Date: Thu, 4 Jan 2018 08:50:00 -0800
Reply-To: David McNeely <davmcneely40@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: David McNeely <davmcneely40@GMAIL.COM>
Subject: Re: Locking differential
In-Reply-To: <DM3PR20MB07159921DE04266E2BEF4FD9A01F0@DM3PR20MB0715.namprd20.prod.outlook.com>
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Dennis, I believe that an increase in tire diameter, which is also an
increase in tire perimeter, does alter the speedometer and the tachometer,
slightly or more depending on how large the increase is. What the cable
counts is rotations. A larger tire means fewer rotations per mile,
therefore both the tach and the speedometer register lower than with the
factory set up. In another vehicle, I have been stopped for speeding when
I had oversized tires. The officer and I had a discussion about that, and
he let me off with a warning due to that fact. And it is a fact, unless my
mathematics education was wrong. If this is wrong, please advise me how it
is wrong.
This does not alter your reasoning regarding the tire the original poster
is running, or the other sizes you mention, because of the nominal increase
over factory size.
On Wed, Jan 3, 2018 at 7:51 PM, Dennis Haynes <d23haynes57@hotmail.com>
wrote:
> A 205/70-15 tire is ~26.3" diameter which is a very mild increase over the
> original size of 25.6". This is about 795 revs/mile. The reading between
> the tachometer and speedometer does not change with tire size, only how far
> or fast the vehicle actuals travels does. A lot of folks go with 215/60-16
> or 215/55-17 as they are also this diameter. I like to 225/60-16 or
> 225/55-17 to get bit more diameter and width along with increased weight
> ratings. Syncros 235/55-17 is becoming a favorite. So, at 30 mph in town
> speed what is the problem with 3rd gear and 2,400 rpm? Sounds like a sweet
> spot. 3rd gear is almost 1 to 1 leaving the final drive as the real gear
> reduction from engine to axles. 4th is an overdrive, the output spins
> faster than the engine which further reduces torque, leverage in wrong
> direction. I think you probably have a good reasonable setup with the 2.2.
>
> Dennis
>
>
> -----Original Message-----
> From: Stephen Edwards [mailto:chibicyclist@gmail.com]
> Sent: Wednesday, January 3, 2018 12:09 AM
> To: Dennis Haynes <d23haynes57@hotmail.com>
> Cc: Vanagon Mailing List <vanagon@gerry.vanagon.com>
> Subject: Re: Locking differential
>
> Thanks Dennis and everyone who chimed in.
>
> The WRG's do have a “100H” stamped on the sidewall. They were so covered
> in salt today that I couldn’t make out anything else but will take a look
> tomorrow when I have time to wash the salt off!
>
> I think you said they’re slightly oversized - not what the seller told me,
> but this makes a lot of sense - I can barely get out of 3rd going round
> town. At 30mph in 3rd gear I’m seeing a hair under 2400 rpm on the tach.
> This is with a Subaru 2.2 motor but the torque range isn’t all that
> different; much under that and I can hear it laboring.
>
> Seems like no-one is advising me to get the locker, which is fine with me.
> For the short time I have to use it in sand, letting a bit of air out of
> the tires is no big deal if that will fix it.
>
> Steve
>
>
> > On Jan 2, 2018, at 12:23 PM, Dennis Haynes <d23haynes57@hotmail.com>
> wrote:
> >
> > I may have made an error in a previous post. Are these the XL rated
> tires with a load index of 100H? XL rated tires have some unique carrying
> capacity features. Depending on being "p-metric" or "European Metric" the
> full load rating is reached at 41 or 42 psi. Above that is for handling or
> fuel economy optimization. As for airing down to get the floatation effect
> some will go all the way down to 16 psi. Bead lockers and/or tubes for
> extreme off road groups. At these low pressure tire damage is common.
> >
> > Dennis
> >
> >
> > -----Original Message-----
> > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of Stephen Edwards
> > Sent: Tuesday, January 2, 2018 10:43 AM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: Re: Locking differential
> >
> > How far down does one air? The regular recommended pressure is 46 front,
> 48 rear per Van-Cafe.
> >
> > As for airing up, I guess I can buy one of those air pumps that you hook
> up to the cigarette lighter.
> >
> > Steve
> >
> > Sent from my iPhone
> >
> >> On Jan 2, 2018, at 12:19 AM, Kyle Stuhr <uglybones@hotmail.com> wrote:
> >>
> >> Airing down will make a much bigger difference in contact patch area
> than will increasing width. Air down with your current setup before
> anything. Airing back up might be a problem though.
> >>
> >> Sent from the briny depths.
> >>
> >>> On Jan 1, 2018, at 8:38 PM, Stephen Edwards <chibicyclist@GMAIL.COM>
> wrote:
> >>>
> >>> Vanagon list:
> >>>
> >>> What’s the verdict on lockers? I have an 88 GL with a Subie installed
> and occasionally need to pull a boat out of the water. The place where I go
> has a sandy beach and the rear wheels get stuck every time. I need a
> rebuilt tranny anyway, but I’m told that adding a locking diff will add
> $1500 to the cost. Is it worth it? And aside from the cost - are there any
> other downsides to having one?
> >>>
> >>> Steve, in Chicago.
>
>
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