This area often gets over looked because it is mostly covered by the engine undertray, but the following pictures show the condition of the front chassis rails on a 51 plate car that we have recently repaired.
We have found that it is common for the Mk2.5’s to be showing signs of significant rust in this area.
And that was before we started really attacking it with a hammer!!
Hi Garath, yes I mentioned this front anti-roll bar mounting area several months ago while I was restoring a Mk2 last winter for one of my customers here in Wales, nasty rot 
good photos though
Dr. Eunos
Replacement sections can be brought from Mazda:
http://forum.miata.net/vb/showpost.php?p=4961061&postcount=57
US owners are filing claims with the NHTSA, to try and trigger a recall (there is precedant). Is it worth notifying VOSA of this? Unlike damage to the outer sills, this certainly seems to be a major structural concern; at the very least, how a car stands up in a crash.
http://www.dft.gov.uk/vosa/onlineservices/vehicledefects.htm
The fact this rust cannot be detected during an ordinary inspection might be key to getting VOSA interested. I’d imagine this will basically write off a lot of relatively young cars, especially if both chassis rails have rotted through.
AT,
I’m pondering your question myself. Our 02 Sport had the undertray removed on a ramp last week to reveal rot much as Gareth’s photos. The nearside is shocking, and there is a spidered crack working it’s way forward from the chassis rail. The offside is not so bad but will need extensive repair.I remember last year going over, slowly, a road hump diagonally, and a loud crack came from the front nearside. I thought it was ARM or droplink issue. Now I know.
I also know of two other local cars with the same issue, one starting and the other even worse than mine. Both these cars are well looked after, kept out of the elements with, ironically, the worst one being used during summer weather only. The owners are very angry. So am I…given this same month I am re-metalling the dreaded rear cill/wing rot as well. As it stands, my otherwise presentable Sport is spares or repair. Sitting in a car park you’d think it never saw daylight and lived in a Car-Coon. I did seriously contemplate scrapping it, but my wife disagreed so who I am to argue?!
Feast your eyeballs.
http://mx5life.com/community/threads/pennys-renaissance.3566/page-2#post-108492
New sections arrived.
There is no sound metal to patch left on the nearside. The whole section is either riddled or not existant. The off side is repairable…just.
Strip down time.
There you go!
Have some!
Not a lot to prevent the engine/tranny paying you a little visit in even a minor-ish frontal!
New ones!
Wow
This level of corrosion takes me back to my first car a Ford Anglia which had holes in the inside wing big enough to put a fist through.
But for a modern car it’s shocking. I wonder why this is occurring. Do we have any idea if it’s the design, poor drainage, poor steel or what.
I take little comfort driving a mk3 which will be six years old next year and four years off the age of some of the problem cars shown. Any early signs of similar problems on mk3s. I had a rust free imported mk1 it’s not the first time it’s crossed my mind that I should have kept it
Our level of corrosion took me back to my Building Society account.
Call it poor design, but I would not say poor steel. The new ones were massively heavy, and very thick steel. Here is an interesting point. The replacements are not sandwiched in exactly the same OEM design but solid,so go figure
. Lessons learned somewhere? Are Mazda aware of it more than they are admitting ? Perhaps these replacements are engineered more cheaply as I expect they will be needed for accident repairs. Maybe later a way was found to dial the water traps out of the design. I am only guessing.
They have been described to me by both the people who fixed it, + an insurance accident assessor who happened to be around, that the sandwiched design of these chassis legs is a stupid construction.They provide the perfect habitat for moisturecwith salt etc to quietly rot them from the inside out unseen or detected unless people are aware, then get an light in poked in and with luck if it’s in infancy get it injected/treated. The big but to the common garden owner is by the time it’s visible they are likely dangerous. In our case the subframe onto which the engine is bolted was effectively keeping it all together instead of the other way around. And this, may I add, is a 2002 low miles car dry stored every night that does about 70 miles per week in town.
Next month sees the welding in of new rear wings & sills…thanks to
the well documented “Other Great Water Traps”. And yes, I do keep our
drainage channels clear!
So people if you are viewing to purchase an otherwise mint Mk2.5 now you know. All that “Garage Queen” glisters may not be gold.
Mazda circulated a brochure insert at one time showing “galvanised sections” to include…it appeared, the chassis legs. My backside…there is NO zinc-dip treatment in the body tub of a Mk2.5.
Just paint spat on & wiped off by the bean counters.
Scottishfiver,
I take those repairs were of a significant cost. The photographs are horrific.
It is interesting that the replacements were of a different design to the original. Can the Club, or someone, find out from Mazda why the parts were changed?
I’m not aware of the same issue occurring on the 1998-2000 Mk2; do these cars have the same sandwich contrustion chassis rails, or is it more like the replacement parts Scottishfiver has used?
Perhaps someone who has been through the process can pen a letter or article for the club magazine, STHT, drawing attention to this for members who aren’t on the forums.
Hi AT.
I don’t mind publishing the costs. The chassis legs are £314.00 + VAT
each. The intensive labour, around 40 hours, paint, new fluids and
numerous sundries brought the total bill to £1,980.00. This included
some anti rot work throughout the chassis at my request.I have purchased new rear wing/sill panels, so I expect the total for
that to reach around £750/£850.00. Broadly we are absorbing repair costs
of around 80%/90% the actual value of the car. To some, this is lunacy.
To my wife, it was her choice being in a comfortable enough position to
deal with it. To me, it was a scrapper. At the end, we will likely have
one of the most rot proof 5’s in the UK. That is the only good point I
can think of other than the fact the car is mechanically 100%, has new refurbed Sport alloys, fresh Toyos, a new Panasonic battery, all ARB’s replaced,has had a professional valet & laser tracking so in many ways it’s basically a “new” Sport!
Taff worked on Mk2 in trouble I believe…according to his post in this thread.
Within the last 48 hours I am aware of an additional & seemingly mint 2004 Mk2.5 which is essentially a financial write-off due to rotted rails, cills, and arches but mainly the rails.
This “cherished” example was at a main dealer for new front ARB’s and a leaking sump
nut I believe…or something equally minor…only to have it all
revealed.
NB: An inconsistency exists in that they are either completely solid, or (potentially) terminally porous and therefore dangerous
Production run variances? Historic Ford interference?
Seems to me in a very few years it will become a rare event to find a Mk2/Mk2.5 not ready for the scrap yard.
Do you think I ought to pen something for STHT? I’m not mechanically minded, but I do have plenty evidence & experience now.
Hi Great work with the photos and update on front chassis rails!
I am currenty looking to buy my first MX5 was looking at MK2.5.
But am hoping you can answer a couple of questions.
How can I check the rails? looks like it’s a lift job?
And if there rusting from inside out. How to I check for this?
With all the talk of rust on MK2.5 could be talked into MK2. Is it any better for rust? Or would I be safer going for MK1?
Once again loving all the information on the forum! even if it is scary.
Tom you can, to a degree, check for rail rot simply by getting underneath, and removing a front wheel to make it easier to poke your face in. The best way to make sure, and this is a purchase problem, is to drop the underside tray…which will have rusted bolts no doubt. With hindsight, I would defintely get a probe into the machined holes visible from the engine bay and see inside the rails.
It may well be they look and sound good from the outside but have advancing rot inside.
As for which Mx5 rusts the most? They all rust. Just some do it quicker than others. My Mk1 is totally sound bar some crusty rear sills, but at 18, that’s fine. Imports tend to be more rot free due to a lack of Jap salt…and in anycase the Japs don’t use their cars as we do given their excellent public transport…hence low miles imports.
If you get a good one, deal with any suspect rot right away and get the rest of the car cavity injected.
Hi Scottishfiver,
Thanks for getting back to me and the great information,
were are the holes from the engine bay? And i take it when you say injection treatment you mean waxoyl etc treatment for inside the rails etc?
Thanks again!
Thomas.
Yes; I should think a letter should suffice, with a single image showing the location of the rot; a shot including that front ARB bracket is most useful, as that bracket is most distinctive.
I think this damage is totally unacceptible; more so than sill rust. This is so clearly a failure due to Mazda manufacturing process; whatever they have used in between the sheets (on the US sites, they describe a resin like substance, I suppose its an epoxy used to bond metal, that breaks under impact) is not upto the job. Its not something that is covered as port of the annual body inspection, and so no owner can be expected to spot this early on. Given that a MOT inspector will probably not detect it, its horrific to think that it might only be detected as a result of an accident. To me, this is a bigger issue that the differential question.
The Import argument is less applicable now; most have been here over 10 years, and significant importation effectively halted at the start of the banking crisis (car in Japan are now too much money). I’m onto my 4th import; the current one being a 1996 car, imported by Mazda Cars in 2000. Currently, I have had a sill repaired, and the other has some suspicious looking lumps, which I expect to progress to holes over the next couple of years. The passenger door frame has holed, as a result of a failure in the panel sealant. Elsewhere, the panel sealant has dried out, cracked, and allowed rot to develop. During a recent front end strip down, I found extensive rusting on the front inner wings, including where the sealant has failed (eg. there is a complex overlap of panels by the corner of the windscreen. I seem to have caught these in time, treated and painted. The front cross mkember has a couple of holes; one in a non-structural area, and the other where it butts up against the chassis leg. I am debating my options on that; its a very small hole, which has now been neutralised, so I don’t expect it to get worse. The chassis legs though are rock solid.
The choice is to whether stick with the present car, accept that it is slowly dissolving and repair as needed, or pay a bit extra for a fresh Roadster from Japan, while they are still available; they haven’t yet reached silly Corolla AE86 money. At the moment, a fresh Mk1 from Japan is £2-3k and up. More expensive than ads here, but considering what is not needed…
Rusty Roadsters have also been found in Japan; so far in early cars mainly, and in the same spots as here (sills).
This is awful. Is it limited to Mk2.5 or is the Mk 1 of similar design and prone to the same symptoms?
Phil, all Mx5’s have chassis rails. The amount of sound metal in our rotted originals is around 20% internally. I have these in my lock up for potential examination by any interested partiesIt is entirely possible the chassis rails were beginning to crumble when we bought the car 6 years ago at 4 years old. It has been pampered, always allowed to drain before garaged, never driven in salty bad weather, and generally very well looked after. We could have eaten our dinner of the car on purchase. Before that, 1 careful owner, Main Dealer serviced, garaged and used sparingly. How good does it get? We also have an 18 year old imported Roadster which has crusty rear sills soon to be sorted but the front end is as solid as the day it left Hiroshima. That car has been campaigned for 6 years in my ownership through the worst UK road conditions you can think of. I’m always careful to pressure wash the crud form underneath every week.
Last year.
Mk1
It may look familiar to some?
The discolouration is actually wax.
If you study an exploded Mk3/Mk3.5 plan it is fundamentaly the same concept but I would hope Mazda have since improved production treatment.
Personally, given the raft of Mk3 “issues” ranging from cracked windscreens to failing ARBs, cheap spit-thin leather seats on Mk3.5’s to leaking brake lights I would not be feeling very smug if I owned one.
Also note below how the Mk3’s turrets rely soley on sound chassis rails.
No mention of zinc-dip or galvanising here you will note.
http://www.drivingenthusiast.net/sec-mazda/products/mx5-miata/default.htm
The only thing I can say is, without seeming alarmist is that better safe than sorry and get it thoroughly examined.
You have, in my opinion, nothing to lose and much to gain in doing so.
Best regards
RB
You have my admiration. I don’t know if I could have done this but as you say you will hopefully have a car that will last for as long as you want to own it.
I support your proposal for an article for STHT. Have a go at a proper article, how it was found, what made you decide to repair, how the job was done etc. Having had my previous Mk1 on the front cover there is great satisfaction in seeing your efforts in print!
I think that while the potential to buy a badly corroded car is bad enough a more serious issue is that people may be riding around in a carthat is seriously weakened and may be a death trap in the event of a heavy frontal.
I duly support the view that the owners club should take this issue up with Mazda and more importantly VOSA. have you ever thought of taking up the issue with Mazda. Looking at the catalog for my Mk3 it talks about a, “12 year anti perforation warranty” and the bodywork is checked at every service. I guess the reality is this counts for little as they will always find a way out of it.
Can we have a commitment from one of the moderators to raise this at an appropriate level.
Mk1s are usually solid in this area; I am not aware of cars with this sort of problem. Some Mk1s with uprated ARBs might have torn mounts, but thats metal fatigue, and exceeding what the engineers intended. The issue is because of the crumple zones introduced with the Mk2.5; instead of the solid box sections (one layer of metal), Mazda used a telescoping system, of sheets of steel, that I think were bonded or glued together; in an impact, the chassis legs collapse in, instead of bending. The corrosion, from what I understand, starts at the interface between these sheets. The glue must be failing, allowing moisture to get in.
I’ve not heard of this problem in Mk2s; I’m not sure if this means the Mk2 didn’t have the same crumple zones as the Mk2.5, or that Mazda back then had a different way of putting the sheets together, that has proved longer lasting.
I would not be surprised that, as far as the MX5 is concerned, the issue is confined to the NB-FL shape, and is as a result of engineers having to retrofit a safety system into a basically old body shell. I can think of lots of cars, where the facelifted version is worse than the original. Indeed, owners of 1995-97 MX5s will know these cars will rust in the sills more than earlier cars. My theory is that Mazda changed the painting process to one that was more environmentally friendly, resulting in the corrosion issues.
I have just stripped down the front end of my 1996, 240k km Roadster (not to check the chassis rails though!), and found the chassis rails to be utterly fine. And this is a car that sits out on a drive most of the time,and is washed once in a while.
