DD3 Brake Chamber rebuild

[NJT5047]

Experimenting with the park brake at 50 MPH (or 30 or even 20 MPH), on pavement, could be counterproductive on an old coach.  If the park brakes work really well, you may pull the drive axle and associated components loose.   May not either...ya'll let me know.   
This is something to test at a barely rolling speed....I would think. 
On a wet street, this activity would assure loss of control.   Reckon one cannot always predict failure induced emergency brake applications, but deliberately setting the park brakes at any speed could be dangerous. 
I will be too happy to evaluate all data available from those that attempt this daring feat!  
My does centavos, JR