Thread: Transom Bolt Stretch?

Are the bolts hardened #8s stainless? Should also be NY-lock stainless nuts. All bolts should be tightened each year, some will work loose.

Not sure. Will they have a #8 on the heads? They're what Midwest Marine installed the motor with when it was new 3 years ago.

I can't see the bolts stretching. They are stronger then any part of the transom.

A grade 8 bolt will have 6 lines on the top of it. Here is a very simple chart, but these three grades are most common. There may be decimal numbers on the top of your bolt. That would be metric. Grade 8 bolts will rarely stretch or bend. They will...but the hardness of them normally causes a break before a bend or stretch. The threads can stretch some. Grade 5 bolts are VERY common. You will see them alot in hardware stores and such. The nylon lock nut that brush was talking about will have a nylon band on the end. They work well, but are not the best as the nylon will get old and loose its quench. The best I have seen that have the least tendency of loosening are a regular lock nut that is slightly oval in shape at the tip. Forget lock washers...I've seen too many of those break or flatten and do nothing more than what a flat washer could do. If you still have trouble put some blue locktite on the threads. Its medium strength and can be removed with force. Do not use the red....it sets hard and does NOT like to let go. It has its place...but you have to be careful where you use it.

Hmm.., my bolts are gold with a numeral "3" and letter "F" on the heads. There are no lines like those in your picture.

My lock nuts do have a nylon ring like you mentioned. Are the good lock nuts all metal like the old chevy rocker arm lock nuts?

Logged in, no ability to edit; After a better look, the bolts do look like they're stainless but the rest of previous post stands.

I doubt the bolts are stretching. Either the transom is compressing (which WILL happen, even if not noticeable.) Or they are just loosening.

In my experience, you usually only have to go back and tighten once or twice if the transom is good, and the nylock nuts are good. The nuts DO wear out after being used numerous times OR after high speed use, like with an air ratchet. If the nylon got hot, you may want to replace the nuts.

-TH

I am with scrapper on the nuts. Nylock nuts tend to loosen over time as the nylon ages. Esna all metal lock nuts work better.

Note: locking hardware is intended for single use, no matter if it is all metal esna or nylock. Blue Loctite is your friend on almost all metal to metal threads except sensitive torque applications.