Got my car fitted with four new UJs and two new calipers ready for its MOT. My brother gave the throttle a blip before it came off the ramp and it ripped half the alternator belt.

Now I thought the belt was a touch loose as it did sometimes still squeal, but popping a couple of cords suggests it was over tight. Fingers crossed it isn't actually the damper squealling. Or a duff pump/alternator reluctant to turn.

It was a cheap belt. Are they known to give way?

 

They can seperate. Usually age related more than $ quality.

Too tight will generally cause issues with rotating bearings, etc, and eventually the belt will fail.

Too loose and they will not drive. Unlike a "V" belt that can still provide some drive whilst being very loose, these multi-rib are far less forgiving.

Mis-alignment of the pullies is a big cause of seperating, usually an idler/guide pulley with a bearing going bad, and alignment is compromised.

Heat is a killer to the fabric of the belts. Due to the tentions they run at, they also run quite a bit hotter than the older "V".

 

It failed on half shaft play :/

New wheel bearings and diff I think. Just put new bloody hub nuts on too.

 

Why would the half shaft play be the cause? If I understood correctly, your brother blipped the throttle while in neutral on a ramp?

 

Ah, no, sorry.

We replaced the UJs in the half shaft to cure the play and rumbling.

Quite unrelated, it popped a belt going to the MOT.

We replaced the belt and got it to another MOT a few days later, when...

It failed on half shaft play.