Brake actuating arm O-rings

[suecanada]

 I promise not to ever bother you again about this but how can an O-ring really fit properly in a squared groove??  Is the profile on your brake actuating arm's grooves really squared? How many grooves do you have if you have an '83 R65LS? I have 3 but they aren't square on the bottom and they are shallow.

[Bob_Roller]

There are only two grooves that are deep enough to accept o-rings, the grooves at the very ends of the brake shaft .

The grooves are deep and squared, to prevent the o-ring from being forced out of the groove .

All of the applications that I've worked on in aviation are similarly shaped .

I have no idea why there are three extra grooves in the brake shaft, they are unusable to hold o-rings .

Putting o-rings on the three shallow grooves won't help out, as best as I can see, as they are not in contact with the final drive cases, they are in the cavity with the gear oil .

Next time I have  brake shaft out, I'll do some measuring and make sure .

I'm getting gear oil on my rear wheel on my '81 R65, replaced the o-rings last June, when I put an LS style rear wheel on, thought they would last longer .

[suecanada]

Thanks Bob! I bet I'm putting those O-rings in the wrong grooves...the shallow/non square ones, I bet! But I will take it out soon and check for sure.
2 o-rings into the square grooves at either end! Got it.

Anyone else with an '83 R65LS so we have a consensus that there are 2 square grooves at each end of the arm into which O-rings properly fit plus 3 useless shallow grooves....??

Snowbum tells us that this brake actuating arm comes in all shapes and sizes!

[montmil]

Sue, The O-rings fit on the brake shoe actuating cam rather than the actuating arm -which is on the exterior of the rear wheel and hooks up with the brake rod.

Both my '81 and '83 R65s have but two square-bottomed O-ring locations.