Grade 8 vs grade 5
Thread Starter
|
Post Fiend
Joined: Apr 2002
Posts: 5,964
Likes: 1
From: Woodruff, SC
Grade 8 vs grade 5
I'm in the process of putting bolts in the places where i removed the rivets and such on the frame with grade 8 bolts. I also want to replace the rear cab and running board mount bolts too but can't find G8 fine thread bolts for them. I've tried all the hardware stores around as well as HD and lowes.... No luck, Would G5 be ok or does anyone know of a place that might have G8's in fine thread.
Senior User
Joined: Jan 2004
Posts: 265
Likes: 0
From: Lancaster CA
In California we have a place called Fastenal they carry alot of the different bolts. I got a 3/4 fine threaded left hand tap from them once and remember they had all kinds of hardware in the store
Elder User
Joined: May 2006
Posts: 907
Likes: 1
From: Kansas City, Mo
Bolts
LMC Truck.com has those needed bolts. Don't know the grade. I know my ACE hardware has a large supply of bolts, including stainless. Aviation parts places have supplies of grade 8 bolts. In large cities there are bolt and rivit supply businesses. Have a great day,chuck
Cargo Master
Joined: Apr 2007
Posts: 2,063
Likes: 38
From: Valley Center, California
Not a simple question.
Most people think the higher the grade, the better. Depends on the application. The grade is primarily the tensile strength. That being said, the higher the tensile, the more brittle..... It can clamp like a mother but it might not take a hit as well as a more "rubbery" (for lack of a better term) bolt.
So if shear is a concern, higher grade isn't always better.
Anyway, I suggest you replace with what's specified. Stay away from the local outfits like Depot of Lowes etc. It's crap. Aircraft and Speciality Fastener places that have to comply with ANSI standards is best.
Dawg-A-Roo
Most people think the higher the grade, the better. Depends on the application. The grade is primarily the tensile strength. That being said, the higher the tensile, the more brittle..... It can clamp like a mother but it might not take a hit as well as a more "rubbery" (for lack of a better term) bolt.
So if shear is a concern, higher grade isn't always better.
Anyway, I suggest you replace with what's specified. Stay away from the local outfits like Depot of Lowes etc. It's crap. Aircraft and Speciality Fastener places that have to comply with ANSI standards is best.
Dawg-A-Roo
Trending Topics
Lead Driver
Joined: Jun 2005
Posts: 8,463
Likes: 724
From: Calgary Canada
Originally Posted by eman92082
So if shear is a concern, higher grade isn't always better.
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
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
10 Most Surprising 2026 Ford Truck Features!
Joe Kucinski
Lead Driver
Joined: Aug 2002
Posts: 6,682
Likes: 12
From: Saskatoon SK Canada
Sheer strength on a bolt is about 60% of the total tensile strength. A grade 5 bolt is about 120 000 psi and a grade 8 is 150 000 psi. You loose sheer strength on bolts over 180 000 psi this is where you get the brittle bolts. A grade 5 bolt will have failed way before a grade 8 bolt starts.
Go look at a farm equipment. They use shear bolts for protection of equipment. In many of the manuals it says to use grade 5 bolts and not to use grade 8 bolts or damage will result.
Just use coarse thread grade 8 bolts with lock nuts and you won't ever have a problem. Lock washers are useless.
Go look at a farm equipment. They use shear bolts for protection of equipment. In many of the manuals it says to use grade 5 bolts and not to use grade 8 bolts or damage will result.
Just use coarse thread grade 8 bolts with lock nuts and you won't ever have a problem. Lock washers are useless.
Last edited by 51dueller; Sep 22, 2007 at 07:27 PM.
Fleet Owner
Joined: Jul 2004
Posts: 27,291
Likes: 1,055
From: NM
Originally Posted by 51dueller
Just use coarse thread grade 8 bolts with lock nuts and you won't ever have a problem. Lock washers are useless.
Lead Driver
Joined: Aug 2002
Posts: 6,682
Likes: 12
From: Saskatoon SK Canada
While fine thread is capable of of more torque and slightly more resistant to vibration but it also has some downsides too. It is more prone to thread type failures due to over torquing, rust/corrosion and cross threading.
Later Ford trucks used coarse threaded bolts on their frames with no problems. Look at many twin I beam trucks. It's just plain old bolts holding on the radius arm crossmember which takes the most abuse on the whole truck.
If Henry was so smart to use fine thread on the chassis so why does the Flathead V-8 not use ONE single fine thread bolt? I'd hate to try to remove 24 fine thread head bolts, as you would have to use heilcoils for some holes.
Let's face it we overbuild these trucks. Fine thread is overkill for our uses. Look at production vehicles, you won't find a single rivet on those frames and they see much bigger payloads then they did back then.
Later Ford trucks used coarse threaded bolts on their frames with no problems. Look at many twin I beam trucks. It's just plain old bolts holding on the radius arm crossmember which takes the most abuse on the whole truck.
If Henry was so smart to use fine thread on the chassis so why does the Flathead V-8 not use ONE single fine thread bolt? I'd hate to try to remove 24 fine thread head bolts, as you would have to use heilcoils for some holes.
Let's face it we overbuild these trucks. Fine thread is overkill for our uses. Look at production vehicles, you won't find a single rivet on those frames and they see much bigger payloads then they did back then.
Thread Starter
|
Post Fiend
Joined: Apr 2002
Posts: 5,964
Likes: 1
From: Woodruff, SC
Thanks for the input and info guys!
If it wasn't for the nuts welded to the rear cab and running board mounts I probably would of put in G8"s but seeing thats theres not too much stress on them (except my big butt
) I should be ok with G5 on them? The rest are G8 ( Spring hangars , Front bed mounts and front cab mounts).
If it wasn't for the nuts welded to the rear cab and running board mounts I probably would of put in G8"s but seeing thats theres not too much stress on them (except my big butt
) I should be ok with G5 on them? The rest are G8 ( Spring hangars , Front bed mounts and front cab mounts).
Last edited by TheWiz427; Sep 22, 2007 at 10:16 PM.
Junior User
Joined: Jan 2007
Posts: 94
Likes: 0
Grade 8 does have a higher tensile strength but since they are harder and more brittle I doubt that they will withstand as much shock load. On my front suspensions I always use grade 5 with no failures yet. I do use grade 8 where there is a possible wear factor. I only use the cheap grade 3 to hold on items where there is little stress and no safety concerns if it would fail. Grade 5 is 90% of my usage and cheap at Tractor Supply.