MX-5 OC Forum

MX-5 Protecting the bottom

When 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.

Reading 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!

While 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.

To 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”.

The 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!

The only initial problem for me was how exactly to begin!.

I 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.

Yes, 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.

OK, 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!

What 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 the MX.

This a brief summary:

• Thorough hot wash/steam clean.

• Jack car and support.

• Remove wheels.

• Remove all plastic and metal shielding.

• Comprehensive detail clean degrease.

• Remove all cavity plugs.

• Corrosion treatment.

• Touch up painting, on cross-members and stone chip damaged areas.

• Blanking and shielding from overspray and areas that must be revealed.

• Treating.

• Reassembly.

• Enjoy.

I 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.

I 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.

I 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.

Finally 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.

For 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 !!

Additionally, I painted the rear exhaust box with black manifold paint as well as the hub area and rims of all the brake discs.

Please 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.

Products use:

General;

• Gunk 2 x cans

• Dr X's Muc Off cleaner. 1 x can

• Hammerite smooth spray black 1 x can

• Simoniz Very High Temperature Paint black/matt gray 1 x can

Dinitrol;

• Rust converter RC900 400ml 1 x can

• Metallic hard brown for high salt areas 500ml 1 x can aerosol

• Corromax 3125 soft brown penetrating, cavity 1000ml 2 x can spray

• Car 4941 black hard, underbody 1000ml 1 x can spray.(30%used)

• Corroheat 4010 clear hard heat resistant 500ml 4 x cans aerosol

• Spray gun and 400mm hose with multi-directional applicator nozzle for cavities. (equivalent required with all aerosol kits)

• Set of cavity drilled access points plugs (not necessary for Mk 3)

Available 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 listed at: CORROSION PROTECTION

Please state you are MX-5 OC and your membership number on ordering any Dinitrol products for a 10% discount.

DINGKMX5KIT1 - Aerosol

DIN3125S X 4

DIN4941S X 2

DIN4010S X 4

DINRC900S X 1

DINE17149 X 1 Extension

DINPLUG10BL50 X 1

@ £69.95 less 10%

DINGKMX5KIT2: Litres(Spray)

DIN3125M X 2

DIN4941M X 1

DIN4010S X 4

DINE17005 X 1 Gun

DINPLUG10BL50 X 1

DINRC900S X 1

@ £69.95 less 10%

The 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 yourself.

Note, 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.

Please 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.

Equipment:

• Trolley Jack

• Axle stands x 4

• Air Compressor and spray gun.(not required with all aerosol kits)

• Scissors

• Screw driver

• Set of small socket spanners.

• Box knife

• Garden hose with rose spray head.

• Head torch

• Protective, gloves, mask and goggles.

• Old news papers

• Cleaning equipment.

The 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 penetrating!!

Over 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 little motor!

Time 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.

If 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.

Further information:

Sarah Close Mk1: http://snurl.com/mk1rust

Comparison of 1999 Mk2 and 1991 Mk1 imported 2005:

http://snurl.com/rustymx5-photostream:

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

Preparation

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 possible.

Illustration 7: Front suspension

Illustration 8: Underbelly of boot

I have been looking at a company called "Chassis Clean" that would clean and protect in a very similar way using Dinitrol products, anybody used them and with good or bad results.

Got the 5 back today after being steam cleaned underneath and Dintrol wax applied. Looks fantastic and should keep the rust bugs away for a long time.

Sue & Ian,

Very nice looking job. Dinitrol is such a great product, easy to apply, effective protection and looks good. Would  you please give us an idea of the total cost of this professional treatment and more details about your MX, e.g. import, condition etc and if there was any major corrosion. Good pictures

Graham, Job was done by "Chassis Clean" based in Cheshire, a family farm that have found this to be a good source of other income, therefore they donot need to push or rush the job through, time was taken at every stage even the pit had central heating radiators heating the car all the time, took three days and cost £375 for an MX. My car is a 96 UK which I found earlier this year having had a very elderly owner, kept in a heated garage under cover, full Mazda service history, all old mot's supplied and a very mint example with 12k on the clock, no rust or even dirt underneath, even the wishbones and shocks were still black paint, so hence the full waxing as i wish to keep it that way. Regards. Ian

Very interesting specimen. There must be many such examples and given this kind of treatment increases the pleasure we all enjoy. I assume they treated the cavities of all the chassis members and did you have the inner sills and any other areas internally treated? The cost seems reasonable given how labour intensive the job is. Doing it myself cost less than £100 and I did it in the warm spring weather in the shelter of my own garage. I am driving the car all this winter and will check the underside in the Spring to see how effective the treatment is at keeping the underside clean and retreat any areas where there is obvious flaking or chip damage. There was one big downside to doing this and thus using the car more in the winter weather, I needed, thus got a set of winter tyres which have set me back a further £400. What has surprised me is the car handles even better on these tyres both in the wet dry and on snow, than those already on the car. Now I am on the lookout for a set of wheels so I can just swap them at the end of the winter and save on fitting costs. 

Sorry I do not have pictures here but only photo bucket seems to work. See above a link to my pictures or through my gallery.

 Graham, inner sills were done, inside of wishbones, plastic and metal covers removed, inside doors, above rear wings from the boot, they have done a good few 5's and are very thorough. Hopefully now I can use it a little during the very cold spells, don't think it was ever out in the winter. I have a set of Minator wheels that I am going to use for the summer and keep the kerbed originalls for winter. Ian.

Thanks Ian,

Yes, I will also do the doors and the cavities accessable from the boot which included the one above the rear wing. I just need some advice on the best way to access the doors although I may be able to do this through the drain holes, I would rather remove the door panels, so anyone reading this whom can advise on how to do this on a Mk3, it will be much appreciate.

I see you have signed in  as a different user, bit confusing at first till I had realised.

It is interesting, my car has been on the road 2 years now from new and just about to clock 12k and you have a model some 14 years older in much the same condition. I look forward to possibily meeting up at some event in the future.

Sorry for the confusion, I was away and replied on my laptop, its a long story but I had to amalgamate two accounts to link my membership to one of them a while ago and the other was closed down.

Not sure how to do the doors on a MK3  on the MK1 they removed the panels,

I will be attending various events next year, Silverstone Classic and the Autumn Rally at Chatsworth are planned at the moment a lang way  for you, Oops Scottish accent coming back. Ian.

Graham

I have a new post as a newbie, with some fab photo's of the 5, have a look. Ian.

There is an additional 15% off for the month of July on the kits.

http://www.rejel.com/rejel-store/categoryid/1213/list/1/level/a/productid/9556.aspx

http://www.rejel.com/rejel-store/categoryid/1213/list/1/level/a/productid/9555.aspx

Just Quote your membership # on check-out for the club 10% discount to be applied.

That will give total 25% discount.