Bolt/washer sizes...

[Toaster Pilot]

Trying to re-fit the exhaust manifold to my A6 and it turns out that the M10 studs that hold the manifold to the turbo are no longer available, and have been replaced with a revised part that is a simple M10X50 bolt. They're £7.58 each from Audi and need ordering from the factory so I'm just going to get a pack from somewhere else, at about £1 for 1000000000

Only thing is it says on the parts catalogue to use a washer with the bolt and lists a size "10,4x24x3" - this doesn't seem to relate to any size that a typical hardware place has against a washer, simply listing M10 and not any other information.

How can I be sure I'm buying something that's as close a match to what it should be as possible?

[Toaster Pilot]

I can't get one from Audi because of the lead time, I want to buy this stuff on my way home from work today and get the car back together - I'm just concerned that the OEM ones might be a bit thicker than what I'm going to buy but if it won't cause issues than I'll just go with it

[Toaster Pilot]

I've also lost a couple of the nuts for where the manifold joins to the block - they're copper and I'm not sure I'll be able to get copper replacements readily/quickly, would I be OK to replace them all with stainless or should I go and try to find a fastener specialist place that will stock more obscure stuff?

[Toaster Pilot]

doogz said:

10.4 is the size of the hole in mm. 24 is the outer diameter, in mm. 3 is the thickness in mm.

Really though, anything will do.

That's a 'large' M10 washer. A normal sized one is 21mm OD.

Just noticed this post - awesome, thank you.

[Toaster Pilot]

ianrb said:

The nuts will not be copper, they will be steel with a copper coating. Just use a normal nut and a dab of Coopaslip.

I think they're self locking though.... can't find any in stock locally

[Toaster Pilot]

doogz said:

Toaster Pilot said:

I think they're self locking though.... can't find any in stock locally

What sort of nuts are they?

They won't be nyloc. If you tighten them properly, they should be fine, could fit some spring washers if you're worried?

ebay link

They're like that.

I've bought 3 high tensile steel M10 bolts with washers, 20x standard m8 nuts, 20x spring washers and 20x flat washers, for £3 from a local place - so that's my plan at the moment with some careful checking that the 50mm bolts are going to be fine with the slightly thinner washers.

Edited by Toaster Pilot on Monday 27th January 12:55

[Toaster Pilot]

They're in the car (I'm at work ) but I'll have a look later - any particular grade I should be looking for?

[Toaster Pilot]

- I'm an IT guy who is trying to learn general spannering/car maintenance and failing, so I bow to your superior knowledge.