that the problems with the flywheel/hub assembly stopped there, but they did not. After we had successfully fabricated a pilot bearing (along with bushings) into the flywheel, we once again got everything reinstalled in the Jeep and got it back on the road for test drives. By this time it was well into April 2004, as machining work takes some time and I myself was pre-occupied with the approaching end of the school year. The test drives showed a lot of improvement. The transmission shifted perfectly now, and the drivetrain vibrations were reduced. However, they weren't gone, not by a long shot.... and they had to be eliminated to prevent possible premature failure of the motor or transmission bearings. Furthuremore, you want to drive Electric vehicles at high RPMs to get better efficientcy (and thus a greater range). With the Jeep, the bad vibrations prevented me from comfortably driving it past 2500 RPMs, whereas driving it at 4000 RPMs or so is much more efficient.
As you might have guessed, the need to solve the vibrations mandated that the transmission and drivetrain had to be removed from the Jeep. I chose to remove the transmission instead of the motor this time because leaving the motor installed in the Jeep meant that I could spin up the flywheel/hub assembly to do testing on it. Pinpointing the vibrations proved to be a long and semi-painful process which took most of the summer. Without getting into a lot of details here (to avoid writing a book), let me say that our findings showed that the motor hub and flywheel were .007" off center. This may seem like very little, but when you have a chunk of metal spinning at 5000 RPMs, being .007" off is completely unacceptable. It actually was the hub part of the assembly which was machined incorrectly or carelessly (or both) which was causing the entire assembly to spin off center and thus create the vibrations. I was not going to pay for this mistake, so I sent the assembly back to the EV parts distributor and requested that a new hub be machined. After almost a month (cheaply getting packages to New Hampshire from here takes awhile), I got a new hub. The new hub was much better and after getting the flywheel asssembly reinstalled I was happy to find that the vibrations were basically gone. I did, however, also have to balance the assembly with washers to remove more of the vibrations. (Soon I will put a page on this website talking about the hub/flywheel vibration problem more technically ).
Once I had the vibrations all sorted out, it was already Mid August 2004. Now I heavily tested the Jeep and found and fixed a few more small things. One such was the rear driveshaft U-joints which were at too intense of an angle to operate safely when the suspension flexed. This problem only surfaced after I began driving the Jeep more and at higher speeds, but was relatively simple to fix compared to the vibrations in the flywheel/hub assembly. Basically, I added shims in the rear leaf-springs and had the driveshaft lengthened by a local driveshaft specialist. The problem with the rear U-joint angles was mainly a result of the larger leaf-springs in the rear which changed the angle of the rear axle differential in relation to the output of the transfer-case.
There were, of course, other things along the way which needed to be done more than once (such as the Torque Rod) which slowed the conversion process down some. Though the two major issues (discussed above) were the main reason for the huge delay in the completion of this project, it is frustrating as hell. Both problems were a result of bad design and machining of the hub/flywheel assembly. Ironically the hub/flywheel assembly parts were the only metal parts made professionally for the Jeep conversion; whereas all other metal work and fabrication was done by me, Mark and Chris.
I am truly happy that the Jeep is in a finished state. Although this past year+ project brought me a lot of frustration and headaches at times, it also provided me with a lot of new knowledge, experience, and skills. Not to mention that I now own a very unique, quiet, environmentally-friendly, and good looking Electric Vehicle. The best part is taking a step back, looking at the Jeep, and realizing that I built this awesome Electric Vehicle with my own two hands in my home garage. :-)