[928uk] Cam gears

[Paul]

The failure mode is for the sharp edges on the cam teeth to slice through
the teeth on the belt

This is exacerbated when an incompetent workshop cancels a belt tension
warning by randomly increasing belt tension

Sadly that is my real world experience

I have used cam sprockets from 928Int fitted at the moment, and some spare
used sprockets that generous 928Org lister sent to me

I will purchase some from Roger next time I visit the US, as I can afford
to do so now

Meanwhile I simply use very short belt change intervals, mileage wise, and
check the belt for any sign of wear as often as I can remember to do so

Paul
87 S4 Manual - Cam Belt Failure in Oct 2003

On Mon, 10 Jan 2022 at 13:19, Jonathan Rackowe via 928uk <
928uk at lists.928.org.uk> wrote:

> To my mind, the big question is whether the wear on the gears is
> sufficiently bad for the the belt to slip/move, by one or more teeth. I'm
> no expert, but I would think that unlikely. Sure, in the long term
> replacement of the cam gears would be good, but is it really necessary
> immediately, as some have suggested/implied?
>
> I for one would love to know the statistics on 928 engine damage caused by
> cambelt movement (or belt failure??) due to worn cam gears. And how bad do
> the gears have to get for this to happen? Does Roger, Paul or anyone else
> have real-world info on this that they can share with us please?
>
> Best regards,
> Jonathan
>
>  928 GT 1991 Amethyst Metallic
>
>
>
>
> On Sun, 9 Jan 2022 at 14:35, Richard Armstrong via 928uk <
> 928uk at lists.928.org.uk> wrote:
>
> > I'm not sure that the wear is as bad as some people are indicating. The
> > wear in the left cam seems to be worse than the right which is a bit
> > odd, but although it looks like there is a lip at the front of the
> > teeth, I'm not sure there is - doesn't look like one at the back.
> > Hard anodising is difficult to judge. Certainly Roger's cam gears are
> > lovely and I presume the black anodising is hard?
> > Shame we don't have a source over here as the shipping and customs duty
> > from the USA makes them expensive
> > Richard
> > On 08-Jan-22 6:32 PM, maff.hickling wrote:
> > > HiIve spent the day stripping everything out to change my cam belt and
> > need some advice on the cam gears. Theres a link below to some photos, I
> > hope some of you might know if these are to worn to leave on the car?I
> > think they can be recoated or would you advise to just replace them. If
> the
> > link doesn't work let me know its the first time ive done it.
> >
> https://www.dropbox.com/sh/rw4v6q0c8bne2ex/AADYcbxCQx1baxXr0Nn5rpGda?dl=0Sent
> > from my Galaxy
> >
> > --
> >
>