Hi All
I have an old vintage Zenith turntable that uses the old belt/spindle system for speed changing, I've replaced both belts and Idler tire, cleaned the spindles and oiled the motor bearings, however it still takes time to get up too speed when first turned on, any ideas as to what to do next, short of replacing the motor, which by the way is almost impossible to find.
Mark

Considering the unit to utilize the common stair stepped top motor shaft, of either 2 pole
or its heavy duty 4 pole counterpart:

Seems that the old Zenith used the larger motor unit and cantilevered two bottom rubber idlers between positions for speed change.

Initially you might have the platter removed so that a minumal loading would be placed on the motor.Usually if you go to the top of the unit (or bottom) it is possible to see the motors spiral rotor segments of its pole pieces and copper segment rod ends.
A closely/strongly placed common flourescent lighting of that area will typically produce a stroboscopic pattern with a uniform degree of drift as you watch those elements. The pattern being a harmonic of the 120 PPS drive from the lamp. Watching the pattern drift from a cold turn on until about 3 min of run time, should result in the pattern staying at the same uniform "drift". Should the pattern drift and make a sliding continual variation, I would suspicion the motor rework not being adequate and the unit still having a sludge / glaze / tightness and does not maintain a uniform speed until only after warmup and expansion.Thereby an initial sluggish motor
speed problem and not one of the "rubbered" drive components.

Any chance that you totaly dis-asssembled the motor and done a FULL rework of all of its composite
rotating elements. This would be a flush out degreasing of all the old lubricant in the felt "wicking" washers surrounding the porous bronze bushings that relube the units shafts. Being sure that you have all traces of any sludge or glaze off the top and bottom of the motor shaft at the two points where the bushings surround them. Along with the porous
bronze bushings being immaculate degreased.
Usually the motors top shaft movement is limited by a pressed on collar, therefore one has to move the shaft up and down and work on it one half at a time. Whereas the bottm shaft stub is unshrouded and thus totally free to work with.
I typically just pull the disassembled rotor with that typical pot metal top collar with its internal bushing. That permits me to use thin "file card" cardboard to make a rotary ptotective collar for the bottom motor shaft and chuck it into a var speed hand drill.
I then use a WD40 wetted (1/4 X 3 inch strip) of #800 wet and dry paper and compress between thumb and forefinger to permit balanced 180 degree opposing pressure. Then slowly rotate while you, just ever so slightly,remove just the surface glaze on the motor shaft. That then leaves a uniform cavitated surface area for retention of a uniform fine oil film.
Flip to the top side of the shaft and protectively rechuck and do the easy part, the bottom stub the motor shaft. Much easier than the dual operation on the halves of top motor shaft.
I typically use 30 weight motor oil for lube, the modern formulations let it do a fine job in the harsh temperate and speed demands of car engines....a piece of cake for a mere phono motor and its temperate situation.
Oil the felt washers, reassemble, lube the contact points of the top bottom motor shaft at
bushing points, remount the motor and initiate the same speed test from a cold start.

73's de Edd

If anything, you want the glazing! Absolutely never sand paper the shaft of an electric motor, except to remove burrs. When a motor is first purchased, it should be run for at least 30 minutes with oil and no load. This puts the glaze onto the shaft, which gives it minimal friction properties. This procedure is much like breaking in an engine. You will notice that the bearing journals of a well taken care of engine are bright and shiny. All lifters and push rod ends are polished at the factory to a mirror shine. A 60 degree criss-cross is put onto the cylinder walls to aid in polishing the rings so that they seat perfectly. However, once they seat, the cylinder walls are polished to a high degree of lustre. Any mechanic that tells you that the criss-cross should remain at all times, is not a mechanic you should continue to do business with. All gear teeth and contact surfaces in the transmission and differential are polished to the most amazing crystal glass shine, when they come from the factory.

Never ever sand a motor shaft. The porous bronze bushings are what retain the oil. As long as they feed the oil in a uniform manner, the shaft will receive a uniform film of oil. The cling of the oil alone will make it go all over the shaft.

Be absolutely sure to degrease the motor, however. Clean it very well. Do not get chemicals or water onto the field coil. Use gasoline or mineral spirits on the bearings, felt, and shaft. Allow all to dry well. Use light weight 3 in 1 oil or sewing machine oil on the motor shaft. Soak the felt as well. Assemble the motor exactly as it was when you took it apart. Tighten the screws snug. Thump the side of the motor against your work bench in a solid manner. Spin the shaft and see to it that there is absolutely no friction. Smack the motor against the bench a few more times and wiggle the shaft firmly with your hand, if you have friction problems. Once the shaft turns freely, tighten the screws all the way, in an even manner.

The biggest things that influence initial motor speed are the grade of lubrication and the degree of accuracy with which the motor has been aligned. Using auto motor oil is unacceptable. Cold starts will always be sluggish and cold. These phonograph motors, unless designed for a player/cutter, are not that strong. Along with this is the necessity for maintaining absolutely oil and grease free drive surfaces. Even finger oil is enough to cause intolerable slippage.

T.

:If anything, you want the glazing! Absolutely never sand paper the shaft of an electric motor, except to remove burrs. When a motor is first purchased, it should be run for at least 30 minutes with oil and no load. This puts the glaze onto the shaft, which gives it minimal friction properties. This procedure is much like breaking in an engine. You will notice that the bearing journals of a well taken care of engine are bright and shiny. All lifters and push rod ends are polished at the factory to a mirror shine. A 60 degree criss-cross is put onto the cylinder walls to aid in polishing the rings so that they seat perfectly. However, once they seat, the cylinder walls are polished to a high degree of lustre. Any mechanic that tells you that the criss-cross should remain at all times, is not a mechanic you should continue to do business with. All gear teeth and contact surfaces in the transmission and differential are polished to the most amazing crystal glass shine, when they come from the factory.
:
:Never ever sand a motor shaft. The porous bronze bushings are what retain the oil. As long as they feed the oil in a uniform manner, the shaft will receive a uniform film of oil. The cling of the oil alone will make it go all over the shaft.
:
:Be absolutely sure to degrease the motor, however. Clean it very well. Do not get chemicals or water onto the field coil. Use gasoline or mineral spirits on the bearings, felt, and shaft. Allow all to dry well. Use light weight 3 in 1 oil or sewing machine oil on the motor shaft. Soak the felt as well. Assemble the motor exactly as it was when you took it apart. Tighten the screws snug. Thump the side of the motor against your work bench in a solid manner. Spin the shaft and see to it that there is absolutely no friction. Smack the motor against the bench a few more times and wiggle the shaft firmly with your hand, if you have friction problems. Once the shaft turns freely, tighten the screws all the way, in an even manner.
:
:The biggest things that influence initial motor speed are the grade of lubrication and the degree of accuracy with which the motor has been aligned. Using auto motor oil is unacceptable. Cold starts will always be sluggish and cold. These phonograph motors, unless designed for a player/cutter, are not that strong. Along with this is the necessity for maintaining absolutely oil and grease free drive surfaces. Even finger oil is enough to cause intolerable slippage.
:
:T.
Thanks Thomas, I will take out and apart the motor as you and Edd say rework it, hopefully this will solve the problem, thanks again guys:)
Mark

:Considering the unit to utilize the common stair stepped top motor shaft, of either 2 pole
:or its heavy duty 4 pole counterpart:
:
:Seems that the old Zenith used the larger motor unit and cantilevered two bottom rubber idlers between positions for speed change.
:
:Initially you might have the platter removed so that a minumal loading would be placed on the motor.Usually if you go to the top of the unit (or bottom) it is possible to see the motors spiral rotor segments of its pole pieces and copper segment rod ends.
:A closely/strongly placed common flourescent lighting of that area will typically produce a stroboscopic pattern with a uniform degree of drift as you watch those elements. The pattern being a harmonic of the 120 PPS drive from the lamp. Watching the pattern drift from a cold turn on until about 3 min of run time, should result in the pattern staying at the same uniform "drift". Should the pattern drift and make a sliding continual variation, I would suspicion the motor rework not being adequate and the unit still having a sludge / glaze / tightness and does not maintain a uniform speed until only after warmup and expansion.Thereby an initial sluggish motor
:speed problem and not one of the "rubbered" drive components.
:
:
:Any chance that you totaly dis-asssembled the motor and done a FULL rework of all of its composite
:rotating elements. This would be a flush out degreasing of all the old lubricant in the felt "wicking" washers surrounding the porous bronze bushings that relube the units shafts. Being sure that you have all traces of any sludge or glaze off the top and bottom of the motor shaft at the two points where the bushings surround them. Along with the porous
:bronze bushings being immaculate degreased.
:Usually the motors top shaft movement is limited by a pressed on collar, therefore one has to move the shaft up and down and work on it one half at a time. Whereas the bottm shaft stub is unshrouded and thus totally free to work with.
:I typically just pull the disassembled rotor with that typical pot metal top collar with its internal bushing. That permits me to use thin "file card" cardboard to make a rotary ptotective collar for the bottom motor shaft and chuck it into a var speed hand drill.
:I then use a WD40 wetted (1/4 X 3 inch strip) of #800 wet and dry paper and compress between thumb and forefinger to permit balanced 180 degree opposing pressure. Then slowly rotate while you, just ever so slightly,remove just the surface glaze on the motor shaft. That then leaves a uniform cavitated surface area for retention of a uniform fine oil film.
:Flip to the top side of the shaft and protectively rechuck and do the easy part, the bottom stub the motor shaft. Much easier than the dual operation on the halves of top motor shaft.
:I typically use 30 weight motor oil for lube, the modern formulations let it do a fine job in the harsh temperate and speed demands of car engines....a piece of cake for a mere phono motor and its temperate situation.
:Oil the felt washers, reassemble, lube the contact points of the top bottom motor shaft at
:bushing points, remount the motor and initiate the same speed test from a cold start.
:
:73's de Edd
:Thanks Edd
I will take it out and do as you state, hopefully with good results.
Mark

30 weight motor oil will give sluggish starts. Light weight motor oil, like 3 in 1 or sewing machine oil, is what you want. It will also flow through the bronze more readily.

T.

:30 weight motor oil will give sluggish starts. Light weight motor oil, like 3 in 1 or sewing machine oil, is what you want. It will also flow through the bronze more readily.
:
:T
Hi Thomas
Ok, I have a can of that 3 in 1 I've used it on other things with very good results.
Mark

Mark, heed Tom's advise, anything heavier than 3 in 1 oil will actually be a drag on the motor not a lubricant. The motor are designed for constant spead and sacrifice torgue to achieve it. Now if you could find a can of whale oil, you'd be in business. PL

: Mark, heed Tom's advise, anything heavier than 3 in 1 oil will actually be a drag on the motor not a lubricant. The motor are designed for constant spead and sacrifice torgue to achieve it. Now if you could find a can of whale oil, you'd be in business. PL
Hi Planigan
LOL! thats a good one!!! No, I have a can of 3 in 1 I've used in other situations with great success! just needed to get this thing cleaned up and relubed! since I've done all this it works like new! even though its almost 60 years old:)
Mark

:30 weight motor oil will give sluggish starts. Light weight motor oil, like 3 in 1 or sewing machine oil, is what you want. It will also flow through the bronze more readily.
:
:T.
HI Thomas & Edd
Well, success! it is no longer sluggish, works great! amazing what a little cleaning, oiling and greasing will do! thanks guys:)
Mark