81 replies to this topic

[firstforward]

but what would you do to stop the corrosion from electrolysis ?

I don't in any way know about this subject but with my limited connection with sea going boats they have problems of corrosion by electrolysis and install a sacrificial anode a metal component that is softer than the other metal, I think they install Zinc that dissolves to stop the hull corroding, can something like this not be employed on a car with stainless steel.......just a thought.

would i then have to soak the mini in salt water ?

I guess you know less than me

Something I Googled but I am sceptical that anything works as, why have we not all heard about it,

There are many vehicle rust protection systems commercially available. Those that work by treating the metal object to be protected from oxidation as a cathode in a direct current electrolysis circuit have limited effectiveness. The main drawback is the need for an electrolytic solution between the cathode and anode to complete the series circuit. Even with the placement of several anodes around a vehicle there is little guarantee that the necessary ionic path will be present to complete the electrical circuit needed to prevent corrosion.
There is a cathodic protection system based on capacitive coupling that works excellent for vehicles by overcoming the shortcomings mentioned above. Basically, a positive plate carrying a pulsed DC voltage is placed adjacent to a dielectric material which is placed adjacent to the car body. The positive plate and car body share a common ground. During each pulse a positive charge develops on the positive plate and a corresponding negative charge develops on the adjacent car body which acts a negative plate in capacitive coupling. As each pulse cycle ends the excess electrons on the negative plate repel away and create an impressed current in the car body. These surplus electrons bleed off and become available at corrosion sites to reduce any chemicals on the car surface that might otherwise cause oxidation of the steel.
The car paint acts as a dielectric coating and becomes a potential capacitive surface. When an aqueous solution contacts the paint surface a capacitive surface is formed. The car body is the negative plate, the paint is the dielectric material and the aqueous solution functions as the positive plate. If an electrolyte makes contact with any exposed area of the car body (such as a nick in the paint) and creates an oxidizing environment, the chemical in the electrolyte which would normally remove electrons from the steel are more likely to be reduced by the surplus electrons pumped in from the capacitive coupling. What makes this process so effective is that no ionic path is required between the corrosion site and the anode (coupling positive plate of the capacitor). The complete redox reaction takes place between the cathodic car body and the anodic electrolyte acting as negative and positive capacitor plates respectively.

Whether this would work for SS to MS???

[midridge2]

today i recieved a reply from vosa after i had to send them another chase up email.
I apologise that you do not appear to have received an answer to your
query.

The Inspection Manual advises that adhesive bonding, along with certain
other joining methods, are bonding processes and are not regarded as strong
enough for repairs to load bearing members although they are normally
adequate for other repair work. A front wing on a mini is not a load
bearing panel and its attachment method is not therefore MOT testable.

I hope this information has assisted you with your enquiry, but if you have
any further questions please do not hesitate to contact us again.

shifty, have you had a reply from them yet?

any comments on this advice from vosa?

[Bungle]

so we can now fit front wings with self tapping screws like modern cars

but a boot floor has to be steel and welded

Edited by Bungle, 10 January 2012 - 05:29 PM.

[midridge2]

correct, but the floor is load bearing and part of the monoque sp shell.

[tiger99]

So where will VOSA be when someone is killed because adhesive bonded wings come adrift, the inner wings buckle, and the subframe tears off from the rear mounts at 70mph?

That opinion, and opinion is all it is, not a legally binding statement, was not made by a competent engineer, but by a pen pusher. And, the better class of MOT testers will know how the front end gets its rigidity and will fail it regardless if they spot the adhesive bonding.

[midridge2]

oh dear oh dear vosa is wrong even though it came from the body that deals with what standards a car has to meet to pass a mot, were does it say it was a pen pusher who replied to the email? were does it say its a opinion rather than a fact, if vosa says they can be bonded how can a tester go against the testers handbook and fail it?

next you will be telling us its illegal to fit copper brake pipes.

as an after thought, why dont you email vosa and tell them that they are wrong and you are correct and post the message up and the reply?

Edited by midridge2, 10 January 2012 - 09:09 PM.

[tiger99]

The reason I know it is a pen pusher is that a real engineer would have no difficulty in identifying the load paths through the monocoque, and would be well aware that the front wings are an essentioal part of the structure, unless bracing bars are fitted. It does not take a genius to see that the inner wing, being basically a flat sheet of metal, one with a large hole, has virtually no rigidity on its own, and if it has no rigidity it cannot carry the subframe loads.

And, I suggest that you check the spec on what is being sold as copper brake pipe by some suppliers. It is, in every singe parameter, very inferior to either bundy or cunifer. The very worrying one is the number of pressure cycles it will stand before fatigue failure, a pathetically small number when extyrapolated to the actual peak pressure in a Mini brake system.

[midridge2]

so are you going to contact vosa and tell them that?
and is copper brake pipe illegal? if so are you going to inform minispares to stop selling it? you have a duty of care to protect the mini community from doing dangerous things if your knowledge is better than theirs.

[Frisco]

Mini wings are structural, it doesn't matter what someone in a vosa admin department said in an email.
If you remove them or fit them in a weaker way (which bonding is IMO) and dont fit brace bars then the front panel is basically unsupported and the subframe is mounted to it.

[midridge2]

so all the things that vosa told the ace website about modifications to minis should be ignored because they came in a email, could one of the admins/mods remove the sticky with the emails from vosa that went to ace, its all just there opinion and the "experts" posting in this subject should set the standards for MOT tests because the vosa lot are just pen pushers and not really qualified to set the standards.

[Frisco]

Take it as you like mate. All I know is that there is no way I'd remove the wings or bond them on without fitting brace bars to support the subframe.

The email isn't going save your live when the sh*t hits the fan

[tiger99]

As for Minispares, their rear camber adjusters have a dreadful reputation for fatigue failure (actually quite difficult to achieve with a simple mild steel bracket, unless you don't know what you are doing) so I would not regard them as any kind of authority on the fatigue life of anythinmg, far less copper whose spec is for general use, not specifically brake pipes.

[The Matt]

today i recieved a reply from vosa after i had to send them another chase up email.
...A front wing on a mini is not a load
bearing panel and its attachment method is not therefore MOT testable.

Not MOT testable, but it is still deemed a modification to the monocoque in terms of removing it and replacing it with non-OE kit (I.E. GRP fronts etc.)? If they are saying that the outer wing is not a load-bearing panel, then neither is the inner wing the wings welded to the inner wings and front panel together form a structure, without which the whole front end is a little wobbly unless you solid mount the front subframe. They need to decide where they stand on this and I wonder if the way to get definite answers is to compile a set of drawings and pictures of flip-fronts, replacement flat boot floors, tubbed out rear arches and rear bin removals to show them what is "normal" and that some of these modicfications have been in place, safely, on some Minis for 30-40 years!

We actually need a compilation of questions all in one round-Robin email to VOSA regarding where the "normal" modifications are either compliant or non-compliant with their regulations.

I'm interested in the battery box comments/questions.

As an ex-MOT tester that is familiar with Minis and their structure (though 12+ years out of date with regulations) I would deem a GRP battery box as an insufficient repair as if falls within a prescribed area (it's within 30cm of a subframe mount etc). I would deem the removal of the battery box and the fitment of a blanking plate OK (as long as it was seam-welded in place). It's a modification to an area, but MOT wise I would pass it. Might make a note in the form of an advisory that it was there though just to cover my arse.

As I say though, I've not tested a vehicle since December 99, so that's how current I am with regulation!

WIth regards to welding stainless to mild steel, I've had success on exhausts using a MIG welder, normal bog-standard MIG wire and argoshield 5 gas. I would NOT recommend welding stainless to mild steel on a structural joint though. I "believe" that introducing the MIG weld to the stainless steel can cause some embrittlement along the joint, along with still being a joint between differential metals. I am by no means an expert in metal fabrication and have no real skills with metal work at all, but I've talked in length with some of the old boys at work about it for some of the stuff I've designed. The better idea really is to bond stainless to mild steel panels together as the materials aren't in direct contact with each other, the adhesive acts as an insulating layer, people fail to see that a decent bonded joint using a decent adhesive is far, far stronger than a LOT of other jointing methods. We use some pretty hot glues at work and we test them to death. A little 3mm bead of MIG weld isn't always the strongest option.

[Bungle]

as someone that's quite good at stringing a sentance together and has a good technical knowledge would you like to send a email off and see what we get back ?

[Jake Didsbury]

Well for one electrollisis is big problem, mild steel and stainless steel have different electrical potenials so they actually begin to corrode eachother when put together, same with aluminium that was a big problem with landrovers (which i think someone has already said that) gets me when you go to the stalls at the mini shows and they are all advertising 'stainless nuts and bolts!' etc its all well and good untill the bolt corrodes inside the mild steel thread - however, maybe you could cure that with some copper slip inside the thread i dont know.

I think the only real way you could do it was to have the whole body shell made from stainless, and then have gaskits between any mild steel mechanical connections.

There have been times when i have thought it would be great if you some how stop the rust, but when you think about it, (which leads me onto the next reason why they probably dont do it) is becuase there would be much less demand for the repair panels because they would be lasting longer, thus they would be almost doing themselfs out of business!

They never bothered rust protecting the mini like they could have done in the first place becuase if someones rotted away they might buy another...

Many people have said to me its actually impossible to completley stop rust, but i think there will be a way out there somewhere

Jake

Edited by Jake Didsbury, 13 January 2012 - 10:49 PM.