This page contains contributions list members have made regarding modifications to and maintenance of the drive line components of their Defender 90s. Drive line components include drive shafts, universal joints, differentials, axles, constant velocity (CV) joints, hubs, and related components. The anciliaries category contains information on fitting any extra components that serve the actuation of locking diffs, such as ARB compressors, actuator cables, etc. as well as axle breathers. Before we get started, here's some good general information on Land Rover dirve lines from Bill Davis @ Great Basin Rovers:
Date: Thu, 22 Apr 1999 13:59:45 EDT
From: Gbrovers@aol.com
Subject: Re: [D90] GBR: we wanna know your secrets.... ;~)
Here are some general comments on Land Rover drivetrain strength and
quality issues. I will preface the discusion by saying all vehicles have
strong and weak points - including Land Rovers. I don't want to get into the
- - this brand is better than that brand, because there is no such thing as
one
vehicle that is better than all others in all situations. An example - I
would much rather have a Suzuki Samari on an extremely narrow trail than a
Hummer but I would much rather have a Hummer if I were transporting military
troops across the muddy plains of northern Europe, which is actually what
they were designed for!
A couple of Land Rovers strong points are they have extremely strong
frames and also have very robust and relatively flexible stock suspensions.
Unfortunately their weak points are axles and differentials compared to
other
vehicles such as American trucks and Land Cruisers.
The problem with their diffs is that they are a spiral bevel
(non-hypoid) design instead of a hypoid. Hypoid diffs of the same
comparative
size are at least twice as strong. Land Rover as far as I know is the only
light duty vehicle manufacturer left in the world that still uses spirel
bevel diffs. Hypoid diffs were originally designed by car manufacturers to
lower the driveline hump between the rear seats of passenger cars. It turned
out that they were also much stronger so the size of the diff could also be
reduced etc. Besides Land Rover the only other vehicles using them today are
some heavy duty trucks, because you don't have the size limitations like
cars. You can build the strength into them by just making them bigger.
Hypoid
diffs are more expensive to manufacture so its cheaper in some cases to make
a bigger spiral bevel in truck applications. In addition to being stronger
hypoid diffs are usually quieter. The only disadvantages of hypoid diffs, in
addition to being more expensive to manufacture, are the driveshaft angles
are increased slightly because of the lower pinion and there is more sliding
friction between the gears. The driveshft angle is usually not an issue
except on very short wheelbase vehicles and can be mitigated with the use on
double cardon joint driveshafts or reverse rotation gear sets. The friction
issue was solved by upgrading the lubricant. The next time you buy gear oil
read the label and you will notice it is hypoid rated.
The easiest and most cost effective way to increase the strength of
your diff is to convert to a 4 pinion or 4 pinion style diff. This is
because
a 4 pinion diff carrier is much stronger and won't flex under load so the
contact patch of the gears won't shift as easily. All of the current
traction diffs available for L/R's are a 4 pinion design. You can also
switch
to a hypoid conversion, such as Jack McNamara, but they are expensive. I'm
working on a domesticly produced version at a more reasonable price but it
is
a ways off.
Land Rover axles as noted earlier aren't a strong point either,
following is a list rating them by application
Series Rovers - part time 4 wheel drive 10 spline rears -
pathetic
fronts - ok because of the torque split
Early coil sprung full time 4wd thru 1993 10 spline rears - ok
because of torque split
fronts - ok because of torque split
Later coil sprung full time 4wd post 1993 24 spline rears - ok
and better than 10 spline
fronts - ok but they went to a smaller CV end
of the inner axle which is not good
All of these axles can quickly go from ok to marginal with the addition of
traction diffs, larger tires and heavy off road usage. The problem with them
is they are relatively undersized, in some cases poorly designed and
manufactured from commercial grade materials. They can be easily upgraded to
higher quality axles. I carry a selection HD axles, which can be seen on my
web site www.greatbasinrovers.com along with a more detailed discussion of
axle technology. Please bear in mind the site is still under construction.
I am still a distributor for KAM but there product line is not
competitive in the U.S. market so I only special order it.
The GBR name is a brand identity I am establishing because a lot of
my product line is manufactured for me to my specifications. I have stuff
made in Europe, Australia and the U.S.
Bill
Great Basin Rovers