| |
Editors note: These are advanced techniques
to be used by experienced 4 wheelers. The situations described may be
inherently dangerous and the driver must assess and decide upon the
appropriate driving technique for any given situation. This article simply
presents some optional techniques to consider.
Clutch Technique - Engaging Options
Anyone
who has done some serious four wheeling is probably familiar with the
technique of 'key starting'; using the starter motor to move the Jeep, in
gear with your foot off the clutch pedal. This is most often used when
restarting a stalled Jeep on the trail or when you need to move very slowly
through a short, tricky situation. The technique is a very useful one, but
the value of the technique is sometimes overstated. There are drawbacks to
using it. Moving the Jeep with the starter puts a high stress on the
starter and flywheel. Sometimes, it is more appropriate and safer to start
with the clutch disengaged.
Engine Braking
Normally, on steep descents with a manual transmission, the best
technique is to shift to a low gear and descend using engine compression to
slow your descent, keeping your foot off the brake. The RPM's should be kept
in the middle range so you can add or subtract power to maintain control.
Engine braking is by far the best technique for long descents because brakes
tend to heat up and fade with this over use.
When
the descent becomes extreme, the engine braking can actually decrease
control. Sometimes a hill is so steep, your Jeep will just begin sliding
down it and your low gear is too low. The tires begin sliding because they
are not rotating fast enough to keep traction and you in control. In this
case, it is best to shift into 2nd or 3rd gear, depress the clutch pedal,
and ride the brake. If you get into trouble, you can momentarily ease out
the clutch and
use power to straighten out. You need a good touch on the brakes, you don't
want to start skidding; just enough
to slow you down a bit.
Keeping the transmission in 2nd or 3rd is can
be very handy if you are in a very steep descent, and the nose of your Jeep
is going to hit the bottom hard with the risk of rolling over on your lid.
What to do?
Let out the clutch and give it some power just
before you hit bottom. Even if the rear tires come off the ground,
the front tires will be pulling you out of an endo. [This doesn't feel
natural, but it is the appropriate technique]
This technique works great on short extremely steep descents where
overheating the brakes in not a concern. If the descent is long and engine
braking isn't working, maybe you shouldn't be doing it, or maybe you should
pick a higher gear for more effective engine braking.
Key Starting
Using
the starter to get out of bad off-camber situation can be a life saver. The
starter will move you without the
sudden engagement that can happen with a clutch. Jerky movements can often
cause a roll, so the use of the starter to move the vehicle is often the
best way out of a bad spot. Sometimes you may find yourself stalled, mid
obstacle. The choice is to either back off or finish the obstacle, and using
the starter motor can sometimes be the easiest way back out or over. Often
you'll see someone try to key over an obstacle they just couldn't make under
power. Running with the starter does not increase traction or ground
clearance, so this normally doesn't work.
The starter is smooth because it has no jerky engagement like the clutch and
it will turn the engine slower than it turns at idle. It is really your
ultimate crawl ratio, of course if your engine fires up, you won't be
crawling at that speed for long. For those with fuel injection, it may be
wise to install an on-off switch for your ignition. It may be impossible to
just turn over your engine in order to move the Jeep without it actually
starting it.
All this 'key starting' is tough on the flywheel and starter. It tends to
chew up the teeth on the flywheel and the
flywheel isn't fun to replace. Normally a machine shop can press off the
ring of teeth on the fly wheel and turn them over or replace them, but the
labor involved in removing the flywheel and replacing it is substantial.
The starter teeth can also get pretty chewed up from running on the starter.
Eventually they may tend not to mesh well and the flywheel and starter gear
may wear more quickly. For people driving late CJs, the Ford starters are
only about $25, but people driving Wranglers will find the Mitsubishi
starter is closer to $100. This gets pretty pricey if you are going through
a starter or two a year. Many savvy Jeepers buy the 'guaranteed forever'
starters and keep a spare on hand.
The best thing to do is only 'key start' when you must, or when there is a
clear advantage in doing so. If you haven't 'key started' before, it's worth
a try to learn it before you need it. It is an unusual
feeling if you haven't done it before. Always do it in the lowest possible
gear to minimize strain on the starter.
|