I’m adding wedge shims from Mark at Breeze and in doing so need to replace the bolts. The grade 5 bolts appear to have held up rather well.
My pipes are ceramic coated as are the headers
In doing this mod, my bolts are too short and need replacing.
My question is what would you guys recommend for fastener material understanding the effects of galvanic corrosion in using dissimilar metals.
If I use stainless bolts, do I run the risk of advanced corrosion on the headers if the coating is compromised?
Also I see that it’s recommended to use wide flange, serrated carbon steel nuts. Not liking the idea of using carbon nuts on stainless bolts. Also the serrated nut I would think will compromise the coating when torqued down cause of how it’s designed to bite into its mating surface.
For those of you who have miles on your car and ceramic coating, how would you recommend it be fastened for longevity?
I’m adding wedge shims from Mark at Breeze and in doing so need to replace the bolts. The grade 5 bolts appear to have held up rather well.
My pipes are ceramic coated as are the headers
In doing this mod, my bolts are too short and need replacing.
My question is what would you guys recommend for fastener material understanding the effects of galvanic corrosion in using dissimilar metals.
If I use stainless bolts, do I run the risk of advanced corrosion on the headers if the coating is compromised?
Also I see that it’s recommended to use wide flange, serrated carbon steel nuts. Not liking the idea of using carbon nuts on stainless bolts. Also the serrated nut I would think will compromise the coating when torqued down cause of how it’s designed to bite into its mating surface.
For those of you who have miles on your car and ceramic coating, how would you recommend it be fastened for longevity?
No, NO, NO stainless! No deformed (stover) nuts either. My recipe is plated bolts, an internal and external serrated washer and deep brass nuts.
I've been using brass nuts on exhaust systems for over 40 years (including on about a hundred roadster sidepipes!). You don't get the galvanic corrosion or rust with brass and due to the thermal expansion properties between steel and brass they naturally tend to stay tight. Sometimes due to tight clearance between the sidepipe flange and body I use buttonhead bolts rather than socket heads. Also, when stacking up a combination of flange spacers &/or wedges if you assemble them to the sidepipe using high temperature RTV (Permatex Ultra Copper) in lieu of gaskets and let it set up you'll find it much easier than trying to manipulate a heavy pipe+gaskets+wedges into position while struggling to get bolts in place!
No, NO, NO stainless! No deformed (stover) nuts either. My recipe is plated bolts, an internal and external serrated washer and deep brass nuts.
I've been using brass nuts on exhaust systems for over 40 years (including on about a hundred roadster sidepipes!). You don't get the galvanic corrosion or rust with brass and due to the thermal expansion properties between steel and brass they naturally tend to stay tight. Sometimes due to tight clearance between the sidepipe flange and body I use buttonhead bolts rather than socket heads. Also, when stacking up a combination of flange spacers &/or wedges if you assemble them to the sidepipe using high temperature RTV (Permatex Ultra Copper) in lieu of gaskets and let it set up you'll find it much easier than trying to manipulate a heavy pipe+gaskets+wedges into position while struggling to get bolts in place!
Ok thx Jeff
I had ordered a few extra gaskets given they’re cheap and wasn’t sure how many I would need. Haven’t really used the temp chaulk. I’ll look at that.
Also thx for the heads-up on the fasteners. That’s just a grade 5 plated bolt socket head bolt then isn’t it?
And these bolts although they might be a little short if you're adding wedges.
Personally I don't like the mess of RTV, Remflex has some nice gaskets.
And in a rare instance of not agreeing with Jeff, any type of "lock washer" really isn't doing anything other than making you feel good. Proper torque to achieve stretch is what keeps nuts & bolts tight.
Prat & Whittney, Continental and Lycoming (aircraft recip engines) have been useing Brass exhaust nuts since World War II for a reason. They dont corrode and they dont loosen up over time......a very long time! Oh yea and they all use carbon steel exhaust studs. Seems to me like a good way to go.
Just like Jeff says, NEVER use SS bolts or nuts on an exhaust system, unless you like to cut things with a torch. Any good hardware store will have those bolts in the length you need
Mrk III, 331 stroker, Borla stack injection, T5, 3:55 IRS, Power steering and brakes. Kleiner body & paint
Thanks guys
It’s a good thing I knew enough about metallurgy to ask. Some guys think SS is always better and is stainless in all conditions which just is not the case…..but that’s a topic for another thread
Thanks for your guys feedback.
Agree. I almost never use SS. What really sealed the deal for me was 4-5 years ago I built a little trailer to haul trash to the dump. Since it sits outside I used 3/8 pvc sheet for the sides and all SS 1/4" nuts and bolts. 3 years later a small tree fell and knocked a 6" chunk out of one of the sides so I needed to remove just that side. EVERY on of those bolts/nuts was corroded together and had to be cut to remove.
FFR MkII, 408W, Tremec TKO 500, 2015 IRS, DA QA1s, Forte front bar, APE hardtop.
Agree. I almost never use SS. What really sealed the deal for me was 4-5 years ago I built a little trailer to haul trash to the dump. Since it sits outside I used 3/8 pvc sheet for the sides and all SS 1/4" nuts and bolts. 3 years later a small tree fell and knocked a 6" chunk out of one of the sides so I needed to remove just that side. EVERY on of those bolts/nuts was corroded together and had to be cut to remove.
Most of the “SS” we are used to accessing is 304 which is about as useless for most applications as you can get. It’s a cheap, generic material which allows manufacturers to state they’re using SS.
In the future if you’re able to isolate one metal from another, consider using nickel anti sieze on your fasteners from the nuts. Having said that it doesn’t help with the galvanic corrosion of dissimilar metals.
I’ve worked a lot with SS and nickels in the past.
In fuel cell development we used 347ss fasteners which withstand very high temps and the effects of sulphur. Having said that very expensive.
In oil and gas, we used a lot of 400 series SS due to resistance of adverse reactions of the components and the carbon/sulphur, etc, at high temp.
In marine applications use 316ss. Certain chemical make up helps it resist the acidic corrosion from salt and provided you use the “correct grades” of SS, use nickel based sieze and isolate one disimilar metal from another, they last.
A few years ago I built a house in Tofino on the ocean. Used aluminum for the gates, custom built steel hinges and all hardware was 316ss. All was isolated appropriately, aluminum and steel was all marine grade powdercoated, SS hardware was all engaged into steel posts imbedded in concrete using anti sieze. All that to make for 100% repairability and adjustment.
2 years in, not a spot of rust anywhere. Having said that it took a fair amount of planning and like I said earlier, so long as you know what grade SS you need to use for your application and how to execute the install, SS is a solid product.
But coming full circle back to the point of this thread, if I had SS pipes and headers, I’d absolutely be using SS hardware, not standard off the shelf stuff, but I’d source the correct grade and have it cosmetically appear the same and a one-and-done.
But given I am ceramic coated steel headers I absolutely agree with Jeff and others, plates with brass nuts all the way….
I've been in the food processing and packaging equipment industry my entire career and have extensive experience with stainless steel fasteners. As Doc said, most are made from 304 which is sometimes referred to 18-8. 18% chromium and 8% nickel. There is nothing fundamentally wrong with 304 SS fasteners as long as their qualities are understood like any other fastener. Hook's Law applies to stainless fasteners just like any other.
The issue I've seen when using 304 bolts with 304 nuts, as well as aluminum & titanium fasteners, is when they are assembled dry and gall. Galling can result in the fasteners becoming so seized that the part is no longer removable. This is also known as “cold welding” since the materials don’t heat up very hot, but act like they have welded together. My experienced with most stainless fasteners that have galled is the only way to get them apart is either twisting them in two or cutting them apart.
Using stainless fasteners without lubrication on the threads is like playing Russian roulette so don't. Using an impact wrench on stainless bolts & nuts almost guarantees galling. Lubrication is key with stainless fasteners, oil is okay but actual anti-seize is best. Or use dissimilar metals like stainless bolts with brass nuts like I did.
My experience mirrors Mike 100%. SS fasteners without lubrication, especially with nyloc nuts, is just asking for trouble. On the exhaust I used SS bolts with brass nuts (double-nutted for added thread-locking) and Permatex ultra copper RTV as both the gasket material and thread lubrication/locker.
MkIV Roadster build: Gen 2 Coyote, IRS, TKO600. Ordered 10/24/18. Delivered 1/29/19. Engine installed 8/8/21. First start 9/12/21. First go-kart 9/17/21. Off to paint 4/11/22. Back from paint 12/30/22. Build thread here.
My experience mirrors Mike 100%. SS fasteners without lubrication, especially with nyloc nuts, is just asking for trouble. On the exhaust I used SS bolts with brass nuts (double-nutted for added thread-locking) and Permatex ultra copper RTV as both the gasket material and thread lubrication/locker.
If you don’t mind me asking how long has it been assembled in this way?
Have you had it apart or had to make any adjustments?
If so how’s that worked out?
Thx in advance
It's been about a year and a half, and almost 1,000 miles now since I assembled them, and they've been working perfectly. I've had no issues and no reason to take them apart or make any adjustments other than to add some reinforcements to both the header ball flanges and the side pipe hangers to prevent the exhaust from sagging. That's all covered in multiple posts in my build thread (see link in my signature).
MkIV Roadster build: Gen 2 Coyote, IRS, TKO600. Ordered 10/24/18. Delivered 1/29/19. Engine installed 8/8/21. First start 9/12/21. First go-kart 9/17/21. Off to paint 4/11/22. Back from paint 12/30/22. Build thread here.
My experience mirrors Mike 100%. SS fasteners without lubrication, especially with nyloc nuts, is just asking for trouble. On the exhaust I used SS bolts with brass nuts (double-nutted for added thread-locking) and Permatex ultra copper RTV as both the gasket material and thread lubrication/locker.
Hokey smokes John! Even after cutting and reconfiguring the intermediate collector you still had to stack up 3 wedges That's even more severe than the pile of wedges that I had to use on one a couple of years ago (not FFR headers or pipes).
Hokey smokes John! Even after cutting and reconfiguring the intermediate collector you still had to stack up 3 wedges That's even more severe than the pile of wedges that I had to use on one a couple of years ago (not FFR headers or pipes).
Oh my I was wondering if 1-2 shims on my FFR pipes was a bit much in mine. (One on drivers and 2 on passenger)
Jeff just curious what kinda pipes are those, mated to what kinda power plant that needed that level of shimming?
Hokey smokes John! Even after cutting and reconfiguring the intermediate collector you still had to stack up 3 wedges That's even more severe than the pile of wedges that I had to use on one a couple of years ago (not FFR headers or pipes).
Yeah, Georgie added as much offset as he could to that collector but that side still needed to come back a bit more. It looks hideous but works just fine and nobody can see it.
MkIV Roadster build: Gen 2 Coyote, IRS, TKO600. Ordered 10/24/18. Delivered 1/29/19. Engine installed 8/8/21. First start 9/12/21. First go-kart 9/17/21. Off to paint 4/11/22. Back from paint 12/30/22. Build thread here.
Oh my I was wondering if 1-2 shims on my FFR pipes was a bit much in mine. (One on drivers and 2 on passenger)
Jeff just curious what kinda pipes are those, mated to what kinda power plant that needed that level of shimming?
I did development for Harley Davidson and Mercury Marine, both use stainless fasteners, Harley for aesthetics and Mercury for salt water durability.
Mercury had a fastener department and corrosion labs. They do have a corrosion test facility on the Gulf coast and they did contract work for other industries. The majority of SS fasteners went into aluminum. The crew at the FL test facility would not re-install any fastener without Permatex #3 on the threads, That sealed against oxygen and saltwater to avoid thread corrosion. Where possible they never used male and female SS fasteners, because of the galling Mike mentioned. Brass is OK but likely not up to grade five torque specs.
Harley styling liked socket driven SS flat and button head fasteners but the Service departments hated them, especially with countersink heads. The breakaway torque is high and the drive socket is small and shallow leading to stripped hexes.
jim
Jeff do you have a source you could share for the 1.5-2” zinc plated socket head screws for this application.
I live in the Vancouver, BC area and you sure wouldn’t think so but having a tough time finding these. Trying to find the simplest items is surprisingly difficult in BC lately. Not sure what’s up. Everything’s “gotta buy a box of 100”.
All the small mom and pop shops that I used to rely on have closed up shop
I’ve checked McMaster-Carr as well as all local hardware stores. Lots of black-oxide and SS. Heck I can even find aluminum and titanium……but not simple zinc plated.
I initially used SS socket head bolts, however, when I took the body off for paint, I replaced with ARP SS 12 pt. bolts with brass coupling nuts, and oversized SS flat washers. The 12 pt. leave plenty of room to get a socket or box-end wrench on them, and they are strong and nice looking. Haven't had them off since then, but no observed problems in 5 years.
If Brute Force doesn't work, you're not using enough of it. Basic Stuff: MK4 Complete Kit #8439, Wilwood's, 17" Halibrands. Extra Stuff: Stainless brake and fuel lines, Breeze cooling, Battery mount, SS Roll Bar. Old Fart Stuff: Heater, Seat Heaters, Footbox Fresh Air, Stereo, Keyless ignition, Power Steering, Hyd Clutch. Young & Dumb Stuff: 427w Dart, TKO600, 3 link Moser M9/Ford 9", 3.5:1, Eaton TruTrac Posi. Graduation Thread
Jeff do you have a source you could share for the 1.5-2” zinc plated socket head screws for this application.
I live in the Vancouver, BC area and you sure wouldn’t think so but having a tough time finding these. Trying to find the simplest items is surprisingly difficult in BC lately. Not sure what’s up. Everything’s “gotta buy a box of 100”.
All the small mom and pop shops that I used to rely on have closed up shop
I’ve checked McMaster-Carr as well as all local hardware stores. Lots of black-oxide and SS. Heck I can even find aluminum and titanium……but not simple zinc plated.
I just get them at the local hardware store. I'm not sure why you didn't find them at McMaster-Carr though>>>>
However, I suggest that if you think you might be using wedges you hold off on purchasing bolts until you can mock it up and determine the proper lengths. For example, 1 1/2" will do for flange to flange but if you have to add a wedge or spacer they may not be long enough and you might need to buy a box of 2" instead.
NO zinc plated bolts. Just use what every builder uses, the black socket head bolts like Factory Five sends.
Why no Zinc?
I don’t see anyone else using black oxide bolts other than for mock up. My build came with zinc plated and are too short using Breeze shims
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Originally Posted by Doc76
That's even more severe than the pile of wedges that I had to use on one a couple of years ago (not FFR headers or pipes).
