4x4 Diff locks - Readers' Opinions.
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[Diff' Locks].
From email Sat Apr 10 17:44:51 1999
Date: Fri, 09 Apr 1999 23:33:22 -0700
I really must give my $0.02 worth. Even seeing Detroit Lockers referred
to as "maldesigned and dangerous" in quotes irritates me. Do any of
those who pontificate use Detroit Lockers? I have one one in the rear of
a BJ40 (90" WB) and one in a Ford F350 Crewcab (an interesting truck:
7.3L turbodiesel, 5 speed, double transfer case with 3.84:1 low range,
11.00R16 Michelin XL, 4.88 axles with rear Detroit and front ARB, 330L
fuel capacity, popup camper, 95L water, hydraulic winches front and
rear, front = Braden AHSU3 with 90m 11mm cable, rear = Pierce with 40m
10mm cable, beld driven air compressor with front bumper air storage
tank, 160A alternator/welder). I also have a Dodge M37 with a Hercules
diesel with front and rear Lockrights and power steering. I live in
Anchorage, Alaska, an icy wintertime environment. I mainly drive the
Landcruiser and M37 in the winter. I have not had any bizarre
experiences driving either vehicle. Yes, they take a little bit of
"getting used to"
but not much. And they are predictable. There is some
throttle oversteer on ice which completely goes away with lifting the
right foot up, and also is 99% avoided in 4WD. There is some, but not
unbearable understeer in 4WD in the Dodge due to the front locker. It is
avoidable by lifting the throttle. It is not present in 2WD when the
hubs are locked in.
My opinion is that I actually prefer a rear automatic locker even
(especially) in this icy place. A vehicle with a rear auto locker and an
open front diff feels more stable and positive than the same vehicle
with two open diffs. Naturally, my front ARBs in the BJ40 and F350 are
left open in these conditions. I found the rear ARB I previously had in
the BJ40 virtually useless in the winter. Useless because of the time
and necessity for decision making, useless because of the necessity to
turn it off immediately, and useless because of the inability to
self-freewheel which does lead to "dangerous unpredictable handling"
The only appropriate use of an ARB on either axle is very slow speed
extreme off-road use. And that's all mine are used for. But me Detroits
help me every time I drive the vehicle.
Detroit vs.
Lockright:
I have first hand evidence that Detroits are
stronger, much stronger than Lockrights. I have broken a Lockright. I
think a Detroit cannot be broken, because the ring or pinion gear,
half-shaft or driveline would break first. If a choice can be made, I
would always pick a Detroit. The Lockright is the only locker available
for the old Dodges, and I'm certainly glad to have them (I also have a
48 Power Wagon that I'm converting to diesel power).
If you have the need for significant traction enhancement, don't waste
your money on an LSD. Most of them require special lubricants, they wear
out, they are inherently unpredictable due to their dependence on
friction. Think about it: a Detroit requires 2 or 3 ft-lbs to unlock
when the wheel is jacked up. A small child can do it. Even a very strong
he-man can't turn a wheel attached to a new tight LSD when the other
wheel is on the ground. Yet the Detroit gives absolutely positive
traction when one wheel is on dry ground and the other is on water/ice.
The LSD might spin. Which is more predictable? For a typical axle,
perhaps a Dana 60, a Detroit is US$500, a Lockright about $320, a LSD
$250-375. Not really all that much difference. But a big difference in
performance.
Charles Aarons,
Anchorage, Alaska.
Date: Sat, 30 Dec 95 19:29:43 0500
From: S. Dannenberg (email)
Subject: detroit Lockers, Lock rights
...
I have well experienced the limitations of open differentials, and have
had some experience with what were probably clutch plate type limited
slip differentials. (For example, when I was growing up my family for
years had a 2 wheel drive Wagoneer with posi. We virtually never got
stuck, and in fact used to use it with a tow chain to extract lesser
vehicles from the snow. However, there is much more to good traction
than transmitting power to the wheels--the old Wagoneer also had good
ground clearance and I think had a well engineered suspension and had
excellant weight distribution.)
Currently I have a Land Cruiser (FJ60) with open differentials in both
ends and have been casually boning up on the various options for
improving the vehicle's traction.
I address my comments to your section about Detroit Lockers and
Lockrights. You wrote that Detroit Lokcers and Lockrights are the same
and quoted someone who installed a Lockright (in the rear I presume) on
a full time 4WD vehicle with no serious change in handling. I want to
address the former issue first. From what I have read, Detroit Lockers
and Lockrights are not identicle. More than once I have read that
"Detroit Lockers are maldesigned (sic) and dangerous...". This was for a
Land Cruiser application. I have read that the Lockrights are more or
less what they claim--easy to install and provide wonderful traction off
the highway.
However, people are reporting that Lockrights can lock or unlock
unpredictably on the road and cause dangerously unpredictable, or at
least unexpected directional and handling changes--particularly when
starting from a stop while cornering or slowing down to corner. For this
reason it is not uncommon to see Lockright kits for sale advertised
along the lines of "In original box, used 300 miles". I spoke to some
people about this and believe that in general terms I can explain what
is going on.
I think Mr. Ritter is partially correct about the full time 4WD helping
to reduce the problems often associated with Lockrights for two reasons:
First, some of the torque is going to the front axel and therefore lower
forces are at work to engage, or rather disengage the locking mechanism.
Second, the traction applied to the front wheels will help the vehicle
hold the road and thus help compensate for any "twitchiness" in the
rear.
That being said, however, I think that the good performance of the
Lockright on Ritter's vehicle is results more from the fact that it has
(I assume) an automatic transmission, than the fact that it is full time
4WD. As I understand it, the Lockright disengages or engages at least
partly in response to changes in torque. Also, as I understand it,
because an automatic transmission has a torque converter, there is a
constant amount of torque on the drive train, or if not a fixed amount
of torque, the drive train certainly experiences a relatively smooth
increase/decrease in torque during acceloration/deacceloration and
shifting--without the abrupt changes in torque which occur whenever the
clutch is depressed and released in order to allow shifting of a manual
transmission. In order to shift gears with a manual transmission (unless
one is really good), the clutch needs to be engaged specifically to
relieve the torque on the transmission which naturally and abruptly
relieves the torque applied to the entire drive train. When the clutch
is disengaged, the drivetrain experiences a sudden increase in applied
torque.
Often, when starting from a stop and turning, I shift gears while still
turning hard. Similarly, I often downshift while turning hard. I can
well imagine that if the change of torque being applied to the drive
train as I turned and shifted gears caused the rear to lock or unlock
that there would be rather abrupt and severe consequences to my
vehicle's handling and possibly direction. The frequency and severity of
these occurances would vary according to road conditions and especially
one's driving style.
Does this make sense? Could it be said then that Lockrights are ok off
on forgiving surfaces, and acceptable in vehicles with automatic
transmissions in all conditions, but one should think twice before
rushing to put on in a vehicle that has a manual transmission and gets a
lot of paved road use?
David Dannenberg
Date: Thu, 21 Dec 1995 14:05:52 -0800
From: email (Jim Showalter)
) From your web site, in the dissertation on differentials:
"Yet another arrangement uses the fact that a fine-pitch worm gear cannot
be driven backwards, and that a coarse-pitch worm gear can only be driven
backwards with difficulty. These LSDs use pairs of coarse worm gears,
mounted in the carrier, to drive the side-gears and hence the wheels. Each
worm gear contra-rotates with its twin through end gears."
This is called a Torsen differential. I have been trying for several days
to locate Torsen, Inc. Do you have any idea where they are located? They
don't appear to have a web site, so web searches haven't worked.
Jim Showalter, jshowalter@adb.com
