Who'd be interested...stainless bolts?

[supercharged spaniel]

First things first I'm not going to take credit for any of this I am mearly helping things move along.  Nick has been the one who got me looking and put me in the right direction and we've talked about it on and off.

Anyways there is a company just a few miles away from me that specialises in stainless bolts, fastenings and so on.  Nick had mentioned that he had started to replace the bolts around the engine/bay with stainless ones from the company and sent me the link.  On first sight it's a daunting and ridiculously tedious task of trawling through sussing the sizes etc.  For anyone who isn't aware stainless doesn't rust.  I've bought loads of bolts new from VAG and they're already starting to rust.

Anyways moving on,  I have spent best part of every moment I've had free today inbetween Solidworks training lol on the net cross referencing and ordering bolts, washers and so on for as many things as I can think of.  I've used Vag cat, my memory and a mircrometer in my engine bay where I can't find a thread length getting the right sizes.  The company is easy to order from and I've quite un economically ordered 2 orders today as it wouldn't save a cart and I had to leave it half way through.  So please have a look at the list, there are some I have yet to add as I'm a little uncertain what sizes as yet, charger elbow bolts and T piece bolts  (Nick wink wink lol).

What you'll be all pleased to know is they cost buttons.  All the stuff I've ordered today including the big beasty charger pivot bolt has cost me around 12 quid and thats two orders both with seperate postage costs.


Apart from the few I've mentioned that still need adding that's pretty much covers all the bolts visible around the engine.  Think of any wack em up and sizes if you know them and I'll find them.  In a week or so and when I get mine ordered and have ironed out any discrepancies I'm going to ring the company and organise a G40 set that is available off the shelf.  I don't persoanlly see the need for the club to buy sets in (although you might want to) but a link to the website and the option to click 'Polo g40 set' would be great as there are some for other cars already available.

The ones underlined need to be confirmed by me as I'm not 100% sure yet but will let you all know asap

 
Intercooler support bolts (2 lower 1 upper) & front panel plastic tool tray x 2 M6 x 25 Hex Setscrew DIN 933 A2 (DIN933M6x25) @ 0.20 each

Intercooler fastening washers (lower 2) x2 M6 Penny Washer 18 x 1.6mm (DIN9021M6) @ 0.08 each

Intercooler upper fastening, washer M6 Washer form B (BS4320M6) @ 0.03 each


Intercooler lower brace securing nuts 2 x M6 Hex Dome Nut DIN 1587 A2 (DIN1587M6) @ 0.35 each OR 2 x M6 Nyloc Nut DIN985 A2 (DIN985M6) @ 0.13 each (to be confirmed)

Intercooler upper support bracket bolt 10mm x1 M6 x 10 Hex Setscrew DIN 933 A2 (DIN933M6x10) @ 0.15 each

Lower front radiator support bar bolts 13mm x 4 M8 x 20 Flanged Hex Screw DIN 6921 A2 (M8 x 20 [QLJUWC]) @ 0.52 each

Charger boost pipes 5mm Allen heads x 4 M6 x 10 Socket Cap screw DIN 912 A2 (DIN912M6x10) @ 0.16 each
4 x M6 x 20 Socket Cap screw DIN 912 A2 (DIN912M6x20) @ 0.20 each

Radiator front panel bolts x 2 M6 x 30 Flanged Hex Screw DIN 6921 A2 (DIN6921M6x30) @ 0.40 each

Charger pivot bolt 1 x M12 x 110 Socket Cap screw DIN 912 A2 (DIN934M12 @ 2.18 each


Throttle body elbow 6mm Allen heads x 2 M8 x 1.00 x 20mm Socket Cap screw A2 (DIN912M8x1.00x20) @ 1.15 each

Front panel plastic tool tray washers x 2 M6 Washer Form C (BS4320CM6) @ 0.06 each
 

To be added.....
Charger elbow bolts
T piece bolts

[supercharged spaniel]

You could also have charger casing bolts actually.  Damn it didnt underline them.  A complete list will be posted soon.

[gurtbonger]

a good idea!  ill b getting a kit.

[Yoof]

Dan- sounds like a good plan, just be careful with stainless bolts, unless you pay for good quality ones, the cut of the pitch is crap, and they're not very nice to work with.

Also I'd not use them with anything that get very hot (exhaust manifold, or bolts around the charger).

[Nick_S]

Good gear from this supplier, and quick hassle free delivery too. They will be A2 grade stainless, which is good enough for a car. A4 grade (marine/food) is better quality with less iron in, but many of the sizes are hard to get hold of.

Here is the spec of the charger pivot bolt from them:

M12 x 110mm Socket Capscrew
ISO Coarse thread
 sale quantity one unit
Major Diameter 12.00mm
Thread Pitch 1.75mm
Length under head 110mm
Thread Length 36mm
Hex Wrench Size 10mm
Cap Height 12mm
Cap Diameter 18mm
Thread Included Angle 60°
Material Grade A2-70 (304)stainless.
Manufacture Cold-forged, Rolled Threads
Applicable Standard DIN912
Alternative nomenclature Allen Screw


Cold forged with rolled threads = good gear

[PeteG40]

i'd be tempted to use a4 on anything which might take any strain whatsoever as a2 stainles is weaker than the bolts you'll be replacing

[Nick_S]

Aggreed. Anything holding a high load like suspension parts should still use OEM bolts. Most of these are hidden from view anyway.

[supercharged spaniel]

Yeah good point pete to be fair.  But none of those really get super hot or hold a lot of tension. Even the rad support bar bolts don't hold that much weight.  so as long as we stick to oem for major strength points like suspension.  How have your charger elbow bolts held up nick? They're the only ones I'd think would gather or be subject to real heat?   

[Yoof]

'A2' Grade as you put it is shite.

Personally I don't like stainless bolts their yield strength is less than that of a steel bolt, even an A4 grade is just above a 8.8 steel bolt, but far less than a 10.9 from what i remember.

Stainless also has higher friction than steel- so when torquing bolts up properly, you're actually getting less preload for a given torque value.

Also for anyone using windy guns on stainless bolts, make sure they don't cold weld.

^ The above are reasons why I don't use them. But they do look better, and don't rust (but still oxidise over time).

[Nick_S]

Not had any problems with the outlet elbow bolts. Aluminium will melt/break before stainless steel anyhow, so not a real concern for me. The bolts which have been replaced on mine don't get a torque wrench on them even when OE.

[supercharged spaniel]

Well personally I'm not worried about small bolts used for mounting stuff like radiators and so on but like has been mentioned, for things under load the originals are best left as they are. These Listed are mainly for cosmetics/aesthetics.  With that in mind Id say what I've listed and the charger elbow bolts are probably all that's needed. The rest are things like engine mounts and manifold nuts/bolts which are best left. The crack inlet mani bolts make when you crack one of those loose always makes my arse nip lol. 

[Fred]

A2 is 304 Grade
A4 is 316L Grade
 
Used to weld a lot of stainless handrail at work and it
was 304 but we always used 316L welding rods to put
some goodness back in.

One thing to be sure about is if your putting stainless bolts
into alloy then put some Silicone grease or blue Hylomar (good for vibration)
on the threads 1st as it may start an electrolysis reaction wich will eat away at the alloy
with no detriment to the stainless at all.
Better still, buy new OEM.

Fred.

[Nick_S]

Cheers Fred.

I copper slipped mine to keep chemistry happy in there

[scotsjohn]

A2 is 304 Grade
A4 is 316L Grade
 
Just a wee bit of input for enlightenment, the 304 and 316 are the respective percent content of nickel, chrome and molybdenum in the steel. Stainless is a bit of a juggling act to give steel abilities outwith the norm ( ie nickel improves low temperature performance,chrome improves resistance to oxidising and moly gives good wear characteristics).  Just don't put too much
faith in it for anything other than low stress fastenings.

[supercharged spaniel]

Some great input here guys. Nothing I've bought stainless bolts for, hold any real stress/weight so I'm happy but it's nice to know a little more detail about when and when not to use stainless.