Went to buy my new stainless bolts today, for the front wishbones.
On inquiring I was told that they are NOT high tensile bolts (ie 8.8 etc) in fact the chap said that were basically the same spec as mild steel, only slightly harder.
I ended up getting BZP 8.8's.
Thing is how many of us are driving around with stainless bolts, thinking that all is well?

I've never seen stainless bolts of grade 8.8, although I'm not saying there aren't any, I think most people know not to use stainless in very high stress situations. worth repeating tho.....

Cheers

Chris

i just bought some bolts, from namrick which are high tensile, but it says they are grade s.
What is the difference between that and grade 8.8?
I take it they are strong enough as they make them for cars.

'S' grade is the imperial version of 8.8 (metric) There is no High Tensile version of stainless

we use a lot of stainless bolts where I work.

I asked this question of the supplier when he came to top up cos, one or two might find their way elsewhere.......

I cant remeber the grade but I was told they were fine for my application and that they used stainless in a car they raced.

atb

steve

Bolt Grades and Classes are often confused, especially Grade 8, and Class 8.8.
Class 8.8 is almost the equivelent of Grade 5.
Imperial fasteners use Grades i.e. "Grade 5 or 8". Metric fasteners use Classes, i.e "Class 8.8 or 10.9". They are not interchangeable.
Just for comparrison, Grade 8 = 150,000 PSI, and Class 10.9 = 1034 Mpa, which are as near equal as makes little difference.
The bolts commonly used to fasten on CV joints are Class 12.9...tough little ba$tards.
Grade 8 are ideal for suspension mounts, and Grade 5 are OK for just about everything else on your Locost.
Just don't buy any fasteners less than Grade 5, and you won't be tempted to use them in a critical location.
The highest grade of stainless fastener is 316-80, which is only about 116,000 PSI, and Grade 5 is about 120,000 PSI.
If you are using stainless fasteners with stainless nuts, you should use a lubricant compatible with stainless, as stainless threads can easily "gall", causing them to seize.

Bonjourno

I bought a load of stainless bolts from Newark show last year - various sizes. They all say 8.8 on the heads which I assumed was the grade (or class or whatever). What does it mean then? As well as the sizes, the labels on the plastic bags say '8.8 hexagon sets'. Que?

Liam

It says 'India' on bus tyres, but I've never known one to go that far!

quote:

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Originally posted by stephen_gusterson
we use a lot of stainless bolts where I work.

I asked this question of the supplier when he came to top up cos, one or two might find their way elsewhere.......

I cant remeber the grade but I was told they were fine for my application and that they used stainless in a car they raced.

atb

steve

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thats interesting......

as you know Viper, I work for a company that makes x-ray machines. Cos of this I am involved in stuff like density (SG) of metals and other materials.

Stainless steel measures under x-rays, and is quoted in tables, as being near as anything the same as mild in density - in fact most common metals have a density between 7 and 8.

The physics seem to show that a stainless bolt weighs very close to a mild steel one.

atb

steve

[Edited on 28/3/03 by stephen_gusterson]

Mark started it !!!!

Says BISTO on Buses but they don't sell it !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

One s/s bolt v one m/s bolt the difference would be un noticable but over a whole car? as an example pick up an 8x4 sheet of 10swg m/s then the same in stainless and then tell me there is little difference. Oh and another point to bear in mind stainless tends to bend a lot easier than mild steel, on the Tuscan we run we use a lot of aircraft spec K nuts and alloy bolts in non load bearing areas and we have managed to save a lot of weight, so much so we had to add weight to bring it up to the minimum allowed. I would be very surprised to see any race car using stainless bolts, i can't see any advantage, granted on a road car i can see the point in areas that don't often get looked at, but on a properly maintained race car every nut and bolt gets inspected and re tightened after every run, i would be interested to know what car and class they raced...
Rorty, i believe you are into buggies, a car that is run in probably the most inhospitable eviroments, do you use stainless fixings? and if so whereabouts?
Oh and i know there are different grades of s/s as there all metals but in my opinion, and this is just my opinion, s/s should never be used in a load bearing enviroment. (excepting foodstuffs etc).
of course i could be talking total billox and i am sure some one will be kind enough to tell me so.......

Liam:

quote:

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I bought a load of stainless bolts from Newark show last year

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quote:

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Rorty, i believe you are into buggies, a car that is run in probably the most inhospitable eviroments, do you use stainless fixings?

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I dunno how relevant this would be to this topic of s/s bolts compared to mild steel bolts but here goes anyway:

One of our suppliers (laser cutters) said something interesting to me the other day,

A 16mm thick stainless sheet would require the same settings to cut as 25mm mild steel sheet on his machine(30 bar nitrogen or something like that).

Does this mean that s/s is 64% stronger than mild steel?

cheers
darren

No, it's harder, not tougher and hence more brittle, ie it cracks easily. Thats why if you get a ss exhaust and look after a bit it appears to be going rusty! They have to use a crappy type to stop it falling apart.

No, its just got a higher melting point

over on TOL, Drr. Hess made his entire frome from S/S tubing. Is this a bad thing?

dave

I used to work at an IMI foundry where stainless steel was made. They sold steel to countries all over the world. Kanematsu Gosho was one firm in Japan who they supplied. The grades all had AISI numbers, like 316 and 304 etc. I used to load them into containers for transportation and I noticed that two of them,I think 431 and 416, which were used to make reinforcing bar both used to surface rust when exposed to atmosphere. I also remember that the scrap bins were divided into magnetic and non magnetic and 18/8 was a general term used for non mag scrap, which was sold off to cutlery firms like Viners.

yours, Pete.

I asked my bolt supplier (a local shop in Worthing called "the Nut House", appropriately enough) about s/s bolts and he said they have a lower shear value than 8.8 steel bolts... Anyway he didn't recommend them for the front suspension mounts - so I bought plated 8.8 bolts instead.

[Edited on 2/4/03 by Jon Bradbury]

Not wanting to put a downer on you, only thinking of your safety, but did you check the "plated" bolts were post treated? Depending on the type of plating, the bolts may suffer from hydrogen embrittlement.
If the fasteners are boxed, and from a reputable manufacturer, chances are, they're alright. It should say so on the box.
I always make sure any custom plating I have done comes with a certificate of post treatment by the plater. It's easy and cheap to do.