Quick exhaust manifold bolt question
Thread Starter
|
Senior User
Joined: Sep 2004
Posts: 475
Likes: 0
Quick exhaust manifold bolt question
I've decided I'm just going to replace the studs with M8 x 1.25 x 35 stainless bolts which from what I've read is fine instead of buying the high dollar factory studs.. I was just wondering do I go with stainless lock washers or just stainless flat washers? I'm assuming locking ones but, wanted to be sure. Also, wheres the cheapest place to buy them? Home depot, local hardware store, or?
Thanks,
Kyle
Thanks,
Kyle
Posting Guru
Joined: Mar 2005
Posts: 2,060
Likes: 7
From: Burnsville, MN
Now this will be interesting, because there are different grades of stainless steel. For instance, some stainless will attract a magnet and some will not. Somehow I doubt Home Depot bolts would be good for a high temp automotive application. Lets see what the guru's say....
Hotshot
Joined: Mar 2007
Posts: 10,101
Likes: 40
From: Pa
The home depot bolts are more than likely 18-8 stainless bolts made by the lowest bidder. Bolts made out of 316 stainless are fairly common but they are still soft. Companies do produce hard bolts but they use a 400 series stainless or a special stainless alloy folowed by heat treat and passivation. Passivation is what brings back the SS rust protection. These processes really adds to the bolts cost. The problem with stainless bolts is they have a poor shear strength because they are softer than an ordinary grade 5 bolt. If it were me I would would use a grade 5 or 8 bolt with an ultra corrosion resistant coating which you can get from Mcmaster-Carr. The bolts on my 08' cover are steel bolts with that coating and 2 years later they are rust free.
Hotshot
Joined: Mar 2007
Posts: 10,101
Likes: 40
From: Pa
The OE replacements will eventually suffer the same fate. A couple years ago my dad got his replaced with OE replacements which are the same as the old ones they pulled out. My 04' came from the factory with stainless studs.
Hotshot
Joined: Mar 2007
Posts: 10,101
Likes: 40
From: Pa
I went with a set of long tube headers which solved the problem. If you want to retain the stock manifolds I would try a grade 5 or 8 bolt with a good corrosion resistant coating. The problem with the stock manifolds is they are thick, heavy and expand/contract a lot which is hard on the studs.
Trending Topics
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 423
From: Long Island USA
Use stainless flat washers.
And yes, the Home Depot hardware is probably "18-8" which is what is used on marine applications. The washers themselves would be perfect that way.
Not so sure about the bolts. But then, is aluminum better/harder/softer than 18-8 stainless?
See what "hardness" those Home Depot bolts are and report back.
And yes, the Home Depot hardware is probably "18-8" which is what is used on marine applications. The washers themselves would be perfect that way.
Not so sure about the bolts. But then, is aluminum better/harder/softer than 18-8 stainless?
See what "hardness" those Home Depot bolts are and report back.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 10 Most Expensive Ford Trucks Ever Sold on Bring a Trailer
Joe Kucinski
2027 Ford Super Duty Buyer's Guide (Every Model, Engine, & Package)
Brett Foote
Top 10 Ford Truck Tragedies
Joe Kucinski
AEV FXL Super Duty - the Super Duty Raptor Ford Doesn't Make
Brett Foote
Lobo Vs Lobo: Proof the F-150 Lobo Should Be Even Lower!
Michael S. Palmer
Ford's 2001 Explorer Sportsman Concept Looks For a New Home
Verdad Gallardo
10 Best Ford Truck Engines We Miss the Most!
Joe Kucinski
2026 Shelby F-150 Off-Road: Better Than a Raptor R?
Brett Foote
2027 Super Duty Carhartt Package First Look: 12 Things You NEED to Know!
Michael S. Palmer
Thread Starter
|
Senior User
Joined: Sep 2004
Posts: 475
Likes: 0
I'll check home depot tonight and let you guys know.
As far as a good grade 5 or 8 bolt with a good corrosion resistant... Where would I get them? I'd like to stay away from ordering online when it comes to nuts and bolts.
As far as a good grade 5 or 8 bolt with a good corrosion resistant... Where would I get them? I'd like to stay away from ordering online when it comes to nuts and bolts.
FTE Leadership Emeritus
Joined: Jul 2002
Posts: 42,561
Likes: 423
From: Long Island USA
Local auto parts store, NOT a name-brand one, had a load of stuff. I used "zinc plated" grade 8's to bolt up my ebay headers. With anti-seize on the threads, with lock washers, and 18-8 STAINLESS flat washers against the header flange.
Hotshot
Joined: Mar 2007
Posts: 10,101
Likes: 40
From: Pa
See what "hardness" those Home Depot bolts are and report back.
Tensile stregth (from McMaster.com)
18-8 - 100,000 psi Min
316 - 101,500 psi Min
Bumax 88 - 116,000 psi Min
Grade 10.9 - 150,00 psi Min Hardness 32-39 Rc (A file is roughly 62Rc)
Postmaster
Joined: Jan 2009
Posts: 4,584
Likes: 3
From: Chesapeake, Va.
I would buy grade or better aircraft or marine stainless studs and use red Loctite on them, in the heads, provided there was enough room to install the manifolds/headers and have 2 or 3 threads showing after waffle stainless washers and nuts were installed with a dab of antisieze on the threads for the nuts, of course.
Tuned
Joined: May 2010
Posts: 434
Likes: 23
From: Somewhere in Alaska
From the Loctite website
Probably not the best product to use on exhaust manifold bolts...
Loctite® Threadlocker Red 271™ is designed for the permanent locking and sealing of threaded fasteners. The product cures when confined in the absence of air between close fitting metal surfaces. It protects threads from rust and corrosion and prevents loosening from shock and vibration. It is only removable once cured by heating up parts to 500°F (260°C).