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View Full Version : Spring lock washers = bad?



podolefsky
15 September 2011, 1430
OK, this is just slightly el moto specific...I've been using spring lock washers (helical type) forever. I just learned that they are considered ineffective, if not worse than just a plain bolt when it comes to vibration loosening.

Unless someone has a good counter argument, I'm not using them anymore.

Chart and videos here are pretty convincing:

http://www.boltscience.com/pages/helicalspringwashers.htm

DaveAK
15 September 2011, 1438
I've heard negative things about them in certain applications, but I can't remember where that was, or what applications. I'm using them all over my bike and haven't had any loosen. And I've got a dirt road to ride on every trip I make.

(Obviously this post is not intended as a counter argument, good or otherwise!) :)

Remotecontact
15 September 2011, 1451
Loctite and locknuts have never let me down.

jpanichella
15 September 2011, 1505
Loctite is your friend.

And nord-lock washers actually work too, expensive though.

jpanichella
15 September 2011, 1507
http://www.nord-lock.com/

http://www.mcmaster.com/#nord-lock-washers/=e2t492

podolefsky
15 September 2011, 1558
Yeah, agree about locktite and locknuts. Nord-lock looks cool, but probably overkill. Everything that was originally Suzuki is thread lock or just plain bolt with proper torque.

This is nice to know, actually, because all the screws that attach my battery bus bars have lock washers. Because of fit issues, if I leave off the lock washes I can fit another 1mm of thickness to the bus bars (equivalent of going from 1 AWG to 2/0).

billmi
16 September 2011, 0544
If a manufacturer specified a spring lock washer, that's what I use. If I'm picking the parts, I go for the lock nuts with the nylon insert.

podolefsky
16 September 2011, 0906
Everything you ever wanted to know about fasteners:

http://gltrs.grc.nasa.gov/reports/1990/RP-1228.pdf

My read of this is that if you are torquing down the bolts or nuts enough to flatten the washer, spring lock washers are useless...or worse.

DaveAK
16 September 2011, 0929
Everything you ever wanted to know about fasteners:

http://gltrs.grc.nasa.gov/reports/1990/RP-1228.pdf

My read of this is that if you are torquing down the bolts or nuts, spring lock washers are useless...or worse.
Absolutely useless if you're torquing anything down. But I rarely torque anything anymore. I just use whatever was there originally, and if it's something I'm adding I just make a judgement call between spring washers, flat washers or nylocs as appropriate.

podolefsky
16 September 2011, 0934
Sorry, didn't mean torquing as in torque wrench - just as in to any degree that flattens the washer out.

In terms of using what was already there, I'd say use your judgement. I'm fairly sure I have a number of things where the manufacturer put on lock washers when they shouldn't have.

DaveAK
16 September 2011, 1022
Sorry, didn't mean torquing as in torque wrench - just as in to any degree that flattens the washer out.

In terms of using what was already there, I'd say use your judgement. I'm fairly sure I have a number of things where the manufacturer put on lock washers when they shouldn't have.
OK, I misunderstood.

Off the top of my head I think the only manufacturer supplied lock washers were on my electrical stuff - controller, contactor and motor. I don't recall any Kawasaki ones. In some of my self fabricated additions I've used lock washers, and other places just regular nuts and washers, or nylocs if I was worried about them shaking loose.

podolefsky
16 September 2011, 1047
Hmmm - yeah, also noticed there are lock washers on my contactor, motor, and controller...just on the electrical connections. None of the other mechanical fasteners have lock washers (like the ones that hold the motor together).