Replacement steel nuts, bolts, screws etc.

Little Dog

A2OC Donor
European-Union
A very simple question.

My A2 has reached an age when the steel fasteners are corroding and need replacing. Rounded off the head of a long M10 bolt just last weekend.

I've noticed that the fasteners have a green coating on them. Is this something to prevent galvanic corrosion? Do I need to source genuine fasteners; I've never noticed this coating before on aluminium cylinder heads etc?

Thanks
 
Quote from AUDI A2 - Body Construction and Function Self-study programme 239
Threaded connections on the Audi A2.

All fastening components that come into contact with aluminium are coated with
Dacromet, Delta Tone or a similar coating to prevent contact corrosion


In addition these parts are coloured with a green lubricant on an alkyd resin basis to
provide a clear distinction to normal fastening components.


"> Available coatings for prevention of contact corrosion

1. coatings containing zinc and
aluminium dust
(Delta Tone®, Dacromet®)

2. special zinc alloy coatings

(Zn/Sn mechanically or ZnNi by electroplating)

3. galvanised aluminium coatings


4. zinc coatings

(for non-ferrous metals)

5. Duplex systems

(zinc + paint)

 
Very useful thank you Alan.

So that fact that my bolts are rusting is a problem. The coating has gone and next to go will be the aluminium :(
 
My A2 has reached an age when the steel fasteners are corroding and need replacing. Rounded off the head of a long M10 bolt just last weekend.
Thanks

The fasteners (with inbuilt washers) holding the heat shield on are made of steel and are known to rust and the shield comes loose and rattles or falls off!

See my illustrated thread where I fix using aluminium rivenuts etc. http://www.a2oc.net/forum/showthread.php?30852-Fixing-the-weather-heat-shield-another-thread

Why Audi made them of steel when they are so prone to salt corrosion, I don't know. Talk about don't spoil the ship for a ha'p'orth of tar.........

I also recall reading that any mechanical work on an A2 should use tools that are reserved for aluminium vehicles to avoid cross contamination. Not too sure if these tools were coated or not, but it seems a way for Audi to make garages buy another set of special tools!
 
Which bolts are we talking about specifically?

I need to go under the car and replace the hand brake cable I'll get some pictures. Its a bit cold at the moment so I will do my best to describe.

At the rear I think there are 4 large bolts each side through steel into aluminium that retain the rear axle beam assembly

A the front there are 4 through a steel component that could be a tie between each side of the suspension or a sump guard with an engine tie bar attached. I think one screw is into a retained steel nut and the other three possibly into aluminium?

There are other larger bolts in this area securing the front suspension to the aluminium shell but I will have to get pictures.

All corroding, heads rounding off etc, need replacing / plating.

Thanks

Phil
 
The fasteners (with inbuilt washers) holding the heat shield on are made of steel and are known to rust and the shield comes loose and rattles or falls off!

See my illustrated thread where I fix using aluminium rivenuts etc. http://www.a2oc.net/forum/showthread.php?30852-Fixing-the-weather-heat-shield-another-thread

Why Audi made them of steel when they are so prone to salt corrosion, I don't know. Talk about don't spoil the ship for a ha'p'orth of tar.........

I also recall reading that any mechanical work on an A2 should use tools that are reserved for aluminium vehicles to avoid cross contamination. Not too sure if these tools were coated or not, but it seems a way for Audi to make garages buy another set of special tools!

The thread on securing that rear heat shield is useful thank you. When the car was new I fitted rubber washers between the retaining nuts and the aluminium shields. It was an Audi supplied washer. They have disappeared from the fuel filter shield, thanks servicing mechanic, and that shield has fallen off.

I think the tool cross contamination issue applies to body shop abrasive tools? They don't want any trace of steel under paint on aluminium or aluminium on steel for that matter. Or at least that was what I was told after I scrapped two doors on a gate post :(.

Phil
 
I've attached 2 photos of the front and rear assemblies you mention and you can point out the bolts from there (and possibly get a better idea of what you're dealing with too). All bolts are still available from Audi parts departments or TPS (my favoured parts supplier) or even VW Van Centres and are worth paying the extra for peace of mind and protection from galvanic corrosion.

Screen Shot 2017-12-12 at 10.02.33.png

Screen Shot 2017-12-12 at 10.00.47.png
 
On a separate note, I'm going to tackle the heat shield retaining fixings soon as I've lost a few of the studs from corrosion. I've decided to go down the rubber well-nut route in the first instance, as I'm having trouble finding full aluminium rivnuts. I'm using A4 stainless (marine grade) bolts and A4 stainless penny washers and this should hopefully keep things secure for another 13 years at least. I think one reason that some haven't had great success with rubber well-nuts so far is that the holes they pass through need to be properly de-burred to avoid chafing through the rubber. If it doesn't work out, I will just have to put faith in some rivnuts and hope that they're actually alloy, not zinc plated steel.
 
Good thread that and it's given me the inspiration to do the job on Tank. I heard that A2 Cars were offering some kind of bonded in remedy for the corroded studs, but wasn't going to go down that route. Most of the rivnuts I've come across are either steel or plated steel, hence my reticence to use them. I've use rubber well-nuts in the past on automotive projects and don't see why they shouldn't work here (as long as the holes they're fitted into are de-burred properly). They have the advantage of not reacting at all to any of the components around them and the brass inserts will not react to the bolts used either.

I've got a right angled compressor driven drill and grinder at the ready, so I can work under the car just on axel stands and am really just waiting for a bit of warmth and a day off to get it done - the rattling shield on the centre tunnel is driving me bonkers.
 
I've attached 2 photos of the front and rear assemblies you mention and you can point out the bolts from there (and possibly get a better idea of what you're dealing with too). All bolts are still available from Audi parts departments or TPS (my favoured parts supplier) or even VW Van Centres and are worth paying the extra for peace of mind and protection from galvanic corrosion.

View attachment 32647

View attachment 32648

3, 5 and 9 on the first picture and 10 on the second thank you.
 
Brilliant - if you take a trip to your local TPS (Middlesborough or Leeds appear to be the nearest, or even better, call them up with your VIN and the following part numbers, they'll be able to order them in for you to collect.

Part numbers are:

3 - N104 162 01
5 - N104 921 02 (double check this - the part catalogue is quite confusing on this one)
9 - N909 830 02 or N909 830 01 (2 part numbers listed)
10 - N909 969 01

These part numbers should all be valid, but VW sometimes updates them with no notice. When you get prices, post back for info for others will you?
 
Thanks Skipton and will do. Got some pictures to post but struggling with that at the moment with that :(

Is there instructions anywhere on how to upload images please?
 
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Hi Spike I'm confident I identifed the rear bolts correctly. These are three of the front bolts:



This is my heat shield bought new 2003 and 140k miles, note the heat shield is in good order but the steel fuel pipe retaining clips are disintegrating have just gone on my things to do list:



It has lasted well because I fitted these rubber washers between the pressed steel nut and aluminium shield:

 
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When you get prices, post back for info for others will you?

Purchased the 4 bolts through the front sub frame yesterday. Two shown here:

vBceSef.jpg


Surprisingly expensive at £4.20 each.

They were expensive because I had supplied 4 of the larger bolts, one seen above, for securing suspension rubber housing to the shell. So the big bolts are £4.20 each.

I can't advise the price of the 4 smaller steering rack bolts because they were supplied as FOC replacements for the bolts supplied in error.
 
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