Poly-V's vs A Section Belts
Up until 2002, the Super 7 was fitted with 2 standard A-Section V belts. Clearly they work! However, from 2002 onwards the tradition changed to J-Section Poly-V's, of the type universally used under the bonnet of your car. These belts provide more grip, flexibility and longevity - particularly in a hot, greasy environment. The main benefit to the user is a smoother and noticeably quieter drive.
Your elderly Super 7 can be dragged up to this standard with a bit of work. Separate designs are offered for the Motor-Countershaft and Countershaft-Spindle installations.
In exchange for machining two new pulleys for the mandrel and countershaft, you are rewarded with a very smooth drive (particularly at high speeds) from a belt that is a delight to slip across the pulley steps. The bronze back gear and all bushes are recycled from your Myford pulleys.
This conversion is suitable for ALL Super 7's (ie 1953 - 2002). Alternative countershaft pulleys are detailed for the early and later clutch arrangements and both can be accommodated with the castings offered.
For the ultimate Poly-V experience, new pulleys can also be cut for the primary drive. The conversion involves cutting a new motor pulley and modifying the countershaft pulley to accept an iron Poly-V ring. The construction notes provide a huge amount of detail including the dismantling of the countershaft clutch. A point to note here: Whilst the Super 7 can be used to manufacture the motor pulley, once the clutch/pulley has been removed for modification, the lathe of course cannot be used… Accordingly, a second lathe is required to complete the conversion – ideally a substantial lathe with a centre height greater than 5”.
Please note, this conversion is NOT suitable for many of the older Super 7 lathes. There are two things for you to check on yours:
- This modification is designed to suit Super 7’s built after June 1958 (Serial No. SK 8128). It is not suitable for the earlier models where the clutch was fitted within the countershaft pulley. If the larger primary pulley on your lathe is an alloy die-casting, it is one of the older models...
- Check your belt guard against this photo. Unfortunately, the Poly-V pulleys will not fit within the older guard. However... if you find a late model guard, it will fit your earlier lathe.