Your NUTS n bolts

[BullDAWG]

Just a question about nuts, bolts and carriage bolts.

On most of my implements for both the cub and SA I own have both regular nuts and bolts AND square head nuts and bolts. Most of the regular (hex head) bolts and nuts look to be replacements while the square appear to be original.

I know the square headed ones are easier to use a crecent wrench on em but why did they change em on newer equipment. Does anyone know when the change was made? And is there any difference between old implement carriage bolts and new ones??? Most of the new ones are all thread to almost all thread where as the stock IH ones have a square mushroom head and only 1-2" of thread vs newer ones that are round mushroom head and all thread. My biggest concern is if the factory ones were grade 5 or 8 and the new ones are not even graded will things like coulters and brackets on implements that used carriage bolts fail using these new bolts??? I don't see any markings on old or new carrage bolts like they do on bolts. On new bolts they have 3 lines for grade 5 and six lines on bolt heads for grade 8. But on carriage bolts I've never seen any grade markings.

[Eugene]

Check with your local tractor dealerships, they usually carry higher grade carriage bolts.

[olebluegrassboy]

We buy grade 8 carriage bolts at work, they do have the six lines on the head. I think they come from Mac Master Carr.