Best bolts/nuts for exhaust

[squelch]

I am adding a Fabspeed pre-muffler to replace my cat. Looking for recommendations on hardware. I read another thread that mentioned silicon bronze nuts along with stainless steel bolts, but can't find anyone around here who has heard of these silicon bronze nuts.

My local store has the stainless steel bolts and nuts. they also have bronze lock washers and brass nuts.

What would you guys recommend in order to keep this as rust free as possible. Source suggestions for the silicon-bronze nuts would be good too.

Thanks,
Chuck

[RoninLB]

stainless needs care.. i only use marine stainless

silicone bronze at marine store

[KFC911]

McMaster-Carr is where I got mine. I assume you've read Wil Ferch's posts...those are what I'm using.

edited: ps: Chuck, how many do you need in all, I might have some extras I can spare.

[hcoles]

our host sells bronze/brass? barrel nuts and washer head nuts for exhaust systems - they work and you can get them off when needed.. I switched all mine to this type.

[squelch]

Thanks for the input guys.

stainless needs care..

I'm not really sure what that means. Maybe you could be a little more specific.

KC,
I did read Wil's post and would love to take you up on your offer. I need 9 nut/bolt/washer combos. I already have regular local hardware store grade stainless steel 5/16" bolts and don't have anywhere local to get Marine grade hardware. I don't know where to get the silicon bronze locally. It looks like you have to order in bulk from McMaster-Carr. If you have the proper stuff, I would like to buy it from you.

Thanks,
Chuck

[3.2 CAB]

Chuck, what they are talking about with the plain stainless fasteners, is that they have a tendency to gall, and at times after a few heat cycles they tend to loosen, and when you try to tighten them, they might have already galled the threads, and when you do tighten them the threads will sometime start shearing off, due to the galling problems associated with standard stainless steel fasteners. There are many types of excellent fasteners available, anything from hardened copper alloys, the Si/bronze, marine grade stainless steel, etc. I would advise to avoid the local hardware store stainless steel fasteners, due to their questionable composition. But, with whatever fasteners that you do decide to go with, use a hi-quality anti-seize compound on them. Good luck!! Tony.

[javadog]

I use the standard hardware Porsche sells for this application. Never had one fail, loosen, whatever. Not that expensive in the long run. What, $30 or so, for the lot?

JR

[Quicksilver]

"Stainless" is a class of steels that has over 11.5% chromium in it. It does not mean that it won't rust! It means that it has some resistance to corrosion. Depending on the alloy it could just mean that you heat it to 200°+ and it will rust. The cheap stainless at the local hardware store won't do it for an exhaust system. MB911 would know off the top of his head what type of alloy you would want for the exhaust system.

I swear by copper lock nuts. The will do a better job on ordinary studs then good stainless on stainless will.

[hcoles]

I agree with Quicksiver.. my experience with garden/unknow variety of ss nuts/bolts on the exhaust system hasn't worked out very good. I just about couldn't get anything apart. Went to plain steel with a ton of anti-seize or combination of copper/bronze and steel with a ton of anti-seize - now easy to get apart. I take most of this apart every two years.. and reinstall.

[Quicksilver]

To add to hcoles comments...
It is worth the trouble to go and find a copper based antisieze. The aluminum based antisieze that is available everywhere is junk for this application.

[javadog]

The other thing you need to think about, apart from the choice of materials, is that the nut needs to be a lock nut, and one that can tolerate the tempertures expected in an exhaust system. This rules out most of the more common locknuts that you will see at a hardware store. That fact, coupled with the need for a specific material, pretty much forces you to use something designed specifically for the job.

Any particular reason you are trying to reinvent the wheel, as opposed to just buying hardware designed for this installation?

JR

[911Freak]

I take it "case hardend grade 8" bolts and nuts won't suffice? These are the "gold" looking 120 thread bolts.... Not made to handle the ex temps? 400degrees?

[RWebb]

Well, Ti has fabulous corrosion resistance and is used for certain marine applications - scuba respirators, etc.

For the more mundane among us, I just use Cu base anti-sieze (it is copper colored, not silver) and the regular Porsche hardware -- just as JR mentions.

How far out do you want to go?

[Wil Ferch]

As I said in my many posts on this subject...no need to use messy anti-seize and the 5/16" stainless combined with Si/Br nuts are the way to go to get removability without the anti-seize paste mess. Don't need locking type nuts but I've double-nutted mine just in case.

No issues...and better than carbon steel stock.

[911pcars]

"Not made to handle the ex temps? 400degrees?"

Unless the fasteners are for some super-mojo turbo system, ordinary muffler bolts won't see these temperatures. The regular factory-type plated steel fasteners work just fine with antiseize so they can be separated after awhile in service.

Stainless and bronze and copper may be better, but it's also overkill in this application.

MHO,
Sherwood

[RWebb]

And neither Porsche nor anyone on this forum would do anything approaching OVERKILL, would they?

[squelch]

All this input is great. I really appreciate it. I am not trying to reinvent the wheel here, just trying to find some decent hardware. Today I finally found a local distributor that sells the higher quality bolts, though I am still finding it difficult to find the silicon bronze nuts. I could have ordered from McMaster-Carr, but didn't want to order in bulk or wait for the shipping time. I am anxious to get this pre-muffler installed. I ended up buying 316 Stainless bolts, nuts and lock washers. Hopefully this will be sufficient.

On a related "bolt" note... I just realized that my Fabspeed premuffler didn't come with a bolt to plug the O2 sensor hole, so now I'm out again to find the right size for that.

Thanks again,
Chuck

[911pcars]

All this time spent finding optimum muffler bolts could be put to better use finding the correct O2 sensor bung hole plug. Nothing personal. There are those among us still searching for the elusive muffler bearing.

BTW, Toyota truck oil drain plug.

Sherwood

[Porschekid962]

For nuts, bolts, fasteners, plumbing, there is one source that beats all. They have everything and supply a huge amount of race teams in the states, F1 teams, heck they even supply Boeing.

Coast Fabrication in southern CA.

www.coastfab.com

16761 Burke Lane.Huntington Beach, CA 92647.

Phone: (714) 842- 2603.Fax: (714) 847-1824

[911Freak]

Ahhh yes the elusive chrome muffler bearing! that polished or plated LMAO!!