Happy to clarify! Some nomenclature: The FRAME COMPONENT is what is welded to the stays, and has the slot that the INSERT fits into. These pieces make up the DROPOUT ASSEMBLY. We consider inserts a wear item, the same as tires or a chain. Inspect them regularly, and replace as needed.
Tolerances are very important for sliding dropouts to work well. Any extra clearance gives the insert room to move. This may produce some unwanted noise, and in some cases can result in failure of the insert. We don’t know what tolerances other manufacturers use, so we can’t comment on whether or not our inserts will work well.
The slot in the frame component is manufactured to a dimension/tolerance of .355"/357". The mating boss on the insert is manufactured to a dimension/tolerance of .352"/.354". Worst case, there’s .005" clearance between the frame component and the insert. In reality, the clearance is about .003" because we do our best to hold the median of the dimension/tolerance.
It’s fairly unlikely that a cast frame component holds this tolerance. There’s probably a lot of grip from the texture of a cast part, so it could be that inserts are held tightly in a cast part. If there is excessive clearance, the inserts will rock in the slot, and will eventually fail.
Unless it’s CeraKote, paint or powdercoat will negate close tolerances. The fix for this is open up the slot in the frame component, but paint/powdercoat is soft compared to any metal. The inserts will eventually crush the coating, leading to loose inserts, poor tolerances, and excessive movement between the insert and frame component. Our recommendation is to not use frame components made from steel, and DO NOT paint the slots or mating faces.
When assembling sliding dropouts, keep all mating surfaces free of coatings or lubricants. If inserts creak, it is a sign that movement is taking place. Do not lubricate the insert. We all know that lubricants will minimize noise, but will make movement easier. This is the start of a failed insert. The creaking will stop, but the movement will continue. Take everything apart, clean well to dry metal and reassemble. A small amount of blue thread lock on the M8 fixing bolts will help keep things tight. Make sure you always use the double washer included in the hardware kit. The button head capscrews supplied will hold well in most situations. If you prefer a stronger bolt that can be torqued more, see our combination head titanium bolts.
From our website (sorry about the formatting):
Always use our 304 stainless steel washers with the screws:
Help spread the load over a larger area
Hold the parts together better
Keep your frame from getting damaged from repeated tightening/loosening of the screws
Steel Torque Specification:
24 to 26 N-m, 2.4 to 2.6 Kg-m, or 17 to 19 foot/pounds.
A word of caution: unless you have a brand new 5 mm wrench, at the upper range of these values there is a possibility of rounding out the socket head on a steel bolt.
Titanium Torque Specification:
May be torqued 10% more than the above values.
Our titanium screw offers the following advantages over our stock steel button head cap screw:
The hexagon is deeper and manufactured to a closer tolerance
Lighter
Aesthetically pleasing
Can be torqued 10% more than our steel bolt (see above)
Those are the comments on sliding dropouts. To summarize, no paint, no lubricants, use frame components and inserts with the proper tolerances.