Trying to find a 9/16 fine thread carriage bolt. Are these no longer made? Restoation supply doesnt even have them.

 

You might check your local Ace Hardware. I have found them to have the best selection of nuts :& bolts anywhere.

 

They only have course thread

 

www. mcmaster. com

 

What are the carriage bolts going to be used for and how many do you need ? 9/16" bolts are not normally stocked.

 

They are for mounting the rear bumper on a 63 Starfire. 1.5 inches long but could do 1.75. 4 bolts total but could take more if needed as they are used for lots of those full size

 

Why would they have to be fine thread and I have never seem 9/16 bumper bolts. I need some 1/2 by about 3 (maybe 2 1/2) inch ones for the back bumper on my 54 Olds. I have finally concluded the only way I will get them it to weld or braze some 1/2" all thread to shorter bumper bolts and then cut it to the length I need. I will be doing that next week since I have some shorter bumper bolts. Good luck with your search.

 

Supposedly fine thread allows for a better torque grip. Certainly the ones I pulled from the car were original and corroded enough to not risk reusing. Worst case I guess Ill use course thread.

 

You dont have to weld them in. Go to OReillys and have them order bolt retainers. Thats what was used to hold the carriage bolt tight enough in place to be able to get the lock washer and bolt started. It also allows the bumper to be adjusted and not locked in place.

 

Some bumper bolts have a square shoulder like a carriage bolt, but with a chromed head.

 

Try Fastenal, McMaster-Carr, Grainger or some others. Fine threads are believed to remain tight in vibrational situations. Coarse thread and lock washers could work. Or get them longer and double nut them. Or, there is Loc-tite.

 

I am not intending to weld the bolts in the car. I am simply welding an extension on the bolt to make it longer since I can't buy one long enough. I bought a 1/2 piece of all thread about a foot long for less that $1.50. I already have the bumper bolts to add the length to. I will just braze a bolt on each end of the all thread and then cut them to about 3 inches. Done.

 

https://www.amkproducts.com/bulk-fas...oduct_ID=15004

Maybe ?

Coarse thread, but I wouldn't think bumper attachment is a high-torque high-vibration application.

 

Torque is not an issue on bumper bolts. They hold the bumper on. Put a lock washer on it and be done. There is really not a lot to this.