I was having a discussion with a friend of mine this evening about lock/spring/split washers or whatever other name you may have for them and how to use them, I would like to know your verdicts please.

I understand you would use a spring washer on its own, as in without flat washer. The Spring washer then bites in to whatever is being bolted and also exerts force keeping all tight. This is most certainly how a HGV mot tester is taught. The man that has been in the army for 20 years fixing tanks and the like states that a spring washer will not work if a flat washer is not used underneath it.

What are your thoughts please? I notice on my RL lock washers have been used with flat washers beneath them, but then that would be down to the person that did the restoration.

Location: Moonraker county

Hello Richard,
Like many contributors to this forum, personally I'm a big fan of Loctite, with the proviso that the appropriate product is used for the application. You can fit the locktabs to the Loctited fastener if required for cosmetic purposes. Aerotite (aerotight?) or Nyloc nuts where applicable. I tend to avoid using spring washers wherever possible, except for the 'star' type for electrical connections. My two cents worth...
For a learned discussion on spring washers have a look at www.boltscience.com

Location: Far West of New Zealand

Where ever possible I use a flat washer under a spring washer and a flat washer under the head of the bolt the reason being that the flat washer spreads the gripping pressure over a greater area and reduce the chance of deforming the area being gripped. The spring washer is there to stop the nut or bolt undoing by applying bite into the two adjacent surfaces to the spring washer and by the spring effect acting as a brake to stop the nut or bolt un-threading. I use spring washers in situations where there is a chance that vibration or movement may induce a slight amount of wear in the mating surfaces which would loosen the grip of a Loctited nut or bolt where a spring washer would likely maintain a better grip.

Location: Cambridgeshire

I'm not good on mechanical engineering but read threads like this to increase knowledge..It took a while to find anything about spring washers on the he boltscience website but I did find this there: http://www.boltscience.com/pages/helicalspringwashers.htm. Spring washers proved ineffective in 1969 ! That's clearly not accepted practice here...Now I'm confused...

Advice on lock washers was requested on the VSCC Technical Forum some weeks ago. The discussion covered self-locking nuts, tab washers, castellated nuts with split pins and lock wiring.

A suggested solution to the problem of loosening nuts was the Nordlock System which has been successfully used by several VSCC racers.

The system is explained in this video: https://www.youtube.com/watch?v=IKwWu2w1gGk

It is interesting to compare this video with that from boltscience.com

I have not used Nordlock washers yet so I can't recommend them, but I'm going to get some.

Location: South-East Surrey

Have not checked the website given but in theory rigid joints adequately tightened will not loosen.....

A flat washer would seem especially inappropriate with the spur type washers. Assuming only critical high stress joints are of concern, I am dubious of the washers with a raised spur. These confuse torque readings, stress the bolt very one sided, and the base metal slowly yields to the spur. May not come undone but seems to carry a heightened risk of bolt failure. Of dubious merit with ht bolts and hard surfaces, such as retaining a crown wheel.

Location: Auckland, NZ

I did find the bolt science article interesting and that spring washers have been proved ineffective. I work as a mechanic on buses and coaches and you never see spring washers. It's always nyloc, split pins, locking wire, slightly off round on the top steel nuts where there is high heat or two washers together that have fine teeth both sides. The only washers in use would be plain washers to spread the load and prevent the bolt damaging what is being fixed.

Location: Moonraker county

As an apprentice mechanic in the sixties, I was taught to use a flat and spring washer together by an ex RAF fitter/mechanic. I still do that today. Mostly they stay tight.On arrival at Wiscombe on Sunday, the trailer spare wheel was falling off! This due to me forgetting to tighten it! Always check the important nuts/bolts. Can't beat a split pin!

Location: Wales

Interesting, especially as I will be reassembling the car soon.
Lubricated bolts on that Nlrd-Lock video made me wonder as I was told moons ago, that that was a NO NO.

Julian,
Where are you purchasing them from, and would appreciate an appraisal once you have used them please.

Geoff - Never too early to start preparing.

Location: South Norfolk - Next to Suffolk

Geoff

This was the link to supplier quoted on the VSCC site:

http://www.threadrive.co.uk/mrotools/nord-lock.asp?gclid=Cj0KEQjw3Le4BRDxx5bk4aDn9t4BEiQAfmxQGWDIzpkZYb6VXqda27GLrx_S2rffs_iiaLYIrBt-YQIaAs968P8HAQ

As I said above, I haven't used them. I have been preoccupied fiddling about with an electrical/starting problem - but I plan to get some.

Location: South-East Surrey

I can vouch for Nord Lock washers! One of the bus manufacturers uses them and I have never seen a bolt come loose where they are fitted.

Location: Moonraker county

Back to the original question. I have always been of the opinion that a spring washer should be used on its own. If you add a flat washer into the mix (say nut>spring washer>flat washer) the nut will 'bite' on the spring washer, the spring washer will 'bite' on the flat washer, but there is nothing to stop the flat washer turning. Similarly if the arrangement has the flat washer in the middle..

Anyway, that's how I do it. No flat washer...

Location: Cambridge

I'm impressed by the Nordlock washers, I'm going to have to buy some now

Location: Ripon

I use just a spring washer if the surface being used is even. However id it isn't I use a flat washer and spring eg the clamp on the distributor plate.

Location: Melrose, Scottish Borders

I'm with Hugh, no flat washer. For exactly the same reason.

Location: Moonraker county

Hi All,
Japanese Engine manufacturers use a lot of Bolts with a Captured spring washer no flat washer as well.
One thing to remember make sure that the nut you are using no mater what type is the same Tensile as the stud or bolt.
Regarding flat washers using Hardend ones means that what ever Torque is applied it will not compress as will a standard mild steel one will resulting in a lose fitting.
The comment on nuts one that does cause problems is the NYLOCK the lock part works fine but the nut part as standard off the shelf is not HT so if using on HT bolts or studs make sure that the NYLOCK nut is HT.
some thing to think about

As far as I know the original 'spring washers' were just that, wider section and without aggressive end tangs. Not sure if this style is readily available now.
The newer tang type, apart from being too narrow, make a mess of the nut and base metal when unscrewing and are to be avoided.
For originality I try to re-use original washers still with a little spring. I think that with proper tightening and regular checking these are OK.
The most unusual spring washer is the Lucas double spring used on the switchboards - don't drop them!
The cylinder head nuts were fitted with plain washers, as were the manifold nuts.
The List of Spare Parts show which assembly has a plain washer, spring washer or lock washer.
I think that parts assembled with a spring washer and a plain washer look fussy and wrong.

Tony.

Many moons ago I bought the remains of a 1925 Chummy (Longbridge body) which had been badly damaged in a fire - allegedly shortly after it had been delivered new. The lack of wear in the gearbox & most other mechanicals (although the crankcase itself was melted) supported the rarely-used story. So let's take just the flitch plates, or valances as many call them :- the rear flange that bolted to the footboard at 45 degrees had no supporting angle-piece as on later models & the holes to the footboard were 1/4". On the side (@ rear) bolted to the lip on the mudguard were two 3/16" screw-head bolts & nuts, each bolt with 5/8" diam. flat washers under the head, NOT under the nut. (Nut to inside of valance, head against guard-lip). Along valance to bottom edge of guard = three off 3/16" screw-head bolts, nuts & washers again as above. At the front top corner where mounted to the guard support strut, was a 5/16" bolt & nut with (1 1/4" diam.) mudguard washers under each. Not a sign of a spring washer anywhere, and I've selected an area where it's highly doubtful that the panels would have been disturbed. So when, if at all, did Sevens - at least on the panels - start using spring washers? Is the common use of hexagon-head bolts, large-diameter mudguard washers, spring washers everywhere really original? Cheers, Bill in Oz

Location: Victoria, AUS.

I must be missing something here as I cannot see what a split spring washer does.
It requires very little load to flatten one so by the time the spring action comes into play the joint is loose and whatever is going to break or fall off will. I also agree with Bob that all they do is fxxk up your torque settings which if set correctly will stop the bolt or nut coming undone in the first place. So can someone put me straight?

Location: London