Super M Brakes

[farmallphred]

I am reassembling my Super M disc brakes. When I stack the disc pads and actuators assembled with balls the last pad in actually sits higher than the housing. New parts include pads, balls and springs. The balls are the standard 7/8" balls, the pads are the rivet style at 33/64" thick per micrometer. The top pad sits high by 0.060 in. The only thing I can think is that someone previously milled down the housing. Was this a common practice to tighten up the brakes? I am thinking I will shim out the housing with gasket material. Any other suggestions?

 

[Janicholson]

I am reassembling my Super M disc brakes. When I stack the disc pads and actuators assembled with balls the last pad in actually sits higher than the housing. New parts include pads, balls and springs. The balls are the standard 7/8" balls, the pads are the rivet style at 33/64" thick per micrometer. The top pad sits high by 0.060 in. The only thing I can think is that someone previously milled down the housing. Was this a common practice to tighten up the brakes? I am thinking I will shim out the housing with gasket material. Any other suggestions?

That machining is the actual recommended choice. Making shims from sheet metal is better/stable/non-compressible, and conducts heat better. I saaume the grooves are clean. a .045 clearance in minimum .060 in still OK. Jim

 

[farmallphred]

Would the sheet metal shim be the full perimeter of the housing or just intermittent?

 

[Janicholson]

Would the sheet metal shim be the full perimeter of the housing or just intermittent?

I would make a "print" of the housing by putting tag board over the housing (when it is facing up on the bench) then use a ball peen hammer (peen end) to tap around the inside and outside of the housing contact area with the tapping cutting through the paper (like making a gasket) and tapping into the 5 holes as well. then you have an outline of a shim for what is needed. several could be cutout with tin snips and time to make the thickness, or you could take the print to a plasma torch shop[ and have them make the .100 thick shims. Recheck the numbers. ( you could check the functionality of the idea with .100 thick washers on 5 bolts. I would then recommend using the full shim to keep out water/dirt. Jim

 

[farmallphred]

Alternately could the 2 plates actuator contact surfaces be milled down by .050?

 

[BarnyardEngineering]

Alternately could the 2 plates actuator contact surfaces be milled down by .050?

I wouldn't go milling anything down.

Did you toss the old brake discs? Can you stack them in and see how it measures up?

 

[farmallphred]

I had tossed the old pads prior to realizing the issue. I am having shims fabricated. Everything else has been cleaned up, painted and is ready for reassembly. Thanks everyone for the advise.