Lock Washers a Waste of Time?

[tghsmith]

being a BMW motorcycle mechanic many years back, spring wave washers are used where steel bolts are holding alloy parts together,, correct torque values applied (gutentite) thermal cycling, different expansion and all that,, specific drive train bolts were one time use, (stretch bolts) the u-joint to gearbox flange (steel to steel) went through changes as time progressed,, originally split hardened lockwashers, then changed to thick wave washers, then to single use bolts, no washers,installed on clean parts with loctite.. on later bikes some specific bolts came pre-locktited,, heat was required for removal,, the new bolt had a locktite coating on part of the threads, friction activated(once started the bolt was cranked down without stopping,)

 

[matthewsx]

Read this:

www.CarrollSmith.com -- NUTS, BOLTS, FASTENERS, and PLUMBING HANDBOOK

Yes, lock washers are no more effective than a plain washer on a properly torqued fastener. I don't know that I would run around removing them where present but if you are concerned do buy a torque wrench and consult a torque table to get things tightened properly. Loctite or Nylock nuts wherever things need to stay together, safety wire if lives depend on it.

Cheers,

John

 

[Downunder Bob]

On a large marine diesel engine all critical bolts and nuts will have some form of positive locking of the fastener. A split pin with a castellated nut is one popular method. Tab washers are popular with some engine makers, as is wire tying. You will almost never see lock washers used in any critical situation.

 

[RJSakowski]

The above discussion is very interesting and I notice no comment about the spurs on the outer corners of some lock washers, especially those from old time manufacturers. Being ignorant of the technical aspects I thought those spurs were there to gouge the nut and parent metal in a short distance of rotation and restrict further loosening. As for small diameter lock washers sold these days many are as smooth as baby bottoms. No doubt in critical fastener surfaces and mating material surfaces should be parallel and I would use some locktite also.
Have a good day
Ray

I have been been turning wrenches for more sixty years on things from electronic equipment to farm implements. On removing nuts used over lock washers, I have observed that the washer will bite into the bottom of the nut, resisting loosening.

I use a number of methods of locking, depending on the situation. On electronic equipment, I used a drop of cyanoacrylate adhesive applied under the nut just prior to final tightening. The adhesive would wick under the nut and into the threads. The best way to remove the fastener was to over tighten snap the fastener, then replace the fastener.

Double nutting is another method that I frequently use. I can't recall that it has ever failed me. There was a discussion a while back on this forum regarding the proper use of the jam nut. Like toilet paper, the camp is divided on over vs. under. Nyloc nuts also work well.

My outboard props use a tabbed washer and it is used in other situations where the nut isn't torqued down with success. I haven't lost a prop yet. Also, castellated nuts with cotter pins are effective. The spindle nuts on automotive vehicles attest to that. For fasteners not intended to be removed, staking proves effective.

One method that seems sure fire though, is rust. I have had far more experience with rusty fasteners where I had to cut them off or break the fastener than I care to think about.

 

[MrWhoopee]

On a VW bus (the real ones, thru '67), the front wheel bearings are retained with nut, lock-nut and keyed retaining tab washer between. Rear brake drums are retained with castellated nut torqued to exactly 280 ft. lbs. (6 ft. cheater on 3/4 breaker bar, then jump on it) and cotter key (split pin downunder).

In general, metric stuff seems to use wavy washers instead of split.

 

[John281]

At work, we use fasteners that have a small patch of locking material encapsulated in tiny microspheres. The patch is dry to the touch until it's installed and the microspheres rupture. These are generally single-use fasteners. (NDIndustries.com) We make electronics for aerospace where we don't use lock washers either due to the risk of fracture and associated FOD as others noted.

At home, I have found that the clear "Shoe Goo" works well for high vibration applications such as lawn mowers, snowmobiles, and motorcycles. In reality, it's probably not strong enough to keep a fastener from loosening but it's firm enough to keep a fastener from falling off completely but easy enough to loosen when needed.

 

[MrWhoopee]

At home, I have found that the clear "Shoe Goo" works well for high vibration applications such as lawn mowers, snowmobiles, and motorcycles. In reality, it's probably not strong enough to keep a fastener from loosening but it's firm enough to keep a fastener from falling off completely but easy enough to loosen when needed.

Ah, yet another use for Shoe Goo. Since getting it to glue the sole back on my Tevas, I've used it to splice the serpentine belt on my Heavy 10 and have been very impressed with its tenacity.

 

[pontiac428]

On track vehicles in the Army, lock washers are used for mounting non-critical vibrating stuff like lamp housings. On the drivetrain and turret's critical components, lock nuts are the rule. Internal parts like transmissions get lacing wire. The torque wrench is your friend.

 

[BGHansen]

I was taught that torque is how clamp load is obtained. The bolts is stretched into tension which maintains the clamp load, basically it's stretched into a spring. What holds the joint together is friction between the nut/bolt head and the mating surface. If either rotate (lefty loosie), then some of the clamp load is lost. Loctite, nylock nuts and I would imagine star-washers increase the friction so the joint will be less likely to loosen.

Key to achieving clamp load is some distance between the head of the bolt and the nut. Tighten two pieces of sheet metal together with a 1/4"-20 and you maybe get one thread of stretch and little clamp load. Makes sense that a split lock washer would help put the bolt into some tension and help with the clamp load when bolting up thin materials. Don't know how much friction (if any) it adds to keep the nut from turning.

Bruce

 

[mcostello]

My Eye Doctoruses a drop of clear nail polish on the top of eye glasses screws to prevent loosening, easy to remove.