Differences in motors and drive pulleys of Garrard RC88/98, Type A/A Mk2/A70, and RC121 MKII

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gonzoflies
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Joined: 03 Dec 2018 02:22

Differences in motors and drive pulleys of Garrard RC88/98, Type A/A Mk2/A70, and RC121 MKII

Post by gonzoflies » 06 May 2019 22:15

Recently, following the purchase in December of a Type A "birthday cake" model with the metal base (pics attached), a variety of very vintage Garrard changers have ended up in my possession, to wit: an RC98 (brown on cream, with speed rheostat), an R121 MK II (cream on brown), another Type A and a Type A70. All are cosmetically very nice, but have the usual Garrard grease-turned-into-corrosive-glue, and hardened/disintegrating rubber idler and motor suspension problems, which in a couple of the units has caused severe wear of the bronze speed pulleys.

Having such a spread of models is giving me a nice opportunity to explore how their very complex changer mechanisms and tonearms evolved with time. One of the things I notice is that all the stamped steel platters are of identical size and shape, as well as the platter bearings and spindle unit. The motors, though, are all different, although they all are 4-pole units of the same basic design. The pulleys, also, all seem to have slightly different diameters, and have different part numbers in the manuals. My question to the Garrard experts here is: Is there any difference in the motor speed and pulley size for these motors throughout the different models, or are they basically interchangeable? Thank you!

David Morales
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A70BBen
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Re: Differences in motors and drive pulleys of Garrard RC88/98, Type A/A Mk2/A70, and RC121 MKII

Post by A70BBen » 07 May 2019 03:54

The ones for the Type A and Type A70 (and the 70 Mk II) are the same pulley but this does not mean they are freely interchangeable. The induction motors in these models varied slightly in speed. At the factory in Swindon, each turntable was checked for speed. If it was out of tolerance, a motor pulley of different size, larger or smaller, would be substituted to bring speed within tolerance. So the motor and pulley may be considered as being "mated for life" and one may or may not work within tolerance with a different one. I think you can include the RC88/4 in this grouping but the original RC88 had only three speeds.

gonzoflies
Mexico
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Joined: 03 Dec 2018 02:22

Re: Differences in motors and drive pulleys of Garrard RC88/98, Type A/A Mk2/A70, and RC121 MKII

Post by gonzoflies » 07 May 2019 15:51

Thank you A70BBen. Now I understand the apparent discrepancies. It is worth mentioning that the RC I have is an RC98/4, which would be a different animal, given that it has speed control.

A70BBen
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Re: Differences in motors and drive pulleys of Garrard RC88/98, Type A/A Mk2/A70, and RC121 MKII

Post by A70BBen » 15 May 2019 02:58

Correct on the RC98 models. They had pulleys selected to be fast with the "naked" motor . The rheostat speed control slowed the motor, adjustably.

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