Threadlock or Never-Seize

[Deere Dude]

I am putting new brake backing plates on my campers 8000# axles. The 1/2" grade 5 bolts were almost impossible to get off, but I finally got them.
I got new fine thread grade 5 bolts and nuts but am unsure if I should put a lock washer or Lock-Tite or Never-Seize on them :confused3:. The old ones had a lock washer on but just unscrewing the bolts they got trashed. I almost had to grind them off.

 

[JJZ 109]

I use Never Seize on almost everything. In your situation I'd get new lock washers to secure the bolts if they had them before and Never Seize the bolts.

 

[sld]

For things that heat cycle or see vibrations Loctite blue is your friend.

 

[tjkubota93]

Blue loctite will keep them from loosening on their own. It will also prevent them from seizing.

 

[Mace Canute]

Blue loctite will keep them from loosening on their own. It will also prevent them from seizing.

I like using medium strength thread locker for just those two reasons. I will NEVER use any sort of lock washer on anything that I can apply thread locker to.

 

[newbury]

I like using medium strength thread locker for just those two reasons. I will NEVER use any sort of lock washer on anything that I can apply thread locker to.

YUP
Helical Spring Washers

Lock washers are good for those that sell lock washers.

Is a lock washer an effective torque retention device? - Mechanical engineering other topics FAQ - Eng-Tips

But if you don't want to believe me, perhaps you would believe NASA.

Quote:
NASA Fastener Design Manual RP-1228:

"The lockwasher serves as a spring while the bolt is being tightened. However, the washer is normally flat by the time the bolt is fully torqued. At this time it is equivalent to a solid flat washer, and its locking ability is nonexistent. In summary, a lockwasher of this type is useless for locking."

Or the US Navy.

Quote:
Naval Ships' Technical Manual, Chapter 75:
"Although lockwashers may be encountered, using the flat washers with selflocking nuts, self-locking fasteners, self-locking inserts, or thread sealants such as MIL-S-22473 anaerobic compounds is preferable.

 

[Deere Dude]

YUP
Helical Spring Washers

Lock washers are good for those that sell lock washers.

Is a lock washer an effective torque retention device? - Mechanical engineering other topics FAQ - Eng-Tips

Interesting. Maybe I'll use all three. Use a lockwasher and Lok-tite on the part of the bolt that the nut tightens to and never-seize the portion of bolt that is hanging out, just in case, and I probably never will take them off again, ..
The bolts I took off that had the lockwasher came off as expected for about three turns until it hit the bolt stud that was not covered and in the elements. Then everything ground up.

 

[EddieWalker]

I use blue Loctite on everything that requires torqueing down and for a lot of other things that I just don't want coming apart. I also use lock washers all the time, but after reading the information about them, I'm going to have to rethink that. Might be a smarter investment to go with crown nuts or whatever those nuts with the plastic ends on them are called.

Eddie

 

[newbury]

Interesting. Maybe I'll use all three. Use a lockwasher and Lok-tite on the part of the bolt that the nut tightens to and never-seize the portion of bolt that is hanging out, just in case, and I probably never will take them off again, ..
The bolts I took off that had the lockwasher came off as expected for about three turns until it hit the bolt stud that was not covered and in the elements. Then everything ground up.

To decipher the chart - a nut WITH a lock washer does WORSE than the nut alone. As Eddie wrote a nylon locknut is better McMaster-Carr

 

[mikehaugen]

The only thing bad about nylon locknuts is that you need to use 2 wrenches for the entire length that the nut is threaded on. Not a big deal if the bolts are the right length, but when does that happen?

 

[LD1]

FWIW, a properly torqued fastner shouldnt require anything. Now I am just as guilty as any of using all of the above. And yes, I have even used lock washers with nylocs AND loctite before.

But think about your engine. Connecting rods, Main caps, valley pans, oil pump, head bolts, etc. About everything inside the engine that has a bolt. It is very rare to find loctite or lock washers. And they go through lots of heat cycling and vibrations. Heat cycling dont get much more extreme than aluminum heads on an iron block...

 

[ultrarunner]

Most of my cars are all Castle Nuts... zero chance that any are just going to get lose.

About the only place I see them on modern cars are on the front/rear spindles.

Been a big fan of locktite products for decades and we used a lot of specialty formulations in the machine shop...

About the only think I commonly see a big lock washer are trailer balls...

Back in Engineering school we were told lockwashers are not nearly as effective when re-used.

Also keep an assortment of nylock nuts...

 

[tjkubota93]

I have always wondered if spring washers help.

The big lock washers used to hold the pintle eye on a interstate trailer sure gouge the nut when you take them aloose though. Seems like they provide some resistance to loosening.

Like these:

 

[tjkubota93]

Pictures

 

[mikehaugen]

Much of the discussion here is about the "split" lock washers. Wonder if any of the other types have different effectiveness? I have used the internal and external "star" type and am not too impressed, but I have also used some that were like flat washers but sort of conical, and I think they were spring steel... they seemed like they may be effective.

 

[LD1]

but I have also used some that were like flat washers but sort of conical, and I think they were spring steel... they seemed like they may be effective.

I have some of them. Not sure the proper name, but we call them European lock washers

 

[Soundguy]

you do however see safety wires, keeper tabs and pal nuts...

FWIW, a properly torqued fastner shouldnt require anything. Now I am just as guilty as any of using all of the above. And yes, I have even used lock washers with nylocs AND loctite before.

But think about your engine. Connecting rods, Main caps, valley pans, oil pump, head bolts, etc. About everything inside the engine that has a bolt. It is very rare to find loctite or lock washers. And they go through lots of heat cycling and vibrations. Heat cycling dont get much more extreme than aluminum heads on an iron block...

 

[LD1]

you do however see safety wires, keeper tabs and pal nuts...

See that alot in AG stuff. But rarely in autos. I have never seen locking methods of ANY kind on a headbolt, main cap, or rod cap. Not saying they are never used. but I have never seen them on any engine I have tore down

 

[Soundguy]

tear some fords down.

 

[LD1]

tear some fords down.

I try to avoid them. :laughing:

But have tore down and rebuilt plenty of small block mopars and chevys.

As well as countless new 4 and 6 cylinders of various makes when I was on a big scrapping spree a few years back.