Response from Henkel/Loctite in regards to what should be used on stub axle splines (nothing to dramatic):
after asking Henkel about 635 vs 660 for splines:
Tony, how much clearance is there? I like 680 if it happens to be a little loose. 635 was the forerunner to 680. The 680 TDS is attached. Ordering item # 1835201 is a 50 ml bottle of 680. The maximum fill for 680 is 0.015” on the diameter. The maximum fill for 660 is 0.020” on the diameter. 680 is sold through industrial adhesive distributors like Fastenal and Grainger.
Gave him background on our application and asked about red threadlocker usage for the splines. His response (no real comment on using red threadlocker):
Tony, 680 can be used in place of 635. If you use “primer T”, this is called SF 7471 today. However, 680 has primer built into the formulation already and thus, you really don’t need to use primer with 680 for its original purpose which is to aid the cure on coated metals. However, if you want to speed the fixture time simply, you can still use the primer with 680. Ordering item # 135337 is a 4.5 fl oz aerosol can of SF 7471. I usually state 24 hours to achieve functional cure.
Regards,
Mike
Michael xxxx (redacted) | Technical Communications Coordinator | AG Technical Customer Service
Henkel| 1 Henkel Way, Rocky Hill CT 06067 USA