Protecting the bottom
I came into possession of my new MX-5 like most enthusiasts, in the
forefront of mind was how best to look after this dream machine, as
it is my intent to keep it long term. Not only did I wish to give it
the best protection on top, also I felt the need to look after the
bottom, the underside that is, including all of the mechanical bits.
Not just protection but also to make it easier to keep clean.
the owners manual the degree of protection during production is not
totally clear although “cavities and under-body” are claimed to
be treated, the only evidence as far as I could see is just
protection along the line of joints, a thick rubber grey and black
hard underseal,as well as the “protective” paint!
one might feel that Mazda could do more, the basic design of good
drainage in most areas works well but as we all know does not protect
against the ravages of winter salted roads, particularly here in
Scotland, where this can be as much as 6 months of the year and is
increasingly problematic with the additive, molasses I believe, which
makes it stick like glue and also becoming a fine adhering dust on
the road as they dry.
me it seems such a waste not to get out with the top down on a clear
dry winter days and anyway for many it is not a matter of choice with
the need to use the car daily. So to my mind this has to be an
essential treatment to retain the condition and appearance for the
future, and save on the possible massive expense of major bodywork
and parts replacement so clearly shown in the August 09 issue of STHT
“Matter of tRUST”.
owners manual does recommend that additional protection should be
considered and to seek the advise of a specialist. This could be
expensive so I looked at doing what I could myself. I started with
mainly the under-body and the obvious, previously vulnerable areas to
include primarily the wheel arches, sills and side panels and
cavities. So if you have a reasonably new, or old good condition
import what I share here may be an incentive to have a go yourself!
only initial problem for me was how exactly to begin!.
sought the advice of our local experts. Steve Gunn suggested an
annual good clean and spray coat of silicon. In fact as this was so
simple I did this immediately and provided good, if only external,
protection until I decided on something longer lasting.
there are many approaches that can be made, good old oil, rocket,
WD40 or wax-oil based products. Oil based oils are great, but they
are still hydrophilic as well as attracting dust and dirt so need
regular cleaning and reapplication. Some wax-oils can be very thick
on application and can overly change the look and requiring lots of
masking of inspection areas that must be left clear, e.g. the body
supporting areas of suspension struts.
you don't look at the underbelly all the time but I felt the need to
retain the original look as well as protecting. To that end I asked
the advice of our local mechanical genius, Mark Guest who put me onto
Dinitrol. It is expensive but it is also comprehensive, quick and
easy to apply. It is more like a thick coat of paint, goes a long way
so material cost alone is less than £100 available in both air
spray and aerosol cans.
I used 5 different products for
the various areas with actual application tasks being relatively
quick and simple, while the preparation, although not difficult,was
the most time-consuming ..as always!
follows is the method I used specific to the Mk3 so there will be
slight variations to your own model or year and this is not
comprehensive as there are other less critical cavities I intend to
treat in the future, such as areas in the boot, under the bonnet and
even the doors, although I have never heard of problems with doors on
a brief summary:
hot wash/steam clean.
car and support.
all plastic and metal shielding.
detail clean degrease.
all cavity plugs.
up painting, on cross-members and stone chip damaged areas.
and shielding from overspray and areas that must be revealed.
jacked the car as high as possible in stages by supporting on 4
stands ensuring the weight is distributed evenly by packing which
also spreads the load. Checking all was stable I then removed the
wheels. Robbie Marsh's technical tips on jacking in the April issue
was very useful information here.
removed all of the plastic and metal shielding from the wheel arches
and underbody. Most of this is simply a case of releasing and
removing the plastic screw fixing, and a number of screws and larger
nuts and bolts for the metal shielding. The bulb changing section of
the owner manual gives an idea of how simple a task this is. That
said, I found I had to cut in half the plastic shielding behind the
front suspension unit just behind the main strut in order to fully
remove. Also a small cut was needed to remove the carpet- like
shielding from the rear arch.
used Gunk to clean the mechanical parts and a bicycle cleaner, as it
is acid and solvent free, called Muc Off to clean elsewhere, rinsing
with lots of water using a garden hose with rose head. Messy but
essential to give a clean uncontaminated surface to take the
treatment. Then I removed all the plastic and rubber cavity access
plugs. There are lots of them! The ones along the underside of the
sills were coated in the rubber underseal. I used a sharp knife to
cut through the rubber then removed the plugs retaining the coating
of underseal. I then cleaned off any corrosion and treated with rust
converter before touching up any areas as necessary with a Hammerite
spray can, blanking off all areas where I did not want the treatment
to go, particularly engine bay and hinge area of the doors.
I started the straight-forward task of treating four areas;
cavities, underbody, wheel arch areas and all the mechanical parts.
I treated the cavities in the sills, behind the side panel, all cross
members, the main body stiffening channels, wing/wheel arch and
tucked away in the area of the fuel tank inner cavities where the
drain tubes exit.
wheel arches and the inside of the front side panels I used the
special anti-salt wheel arch treatment. For the obvious areas missed
during production I used normal underbody seal leaving areas such as
drains or such as need to be revealed for inspection purposes clear.
I touched up the many bits missed in the area of the exhaust box
particularly the body stiffening tubes to the rear. Finally I
treated all other areas, including parts that have to be revealed,
the whole of the underbelly, all mechanical parts, pipes, well
everything apart from the exhaust and drains with clear engine
lacquer. Why?.. well, to prevent rust, and yes maybe over the top…!
but I believe it will make it easier to clean and retain the look for
longer particularly if this finish is occasionally re-instated after
erosion or flaking. Not absolutely necessary but, well ..it IS an
MX-5 after all !!
I painted the rear exhaust box with black manifold paint as well as
the hub area and rims of all the brake discs.
note, I did not find a need to drill any additional access holes to
cavities. Also it is recommended to spray all areas with the soft
brown penetrating prior to application of hard treatment although I
did not feel the need for this as on the Mk 3 all the joints are
sealed at manufacture
With earlier models or imports
you may have to look at doing both of these particularly if you have
some areas of corrosion, and if you decide to do this you may need
more of the brown soft penetrating treatment than I used. On my Mk 3
with only 18 months since delivery there was virtually no corrosion
other than that which must have been present on assembly on
mechanical parts, particularly the front and rear sub-frames on
which, along with all the internal areas ,I applied the brown soft
penetrating oil treatment.
2 x cans
X's Muc Off cleaner. 1 x can
smooth spray black 1 x can
Very High Temperature Paint black/matt gray 1 x can
converter RC900 400ml 1 x can
hard brown for high salt areas 500ml 1 x can aerosol
3125 soft brown penetrating, cavity 1000ml 2 x can spray
4941 black hard, underbody 1000ml 1 x can spray.(30%used)
4010 clear hard heat resistant 500ml 4 x cans aerosol
gun and 400mm hose with multi-directional applicator nozzle for
cavities. (equivalent required with all aerosol kits)
of cavity drilled access points plugs (not necessary for Mk 3)
individually or in kits, based on what I used, of both spray(litres)
and aerosol cans from Rejet Automotive at a discount to members at
state you are MX-5 OC and your membership number on ordering any
Dinitrol products for a 10% discount.
X 1 Extension
X 1 Gun
litres/spray gun kit for those whom have a spray gun or for ordering
for a profession to do the job for you, but better still a fellow
member who has the kit and possibly charge you much less. Put it out
there on the forum and you my find someone who can help out if you do
not feel you can tackle the task or have little time to do it
what has been used here is for a UK supplied new machine or clean
import. Older machines where rust is more established may need
additional products available from Dinitrol and in greater quantity.
note that I do not offer any guarantee that the above treatment will
achieve a rust free machine but I do feel confident that my
suggestions will help achieve this aim especially when supported by
occasional diligent checking and reapplication where/when necessary.
stands x 4
Compressor and spray gun.(not required with all aerosol kits)
of small socket spanners.
hose with rose spray head.
gloves, mask and goggles.
whole task could easily be completed in a weekend and made even
easier with access to a hydraulic jacking lift or service pit. I have
done just what in my opinion was essential thus not a comprehensive
treatment. I did not treat the outside of the outer sill. This on the
Mk3 is difficult to see as covered by the plastic side pods. I did
think of removing these but believe it needs specialist tools. That
said, the inside cavity in past models is where the corrosion starts
and there is easy access as Mazda have made improvements on drainage
and access to the areas which may prove problematic but the
anticorrosive protection is clearly minimal in some surprising areas
although adequate to cover the corrosion guarantee but not a
guarantee that the red stuff will not appear while hopefully not
time I still think the rear wheel arch and possibly the rear section
of the sills will be the areas affected on the Mk3 if the
manufactures recommendation of further preventative treatment is not
followed. I would recommend that this advice is followed and by doing
it myself the expense is little more than the cost of a few tanks of
petrol and missing out on a few days top-down motoring in this superb
the job so you don't miss a run with this excellent club and enjoy
more on the winter days without those road salt damage worries.
anyone would like to add to this I think a dedicated forum topic
might be a good idea as there is so much input spread over the
various forums with in the club. If you would like more detail on my
experience please contact me direct or through the OC forum.
Sarah Close Mk1:
of 1999 Mk2 and 1991 Mk1 imported 2005:
NOTE WILL INCLUDE IMAGES IN DUE COURSE AS UPLOADING URL NOT WORKING AT THE MOMENT. IN THE MEANTIME TO VIEW DOUBLE CLICK ON THE IMAGE BOX OR GO TO MY GALLERY AT:
- MX-5 Protecting the bottom - by Graham K - a set on Flickr http://snurl.com/protecting-the-bottom
Illustration 1: Supported for access http://www.flickr.com/photos/ghk/4103097600/
Illustration 1: Stripped items http://www.flickr.com/photos/ghk/4103089430/
Before treatment cleaned as much as
Illustration 7: Front suspension
Illustration 8: Underbelly of boot