Diff locks for an 80



 
See also Diffs for Dummies - a simple explanation of what all this diff stuff is about.

For an explanation of the different types of diff locks and limited slip diffs (though not all available for an 80 Series), click here (Willem's home page, http://www.a1.nl/phomepag/markerink/diffs.htm).


A variety of email on the subject....

 

> Re: Lockers: any reason why you didn't opt for the OEM lockers?

A bunch of reasons....Hope I don't piss anyone off, but in no
particular order...

1. Can't engage original lockers at any speed. ie racing up a sand
dune.
2. Air lockers are a seriously stronger diff centre.
3. You get an air compressor.
4. Air lockers engage/disengage reeeeally quickly.
5. Don't have to fumble for the switch to engage/disengage in a hurry.
6. Air lockers are cheaper....

Disadvantages with air lockers are, the compressor rattling is a dead
giveaway that you've engaged them and we've had some club members with
warranty problems for broken front crownwheel/pinion when non-standard
diff is fitted. Also the rear diff becomes an open diff rather than the
original limited (for about 10,000Km) slip.



 
 

Re: Bios on the 4wd and other things. (fwd)

 

George Couyant (george_couyant@hotmail.com)
Mon, 5 Aug 1996 06:00:42 +1100 (EST)
>
> > > > DETROIT True Track LSD (Front)
> >
> which in certain off road situations can be quiet dangerous.
> With the True Track LSD, you have full control of the steering in any
> circumstance and 95% of the traction of a diff lock.

Okay, here's where this group may be of use to you... I know Willem has
other thoughts on LSD's ;-) but try one off road and on before you buy.
Their performance is a big compromise and critical on how they are set up.

To have them behaving properly (and not locking on you doing a U turn),
they have to be set up loose (the 80 is constant 4wd). One wheel has to be
spinning hard before any torque is transfered to the other wheel and by
that time, you've lost traction, dug a hole and watched as a fully locked
80 drives past.. Maybe even me ;-)

They do work well on part time 4wds because they're on the dirt when they
drive the front wheels. The front lsd can be set up stiff.

Manual diff locks certainly do need some driver input and in my experience
it adds to the fun. Also, if you have enough traction to affect the
steering, you shouldn't have it on anyway.

With manual diff locks, you can also use them to your advantage to slide
the rear end around. At Robe, I had to keep the front end where it was and
swing the rear out a few feet so as to get out of a tight situation. There
was also a rather large drop to the ocean right in front of me. All I had
to do was lock the rear in and keep the front *un-locked*, rev to buggery
and drop the clutch in 2nd low to get wheels spinning. Of course, only one
wheel at the front spun (the front stayed put) and both rears spun and
slid the way I wanted (actually dug a path for them first). I'd still be
there digging if I had an auto locking front diff...Well not really, Mel
(wifey pooh) would have killed me..
>
Cheers
gc


LSD's, the true story (was: Bios on the 4wd and other things. (f

 

Willem-Jan Markerink (w.j.markerink@a1.NL)
Sun, 04 Aug 1996 23:21:20 +0000
On 5 Aug 96 at 6:00, George Couyant wrote:

> > > > > DETROIT True Track LSD (Front)
> > >
> > which in certain off road situations can be quiet dangerous.
> > With the True Track LSD, you have full control of the steering in any
> > circumstance and 95% of the traction of a diff lock.
>
> Okay, here's where this group may be of use to you... I know Willem has
> other thoughts on LSD's ;-) but try one off road and on before you buy.
> Their performance is a big compromise and critical on how they are set up.
>
> To have them behaving properly (and not locking on you doing a U turn),
> they have to be set up loose (the 80 is constant 4wd). One wheel has to be
> spinning hard before any torque is transfered to the other wheel and by
> that time, you've lost traction, dug a hole and watched as a fully locked
> 80 drives past.. Maybe even me ;-)
>
> They do work well on part time 4wds because they're on the dirt when they
> drive the front wheels. The front lsd can be set up stiff.

George, it seems as if you are still confusing friction LSD's with
torque biasing gear driven LSD's. None of the gear driven units
(Quaife/Torsen/Truetrac) can be set stiff or loose, their torque bias
is a design spec of the worm gears. And I can send you *very* nasty
complicated exploded views of a Torsen to prove that....duh!....8-))

And yes, friction based LSD's (Auburn is a famous brand in the US for
the 9" rear unit, not sure if they make one for the 8" front axle)
can be installed loose or stiff. I even have a note about adding more
LSD-oil additive in my FAQ I believe, to come close to locker like
behaviour (and friction pad's wearing out fast than you can say shit).

And no, extra spinning doesn't help a gear driven unit. The nifty
thing is that they allow a certain % of rotational difference,
wherever they go; all according to design spec.

The actual torque biasing spec is stated in a multiplication factor:
a TrueTrac is known as a 2.5x unit, ie: if the slipping wheel has a
grip of 1000Nm, it can still send 2500Nm to the grip wheel, ie 3500Nm
total. With an open diff this would have been 2000Nm (1000Nm on each
wheel).
Applying the brakes, say with 1000Nm on each wheel, results in a
simulated torque of 2000Nm on the slip wheel, and (2.5x2000) 5000Nm
on the grip wheel, ie 7000Nm total, minus the 2x1000Nm of the brakes
is 5000Nm.
In case of an airborn wheel, you are stuck, since the slip wheel has
0Nm grip (2.5x0 on the grip wheel is still 0), unless you again
apply the brakes: the 1000Nm of both brakes now results in 2500Nm on
the grip wheel, makes 1500Nm net torque (2500-1000Nm, the airborn
slip wheel doesn't add or substract to the net result, only to the
torque bias to the other wheel).

Torsen and Quaife diff's can have a multiplication factor of up to
6x, but it is said that somewhere down the line steering will be
affected. The Quaife is a modification of the Torsen, it has an
additional friction element inside, so that even the airborn
situation is tackled; and if it wears out, you still have an ordinary
Torsen.

Note further that the Toyota Mega Cruiser has the best (well,
almost) solution thusfar: Torsen's *and* lockers in both axles. This
is the only vehicle that I know of that has both solutions. Even the
Hummer lacks full lockers. Only a pity they didn't include a Torsen
in the center diff.
There is also only one 4x4 offroad vehicle that I know of with three
Torsens (or four/five in case of its 6x6 version), but no lockers. It
is the Swiss army truck Bucho; everything designed for average
non-experienced soldiers, who serve their tour of duty. And for both
this one and the Hummer, the 'brake-assist' procedure is described in
the soldiers handbook....8-))

A last practial note: a friend of mine, TLC dealer/export company in
Austria, installs these TrueTrac's on a regular basis, with an ARB in
the rear. But he wouldn't hesitate one moment if there was a 9" gear
driven LSD available!
[rumours go that at one time in the past, there *has* been a 9" unit for
TLC's....probably a custom order batch, or a modified
series....it is said to have been around in Australia....anyone of
our TLC-nestors aware of this beast? If not, could someone dig around
a little to confirm this? Many thanks!]

End of lesson Traction Adding Devices; for more stuff, see the TAD FAQ
on my homepage:

http://www.a1.nl/phomepag/markerink/main_4x4.htm

--
Bye,
 
       _/      _/       _/_/_/_/_/       _/_/_/_/_/
     _/  _/  _/               _/       _/  _/  _/
     _/  _/ illem    _/     _/ an    _/  _/  _/ arkerink
                     _/_/_/
 
 
The difference 
between men and boys
is the price of their toys
 
<w.j.markerink@a1.nl>
[note: 'a-one' & 'en-el'!]

Re: LSD's, the true story (was: Bios on the 4wd and other things. (f

 

George Couyant (george_couyant@hotmail.com)
Mon, 5 Aug 1996 08:21:26 +1100 (EST)
> On 5 Aug 96 at 6:00, George Couyant wrote:
>
> > > > > > DETROIT True Track LSD (Front)
> > > >
> George, it seems as if you are still confusing friction LSD's with
> torque biasing gear driven LSD's. None of the gear driven units

Yup, it was early in the morning.....
>
> The actual torque biasing spec is stated in a multiplication factor:
> a TrueTrac is known as a 2.5x unit, ie: if the slipping wheel has a

2.5x isn't anywhere near enough. I suppose it's made soft soas not to let
novices get into steering troubles.

> Applying the brakes, say with 1000Nm on each wheel, results in a
> simulated torque of 2000Nm on the slip wheel, and (2.5x2000) 5000Nm
> on the grip wheel, ie 7000Nm total, minus the 2x1000Nm of the brakes
> is 5000Nm.

So like in the Toolangi video, a True Track won't do anything unless you
get on the brakes (like I thought this was supposed to make it easier for
novices?).

It needs traction (resistance) on both wheels for it to transfer torque.

Maybe our 4wding is different to yours in Europe, but having a wheel feet
in the air up a _very_ steep hill is common. Any changes in torque,
braking, power will have you sliding into the ruts or worse. I can
understand however that they would be quite okay in mud.

> Torsen and Quaife diff's can have a multiplication factor of up to
> 6x, but it is said that somewhere down the line steering will be
> affected. The Quaife is a modification of the Torsen, it has an
> additional friction element inside, so that even the airborn

So why have it working all the time if it'll stuff the steering up anyway?

Will your insurance company still love you if you hit the throttle around
a tight bend in the wet and have the steering go on you as you take out a
few garden gnomes in someone's front yard?

> situation is tackled; and if it wears out, you still have an ordinary
> Torsen.

So what's the use? How often do you have to pull the diff down to change
the clutch?
>
> our TLC-nestors aware of this beast? If not, could someone dig around
> a little to confirm this? Many thanks!]

I had come across people with these. All had got rid of them because they
broke and parts hard to get and *very* expensive.
>
> http://www.a1.nl/phomepag/markerink/main_4x4.htm

Good writeup Willem. Might put a link to your page.

I recently drove a Patrol with a rear soft locker and front true track
around our club property and was not impressed. The rear still thumped its
way around with sudden transfer of torque and the front didn't seem to do
anything. Mind you, I didn't get on the brakes every time I suspected a
front wheel was in the air. We then went for a ride in mine and picked the
exact same lines with manual air locker control and didn't put a foot
wrong. Both vehicles ran the same tyres and suspension. The owner of the
Patrol had long ago decided he did the wrong thing.

On another note, Toyota experimented with geared LSDs for the 80. They
even produced a number of prototypes and tested in Australia (in late '89
if I remember correctly). The idea was to go one up on the Range Rover.
Marketing were pushing for robust lsds and engineering were pushing for
performance/strength. Engineering won with the lockers we see now on 80s.
An ARB air locker is 4 times the strength of the stock diffs too.....

It may look like I'm shit canning LSDs in general (which I probably am ;-)
but I'd hate to see any of us go to the expense and warranty hassles
without getting the maximum gain. So guys, try before you buy, and if you
are able to read the track and work a switch (and don't just turn it on
and leave it on ;-) the choice is easy.

Not having a go at you Willem either....Just experience.

Cheers
gc


Re: Bios on the 4wd and other things. (fwd)

 

Chris and Sharon (chrisn@tyndale.apana.org.au)
Mon, 5 Aug 1996 13:00:49 +1030
George Papdan wrote:

<SNIP>

>>
>> > > DETROIT True Track LSD (Front)
>>
>> Ummm why not a front air locker?
>>
>
>Because when the front diff lock is engaged, you have no steering control
>which in certain off road situations can be quiet dangerous.
>With the True Track LSD, you have full control of the steering in any
>circumstance and 95% of the traction of a diff lock.

This interests me greatly. I have always been concerned about this feature
of the Airlockers, in fact I saw the results of that in the ACT forests
recently watching an ACT Police Rescue Troopie which lost traction and
bunged on the Airlockers going up a precipitous hill - it then proceeded to
climb up a tree and tip over onto its side with all diff lockers going...
the copper was *very* embarassed let me put it that way...

All the guys at the club said... "ooohh yeah - shouldn't have done that!
Never should have put the front locker in going up there - it looses
steerage with the locker - it's meant for straight line work" So? What to
think?

Tell me more...
 

Chris

_______________________________________________________________________________

Chris Nicholls
chrisn@tyndale.apana.org.au
PO Box 445 ph: +61-6-241 2112
Dickson ACT 2602 fax: +61-6-241 8926
Australia mob: 018 628 678


Re: Bios on the 4wd and other things. (fwd)

 

George Couyant (george_couyant@hotmail.com)
Mon, 5 Aug 1996 12:13:51 -0500
On Aug 5, 13:00, Chris and Sharon wrote:

> recently watching an ACT Police Rescue Troopie which lost traction
and
> bunged on the Airlockers going up a precipitous hill - it then
proceeded to
> climb up a tree and tip over onto its side with all diff lockers
going...
> the copper was *very* embarassed let me put it that way...
>
Oh well, I suppose artificial inteligence (LSD) beats real stupidity
any day... ;-)

However, with _some_ LSD's (Quaife?) you wouldn't have a choice of
whether it's on or not.....

Any vehicle is dangerous in the hands of the inexperienced. A double
diff locked one even more so. The school of hard knocks is ruthless..

Cheers
gc

--
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Re: LSD's, the true story (was: Bios on the 4wd and other t

 

Willem-Jan Markerink (w.j.markerink@a1.NL)
Mon, 05 Aug 1996 14:47:02 +0000
On 5 Aug 96 at 8:21, George Couyant wrote:

> > The actual torque biasing spec is stated in a multiplication factor:
> > a TrueTrac is known as a 2.5x unit, ie: if the slipping wheel has a
>
> 2.5x isn't anywhere near enough. I suppose it's made soft soas not to let
> novices get into steering troubles.

Don't know if this is related to front axle/steering applications. It
might be a disign limit which doesn't apply to the Torsen/Quaife
unit. Note that there are even a few more brands out in the world, I
am currently trying to get my hands on an article in Car Racing,
which lists a whole bunch of other gear driven units.

> > Applying the brakes, say with 1000Nm on each wheel, results in a
> > simulated torque of 2000Nm on the slip wheel, and (2.5x2000) 5000Nm
> > on the grip wheel, ie 7000Nm total, minus the 2x1000Nm of the brakes
> > is 5000Nm.
>
> So like in the Toolangi video, a True Track won't do anything unless you
> get on the brakes (like I thought this was supposed to make it easier for
> novices?).

What's a Toolangi video?....8-))
It only needs the brakes in case of airborn wheel situations....IMO
also some kind of safety valve, since otherwise it could pull you
into unwanted directions. Yes, it is an unit for an everyday driver,
and a better option than a Detroit or friction LSD. Note that none of
the latter will let you steer tight corners on ice under torque....

> It needs traction (resistance) on both wheels for it to transfer torque.
>
> Maybe our 4wding is different to yours in Europe, but having a wheel feet
> in the air up a _very_ steep hill is common. Any changes in torque,
> braking, power will have you sliding into the ruts or worse. I can
> understand however that they would be quite okay in mud.

Or on ice and snow....
 

> > Torsen and Quaife diff's can have a multiplication factor of up to
> > 6x, but it is said that somewhere down the line steering will be
> > affected. The Quaife is a modification of the Torsen, it has an
> > additional friction element inside, so that even the airborn
>
> So why have it working all the time if it'll stuff the steering up anyway?

I should have said more than 6x. Note that Torsen's are mounted in
Audi Quattro's as well. Keep in mind that one of the design spec's of
a gear driven unit is it allowance for rotational differences, but
above a certain torque multiplication factor there is an influence on
this speed difference limit. I spent some time on the phone with a
tech from GKN, a German company involved in a new generation LSD's,
the ViscoLok. They also make a PowrTrac geared LSD (albeit I still
don't know in which vehicle these come!). I pounded this guy with
questions about design differences and theoretical limits....the
above is a result of this. FWIW: they will supply this ViscoLok to an
US vehicle that will be launched in 1997/98. It will work much faster
than ordinary visco units, and will have a torque bias limit of
3000Nm. Needless to say I immediately pounded this guy with our
HDJ-80 spec's, which IMHO should be able to put out 450Nm x 40:1
total gearing....say 18,000Nm....but I wonder if one halfshaft can
handle that at all....8-))
 

> Will your insurance company still love you if you hit the throttle around
> a tight bend in the wet and have the steering go on you as you take out a
> few garden gnomes in someone's front yard?

Any non-open diff looses the lateral stability of the stuck
wheel....it's the fine line between an auto locker and not being able to
operate a manual locker in stress conditions. If that requires
experience, so be it....can't have it all. But the fact that many of
these gear driven units can be found in normal cars (even the
RAV4/FunCruiser has one in the rear!) tells me there is a good
compromise down the line.
Hey, if the Torsen/Locker unit of the Mega Cruiser would be
available, I would buy it yesterday!
 

> > situation is tackled; and if it wears out, you still have an ordinary
> > Torsen.
>
> So what's the use? How often do you have to pull the diff down to change
> the clutch?

This wearing out is more or less theoretical. No one in that business
has ever heard of one wearing out. It was just a comment to prevent
the idea that 'wearing out' means useless.

> >
> > our TLC-nestors aware of this beast? If not, could someone dig around
> > a little to confirm this? Many thanks!]
>
> I had come across people with these. All had got rid of them because they
> broke and parts hard to get and *very* expensive.

See again my homepage: the older TrueTrac (if it *was* a
TrueTrac....can you confirm that also?) has 2 sets of worm gears, the
newer models have 3 sets. So the old situation might not apply to the
current one....

> >
> > http://www.a1.nl/phomepag/markerink/main_4x4.htm
>
> Good writeup Willem. Might put a link to your page.

Thank you!
Please link it, not only for the increased visits, but also because I
like to get as much comments as possible on this subject. I have had
many interesting conversations with owners of various units. Recently
an owner of a Mitsubitshi pickup contacted me, saying he had an
factory Torsen in the rear, made by DK-Gleason in the US. Seems as if
custom batches are also possible....
 

> I recently drove a Patrol with a rear soft locker and front true track
> around our club property and was not impressed. The rear still thumped its
> way around with sudden transfer of torque and the front didn't seem to do
> anything. Mind you, I didn't get on the brakes every time I suspected a
> front wheel was in the air. We then went for a ride in mine and picked the
> exact same lines with manual air locker control and didn't put a foot
> wrong. Both vehicles ran the same tyres and suspension. The owner of the
> Patrol had long ago decided he did the wrong thing.
>
> On another note, Toyota experimented with geared LSDs for the 80. They
> even produced a number of prototypes and tested in Australia (in late '89
> if I remember correctly). The idea was to go one up on the Range Rover.
> Marketing were pushing for robust lsds and engineering were pushing for
> performance/strength. Engineering won with the lockers we see now on 80s.
> An ARB air locker is 4 times the strength of the stock diffs too.....

I would *LOVE* to get more info on this!
With what type of design did they experiment?

BTW, just curious: what part breakes in a factory diff which doesn't
in an ARB? The spider gears?

As for robustness: the Quaife was originally designed for Formula 1
cars....and it's first 4x4 application was in Range Rovers running
in Paris-Dakar. And those did *not* break!
LR and RR axles are still the only application that I know of for the
Quaife. I have a friend in Germany who has two Quaifes in his RR, and
he loves them! And he wheels *hard*....he almost made it in the
German Camel Trophy team, and has experience in Truck Trial, so he
knows what he's talking about (as does yours truely of course....8-)).
 

> It may look like I'm shit canning LSDs in general (which I probably am ;-)
> but I'd hate to see any of us go to the expense and warranty hassles
> without getting the maximum gain. So guys, try before you buy, and if you
> are able to read the track and work a switch (and don't just turn it on
> and leave it on ;-) the choice is easy.

As for TrueTrac warranty: I have heard more than one story about people going
back with their broken 2-worm unit, and getting a free 3-worm unit in
return, without hassles, even after warranty expired. Doesn't ARB
have a similar policy for their notorious O-rings....;-))
BTW ARB: I heard another horror story recently; not only did the
locker seized operating, but it also pressed out a good amount of
diff-oil out through the wheel bearings....
I am looking forward to the new Command-Locker from PowerTrax, it
operates electrically.

> Not having a go at you Willem either....Just experience.

I love this kind of conversations....the more info and experience
shared the better. A good informed customer is not only a nightmare
for the sales department, but also for the tech department!

--
Bye,
 
       _/      _/       _/_/_/_/_/       _/_/_/_/_/
     _/  _/  _/               _/       _/  _/  _/
     _/  _/ illem    _/     _/ an    _/  _/  _/ arkerink
                     _/_/_/
 
 
The difference 
between men and boys
is the price of their toys
 
<w.j.markerink@a1.nl>
[note: 'a-one' & 'en-el'!]

Re: LSD's, the true story (was: Bios on the 4wd and other t

 

George Couyant (george_couyant@hotmail.com)
Tue, 6 Aug 1996 08:41:24 +1100 (EST)
> am currently trying to get my hands on an article in Car Racing,
> which lists a whole bunch of other gear driven units.

Off road and on road LSDs have an entirely different envelope of
performance requirements. Let's not confuse. =8-}
>
> What's a Toolangi video?....8-))

Oh, sorry, it's the movie on the web page. A front LSD true track would
have done nothing and applying brakes would have been dangerous.

> It only needs the brakes in case of airborn wheel situations....IMO
> also some kind of safety valve, since otherwise it could pull you
> into unwanted directions. Yes, it is an unit for an everyday driver,

No Willem. Let's not scare people off here. Up hill in an 80, on a dirt
track, a front wheel in the air, front diff locked...It will *not* pull
your steering.

> I should have said more than 6x. Note that Torsen's are mounted in
> Audi Quattro's as well. Keep in mind that one of the design spec's of

Entirely different application here. Straddling ruts on a steep uphill
demands that no wheel slips *ever*. Any slip and you lose lateral
stability and *will* fall into the rut. We show this during our driver
training course.

> tech from GKN, a German company involved in a new generation LSD's,
> the ViscoLok. They also make a PowrTrac geared LSD (albeit I still

Same problem off road. When you want it locked, no LSD will ensure that
there is no slip. Viscous locking diffs in my experience are not a viable
proposition for the front of an 80 (even if they were available). Apart
from strength reasons, you fall into the same problem as with friction
LSDs, in that you need a good degree of slip on road, but no slip off
road. The compromise has to be for road use in an 80.

> 3000Nm. Needless to say I immediately pounded this guy with our
> HDJ-80 spec's, which IMHO should be able to put out 450Nm x 40:1
> total gearing....say 18,000Nm....but I wonder if one halfshaft can
> handle that at all....8-))

Good point Willem. And that's where most LSD's (that still fit in the
stock carrier) will let you down. We mustn't forget that in and 80 which
is constant 4wd, the front diff is driven all the time and is subject to
fatigue failures. Now if Toyota had kept the same front diff as the rear,
this issue wouldn't surface as readily as it does.

As for the halfshaft, we grabbed an old 80 front shaft and wound it on
in a "modified" press until it broke. It turned just over 2 x on itself
before it broke near the spline. Had us amazed.
>
> > Will your insurance company still love you if you hit the throttle around
> > a tight bend in the wet and have the steering go on you as you take out a
> > few garden gnomes in someone's front yard?
>
> Any non-open diff looses the lateral stability of the stuck
> wheel....it's the fine line between an auto locker and not being able to
> operate a manual locker in stress conditions. If that requires

Here's the crunch. On the road, you don't have a choice with a front LSD.
Power on around a tight turn in the wet.

1. With an open front diff, one wheel loses traction and you still have
steering. Your 80 will still keep turning.

2. With a front LSD, the spinning wheel still has resistance and torque is
transferred to the other wheel. The result is tight steering or both front
wheels spin and you plough understeer into your neighbour's front garden.

Front LSD's shouldn't be on 80s on the road. Well, not if you're a rev
head... ;-)

> RAV4/FunCruiser has one in the rear!) tells me there is a good
> compromise down the line.

Rear LSD's are a different story. Let's not confuse the issue.

> Hey, if the Torsen/Locker unit of the Mega Cruiser would be
> available, I would buy it yesterday!

That would be ideal on the rear, especially if it's a manual locker. The
Mega Cruiser is a different kettle of fish to our 80 though. It's power to
weight ratio is nowhere near that of our 80s.
>
> > Marketing were pushing for robust lsds and engineering were pushing for
> > performance/strength. Engineering won with the lockers we see now on 80s.
> > An ARB air locker is 4 times the strength of the stock diffs too.....
>
> I would *LOVE* to get more info on this!
> With what type of design did they experiment?

The engineers at Toyota that were involved in that project are long gone.
I'm still intouch with one of them though and I'll see if he can
remember any details. I tried at the time to get written info however they
kept it all very quiet. The fact that they even mentioned it was due
entirely to a few too many beers by the campfire...
>
> As for robustness: the Quaife was originally designed for Formula 1
> cars....and it's first 4x4 application was in Range Rovers running
> in Paris-Dakar. And those did *not* break!

Different application Willem. I had been heavily involved in rallying many
years ago and the parts that go into a $ driven team's cars are the
stuff dreams are made of. Paris Dakar along with most raid events are high
speed/high range events. The torque at the diffs is low when compared to
slogging up a hill in low 1st. They are after resistance to fatigue
failures. Besides, the cars weigh less than half the weight of our
80s...sigh...

> BTW ARB: I heard another horror story recently; not only did the
> locker seized operating, but it also pressed out a good amount of
> diff-oil out through the wheel bearings....

Don't understand how this could happen. Not on an 80. Horror stories have
a habit of starting life as an insignificant event. ;-)

A weeping piston seal will blow diff oil back through the air line when
the diff's disengaged. The problem is generally indicative of a poor
maintenance schedule. If you run old diff oil, you'll have weeping air
lock seals.

As for blowing it out the wheel bearings, what did he do? Weld shut his
diff breathers? ;-)

> I am looking forward to the new Command-Locker from PowerTrax, it
> operates electrically.

I shy away from anything down there operating electronically. Apart from
the obvious reasons, electric solenoids don't exert much force and there's
no room in the diff housing to have a significant lever arrangement to
multiply the force. The result is non deterministic engagement latencies.
The factory 80 Series lockers suffer from this.
>
> I love this kind of conversations....the more info and experience
> shared the better. A good informed customer is not only a nightmare
> for the sales department, but also for the tech department!

Oh good Willem. I was affraid that you'ld be put off that I dissagree with
you wrt what works on an 80 in the bush... ;-)

Maybe we've done this subject enough for now... ;-)
I'm sure we'll get back onto it in time to come...

Cheers
gc



 

George certainly demonstrated the "non deterministic" engagement
latencies of my factory diff locks at Hollister - the dash lights keep
flashing (idicating non-engagement) but we want 'em locked. OTOH, they
do lock up as soon as the wheels start to spin. based on my limited
experience to date, I strongly believe in lockers, though; I can't see
too many situations where you need both wheels driving that also need
differential capabilities. (by lockers I mean fully locking (air or
electric or whatever). 'd rather control them with a switch than some
equally "non deterministic" clutch or ratchet mechanism.

-Dimitry


Diff locks and problems:

Diff locks engaging?

Question: When I shift it into 4low it seems to go in just fine. When I put it in "park" to shift out, it shifts out of low but the diffs stay locked for a while and disengage after a few seconds or minutes. Is this normal?

Answer: Now, I'm assuming you've now talking about the front/rear diff locks as opposed to the centre diff lock.This is quite normal. When the centre diff is locked, energy can be stored in the driveline (commonly referred to as windup) putting pressure on the centre diff. It can't release the centre diff until some of the windup goes away. This is done by reversing or driving straight ahead for a little while.

Other than mechanical damage to the diff lock, possible causes for them not disengaging could be a bad earth (a motor drives the lock out), a faulty speed sensor or the ECU. The last two are unlikely if your speedo still works. If the diff lock is switched off and you drive at more than 8kph, the ECU drives the diff lock motor out.

Diff lockers refuse to engage...

My front and rear factory lockers will not engage. I hit the switch, gently roll the car forward and backward to let the gears play around, but they just won't lock.

First off, let's see if they do mesh under ideal circumstances. Test it out by jacking up a rear wheel. Start the engine, put it into neutral and engage the centre diff lock switch if you have one, or just put it into low range. Make sure that you can turn the free wheel by hand.

Now engage the rear diff lock and get out and turn the wheel again by hand. It should lock. If it doesn't, then we're much the wiser.

Do the same with a front wheel.

Central Diff lock light doesn't come on...

In 4 low, I hear a click, but my dash center diff indicator will not light up. It won't even turn on while I turn the key to start the car. Pretty sure it's just a bad bulb. How do I check this?

A quick and easy way to check if it is really engaging is to select low range slowly move in a tight turn. As soon as you hear a tyre scrubbing or squealing, stop and reverse to let the driveline windup unwind. If you don't hear any scrubbing or the steering isn't stiff, then it's probably not engaging.

If it's the bulb, then I have no idea what's involved in getting to it. I imagine you'll need to remove a bunch of plastic....