Ted, thanks for that confirmation. I've not personally run into that style of crush washer in my other mechanical pursuits. So that's my new fact for the day....
.....I think I'm good to go but if I can find my feeler gauges I'll measure the gap and see how many rotations it is to tight without the washer in just to be sure.
Thanks Guys
You can actually calculate the thickness of washer needed to a far better degree. You screw on the brake/hider in this case then take note of how far it goes past the 12 o'clock position. Then you use some math to calculate the gap or thickness of washer needed to stop right at 12 o'clock. And in fact it's better and more accurate to do it that way than with the feeler gauges. The issue is that the feelers cause the threaded on item to tilt to one side so the play in the thread along with the angle causes an error in the measurement. You're far better off to turn the item on until it stops and then calculate the thickness of shim needed or amount of shoulder to be turned off to clock the item correctly into place.
Keep in mind too that the first time this is done that the threads and the contact shoulders will also "crush" a little until they have enough surface area of contact. So a wise machinist clocking an item will thread it on and torque it down before taking the measurement of the angle and calculating the thickness of the shim or amount to be removed required to clock the item correctly.
It's the angle past divided by 360 then multiplied by how many thou the screw thread is per turn. In this case the thread is 24 tpi so that's 1inch/24 or
.0417 inch. Round it to .042. The brake went 30° past the 12 o'clock so you want to add a shim that stops it short by 30°. You can't make it turn FURTHER onto the thread so it's a case of fitting a shim that holds it back by the amount it goes past. So in your case and assuming that it really is 30° the math would look like 30/360 x .042 = .0035 inch. Now that's a rather thin and specific shim to find. So it's likely that you'd opt for some soft annealed brass shim stock of .005. The extra .0015 would stop it early from the 12 o'clock by .0015/.042=.036 of a turn. In degrees that would be .036 x 360 = 12.86°. And that should be about right for allowing the brake to be torqued into position.
Or you can use the shim washer you found....
Keep in mind that the shim washer has an unknown thickness and the brake/hider will clock into place at some random value. It won't just turn to the 30° past the 12 o'clock you got. So you might find you need to torque down by as little as a few degrees or up to a turn and a bit more. For example if it met the washer with 10 degrees to go you could torque it down with your hands. And that's clearly not enough torque to hold it. So you'd have to go the 10 degrees and another full turn to get the right torque.
Bottom line is though that you need that crush washer... or a nice pack of assorted brass shim stock.
