Jeep Wrangler - Restoration & Custom Outfitting
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4-Point Seat Belt
Professional racing car drivers are required to have their seat belt harnesses
recertified every year, and replaced every 2 years. This is a safety issue, and
after a while, ALL seat belts get to the point where they are worn out,
the nylon becomes decomposed by hot sun, or otherwise compromised to the point that it is not safe
to operate the vehicle. For your safety, you should regularly inspect your seat
belts. The SFI Foundation is a
non-profit organization established to issue and administer standards for
specialty / performance automotive, and racing equipment. Although you and I are
not likely to be taking our Jeeps or SUVs to the race track, some of the off-road
activities done by Jeepers can be considered "performance driving", and we
should have "Safety First" in mind while having all this fun.
HOW A SEAT BELT WITH A RETRACTOR
How a seat belt works may
be a boring topic on its face, but many of you may be surprised at what actually stops you from
launching out the windshield head first in a high-speed crash.
Seat belts in almost all modern cars are what
is known as "3-point restraints"; that is, the seat belt is secured to the frame
of the car at three points: 1) The Retractor Mechanism (usually on the floor), 2) A point over and
behind your shoulder, and 3) The seat belt buckle (or where it clips to the seat).
The seat belt can be pulled out of the
retractor, and should automatically tension itself snug against your body when
you let it go. Some belts have electric motors that pull the belt around an
occupant when he sits on the seat.
When you are sitting in the seat, you can
grab the belt at your shoulder and pull it slowly out of the retractor and have
a few feet of seat belt loose in your hand, as long as you keep on holding it. When you let it go, the retractor
(should) pull it snugly against you. This is ability to extend slowly out of the
retractor is convenient when you have to lean
forward to reach something on the passenger seat. However, if you "crash & burn"
while leaning forward with the belt loose, it won't do you a hell of a lot of
Some shoulder belts cut
into an occupant's neck, and some people try to "fool" the retractor by holding
the belt loose, or somehow prevent it from fully retracting (or buckle it behind
them to avoid the annoying seat belt pinging noise). If you do this, you are putting
yourself in danger of not having the protection of a seat belt in a collision –
which means your head is going to hit the windshield before the belt can "lock
up". If the airbags deploy, it would be even worse, because you'll be
bounced around like a half-deflated basketball. If you survive, maybe that knock in the noggin knocked some sense into your
dumb ass! Most shoulder belts can be adjusted so they don't press on your neck,
and if you don't know how to do this, consult your owner's manual – in any
event, even if you're sitting in your car in an empty parking lot, it is prudent
to use your seat belt, as you never know when some
will seem to 'drop out of the sky' on you. Sometimes I'm convinced that
Extraterrestrials are beaming them down from outer space around me.
An alternative to the
standard 3-Point system is the 4-Point system covered below. Seat belt restraint
systems on newer vehicles may incorporate things such as pre-tensioners, and some may even be wired to the
vehicle's computer. If you have one of these, it may not be possible or
advisable to try to replace it with another style of restraint system.
replace your seat belt system yourself, in most cases, and replacing it with a
4-Point system is advantageous for safety reasons, but be advised that you will
lose some of the 'conveniences' of a retractor system. The following lists some
of the advantages (+) and disadvantages (–) of doing what this article (below)
(+) 4-Point systems are
MUCH SAFER than standard "lap & shoulder" belts
(+) There is no Retractor
mechanism to pull the belt into your neck, or fail to lock during a crash.
(+) 4-Point system will
hold you firmly in your seat and in control on rough off-road trails.
(+) 4-Point system will
hold you in the seat even if the vehicle flips over on its roof.
(+) 4-Point system more
evenly distributes the force of an impact, thereby reducing injuries in a crash.
(–) 4-Point systems take a
bit more time to secure & disengage from.
(–) You will NOT be able
to turn your body to look out the rear window.
(–) You will NOT be able
to lean forward or stretch sideways.
CHECK YOUR SEAT BELTS
There are two basic types
of systems that locks the spool of a seat belt retractor mechanism when the
vehicle is involved in a collision: 1) Activated by car's movement 2) Activated
by seat belt's movement. Some retractors use BOTH types of systems.
To determine which type
you have, sit in the seat and put on the belt. Grab the belt at the shoulder and
pull it very sharply downward. If the belt locks up, you have a system that is
activated by the belt's movement. If it does NOT lock up, you have a system that
is activated by car's movement, or you have a system that is activated by the
belt's movement that is defective. Double check by trying this in the opposite
seat. If the belt in the other seat behaves differently, have the belts checked
by a qualified mechanic; you don't want to take any chances with your safety.
See an excellent detailed article on How Stuff Works.
If your seat belts
have rips, frayed edges, or are bleached by the sun, or are more than 5
years old, they should be replaced.
If your seat belts do
not snap back into the retract mechanism when you let them go, the locking
mechanism that activates the seat belt "stop" mechanism may also be defective.
BELT MOVEMENT LOCK
SYSTEM: With your seat belt
around you, pulling on the belt sharply should STOP the belt from being
pulled out of the retractor; if it doesn't, and you can sharply pull the
belt more than a few inches without it jamming "stopped", you should replace
the retractor mechanism immediately.
CAR MOVEMENT LOCK
SYSTEM: This system is harder to test because you must put your car in
motion (20MPH or faster), then stop it suddenly. You can do this safely in a
large empty parking lot, jamming on the brakes hard enough to screech the
tires (and activate the Antilock Brake System if your vehicle has one). When
decelerating quickly, the seat belt should lock and keep your body from
If your seat belt does
not retract snugly around your body, the belt and retractor mechanism should be replaced.
A loose-fitting seat
belt is WORSE than no seat belt at all.
A seat belt that will
not 'lock' in the event of a collision is the same as not having a seat
If you have a late
model vehicle, your seat belt system may include pre-tensioners and
integration with the vehicle's computer (air bag / crash detection system).
If this is the case, a DIY
job may not be advisable, or even possible. If there is a cable going to
your seat belt tensioner, have it looked at by a qualified mechanic before
attempting to mess with it.
3-point (shoulder & lap) seat belts such as are used in 99.9% of modern cars
wear out rather quickly in a vehicle's life, and a defective restraint system is the last thing you
need if you become involved in a serious collision.
If you determine that you
need to replace your seat belts, and want to upgrade your protection to a 4, 5,
or 6-Point restraint system, and there are
no "complicated" issues such as pre-tensioners
with connection to the crash detection system (computer), you need to
Belt Installation Guide (PDF) and understand what you are doing before you
Over 17 years in my Jeep had taken its toll on the
retractor mechanism of the driver's side seat belt, which would not fully
retract when released. In any event, I needed to replace the seat belts because they were
OLD. I tried to repair the tensioner
temporarily by removing it from the Roll Bar, loosening the cover that says "DO
NOT REMOVE", and holding it against the mechanism while winding the spring
(clockwise) a few turns tighter. This had no noticeable
effect on its ability to retract the belt. After a few more tries, and a few
more turns, I lost my grip on the loosened cover, and what
seemed like 20 yards of coiled leaf spring erupted from my hands like a
I uttered a few choice
expletives, then reasoned that winding
the spring "inside-out" and backwards would increase the tension, but that made the belt "lock
up" and stay seized when pulled on.
As I was looking for a
replacement online, I found that "factory" belts and retractors cost upwards of $75
each, and for all that money, I would end up with the same
POS I started with, only
So I opted for a set of 4-point restraints that do not have retractor mechanisms
(less crap to go wrong), and offer a much better safety factor than 3-point lap
and shoulder restraints.
It took a bit of work, but
I like the way it looks and the way the belt holds me firmly in that
super-comfortable 3A Racing seat – especially when bouncing and sliding around
on the sand back-roads of the New Jersey Pine Barrens.
PHOTO TO COME
Out of all the Web sites
dealing with these 4-point restraints, I couldn't find a single one that had a
photo of someone wearing one of these belts – so here is a photo of me belted
into my new seats with a 4-Point restraint belt.
The two photos of the driver's seat below show the
installation of the 4-Point Restraint system with the new
Racing Bucket Seats I installed previously.
The plastic grommet holes in the seat back are shaped this way for a reason –
the downward, outward sloping holes cause the vertical belts to fall away from
the occupant's neck, and comfortably on the shoulders. The
in the right photo below shows where the belts are attached to the seat frame
with an adapter bracket. In case you were
wondering, the yellow tab behind the buckle serves two purposes: It keeps
loose-fitting clothing from being caught in the buckle, and it keeps the buckle
and metal loop where the belt attaches from digging into you.
left side of the driver's lap belt is secured to the Roll Bar
mount where the factory seat belt retractor attached. The forged, one-piece eye
bolts supplied with the 4-Point Restraint belt system are 7/16" x 20 threads per
inch. The captive nut in the roll bar "floats" in a welded-in mount, so if you
want to avoid rattling noises, a few thick rubber washers and a flat washer
between the Roll Bar and the eye bolt are recommended.
order to secure the new 4-Point seat belt to the seat frame (driver's right
side, passenger's left side), you must remove the original seat belt buckle
where it attaches to the seat frame. You must also bypass any seat belt
interlock switches, because the 4-Point system does not provide an interlock
must fabricate an Adapter Bracket as shown, to attach the seat belt with the
provided eye bolt.
you see a side view of the bracket with the hardware installed. The bracket uses
the original bolt (red
arrow) to secure it to the place on the seat frame where the original
seat belt buckle strap was attached.
the top view of the bracket. Note that the corners of the bracket which face the
edge of the seat are cut off, and the hard edges rounded. This prevents scraping
your hand if you reach down between the seat and the floor to retrieve something
the bottom view of the bracket.
photo shows the right side of the driver's seat with the right shoulder belt (green
straight down, and the Seat Belt Buckle Bracket (red
where the original buckle strap was. After the original screw is started in the
hole, the bracket is rotated into position (yellow
arrow), and the
mounting screw tightened. Note that it is important that the belt NOT be bunched
up in the attachment clip in its final position.
photo shows the Buckle Side Bracket (orange
arrow) rotated into
position, and the original bolt (red
arrow) holding it
to the seat frame. The
shows where the Rear Seat Adapter Bracket attaches to the seat (see
Racing Bucket Seats)
shoulder belts are attached to the floor behind the seat. You can do this by
drilling a hole in the floorboard, or you can (if you have a Jeep Wrangler)
replace the Torx® bolt with the eye bolt supplied with the seat belt
kit. Note that in this photo, BOTH shoulder belts are attached to the eye bolt (red
safety precaution, I always carry a Paramedic's Speed-assist opening pocket
knife clipped to my belt. The seat belt cutter and glass breaker would be used
in the rescue of a crash victim, or to get a child or a dog left by the
owner out of a locked car.
4-Point Restraint Systems
Other items you may be interested in. The two knives shown
have seat belt cutters and glass breaking points.
Compare the price of the 4 and 5 Point restraints (above)
with 'replacement' seat belts for Jeep Wrangler (left).
A good car seat for a small child is an absolute MUST
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