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JOW240725

Member Since: 04 May 2015
Location: Suffolk
Posts: 7907

2012 Defender 110 Puma 2.2 XS CSW Orkney Grey

BZP or Stainless steel bolts

I am hopeless I'm afraid... just looking to bolt on some bumperettes and wondering if i should use BZP or stainless bolts? Thank you.

24th Oct 2015 10:44am

Screbble

Member Since: 26 Apr 2015
Location: Lancashire
Posts: 2108

2004 Defender 90 Td5 XS CSW Zambezi Silver

My two penneth in an attempt to help....

The attraction to stainless steel is the corrosion resistance I guess, but possibly at the expense of tensile strength and at the risk of reacting more quickly with any aluminium etc.

So there are benefits and disadvantages - and this excellent forum has lots and lots of info on the subject. And I mean lots - just search.

BZP or any plated steel fasteners are closer to 'standard' and will serve you well without causing you too much trouble. There's an increasing trend to move away from stainless for the reasons stated and more. Again this forum will prove invaluable in that regard.

It's personal choice - except if it's a situation where tensile strength is important (and stainless will most likely be a no no)

BUT.....

It is important that you use a paste/grease of some sort (ceramic is good) to keep dissimilar metals happy - granted that may not be the case for your project but worth bearing in mind for the future.

All of the above is only my opinion of course!

PS I like stainless in the right application - personal choice

24th Oct 2015 11:10am

leeds

Member Since: 28 Dec 2009
Location: West Yorkshire
Posts: 8582

Re: BZP or Stainless steel bolts

JOW240725 wrote:
I am hopeless I'm afraid... just looking to bolt on some bumperettes and wondering if i should use BZP or stainless bolts? Thank you.

I presume by bumperettes you are referring to rear bumperettes or rear corner protectors?

Stainless steel will be fine. You are hardly likely to be putting massive tensile/shear or shock loads through rear bumperettes.

There are many grades of mild steel bolts as there are stainless bolts.

The most common mild steel bolts are referred to as 8.8 and the most common stainless bolts are normally referred to as A2and less common is A4

The 8.8 mild steel bolt typically has a minimum strength of 800 MPa and yield strength of 640 Mpa

A2 stainless bolts typically have a strength of 700 MPa and yield strength of 450 MPa.

With stainless nuts and bolts you can get galling or cold welding this can be avoided by using an anti seize paste.

Galvanitic corrosion will occur between dissimilar metals and this includes mild steel to aluminium as well as stainless steel to aluminium which has a bigger effect. To prevent this you need a good barrier between the dissimilar metals such as a good paint finish or powder coating, a plastic washer or anti corrosion paste.

Nakatanenga supply suitable paste with all their stainless bolt kits..

So after a long possibly tedious explanation stainless bolts will be fine to attach rear bumperettes with the use of a paste/insulator.

For high strength use I would go for 10.9 or 12.9 bolts and forget the 8.8 bolts

Brendan

24th Oct 2015 1:31pm

Cupboard

Member Since: 21 Mar 2014
Location: Suffolk
Posts: 2971

2011 Defender 110 Puma 2.4 HT Corris Grey

Another option for slightly more corrosion resistance than BZP is galvanised bolts.
Thicker layer of zinc and not shiny.

24th Oct 2015 2:39pm

mikeh501

Member Since: 07 Jan 2013
Location: United Kingdom
Posts: 1142

Goto Westfield fasteners. Get some a2-70 bolts, nylocs and washers. Your good to go.

You won't need high strength for that apllication.

24th Oct 2015 3:27pm

Silver Back

Member Since: 11 Jun 2015
Location: Lincolnshire
Posts: 407

1998 Defender 110 300 Tdi HT Coniston Green

+1 for Westfield. I've brought quite a lot of stuff off them in the past and very pleased with their service and pricing.

They also sell a higher tensile strength stainless fastener if required for other applications.

24th Oct 2015 7:51pm

Mike_B

Member Since: 23 Jan 2011
Location: Moray
Posts: 550

I use a2stainless.co.uk
Fast service, good prices. 10% discount too.

24th Oct 2015 9:01pm

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