Club 80-90 Forums

My mechanic I sometimes use says SS Nuts on SS bolts is a bad idea as they bind together? Has anyone had this happen? I am just about to fit my new ss exhaust & was going to use new ss bolts & nuts.
Thanks

Hi

If they are of the same grade, there should be no problem, built boats for years, only used 316, never had a problem, even with the salt water., squirt of oily stuff will never hurt anyway.

Mark

They'll always undo and always be the same size as when you put them there.

Ian.

It's only really a problem when air tools are used to run them down a thread if they are not oiled first as SS has no natural lubricant and the heat generated can cause them to bind.

I'll agree with your mechanic, SS nuts & bolts are a swine.

Lost count of the times I've had to hacksaw SS bolts in the most awkward of positions because the threads have bound. Bad idea full stop.

Ask anyone on the mechanical side of industry & they'll tell you the same.

High tensile bolts are what you want, with some coppaslip liberally applied.

2 for Yes, 2 for No, LOL, Thanks

Use brass nuts.

If the nuts and bolts are manufactured as matching components then I don't think you will have a problem. I aquired a whole bunch of stuff from a street furniture installer (Lighting and signs) and use it everywhere - even the 8mm fixings on my exhaust. In aerospace applications (which I think is typical) the clearance is adjusted to limit binding. Of course overtorqueing - which most of us do - will bind a SS thread more than steel or brass but at least you will avoid rusting. You will find that the M8 thread more or less self locking as was the imperial thread used by Dexion prior to metrication. I do agree that stainless steel will bind at the slightest oportunity though - particularly irritating in telescoping tube applications.
Vheers
Wolfie

I just happen to be dealing with this issue at work at the moment - thousands of pounds of research going into researching this. The issue is known as galling and it is most common with identical grade stainless bolt and nut. It is usually an issue if you've over-torqued the nut in the first place. Unfortunately A2(304) and A4(316) grade fittings are too similar to offer any cure for this. Best results we have found are coatings on the thread, either applied and cured or just brushed on. Our applications are running at 650C but there are still high temperatrue lubricants available that work at this level.

i remember making a st steel thread gauge on the lathe to check a thread i screw cut in a stainless steel component, as an apprentice years ago.... the two parts jammed together so well you'd think they were welded! absolutely wrecked both parts trying to undo them, stainless and stainless WILL bind together, (without the right anti seize coating applied) brass nuts def the way to go.

I've struggled in the past getting stuff undone, I try to use dissimilar metals on exhaust parts, stainless bolts and copper coated steel nuts.

use titanium and you cant go wrong, a tadge more expensive, for the exhaust to heads I think it cost me £30

Simon Baxter wrote:I've struggled in the past getting stuff undone, I try to use dissimilar metals on exhaust parts, stainless bolts and copper coated steel nuts.

I'd do the same
or at least make buisy with the copperslip