-edible zone-

 Inspection: 

*

 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.A bit large on clearance.

* (note: these bushings have been sold out.  Nowadays you can find replacement motor bushings from a variety of sources.)

* Above photo foreground: The pair of old motor bushings. Background. The new ones.

At that moment in time, (2007) it was virtually impossible to source new bushings for the E-50 motor.......unless you had some manufactured. That is what was done. I contracted with a local toolmaker to cnc some new replacement bushings for the E50 motor. Material for the new bushings was Oilite bronze, SAE 841. The material in the old bushings was, well, old.

* (click thumbnail for full size image)

 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.

* Nex bushing concentricity check: id to od. Read was less than .0005" runout.

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*Assembly

* Upper cover: The oem mounting post was secured by a solid rivent. To replace it the rivet end is drilled out so we can use the new double grommet post which will secured via hex bolt.

* >ower cover: Cleandd and ready.

* Lower cover: Detail view 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.

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Putting the motor together: This assembly requires an alignment between both upper and lower case halves to be concentric to the motor shaft.  Closely concentric so that the rotating part spins freely.  And it won't unless we do.

*Text below is most recent update to my E50 assembly process.

After fastening the bearing assembly onto the lower case. The inner cap tensions the bushing while allowing the bushing to swivel a small amount within its spherical socket fitting. The m2.5 hex jam nuts were carefully ,and somewhat tediously, fitted with my fingers to engage the threads of the machine screws. Once the nuts had a 'start' on the threads I used a screw driver to engage the slotted end of the screw while holding the hex nut with a small plier. In this way I was able to tighten the assembled bushing quite firmly to its end case. Do note that the spherical end of the bushing must not be locked into position. It must be able to swivel within its assembly. Test this by placing the rotor shaft in the bushing and manipulate the bushing attitude using the leverage of the rotor shaft. If the bushing puts up too much resistance there is something within the assembly that is wrong.

The bushing assembly is installed to the upper case the same as the lower but with the exception that there is no end cap. The rotor shaft fits through the upper case. Like the lower case, it is important to insure that the upper bushing can be easily swiveled within its spherical mount.

The importance of the swivel mountings is for aligning the rotor shaft to the bushings. Ideally, upon assembly, the rotor will spin within the upper and lower bushings only touching a film of oil and not making hard contact with any part of the bushings themselves.

* Don't forget about that thrust ball at the bottom thrust.  It's 2mm in diameter and might go unnoticed unless you're looking for it.  So we do. Hold it in the socket with a small dab of bearing grease.

*Before installing the motor to the chassis. And before applying electricity to the motor. With the four assembly bolts not yet tightened, slightly loose. Hold the motor in one hand. With the other hand hold the top of the rotor shaft between thumb and forefinger. Wiggle the shaft back and forth, around and forth, to operate the self aligning bushings within the upper and lower casings in an operation designed to align bushings upper and lower to the rotor shaft. Then, spin the rotor shaft by giving a spin with the thumb/forefinger hand. Observe how long the rotor spins. Repeat this process until the longest spin-down time is achieved. Tighten the four bolts, then double check the spin-down time. If longest spin-down time is achieved after tightening the four bolts, you've got it.

editors note: It has been my experience, after a few years of working on different TD124 players and seeing the variety of conditions that these motors may be found to be in, I have revised my technique for final assembly as follows.....

Noted above in the paragraph prior to this note, it is in the hand-held assembly stage where the most effective method of shaft centering can happen. When the upper and lower case bushings are best aligned, there will be the longest spin-down time. When in good alignment the rotor will free-spin for several seconds before coming to a gradual halt.

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*  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 above: Assembled motor.

* Close-up detail of the double grommet configuration.

* Last two photos: The electrical hook-ups.

*Next: E50 Stator Coils