< Part Two >
+ Part 1: The original setup
+ Part 2: Adding a Pilot Bearing (After initial test drives):
-- No Pilot Bearing: A bad idea
-- Adding a transmission pilot bearing
-- Pilot bearing installation results
+ Part 3: Transmission/Transfer-Case swap (Update)
« April, 2004 »No Pilot Bearing: A bad idea
The original design of the motor hub, flywheel, and clutch assembly for the Jeep was not done by me, but instead by the company I bought the main EV parts from. This design included no pliot bearing. The pilot bearing is a small bearing which is usually pressed into the flywheel to provide support for the transmission input shaft from the front. The Jeep's internal combustion engine had it pressed deep into the center of the flywheel.
When the new flywheel was machined for the Jeep, it didn't have a pilot bearing, which worried me. However, Mark Farver, Chris Robison, and I decided to install the motor and everything as planned, and hope that the lack of the pilot bearing wouldn't bother the transmission. Unfortionately it did, as the initial test drives indicated.
Basically, not having the pilot bearing caused a lot of vibrations and noise from the clutch components and transmission. This was due to the fact that the clutch disc would come out of center with respect to the flywheel when it was disengaged. It became un-centered because the transmission input shaft has some play in it, and without the pilot bearing present to help support it in the front, the shaft would "sag" slightly and become off center with respect to the flywheel. The one and only good solution was obvious, a pilot bearing needed to be some how added to the system. Thus, out came everything in the engine compartment so the motor could be removed. It really is fun installing everything then turning right around and removing it again. Oh well, it's good practice I suppose.
Removing the engine allowed us to see the results of having no pilot bearing. What was most noticeable was that the flywheel had been scratched up a lot near its center. This was due to the transmission shaft wobbling around some whenever the clutch was disengaged.
« April 18th, 2004 »Adding a transmission pilot bearing
To fix the vibration and noise due to the lack of a pilot bearing, a pilot bearing needed to be installed in the center of the Jeep's new flywheel. We decided this could be done with the help of a bushing which would press into the large center hole of the flywheel, and would then hold an original Jeep pilot bearing in place.
The first thing we did was take the neccessary measurements. These had to be very accurate because I had shortened the transmission pilot shaft (to prevent it from hitting the motor shaft), and there wasn't much room for error if we wanted the pilot shaft and bearing to meet up. Using the measurements we took, Mark made an aluminium bushing and pressed the Jeep pilot bearing into its center hole. Then the bushing (with the pilot bearing in it) was pressed into the center of the flywheel.
Now, in order for the pilot bearing and pilot shaft to be able to line up properly, one more change was made to the flywheel assembly. The change was to move the entire assembly 3/8" farther away from the face of the motor. The reason why the flywheel needed to move away from the motor was so that the end of the motor shaft would not interfer with the new pilot bearing, which protrudes slightly from the back face of the flywheel. In order to gain this extra 3/8" of space, two things were done. First, we had a 3/8" spacer ring made by a machinist. After I drilled out bolt holes, we installed the new spacer with the existing spacer rings between the motor and adapter plate. For the second step, we backed the motor hub off of the motor shaft 3/8" which put the flywheel back into the correct position with respect to the adapter plate, while providing the additional 3/8" of space between the back face of the flywheel and the end of the motor shaft.
The last thing left to do was to re-install the rest of the clutch components on the motor. We then re-installed the motor in the Jeep, along with everything else in the engine compartment which we had removed.
Pilot Bearing installation results
After reinstalling the drivetrain and other removed components, the Jeep was ready for a test drive. Several test drives revealed that the pilot bearing install was a success! Most of the vibration was gone, the transmission once again shifted like it used to, and the reduction in gear noise was incredible! I once again asked myself why hadn't a pilot bearing been built into the flywheel for me originally? The resulting difference between having or lacking the pilot bearing was incredible and I just assumed my parts distributor would've been compotent enough to realize this before he sold me a finished product.
However, the pilot bearing did not solve all of the drivetrain vibration I was experiencing. I then had to spend a lot of additional time trying to locate the source of the remaining vibration. It turned out that the source of this remaining vibration was the motor hub, which had been machined .007" off center (unacceptable when something is spinning at 5000 RPMs). The Completion Delays page talks about the delays in chronological order.
Remember, More photos are in the Photo Gallery!