Alternator bolt keeps snapping

[andy_h]

That's a second lower alternator bolt that has snapped (sheared off along the threaded part) in a couple of thousand miles (its the long bolt that it swivels on).

 

Anyone else had the same problem or am I just unlucky?

 

 

[Ed White]

I'd say unlucky. Do the two parts touch before you bolt them, or is the bolt bringing them together and therefore under load. Try and get the mating parts together first, and switch for a high tensile grade bolt. Cheers, Ed

[andy_h]

The long bolt was supplied by CC when the last one snapped, now its done the same

 

Yes the parts touch (passes through mount and alternator as one) it only stops the alternator from moving on its bottom swivel point, so not taking up more than a mm or so in compression.

 

 

[Ed White]

High tensile and nyloc, so no movement, or a stainless one if you have one lying around. Cheers, Ed

[andy_h]

Thanks.

 

Was hoping the cc was would be up to the job, and given its about 5inches long I'm not going to have either type lying around.

 

 

[Jason Plato]

its worth trying to find the root cause of the vibration that's making it fail.

 

I had a K series alternator that snapped 2 bolts and then 500 miles later the alternator shield cracked and left me going home on a flat bed > the alternator bearings / balance was out.

 

dj

[nickh7]

used to have it on my crossflow then Richard Scrivner used his magic mod of nylon washers and never broke one again

 

My bottom bolt sheared on the K but its not that long

 

Regards

[Red SLR]

Quoting Dave Jackson: 

its worth trying to find the root cause of the vibration that's making it fail.

 

I had a K series alternator that snapped 2 bolts and then 500 miles later the alternator shield cracked and left me going home on a flat bed > the alternator bearings / balance was out.

 

dj

 

I would go with this - something is not right. You need quite a force to snap steel bolts and whilst you could put it down to a weak bolt doing it a second time would ring alarm bells for me. How old if the alternator?

[andy_h]

Thanks for feedback.

 

Alternator is fairly old (possibly original circa 1994) but millage is what counts and that's only 9k. I suppose the bearings could have dried out a little to cause inbalance?

 

I like the plastic washer idea

 

The snapped bolt looked poor quality and 'cast metal' in appearance. It had a washer under the bolt head, and another washer and nylock nut on other end.