MOTORCYCLE

>Ace wrote:
>> On Thu, 28 Jun 2007 04:09:17 -0700, darsy wrote:

>>> The Jeep has several drive modes, but only recommends 2wd or
>>> permanent 4wd for road use - part-time 4WD is for loose surfaces
>>> only. Ive no idea why - Krusty probably does, mind.
>>
>> So do I. Its because your 4wd system is much more mechanical than
>> mine, such that the front and rear wheels will want to move at the
>> same speed all the time, so going round corners will be much more of
>> an effort, as youre effectively skidding at least one of the rear
>> tyres round to follow the front. Tyre wear will be accordingly
>> increased.
>
>Err, diffs?

> On Thu, 28 Jun 2007 11:38:52 GMT, platypus
> wrote:
>
> > Ace wrote:
> >> On Thu, 28 Jun 2007 04:09:17 -0700, darsy wrote:
>
> >>> The Jeep has several drive modes, but only recommends 2wd or
> >>> permanent 4wd for road use - part-time 4WD is for loose surfaces
> >>> only. Ive no idea why - Krusty probably does, mind.
> >>
> >> So do I. Its because your 4wd system is much more mechanical than
> >> mine, such that the front and rear wheels will want to move at the
> >> same speed all the time, so going round corners will be much more
> of >> an effort, as youre effectively skidding at least one of the
> rear >> tyres round to follow the front. Tyre wear will be accordingly
> >> increased.
> >
> > Err, diffs?
>
> They work between left and right side, but on vehicles with selectable
> 4wd like darsys jeep, there is no diff between front and rear.

> On Thu, 28 Jun 2007 11:38:52 GMT, platypus
> wrote:
>
>> Ace wrote:
>>> On Thu, 28 Jun 2007 04:09:17 -0700, darsy wrote:
>
>>>> The Jeep has several drive modes, but only recommends 2wd or
>>>> permanent 4wd for road use - part-time 4WD is for loose surfaces
>>>> only. Ive no idea why - Krusty probably does, mind.
>>>
>>> So do I. Its because your 4wd system is much more mechanical than
>>> mine, such that the front and rear wheels will want to move at the
>>> same speed all the time, so going round corners will be much more of
>>> an effort, as youre effectively skidding at least one of the rear
>>> tyres round to follow the front. Tyre wear will be accordingly
>>> increased.
>>
>> Err, diffs?
>
> They work between left and right side, but on vehicles with selectable
> 4wd like darsys jeep, there is no diff between front and rear.

> On mine, the whole front-rear transmission split is through a
> semi-viscous coupling, which is essentially a hydraulic diff, so it
> can cope quite happily with slightly different front and rear wheel
> speeds, as can any modern road-based vehicle with permanent 4wd.

> Ace wrote:
> > On Thu, 28 Jun 2007 11:38:52 GMT, platypus
> > wrote:
> >
> > > Ace wrote:
> >>>On Thu, 28 Jun 2007 04:09:17 -0700, darsy wrote:
> >
> > > > > The Jeep has several drive modes, but only recommends 2wd or
> > > > > permanent 4wd for road use - part-time 4WD is for loose
> > > > > surfaces only. Ive no idea why - Krusty probably does, mind.
> > > >
> > > > So do I. Its because your 4wd system is much more mechanical
> > > > than mine, such that the front and rear wheels will want to
> > > > move at the same speed all the time, so going round corners
> > > > will be much more of an effort, as youre effectively skidding
> > > > at least one of the rear tyres round to follow the front. Tyre
> > > > wear will be accordingly increased.
> > >
> > > Err, diffs?
> >
> > They work between left and right side, but on vehicles with
> > selectable 4wd like darsys jeep, there is no diff between front
> > and rear.
>
> Are they allow to make them that crap? He wants a proper 4x4, he
> does.

> platypus wrote:
>
>> Ace wrote:
>>> On Thu, 28 Jun 2007 11:38:52 GMT, platypus
>>> wrote:
>>>
>>>> Ace wrote:
>>>>> On Thu, 28 Jun 2007 04:09:17 -0700, darsy
>>>>> wrote:
>>>
>>>>>> The Jeep has several drive modes, but only recommends 2wd or
>>>>>> permanent 4wd for road use - part-time 4WD is for loose
>>>>>> surfaces only. Ive no idea why - Krusty probably does, mind.
>>>>>
>>>>> So do I. Its because your 4wd system is much more mechanical
>>>>> than mine, such that the front and rear wheels will want to
>>>>> move at the same speed all the time, so going round corners
>>>>> will be much more of an effort, as youre effectively skidding
>>>>> at least one of the rear tyres round to follow the front. Tyre
>>>>> wear will be accordingly increased.
>>>>
>>>> Err, diffs?
>>>
>>> They work between left and right side, but on vehicles with
>>> selectable 4wd like darsys jeep, there is no diff between front
>>> and rear.
>>
>> Are they allow to make them that crap? He wants a proper 4x4, he
>> does.
>
> Hes got one - Ace is wrong. You can get Cherokees with two types of
> transfer case - SelecTrac which has a centre diff allowing full-time
> 4WD, & CommandTrac which which hasnt got a diff & just locks the
> driveshafts together, hence can only be used in 4WD on slippery
> surfaces.

> Krusty wrote:
> > platypus wrote:
> >
> > > Ace wrote:
> > > >
> > > > They work between left and right side, but on vehicles with
> > > > selectable 4wd like darsys jeep, there is no diff between
> > > > front and rear.
> > >
> > > Are they allow to make them that crap? He wants a proper 4x4, he
> > > does.
> >
> > Hes got one - Ace is wrong. You can get Cherokees with two types of
> > transfer case - SelecTrac which has a centre diff allowing full-time
> > 4WD, & CommandTrac which which hasnt got a diff & just locks the
> > driveshafts together, hence can only be used in 4WD on slippery
> > surfaces.
>
> IIRC my Rangie had a lockable centre diff. Id
> venture that the the ideal would be three viscous diffs for
> fit-and-forget simplicity.

> platypus wrote:
>
>> Krusty wrote:
>>> platypus wrote:
>>>
>>>> Ace wrote:
>>>>>
>>>>> They work between left and right side, but on vehicles with
>>>>> selectable 4wd like darsys jeep, there is no diff between
>>>>> front and rear.
>>>>
>>>> Are they allow to make them that crap? He wants a proper 4x4, he
>>>> does.
>>>
>>> Hes got one - Ace is wrong. You can get Cherokees with two types of
>>> transfer case - SelecTrac which has a centre diff allowing full-time
>>> 4WD, & CommandTrac which which hasnt got a diff & just locks the
>>> driveshafts together, hence can only be used in 4WD on slippery
>>> surfaces.
>>
>> IIRC my Rangie had a lockable centre diff. Id
>> venture that the the ideal would be three viscous diffs for
>> fit-and-forget simplicity.
>
> Not for serious off-roading. Viscous diffs require a certain amount of
> spin before theyll engage, which isnt necessarily A Good Thing.
> Viscous diffs that can also be manually locked otoh would be ideal.

> Hes got one - Ace is wrong. You can get Cherokees with two types of
> transfer case - SelecTrac which has a centre diff allowing full-time
> 4WD, & CommandTrac which which hasnt got a diff & just locks the
> driveshafts together, hence can only be used in 4WD on slippery
> surfaces.