1 Ton FFPW- 1961 Towing Hooks Question

[Hartman]

I am about to install towing hooks on my 1961 WM300. Were the original bolts/nuts fine or coarse thread? Also, I assume they should be hard, #8? Any advice is much appreciated!

[Kevin Mienke]

The tow hooks on my '61 were held with fine thread, grade 8 bolts when I purchased it. However I cannot say, with any certainty, that they were original. In fact, I highly doubt that they were. They did not have the DPCD cast on the head.

In my case, the tow hook bolts were rusted and stripped beyond reuse, so I opted for a grade 5 which holds up well under lateral force. My decision to go with grade 5 was based on research indicating that grade 8 are actually more prone to break than grade 5 when subjected to the lateral force (single shear) that a tow hook would be subject to.

This was a personal choice and not based on historical accuracy. Hopefully someone will come along with a better answer about what bolts were originally used.

[Hartman]

Towing Hooks

Thanks Kevin. I appreciate your your advice. Will proceed accordingly.....Keith.

[Clint Dixon]

The tow hooks on my '61 were held with fine thread, grade 8 bolts when I purchased it. However I cannot say, with any certainty, that they were original. In fact, I highly doubt that they were. They did not have the DPCD cast on the head.

In my case, the tow hook bolts were rusted and stripped beyond reuse, so I opted for a grade 5 which holds up well under lateral force. My decision to go with grade 5 was based on research indicating that grade 8 are actually more prone to break than grade 5 when subjected to the lateral force (single shear) that a tow hook would be subject to.

This was a personal choice and not based on historical accuracy. Hopefully someone will come along with a better answer about what bolts were originally used.

I do not believe any of the old DPCD bolts were graded, at least not as high as 5 or 8 anyway. The ones I have removed from trucks have proven to be quite soft. As long as they are not Chinese junk, any standard American Made UNF bolt of the correct diameter and length should be okay to attach the tow hooks. These hooks should never be jerked on anyway. With that said, where I am missing the original DPCD bolts, I have used either grade 5 or grade 8 UNF bolts - which ever I can find in the correct length from my local industrial and agricultural surplus dealer.

[Hartman]

Towing Hooks

Thanks Clint. I appreciate the information and the perspective.

[Charles Talbert]

I am about to install towing hooks on my 1961 WM300. Were the original bolts/nuts fine or coarse thread? Also, I assume they should be hard, #8? Any advice is much appreciated!

A good quality grade 8 bolt is far superior to grade 5 in any application. We have proven this many times here. Years ago when we were running heavy construction equipment, we proved it many times also, especially on cutting edges and on pan elevator flights. In either application, if grade 5 bolts were used, it was easy to literally jerk the component off due to failed bolts. Personally what I like even better than grade 8 is grade 9. 9 is the strongest commercial grade bolt available,when used in conjunction with grade 9 nuts and washers, you will be hard pressed to break them in any application.

Tensile strength of a grade 9 is 180,000 PSI, a grade 8 is 150,000, a grade 5 is 120,000, a grade 2 is 60,000.

On tow hooks, there are several ways to view it I guess. A term we use around here a lot is if you are pulling like you are running over an egg and not break it, grade 5 should hold you ok. If you want to apply the needed force for the job and not worry, use nothing less than grade 8, if you just don't want to concern yourself with failed bolt issues, use grade 9, but consider your operator in cases where 9's are used. If he's a hot shot without enough common sense to know when to quit, you may want to think twice about pairing him with grade 9 bolts as he may destroy something else in the process. Grade 9's will out last stupidity in most cases. Getting back to the original question, the original bolts were fine thread, they will hold more than course in any grade.

[Hartman]

Towing Hooks

Charles:

Thanks for the information and guidance. I appreciate both very much.......Keith.