Best practice - nuts & bolt replacement

[TomB]

During the rebuild of my car, I was planning on replacing the fasteners, but Im wondering if its its necessary apart from being nice and shiny!  I know you should replace nylocs as the plastic locking ring wears, but what about the bolts?  Do bolts fatigue and need replacing?  Should I just clean them up in vinegar/coke in the kitchen and reuse them, or would you replace them? 

I suppose they are 23 years old, and by the time I rebuild the car again (if ever) they could be 40plus years old.  So I think I've inadvertently answered my own question - I probably should! Do you concur? 

 

 

[ECR]

If you're removing them, I'd replace them. They would all probably be ok strength wise but for the small cost of replacement its not worth reusing. Make sure you replace like for like though ...

[Jonathan Kay]

Have you found the bolt list and fastener packs?

Jonathan

[andydavy]

Probably controversial but I'd replace everything with stainless steel

 

[Wrightpayne]

VW group cars seem to have single use stretch bolts everywhere that are extortionately expensive! 

[TomB]

Thanks JK.  Ive given a list of bolt to Chris at Redline and he's doing the hard work for me! ​Ive asked Chris and they are zinc coated nuts and bolts, not stainless, but equally not mild steel.     

[Jonathan Kay]

Probably controversial but I'd replace everything with stainless steel

What specification would you suggest for safety-critical bits such as suspension and steering?

Jonathan

[rj]

Don't use stainless for anything safety-critical. They then to be a lot more brittle than you want. They will also make both chassis and bushings (milder steel) corrode.

Tom: Be aware of the tensile strenght of the bolts. They are not all the same grade. Imperial bolts have different markings that mean something like 4.4 to 12.9 on a metric bolt.

[andydavy]

Should have said I would not use SS for anything need high tensile rating.

[SLR No.77]

Stainless bolts are lousy under a shear loading, anywhere non strength-critical though they're fine. 

[elie boone]

On anything non critical i use alloy bolts.

[rj]

On anything non critical i use alloy bolts.

+1 - or even nylon.

[revilla]

Don't even think about using stainless steel for critical load bearing bolts, especially where high tensile bolts were originally specified such as on suspension etc.

[TomB]

Hi Everyone, 

Im letting Chris @ Redline pick my bolts, and I see on the itemized invoice the hardness bolts (8.8, 10.9).  I'll stick to standard zinc coated steel I think, Ive got enough on my plate with the rebuild to start ordering SS or alloy bolts for different places on the car. 

But for interest, what would be considered critical and non critical?  As Im think about the rear suspension, diff, prop, roll bar at the moment, all these are considered 'critical'.  'Non critical' could be the bolts fasting the windscreen to the scuttle and the plastic one for the rear wings, and exhaust but Im struggling to think what else.  

 

[Bizzielizzie13]

Back in the day when I had a competition car, a wise works technician said, 'if you have any doubt, try the float test-if it does-use again'!