Clarification of Answer by
18 Feb 2004 15:06 PST
Apologies on not picking up that you wanted dirt/clay based
solutions only. One of the "problems" in looking for such
an answer, is that there is no big "secret" to building
such a track. It is simply that, a dirt track. By dirt,
though, it is almost always understood that it is with a
high clay content so it can be packed down hard to make a
You need to get clay that does not have a high grit content,
such as gravel, or clumps of other material in it, so as to
avoid tire wear as well as pitting of the track surface.
Thickness of the clay and base material counts as well. If
the ground that you are working with is essentially clay to
begin with, and good quality clay (smooth and dense) then
you can scape out your track and pretty much be done with it.
If you are starting off with loose dirt (loam) then you will
have to compact that dirt, then lay a layer of at least 8
inches of quality clay (smooth and dense) on top of that.
At least twice that thickness of clay should be placed in the
curves, especially if they are banked, as these are the areas
that will get the most wear.
Maintenance has to be considered as well, as too dry of a
track is dusty, and too wet of a track can be too slick.
The references below go into more detail on these factors.
The references below speak to dirt/clay tracks of all kinds,
but it appears the composition of all dirt/clay tracks are
much the same, that is, hard packed clay on top of hard
You can get "fancy" and put drainage, such as gravel under
the track or in the corners of a banked track.
With the ongoing maintenance, etc. it looks like going with
a dirt/clay track would be more expensive than going with
asphalt in the long run, but perhaps cheaper to construct.
From Dave Cornutt's "Oval Track Racing Glossary," a definition
of a dirt track.
"Dirt track: A track which is not paved, but rather has a dirt
(usually red clay, or some mixture including clay) surface."
This article on Earl Kouba, a midget car racer gives us an idea
of the thickness of clay needed for a dirt track.
"In 1958 the club was back at the Englewood Speedway (Colorado), a
third-mile dirt, for most of the season. They ran a few out-of-town
races at Grand Junction (Colorado) and hill City (Kansas). On one
trip we arrived at Hill City early and for two days the temperature
was 107 and 108 degrees and the water was lousy. Well, when Earl
Kouba showed up i ran right over and told him that this sure might
be a good track as the promoter claimed he put eight inches of clay
on the straight and 16 inches on the turns."
This West Tennessee Sports Online article speaks to the thickness
of clay needed as well.
"The track is sporting some new surfacing as track owners added 5
inches of clay. Many drivers praised the idea, and comments were
very much in favor of the additional media."
The Speedwaybikes.com web site has some great tips on preparing
and maintaining a clay dirt track.
"Track Preparation / Construction
From: Len Dillon
Clay oval dirt tracks are all over the USA and Canada. They are
used for stock car racing, motorcycle flat track, and horse racing.
They can be an ideal speedway track, but are usually too rutted
and have holes that develop in an average race night that would
prevent a good speedway program. I have prepared Niagara Raceway's
track for many years and have learned the trick for this type of
Clay tracks must be watered to reduce dust. An even light sprinkle
before every race will do this, but would make for a very long and
slow program. Once clay is wet, it takes a long time to dry, so the
common approch is just to soak it really good before the racing
starts. But clay binds together strongly when wet, and the water
does not soak in very deep with only one watering. If only a thin
layer is wet, it peels off of the dry clay underneath, leaving ruts,
and patches of wet and dry clay.
- The track must be first graded to remove all signs of ruts.
- The water must be added evenly, and heavy, making sure the water
truck does not cross the wet surface.
- If there is any signs of ruts, wait till the track can be driven
on without caking mud on the tires, and grade it again.
- Repeat until smooth.
- Repeat the watering until the wet clay is more than 3 inches deep.
Wait between watering for the track to dry enough that the water
truck is not creating ruts. It usually takes 6 to 10 hours of
repeated watering to get the proper results.
From: Steve "bad boy" Lucero
When adding new dirt to a track, don't have it dumped on the track! It
will be impossible to distribute it evenly on the track. Instead, have
it dumped in the pit area, and shovel it onto the track from a moving
pickup truck, so that the new surface is added in layers. It will then
wear off in layers during racing, giving an even surface through the
whole night. The riders will be more confident on it and the crowd will
get closer, more exiting racing as a result."
The Bergfelt Racing Enterprises' web site has a nice page on
types of clay that are used and maintenance issues.
"Dirt and clay is different everywhere. Just the color of
the substance reveals that there are differences. Usually
these variations are due to geographic region differences.
The folks in the South East are blessed with that bright red
clay. I havn't had much of a chance to race on it but I
understand it's really good. A little farther north it gets
a little browner but it's great just the same when it's
prepared properly. Here in Pennsylvania the clay ranges from
gray to yellow as well as reddish. One track in South Eastern
Ohio has a dark colored clay with sand mixed with it. The
point of all of this is that there is a vast difference in the
substance that makes up the surfaces of dirt tracks.
Often times the dirt base that exists on the property on which
a promoter wishes to build a track is absolutely no good for a
racing surface. In that case clay is trucked in. How much is
added and how it is distributed and joined with the base has a
lot to do with the quality of the final track.
Some promoters have a dust problem. This is usually but not
always the case with tracks that are run during the day time,
especially in hot, dry weather. Of course water is added to
help control the problem, but sometimes that's not good enough.
Some promoters add a special concentrate to the water formulate
for the purpose of bonding the clay and retaining moisture.
Some of these work well and enhance the grip that kart tires get.
Another additive that is common is calcium chloride. This is
commonly used in parts of the country that get alot of ice and
snow to melt that stuff that gets on driveways and sidewalks.
Not only does it melt snow, but it also attracts and absorbs
water. When mixed with the water and added to the track surface,
it helps the clay stay moist. If you race on a track that is
treated with 'calcium' be sure to wash it off immediately after
racing. The chemical is hard on paint and will cause any
unpainted components to corrode very quickly.
An inexpensive additive that some promoters use to bond clay so
that it doesn't dig up or get dusty is liquid soap. Although it
will successfully cut down on dust, and keep the track from
breaking up, the surface will usually be very slick and it will
be very challenging to get a grip."
This public message board posting talks of dust problems.
"Keeping moisture in the hard clay is vital to dust control.
Applying the proper amount of water to the clay is a tricky
thing and could be the difference between a muddy surface
and a choking dust storm, two situations that halted racing
at OCFS last season. Chemicals can also diminish the dust,
although there are health regulations attached to their use.
The addition of new clay ... can also help."
The KARNAC.com website speaks of the problems of a too wet track.
"The grader was summoned and the peeling of the top two, to
two and a half, inches of rain soaked gumbo clay was underway.
Packing cars from the big track worked the clay into a smooth
surface and races began at 9:45 PM."
A possible source for clay building materials is Beak, S.A.
If you need further clarification, feel free to ask.
Google search on: building clay race track
Google search on: "of clay" inches race track
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