Stainless bolts

[Oily Fingers]

First, sorry if this is in the wrong section.

Where is the best place to get stainless bolts (to the correct strength) to use on rebuilding the polo?

want to use them on places such as, the sump bolts, engine mounts. And other round brackets, and suspneion arms.

joel

[PeteG40]

i'd not use them for anything load bearing as they are significantly weaker than hi-ten steel!

[AlexG40]

Yep, stainless is gay. Pretty, but gay.

[Jezza-7]

I bought some and then looked at the tensile after and it was no way near the Genuine vw stuff.

Antony on here bought some for is sump and when torqueing them up they all sheared as the tensile strength isn't enough.

I would get new bolts from vw as they are still available and there not too pricey. If your worried about rusting or corrosion i can get some really good stuff to stop it. Can get some stuff for the bolt shanks and then some other stuff for the heads/nuts that are going to be exposed to the elements. Cant say where i can get it but if your interested pm me. I use it on my car and its all free from rust etc.

[Oily Fingers]

well that is good to know,  thanks people!   i think my problem is i have to many ideas floating round.

jezza-7 expect a pm

[lance]

you can get zinc coated ones in all sorts of colours.

[dub-disaster]

I bought some and then looked at the tensile after and it was no way near the Genuine vw stuff.

Antony on here bought some for is sump and when torqueing them up they all sheared as the tensile strength isn't enough.

I would get new bolts from vw as they are still available and there not too pricey. If your worried about rusting or corrosion i can get some really good stuff to stop it. Can get some stuff for the bolt shanks and then some other stuff for the heads/nuts that are going to be exposed to the elements. Cant say where i can get it but if your interested pm me. I use it on my car and its all free from rust etc.

I didn't use stainless bolts for my sump I used 8.8 hex heads and they sheared so I replaced them with 12.9's for the record as stainles bolts on the aluminium crank seal plates would not be clever !!

[prankstar2003]

I've used stainless bolts all over my engine with no problems torquing up. The only exception was the tensioner stud (I'm not talking g40 here) as I didnt want to take the risk there.

Simon

[Yoof]

Thread about this yonks ago, my 2p:

'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).

[Fred]

As Yoof has re-posted

A2 stainless bolts are 304 grade stainless.
A4 are 316L basically having more Nickel content and do have a little more strength.

The Main worry of stainless to alloy is Electrolysis.

This can eat away the alloy with no detriment to the stainless at all.

So don`t use stainless bolts into threaded Alloy.

I`m surprised that even a stainless M6 bolt (10mm head) used for the sump has sheared
with such a low torque figure.
They must have been shite or summat.

I have used them on a sump before today to tempory replace knacked bolts
but i put a bit of Blue Hylomar on the thread so
to act as a decoupler and an anti vibration aid.

The fact that the bolts are exposed on the cast iron lip bottom of the block gives a good seal to keep the
threads in check.

I should think that being 18 year old or more the sump bolts will have had water on them many times
and resting on the Bottom of the block on the bolt ends with no protection would slowly eat down the thread.

We`re only looking at a 1mm pitch giving 1/2 a mm depth of thread pitch so any wear or rusting will have less
every time their messed with.

If you take some verniers and measure the sump bolt thread of a genuine sump bolt it will be a few thou wider than a
stainless equivalent wich will Probably be more wobbly part screwed in than an original bolt.

[prankstar2003]

I used built jetties and pontoons a while back. We only ever used stainless or ally for most applications with not detrimental effects bar binding when not lubricating stainless threads. These were large scale applications subject to many different strain forces. Never did we have a stainless bolt fail on us once installed and electrolysis was never an issue either.

[ereeiz]

Don't boats, other water based vessels and what not have those sacrificial plates bolted to them (like old Volvo's) to encourage the electrolysis to occur on the plate only? I remember a mate telling me all about it a few years ago, although I forgot most of it, that deffo rings a bell!

[Andy]

I used built jetties and pontoons a while back. We only ever used stainless or ally for most applications with not detrimental effects bar binding when not lubricating stainless threads. These were large scale applications subject to many different strain forces. Never did we have a stainless bolt fail on us once installed and electrolysis was never an issue either.

Presumably the design intent was to use stainless parts though? Not the same as on the car, where it's designed around the higher yielding steel fixings.

[Yoof]

A pontoon doesn't exactly heat cycle either....