Date: Fri, 18 Dec 2009 12:51:13 -0800
Reply-To: Al Knoll <anasasi@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Al Knoll <anasasi@GMAIL.COM>
Subject: Re: Syncro Tire Diameter
In-Reply-To: <71d9cdf90912180834g1a09581fl9d31b6b40b893756@mail.gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Bob is often nicely laid out. In photos of his well laid out campsites,
he's the star.
Using the mustard method you can measure the rollout of your tire at
whatever pressure you desire.
Find a no-traffic area such as a parking back lot. Get some packets of good
ol' yaller mustard.
Line up the van so it will go straight. Lay a rather large caterpillar of
yaller mustard about six inches in front of the drivers side rear wheel
perpendicular to the direction of travel so that when you roll through it it
will adhere to the tire and lay down a mark after one then two rotations on
the pavement. Now put a dab of mustard on the drivers side sidewall so you
can see it from the open door, I put mine in the area nearest the ground.
You will use this to count tire revolutions. Now fire that puppy up and
drive slowly about 2.5 revolutions of the front wheel you just marked.
Using your tape measure, measure the distance between the three mustard
marks you laid down. The first one is the start, the second one the first
rollout and the third one the sum of the first two rollouts. This gives you
two circumferences worth of travel. This number in inches can be normalized
to rotations per mile within an RCH on your Post Versalog Slide Rule. 12
in/foot 5280 ft/mile. etc. It will also give you the data to calculate the
effective rolling radius insofar as distance is concerned. The alternate
method although much less accurate is to measure from the axle center to the
ground.
The vc only activates when the rotations of the front axles differ from the
rotations of the rear axle. So the rotations per mile is the more important
measure regardless of the 'rolling radius'.
Of course we didn't actually define rolling radius so all of this may just
be hearsay and not acceptable in a court of law.
Pensionerd. (mit decoupler)
The SA Syncros came with a decoupler that allowed one to engage the front
drive unit
On Fri, Dec 18, 2009 at 8:34 AM, Jake de Villiers <
crescentbeachguitar@gmail.com> wrote:
> Nicely laid out Bob.
>
> Let me add that 'diameter' and 'rolling radius' are two somewhat different
> things. With steel belted radials the rolling radius stays pretty much
> constant no matter the pressure in the tire ie they don't 'grow' with more
> pressure and 'shrink' with less.
>
> On Fri, Dec 18, 2009 at 8:24 AM, Bob Stevens <mtbiker62@gmail.com> wrote:
>
> > On Fri, Dec 18, 2009 at 7:06 AM, Anthony Egeln <regnsuzanne@yahoo.com
> > >wrote:
> >
> > > The conventional wisdom on syncro tires is that they should be
> virtually
> > > identical in diameter, to prevent spurious activation of the VC. I
> > believe
> > > it has been said that the diameters should not vary more than 3/8 of an
> > > inch.
> > >
> >
> > The "tech" info says 3mm. Waaaay different than 3/8".
> >
> > >
> > > But consider this: What if the inflation of the 4 tires is not equal,
> > > which is often the case? Wouldn't that affect the diameter by easily
> 1/2
> > to
> > > 3/4 of an inch?
> > >
> >
> > Where did you get that "factual/actual" information? Did you measure the
> > diameter? Or are you creating a scenario just for discussion purposes?
> > Anyone choosing not to do proper maintenance of their Syncro can develop
> > improperly inflated tires, but that's all that is. Laziness can cost
> $1000
> > for a VC ... not my choice. Same with improperly aligned front/rear ends
> > which destroys tires and begs for VC and $$ problems.
> >
> > >
> > > Here's my dilemma. On my van I have the Bridgestone Dueler AT Revo, in
> > the
> > > 225-70R-15. Bridgestone has discontinued this size....though not the
> > Revo
> > > model. I have 3 nearly new tires, but one tire (and the spare) are
> worn
> > a
> > > good deal on the outer 1 inch or so. This is from when they were on
> the
> > > front with a marginal alignment, since adjusted. Although the center,
> > and
> > > inside, of these two tires is very good, the conventional wisdom says I
> > > really need two more tires in exact diameter, and I can't get them in
> the
> > > Revo.
> > >
> > > Bridgestone recommended a Firestone tire that was similar to the Revo.
> > My
> > > question for the list is this. Can I substitute 2 new tires of a
> similar
> > > tread and diameter to the Revos in a 5 wheel tire rotation without
> > cooking
> > > my VC? Right now I hate to throw away 3 perfectly good tires...to say
> > > nothing of spending $600 + on new replacements.
> > >
> >
> > This is all due to owning a Syncro. Sell the old tires and get new one's,
> > or
> > be prepared to deal with getting a replacement VC (IF) it gets destroyed.
> > Option: get a decoupler and a solid shaft, put them on and sell the VC
> > while
> > it's good, if it is now.
> > You sound to me like you're trying to justify not abiding by what you
> have
> > already called "conventional wisdom". I'd call it facts about owning a
> > Syncro.
> >
> > bob
> >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> >
>
>
>
> --
> Jake
>
> 1984 Vanagon GL
> 1986 Westy Weekender "Dixie"
>
> Crescent Beach, BC
>
> www.thebassspa.com
> www.crescentbeachguitar.com
> http://subyjake.googlepages.com/mydixiedarlin%27
>
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