Assembling the E50
Above photo: checking the old bushing for wear in its precision bore. The gage has been set to read zero at .1875 inches. The technique is to measure in several areas of the bore to gather an overall impression of the condition. In the photo the reading indicates size to be .1879 inches. That was taken toward the upper end of the bore. At the lower end the size read .1882. Roundness was ok with no obvious variation.
The motor shaft outside diameter measures .1869 inches. Running clearance will be .001 - .0013 inches between the old bushing and shaft.
Above photo foreground: The pair of old motor bushings. Background. The new ones.
At this moment in time, it is virtually impossible to source new bushings for the E-50 motor.......unless you have some manufactured. That is what has been done. I contracted with a local toolmaker to cnc some new replacement bushings for the E50 motor. Material for the new bushings is Oilite bronze, SAE 841. The material in the old bushings is, well, old.
Checking size on the newly manufactured bushing. Reading is .1876 at every area within the bore. That is what I wanted. Running clearance will be .0007 inches between motor shaft and new bushing bores. Ready for another 50 years use.
Checking the new bushings for runout of the sperical end to the bushing bore
using a precision gage pin held in V-block, a finger style dial indicator and
by spinning the bushing while observing the indicator. I allowed the
machinist as much as .003 inches of runout ( max ) but he held to within
.0005. I like this shop.
Now on to the assembly.
Upper cover: The mounting post has been drilled out to fit a new double grommet
post.
Lower cover: Cleaned and ready for assembly.
Lower cover: Detail of the spherical socket
Lower cover: New bushing spherical end fits into the spherical socket of the
lower cover. To assist the self alignment process, a small amount of high
pressure grease is added to the joint. The bushing itself has been
impregnated with "Thorens Oil" by placing the bushings in a small tin
can, submerging them in the lube and baking them at 250 F for a few hours.
Lower cover: Oil retaining felt washer is placed around the bushing. The
felt has been soaked in 20 wt turbine oil. (Oil spec: Texaco Regal R&O
46) The oil is only sold in 5 gallon and larger containers. I should
have a lifetime supply...;-)
Lower cover: The retaining cap holds another felt washer (also soaked in Thorens
oil).
Lower cover: The retaining cap with retainer clip designed to fit the
spherical end of the bushing.
Lower cover: The retaining cap in position.
Lower cover: A new thrust pad (Delrin) is cut to replace the old heavily
indented original nylon pad. A slight amount of grease allows the pad to stick into
position as an assembly aid. Fasteners are M2.5 x .5mm slotted cheese head screws
and hex nuts.
Lower cover: With bearing assembly fitted.
Lower cover: Detail of the assembled thrust cap.
Assembled motor: This view shows the new Double Grommet posts installed to the
upper cover. The grommets and posts were sourced from Mirko Djordjevic**
out of Huntington Beach, CA. Mirko manufacturers and/or sources many oem parts for old
Thorens, Garrard and Lenco turntables. Quality of workmanship, as
I've seen so far, looks very good. Prices are reasonable.
Fitting the grommets into the chassis.
Assembled E-50 motor with shield and ready to fit into the chassis
View from the top. Assembled motor.
Detail of the double grommet configuration
Bushing alignment process in outline form:
 | Motor is mounted to chassis complete |
| Assemble both pulleys and belt |
| Leave platter off |
| Leave idler wheel off |
| Switch on the motor (any speed). Observe the driving and driven stepped pulley spin. |
| Use mechanic's stethoscope to evaluate noise level of the running motor. |
| Place stethoscope probe against the running motor at various points |
| Slightly loosen the four retaining screws holding the upper and lower cases against the central core. Not too loose, just loose enough to make our adjustments. |
| Use the plastic handle of your screw driver like a mallet to gently tap the lower case into different position |
| listen through stethoscope to evaluate noise level after adjustment |
| quieter is better, quietest is best. |
It is worth the effort to spend some real "quality time" during this procedure. The benefits of a proper bushing alignment session include quicker start-up to speed stable times. Improved speed stability throughout the day. Improved signal to noise ratio. Longer motor life.
next: assemble the rest
Footnotes: ** Mirko Djordjevic, contact by email: cary300b@hotmail.com