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SR20DET HKS 264 Step 2 camshaft repair

Story:

This camshaft was purchased new by a customer and installed in a high horsepower SR20DET engine built for drifting purposes. Original cause of failure was not clearly determined. Camshaft sprocket retaining bolt may have not been torqued down properly leading to shearing of the camshaft locating pin, camshaft damage, as well as bent engine valves. This camshaft, although brand new, was rendered useless. The shoulder retaining the camshaft sprocket was damaged during the failure. In order to fix this camshaft, the shoulder was TIG welded ensuring only proper penetration and no overheating/warping of the camshaft. After welding the camshaft was mounted in a lathe using a 3 point support. Dial indicator used to zero-set camshaft. After shoulder machining the cam was mounted vertically in a table mill and locating pin bore repaired. During pin shearing failure the bore was damaged and enlarged. Original pin is 6mm with a light press fit. Since the bore was damaged it was decided that a 1/4 inch overbore was necessary for the repair. New hardened pin was machined with a 1/4 inch diameter pressing into the camshaft and a standard 6mm diameter to locate the camshaft gear. Pin was lathe machined using prehardened steel with a Rockwell rating of 40.

Goal:

Repair broken camshaft locating pin and render camshaft usable

Operations:

  1. TIG weld camshaft shoulder
  2. Lathe machine should and restore to standard dimension
  3. Table mill camshaft pin bore to 1/4 pin size with light press fit
  4. Lathe machine new hardened sprocket locating pin
Pictures of work:

 

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