Understanding Replacing Bolts

[masonejoejoex2]

So ive been working on my ford 850 tractor and it seems like some of the bolts are stripped and worn out and need to be replaced like around the hood . Im sure there are lots of bolts that need to be replaced. Ive noticed some are corase thread and fine thread. Are most of these bolts just regular SAE bolts? How do i replace them just go to my local hardware store?

 

[souNdguy]

if you are doing a restoration and want to be exact.. you will have to track down the closest example tot he oem ones.

if it's a work tractor, just find a correct sized fastener for the hole and go.

tan and that sort of thing.. gr2 is fine.. most of the rest of the tractor.. gr5 is fine.

specialty stuff.. go gr8

 

[masonejoejoex2]

no, its just a work tractor , and just trying to put back together
when i work on it, thanks soundguy

 

[HD_Jeff]

USS is coarse thread
SAE is fine thread

Just in case you really wanted to know! :wink:

 

[Keith Williams]

masonejoejoex2,
I messed with the bolts around the hood and found that I could tap the fine thread captive nuts with a course thread tap and get them to work again. I also could find course bolts and nuts easy.
Keith

 

[Dell (WA)]

masonejoejoe2........remember COARSE thread for CASTIRON. Castiron will not take fine-thread taps. Ittza LAW. SAE is usually fine thread and USS is usually coarse thread. Grade-5 is good for almost everything. Most stainless is grade-2. Most galvanized is grade-2. CAUTION: many block holes are BLIND and need to clean them out with Q-tips so they don't hydraulic fracture yer engine block when you install new bolts. Also, 1-thread showing, max 5-threads showing ...or... change the length of yer bolt. ........nutless Dell

 

[masonejoejoex2]

thanks for all the tips and advice i think i know a lot better about what to do

 

[Red Ford]

All things being equal, fine thread fasteners are more vibration resistant then coarse thread ones.

 

[Carrie]

U.S.S.-United States Standard
S.A.E.-Society of Automotive Engineers

SAE was created for the automotive industry. Prior to that everything was USS. Fine thread (SAE) is resistant to vibration.