Mot advisories - what to do about rusty suspension arms

 hello all , 

     I have a black 1.8 s NA that has just passed its MOT.


i"ve owned the car for 10 years , it has only done 60k miles and looks good . 

The story underneath is not so good. 

The MOT gave advisories that all four lower suspension arms are corroded but not seriously weakened. 

So I"d like some ideas as to whether to just run the car for one more year and then scrap it or spend some money to extend its life . 

I do not have the ability to do the work myself so need to go to a specialist . 


I"d like your suggestions please to the following options . Can you give me any indications of cost or suggest specialists whi can do the work . I am not dependent on the car its a pure toy so time off the road is not an issue - but cost may be :-) 


my thoughts are - 


1 remove arms get them shotblasted and powder coated and put back on With new bushes 


2 replace with 4 new lower suspension arms ( is availability an issye) 

Does anyone have any other suggestions or had similar work dine to let me have comparative prices ? 

Also whist car is in bits should I get springs and shocks changed too ? 

Many thanks



Mark ones are increasing in value so I would not be looking to scrap the car next year. If cost is a problem I would suggest wire brushing the parts then placing aquasteel on the outside then cavity wax on the inside. Depending on your mobilty this is something you can do yourself quite cheaply.

On mine, I wire brushed the arms, then brushed Kurust on, followed by Waxoyl.

Later, I sprayed Dinitrol RC900 rust killer inside them, followed by Dynax S50 spray.

I refresh that outer cover of Waxoyl, in September time. 

This is a common enough advisory on the MK1 MX5 and not one to be overly concerned about.

If there were genuine concern it would not pass the MOT.

The suspension was not treated effectively on manufacture, so surface rust appears. Recent MOT protocol is to advise where there is any doubt so over the last 4 - 5 years advisories like this as well as similar with brake pipes, underseal coverings, etc have started to be a regular feature, It is just the MOT station covering its back for something that cannot be properly checked.

If you want to do something about this comment on the cosmetic appearance of your suspension, your idea of removal and shot blasting/powdercoating is best but most of us would clean the parts with a wire brush in situ, rustkill with Hydrate 80 and then paint with smoothrite or similar.

Don’t let this force you to do something you do not want to do with the car.     

Hello everyone - thanks for all of your responses and  suggestions .  It was a huge relief to read all your comments . I am very attached to the car and really would like to keep it for my retirement next year and ideally I want it to last so that I can pass it on to my son . 

It certainly sounds like i wont be scrapping it . 

Just to clarify I dont mind spending hundreds iof pounds on the car to extend its life - however if costs run into thousands then that may not be an option . 

I"ll take all your sound advice and go for the wire brush/rustproofing treatment . 


When the car goes for its annual service with Sam Goodwin I"ll get him to check again and advise . 


Thank you all for your suggestions they are greatly appreciated . 




The cheapest and one of the most effective ways of dealing with this is to lightly wire brush  the arms and then coat in old engine oil working it well into the rusted surface. You will need to go over them again  periodically  but over time this can be done less often as the oil works its way  into the rusted surface and forms a very effective barrier against further rusting.



Sorry I’m going to disagree with the above comments.

I’m seeing more early cars with corroded antiroll bar brackets that pull out of the lower wishbones especially the rear lower wishbones.

Therefore I would get the wishbones cleaned and coated with anti rust as advised above but that will not stop internal corrosion that is already at work.

With regards to powder coating if you are going to that expense and if the car is a real keeper then I would purchase two new rear lower wishbones while they are still available new and get them powder coated. Even that is just to keep them in a box until needed.

The problem about keeping an old car on the road is that to an extent you are chasing your tail to cover all eventualities but at the minimum get them cleaned and coated with anti rust treatment.

Hello Eddie, 

    Thats a really good point - I"m concerned that the rustproofing approach may just be “papering the cracks” and that there could be internal corrosion that you cannot see…



Whatever you decide to do, if you are going to DIY it, jack all four corners of the car up onto axle stands as high as you can making sure it is not wobbly before going under the car. Use plenty of different size wire brushes to get as much rust of as possible before treating them with whatever you decide and wear a pair of goggles. If you can, use some 9" concrete blocks piled high under one side, front and rear just as extra safety. Can’t be too careful when under a car. Oh good lighting is essential too. 

That is very good advice and very welcome - thank you .

However I have a very steep drive and a very narrow garage so was planning to do just one corner at a time . I will of course use 2 axle stands each time .

Thanks again

That is very good advice and very welcome - thank you .

However I have a very steep drive and a very narrow garage so was planning to do just one corner at a time . I will of course use 2 axle stands each time .

Thanks again

I’d make this my next port of call before doing anything else, get an opinion from someone who knows and has seen the car rather than going off an MOT advisory.

Robbie ,
Thanks - Sam has done a good job maintaining the car over the past 10 years so I"ll get his advice first . Thanks

I’ve said this before but a plea from someone who has seen a car falling off it’s four axle stands:

When DIYing under your car, NEVER put all four corners of a car in the air using only two pairs of axle stands. Two is fine, four isn’t. Put two stands under one end but either leave the other end on the floor, with the wheels chocked, or put a pair of ramps under the wheels of the other axle. If you want all four wheels off at once, use substantial blocks, at least at one end.

A car balanced on four axle stands can “rock” fore and aft without much effort because there is always some movement in them, between the inner and outer tubes. Once they rock, the centre of gravity changes and they can also tip. I saw a friend have this happen. Having just put his car in the air on four stands, he leaned back against the bonnet (surprisingly gently) and over it went, backwards, with a loud crash, dropping onto the sides of the stands. Thankfully there was no-one under it at the time but damage was done. If this were to happen with no suspension on the car it would be a big problem to get it off the floor, let alone the damage the stands would cause to brake pipes, fuel pipes, exhaust, etc. If someone were under the car, it might be game over.

I also know of another case (told to me by the Air Ambulance crew who work next to me) where a chap and his 12 year old son were working on a Subaru Impreza in a barn. He was working under the car when it fell on him. His son tried desperately to get the car off his Dad, even trying to get a fork lift to lift it, but by the time the Air Ambulance crew got there he was already dead. A tragedy that will remain with the lad forever.

Work safe!

P.S. Yes, my car’s suspension wishbones are crusty, too.





I can understand what you are saying but you don’t say which car it was you are posting about.  I always check that that my car, MX5 Mk1, does not have unevenness on four stands by pushing etc to make sure, and I did recommend putting some thing solid like concrete blocks down underneath as an extra precaution. Obviously if you are not sure about what you are doing, don’t do it.  


I did mention that it was a Subaru Impreza in the case of the more recent fatal accident. It was a Hillman Hunter that went over while I stood alongside; obviously quite some long time ago but the sight and sound of it (and helping sort out the aftermath) have stayed with me.

But the type of car is irrelevant; it’s axle stands that can be the danger. I’ve drummed this into my sons, who also work on their own cars and I made a point of demonstrating to them how axle stands can allow rocking in certain circumstances; thankfully they seem to have got the message.

Our Mk2.5 failed 5 years back due to the rear wishbones perforated from the inside!They looked ok bar surface crud but actually were cheese. Bit of a surprise. I purchased refurbed ones for around 90 pounds delivered from AK Autos. Suffice to say I flooded the insides with Dinitrol and coated the outsides with POR before our garage fitted them. Cannot recall how much the labour was but less than 100.00. Oddly our Mk1s are still solid … but then I did them with Dinititrol way back. Fitting good refurbed need not be painful but as advised I think OP has had best advice. I think there is a White Paper being presented in Westminster that Mk1 owners will be flogged & put in stocks for scrapping easy fix Mk1s. Quite right. 

Yes I had heard that stocks and public flogging will be introduced if I scrap a Mk1 - so will avoid at all costs . If it does come to it I would offer the car to someone in the club who could bring it back to life . Now worgied anout cheesy wishbones too :slight_smile:


Don’t fret… really. Easy job for a garage.

Mine were off and on within two hours…while they were servicing it anyway.

If…indeed…you even need to bother. Yours sound like typical surface crud…as usual.

As said by many here, scrub 'em up and proof them.