[ST] RE: Time for new sprockets and chain

["Keith Tynan" <keith.tynan@xxxxxxxxxxxxx>]

> Date: Fri, 07 Jun 2002 19:14:20 -0700
> From: Neil Lindsey <neillindsey@xxxxxxx>
> ...
> At 18,000 km my original Regina chain and sprockets are bagged,
Surprised it lasted that long (the chain). Has anyone got a good word to say
for Regina? [One's tempted to utter a bit of schoolboy humour regards the
name, but in the interests of being PC will refrain. Bet it's crossed
everyone's mind though.]

> ...I'd also like to increase the number of teeth on the
> rear sprocket by two to get a bit more zip in the lower gears and perhaps
more
> 'tractability' (for lack of a better word) at low speed.  Weight is not an
> important concern and steel will maximize the wear potential on
> the rear.
I've just gone to 18/45 from 18/43. The 18/43/DID530VM (not ZVM) was a
Triumph OEM replacement. As this had only done a couple of kmiles, I
considered it safe to swap just the rear sprocket. I chose an AFAM hardened
alloy one from JL (couldn't easily locate a steel one - which would have
been my preference).

Whatever you fit MAKE SURE THE REAR SPROCKET IS CENTRED ON THE HUB as
failure to do this will result in rapid uneven wear of the chain. Mine
sprocket has 0.4mm play (0.2mm each side).

There is an improvement in acceleration and tractive effort, but I haven't
found it earth shattering. It still won't pull a wheelie in first just by
opening the throttle. (No jokes please about not being able to get it up...
~:). There are a couple of pics on my website giving the change in net
tractive effort and acceleration for the two combinations.

> I also understand that increasing the number of teeth on the rear instead
of
> drooping a tooth on the front is better from a wear perspective and that
> this will also avoid the possibility that the chain could rub on
> the plastic
> protector that sits on the top of the SS swingarm.
Yeah, but it might slap about more...

> I plan to go for the DID 530ZVM X-Ring chain.  I have a few concerns about
> this choice of chain.  In the catalogue that my shop referred to
> it showed a number of 530ZVM chains. The OEM chain has 108 links.
IMHO the ZVM is for Busas and the like, and not necessary for the likes of
the ST (if you keep it well lubed).

> My first concern is that I can still use this number of links given the
> increase in rear sprocket size.  I don't mind if the wheelbase is
> shortened
> a tad (this should improve the turn-in rate from what I've heard), but I'd
> sure hate to find that the chain is too short.
Yes, 108 is fine for 18/45. It will however shorten the wheelbase by 8.5mm
and lower the ride height by 1.8mm.

> The second concern is that in the catalogue, the chain prior to, and the
> chain listed right after the 108-link item both state a superior tensile
> strength of 10,400 (not sure of the units are), but there is no such spec
> for the 108-link item, or any of the other chains listed in that section.
> The two that quote this strength are also considerably more expensive as I
> recall.  On the other hand ALL the 530ZVM chains are grouped together as
> having the same wear factor, which I thought would tend to
> suggest that they
> are all made from the same material.  I have asked the parts guy for
> clarification, but in the meantime I was wondering if anyone else knows
> what's going on.  Perhaps it's just a problem with this particular
> distributor's catalogue, but the price difference is a bit puzzling.
The book I have quotes the tensile strength for DID 530 chains as:
    VM  = 43.4 kN (wear index = 3630)
    ZVM = 46.3 kN (wear index = 3700)

> The final concern is that by shortening the overall gearing I might end up
> being forced to cruise along in the upper gears between 5000 and 5500 rpm,
> where there tends to be a bit of engine vibration.  I don't recall exactly
> what rpm it occurs at but I'll bet most of you know that there is a point
> where the vibration is more noticeable.  Currently I only pass
> through this
> spot, but I'd rather not be forced to sit there for long periods.
On my ST, 5,000rpm = 80mph and no vibrations to speak of.

> From: Michael Young <myoung@xxxxxxxxxxxxxxx>
>
> Not sure about the rest of it, but one design guideline in selecting
> sprocket pairs and gear ratios is to try to make them relatively prime.
> 18/45 would be an unfortunate pairing given this guideline. I
> don't know how
> much importance to place on this, and really am just tossing this
> out there
> so someone who knows more can comment.
This feature, as far as gears are concerned, is referred to as 'hunting
tooth', and ensures that a regular load is not born by the same pair of
teeth. I've never seen the effect referred to in the selection of final
drive sprocket sizes, as the loads (acceleration, braking and
suspension-related) are far from regular. Personally, I don't see it as an
issue, but for the record, the teeth/links of an 18/43/108 combination will
align (for 18 teeth duration) every 44 loops of the chain (i.e. a road
distance of approx 207 metres). For a 18/45/108 combination, this would be
every 5 loops of the chain (23 metres).

HTH. Now where's that dry weather???

Regards,
- --
BRG
mailto:keith.tynan@xxxxxxxxxxxxx
http://myweb.tiscali.co.uk/keith.tynan
'00 BRG Sprint ST 'Wolfram'


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