Benelli Forum banner
1 - 9 of 22 Posts
Apparently the Factory recommend that the alternator should be removed and this bolt checked on EVERY service……
What on earth would you check? That its still there? Surely they don't expect you to x-ray it for cracks? Maybe only to see if it's loosened off?

I wouldn't have believed that the bolt is under so much stress. The shaft yes, but not the bolt.

All I can think of, is that it was torqued up too tight.
 
Just checked my 10mm bolt - no markings. So must assume it's not high tensile. I expected at least 8.8.
I'm going to pick up a 10.9, just in case.

Yours was either done up too tight for a standard tensile strength bolt, or it wasn't done up tight enough, came loose & fractured. It seems reasonable that the bellville washer would retain the bolt, even if it was slightly loose.

I'll be torquing mine up to the recommended value for an 8.8 10mm bolt, AND using loctite.
 
Just talked to our head mechanical engineer, who reckons that it's NOT (or shouldn't be) a high tensile bolt. You don't cadmium plate a high tensile bolt, because it causes hydrogen embrittlement. Anyway, it's bad for the bolt. It creates fractures. If the bolt IS high tensile - there's the reason vtxbrit's fractured.
 
.. for the record the bolt is not plated, also looking at the sheared end (and bearing in mind i'm an engineer)
:bow:
I can confirm that the bolt is h.t I can have it hardness tested for exact spec but from experience i reckon it's an 8.8 bolt.
by the look of it the head sheared off and it then ran with the locking tabs driving the alternator until they sheared off.
The one supplied in my kit is Cad plated.
If it's not a heap of trouble, could you test it's hardness?
The head is quite short. Don't suppose that would weaken it?
 
Is your engineer saying that it shouldn't be a plated HT bolt
HT bolts should NOT be plated (tin might be ok, but not cadmium). It causes hydrogen embrittlement.

...What would be the reason for not fitting a high tensile bolt in that application? It must surely be a safer bet, I would have thought:D . Maybe the designers just specified the wrong grade of bolt. After all, they have made one or two other errors of judgment that we know about :rolling:!
vtxbrit can shed more light on this, but I would have thought that the higher grade HT the better.
Curious that the bolt recently supplied with my kit appears NOT to be HT, whereas vtxbrit's IS HT. Maybe the factory are saying that it SHOULDN'T be HT?
:confused: :confused: :confused: :confused: :confused:
vtxbrit ?
 
I think I need to find out how soft mine is.
From Wikipedia
Steel with a ultimate tensile strength of less than 1000 MPa or hardness of less than 30 HRC are not generally considered susceptible to hydrogen embrittlement
grade 8.8 means 800MPa ultimate tensile strength (breaking load) and 80% of that (640MPa) yield (when it starts to bend or stretch)
So a 10.9 shouldn't be plated, whereas an 8.8 could be.
Mine could be an 8.8 :confused:
 
First ever 903 recall was to replace the 8mm generator shaft retaining bolt and flat washer with a new bolt with a bend over type lock washer (that is a bastard to bend back once bent onto the bolt head).

Then without any notice, parts replacement stock of shafts were being delivered as kits with 10mm bolts.
If the original was only a FLAT washer, no wonder it worked it's way loose.
:confused:
It wasn't a Belville washer?
 
1 - 9 of 22 Posts