SMTA Brakes

Ellis Kinney · Oct 12, 2018

My SMTA has developed the nasty habit of locking the brakes, usually only one side when applied. Needless to say this causes a jerk to one side or the other. I would like to try to fix this. What do I look for? Ellis

fastfarmall · Oct 12, 2018

They need to be cleaned,that expander especially put it on a wire brush,make sure those balls are round and run in the track, check and see if you need any new parts, then you need to put some graphite powder for a lubricant, it the same lubricant we use to use, for corn seed, in the old style corn planters !! Dont use oil in there!

DeltaRed · Oct 12, 2018

Take them apart and clean. Take the expander apart and inspect the ramps and balls. the balls should be shiny with no pitting or flat spots. the ramps must not have any flat spots as well. Clean/polish the ramps with emery cloth to get them smooth.Dirt and flat spots is what causes them to stick. Clean out the grooves on the disks.Open the outer end of the groove to the edge of the disk.you will need a small grinder or hacksaw to do that.Replace any broken springs.

Janicholson · Oct 12, 2018

An important element in the fix is stack height. Put the housing upside down on the bench using a support that lets the little cap hang free. Place the outer disk, expander (clean and with all springs in place) then the inner disk into the housing so they are nice and centered. Use a straight edge across the housing mating surface. Measure from the straight edge to the friction material of the inner disk. on and M, the maximum space should be .060" or less down to a minimum or .030". To adjust this gap to these numbers, the use of new disks, or machining the housing is needed. Roughing up the friction surfaces (metal and fiber) with 250 grit paper will let them break in when reassembled. Jim

DR. EVIL · Oct 12, 2018

The three big balls to separate the actuator disks are cheap, Buck or two each. Be sitting down when you get the price on the springs. Three per brake, six needed, all six fit in your hand with fingers closed over them, and cost you around $80 total. But they stretch.

Had a brake hanging up on my Stage 2 Super H. New disks, balls, springs, works like new.

MARK ROBKE · Oct 12, 2018

Hey Ellis-my 300u did this,and when I took it apart I found the expanders were badly worn and cracked.This caused the ramp/roller balls to hang up,and under a bit more pedal pressure,suddenly the balls move too far in the ramp,and fully apply the brake to the lock up point.Good luck,Mark.

SMTA Brakes

Ellis Kinney

Well-known Member

fastfarmall

Well-known Member

DeltaRed

Well-known Member

Janicholson

Well-known Member

DR. EVIL

Well-known Member

MARK ROBKE

Well-known Member

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