- 1 One of the well-known issues with a Mazda MX-5 NB and NBFL (2nd generation) are the chassis rails (chassis beams)in the wheel tubs. These are very often rusted..
One of the well-known issues with a Mazda MX-5 NB and NBFL (2nd generation) are the chassis rails (chassis beams)in the wheel tubs. These are very often rusted..
If you are told at the garage after doing a maintenance or MOT that the chassis is rusted then of course you are very frightened. The car you love so much can’t be completely rusted, or can it?
How does the rust form and why does an Mx-5 NA (1st generation) not rust here?
The rust is created by the design of the chasiss rails that Mazda has chosen. The Mazda MX-5 has 2-layer chasiss rails, which is good for the firmness in case of an accident and the stiffness of the chassis. Unfortunately it also has a downside and that is that there can be water between the 2 layers and then it’s trapped. Standing water that can’t go your way, you guessed it, that’s going to rust!
The MX-5 NA (1st generation with flip headlights) does not suffer at all because it has only 1 layer of steel in the chassis rails Water therefore does not remain ‘trapped’ so that they will not rust.
Patch and bad repairs..
Let me start with how, in our view, it absolutely NOT should be repaired.
1. A so-called cheap MOT solution: Weld a plate over the rust so that it is ‘hard’ again and comes through the mot.
With this method you postpone the problem and you will most likely have problems next year during the MOT. This is a (bad) patch and not a solution.
2. Partial repair: Cut away the rusted part and weld a new plate into it.
The rust has probably been largely replaced but again it is not the solution. There are still parts with 2-layer steel that will rust through sooner or later.
How LucaCarMods is doing this repair
As indicated, it is important that all rust is gone and it cannot come back. The solution is to remove all the 2-layer steel from the front chassis rails and replace it with a repair panel which, just like the Mazda MX-5 NA, consists of only 1 layer of steel.
With this rust repair repair of the chassis rails we start by disassembling the front bumper, crash beam, headlights, wheels, radiator, power steering and many other things that get in the way. During the repair, the engine can stay seated but many attachments are removed. Next, the engine and fuel lines will also be packed with a flame retardant welding blanket. Safety is key with this repair.
After most of the parts are disassembled and the important parts are packed, the cutting can begin. This can look rather intense because a rather large piece will be cut out of the chassis rails. What is often even worse than grinding is the rust that seems to be fine from the outside but is already quite advanced inside.
Then everything needs to be cleaned properly so that it is free of old coatings or wax layers. These easily catch fire and also make for a bad weld. If everything is clean then the repair panel can only be trimmed to fit on the Mazda MX-5 NB. Again, you have 2 ways to do it. A weld where you put the panels over each other or put them against each other with a gap of about 1mm in between. We always choose the last option to have good welding, nicer looks and the steel is only 1 layer thick everywhere.
To spread the heat during welding, short welds are made each time and then you jump back to another point. This prevents warping and there will be less heat in the paint layer of the engine compartment.
After this, the weld can be sanded flat with a flap disc on the right-angled grinder and finally the most important step; apply a good moisture-resistant coating both inside and outside Inside the chassis rails we use Dinitrol 1000, this is a hollow space coating and on the outside a robust Dinitrol 447 anti stone chip coating.
After this, the MX-5 NB or NBFL is good again for many years of driving pleasure!
If you want this repair done by us please contact us! In terms of costs, you have to take into account approximately €950.00 Incl. Vat
Of course, you can also do this repair with our repair panels which you can find below.