address comments

src/lib/radio/radio.spec.ts

@@ -229,7 +229,7 @@ describe('MdRadio', () => {
     });
 
     it('should not show ripples on disabled radio buttons', () => {
-      radioInstances[0].disabled = true;
+      testComponent.isFirstDisabled = true;
       fixture.detectChanges();
 
       dispatchFakeEvent(radioLabelElements[0], 'mousedown');
@@ -238,7 +238,7 @@ describe('MdRadio', () => {
       expect(radioNativeElements[0].querySelectorAll('.mat-ripple-element').length)
         .toBe(0, 'Expected a disabled radio button to not show ripples');
 
-      radioInstances[0].disabled = false;
+      testComponent.isFirstDisabled = false;
       fixture.detectChanges();
 
       dispatchFakeEvent(radioLabelElements[0], 'mousedown');

src/lib/radio/radio.ts

@@ -146,9 +146,7 @@ export class MdRadioGroup extends _MdRadioGroupMixinBase
 
   set labelPosition(v) {
     this._labelPosition = (v == 'before') ? 'before' : 'after';
-    if (this._radios) {
-      this._radios.forEach(radio => radio._groupValueChanged());
-    }
+    this._markRadiosForCheck();
   }
 
   /** Value of the radio button. */
@@ -186,7 +184,7 @@ export class MdRadioGroup extends _MdRadioGroupMixinBase
     this._disabled = value;
     if (this._radios) {
       // Update radios disabled state
-      this._radios.forEach((r) => r._groupValueChanged());
+      this._radios.forEach((r) => r._markForCheck());
     }
   }
 
@@ -249,6 +247,12 @@ export class MdRadioGroup extends _MdRadioGroupMixinBase
     }
   }
 
+  _markRadiosForCheck() {
+    if (this._radios) {
+      this._radios.forEach(radio => radio._markForCheck());
+    }
+  }
+
   /**
    * Sets the model value. Implemented as part of ControlValueAccessor.
    * @param value
@@ -403,8 +407,6 @@ export class MdRadioButton implements OnInit, AfterViewInit, OnDestroy {
   }
   set disabled(value: boolean) {
     this._disabled = coerceBooleanProperty(value);
-    // Update rippleDisabled
-    this._changeDetector.markForCheck();
   }
 
   /**
@@ -466,7 +468,12 @@ export class MdRadioButton implements OnInit, AfterViewInit, OnDestroy {
     this._focusOriginMonitor.focusVia(this._inputElement.nativeElement, this._renderer, 'keyboard');
   }
 
-  _groupValueChanged() {
+  /**
+   * Marks the radio button as needing checking for change detection.
+   * This method is exposed because the parent radio group will directly
+   * update bound properties of the radio button.
+   */
+  _markForCheck() {
     // When group value changes, the button will not be notified. Use `markForCheck` to explicit
     // update radio button's status
     this._changeDetector.markForCheck();