which bolts for chassis and suspension?

[mille-schwarzfahrer]

For the restoration of my S3, replacement of all chassis and suspension bolts is needed.

 

Your expertise please: Which grade / strength is required or recommended? "Grade 8" or higher? DIN 8.8, 9.8, 10.9 or 12.9 ? Does it make sense to use generally 12.9? What do you use? Where to get socket (Allen) head bolts in the correct length and for a decent price thru internet? For other, low strength applications: Where to get "Imperial" alloy bolts?

 

Thanx, Friedhelm

[Sheds Moderator]

"screwfix" in the UK will supply UNF fastenings of all shapes and sizes. Nice project, if it were me I might go overboard and use stainless.

[Paul McKenzie]

Don't use stainless -they're not strong enough. If you do use them, only for wing bolts, and other non-stressed applications.

 

Go to Namrick's site and get their standard High Tensile stuff by ordering on the web....I think it's 8.8. 12.9 is overkill and not easily available for all sizes..just use that for known weak areas e.g. radius arm bolts

 

http://www.namrick.co.uk/

 

Nice project,

Paul

[R2D2]

I can't see any reason to use 12.9 Grade bolts in many areas on a Seven. 10.9 should be adequate and generally more readily available.

 

Some of the older UNF bolts may be marked S,T,V or X as an alternative and this is a guide to the material strength. X being the strongest.

 

I would use S or T for nearly all chassis applications and X for bolting calipers halves together.

 

It is not always a great idea to swap hex head fastners for caps in highly loaded applications as the load bearing area under a cap head is less than a hex head.

 

Be careful about using stainless fastners in stressed applications as most commercially available stainless bolts aren't very strong and could break if you use them for suspension or steering.

 

I have never seen any imperial alloy fastners, only metric but Nylon and Alloys in London have a good range at reasonable prices. It may be worth doing a web search in the USA.

 

 

[P Brews]

In any critical area (suspension, brakes etc.), I would only use 12.9 fastners and would specify Unbrako.

[deanteam]

Have you considered calling someone like Redline +441883346515, who have experience with suppling older Lotus/Caterhams. They might be able to put together a 'package' of nuts and bolts for the chassis. It may be a little more expensive but might save a lot of hassle. Have you posted on www/seven-mania.de, there might be other seven owners that can help? We are based close to Konstanz in CH.

[Sheds Moderator]

You can get high tensile stainless, we use them in the food industry where everything but everything has to be one grade or another of stainless. I'd imagine they cost some money though and i don't know where you would get them without buying a gross of each size. As ever, UNFs are getting scarce...

[mille-schwarzfahrer]

Thanx for all your input - very useful.

 

One more question: Are you mixing metric and imperial bolts at your cars? Is there any kind of system behind?

What about all those lightweight alloy fasteners for low strength applications? All metric only?

 

Cheers, Friedhelm

[Sheds Moderator]

Yes, we do mix fasteners! On your S3 it will be all UNF though (I think). Maybe UNF nylons are available but there would be no harm in using metrics with the appropriate nuts. IIRC the modern rivnuts are metric anyway.