Springs, by there nature, are complex components to understand. The 63 brake drum spring, part number, 3694290 (GM Group# 5.810 October 1962 parts catalog) was actually released on August 4, 1949 (Not a typo) and revised over the years. The 63 version was released as a "ROUND" wire spring with a "FLAT WIRE OPTIONAL CONSTRUCTION" note on the drawing. The supplier of record optioned to use flat wire in production. There were several economic factors contributing to his decision, flat (Flat wire size .140 wide X .056 thk) vs. round. The original flat spring released for the 63 model year contained 216 active coils and had a free length of approximately 30 1/2". On April 24, 1964 Chevrolet engineering issued revision number 11, per ECR 14928, removing 3 active coils reducing the total number of coils to 213 with an approximate fee length of 30.00". The round wire version has an approximate free length of 32 3/4", wire diameter .0915 oil tempered spring wire per GM material specification GM 61M and is referred to in the previously mentioned GM parts book. The square wire was released for production and round wire was alternately released for service.
If you're using new springs there will be "NO" space between the coils. However, if you're using previously assemblied springs, these have been "fatigued" (stretched) and will exhibit approximately .020-.040 between coils. These springs will be much be easier to reinstall.
Delco's assembly method consisted of a cone shaped lead-in tool and hydraulic press. Springs were automatically feed to the top of the cone and hydraulically pressed onto the drum. Obviously, the cone is long gone as well as the press. I've installed them by "rolling" the assembled spring onto the drum, keeping in mind this operation must be done uniformly around the drum's circumference. Otherwise you bind the spring making it virtually impossible to assemble.
Hope this is of assistance.
If you're using new springs there will be "NO" space between the coils. However, if you're using previously assemblied springs, these have been "fatigued" (stretched) and will exhibit approximately .020-.040 between coils. These springs will be much be easier to reinstall.
Delco's assembly method consisted of a cone shaped lead-in tool and hydraulic press. Springs were automatically feed to the top of the cone and hydraulically pressed onto the drum. Obviously, the cone is long gone as well as the press. I've installed them by "rolling" the assembled spring onto the drum, keeping in mind this operation must be done uniformly around the drum's circumference. Otherwise you bind the spring making it virtually impossible to assemble.
Hope this is of assistance.
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