Using flange bolts with lockwashers

[=Enigma=]

Is there any rule that precludes the use of flange bolts with split lockwashers? The flange bolts in question are the typw with a notched contact surface. I was not able to find JIS bolts of the needed size in a standard cap screw type so I got the flange bolts instead. I'd like to use them with lock washers to prevent the marring of the painted surfaces they will make contact with.

[BD240Z]

Enigma,

I'm not sure what you mean by a flange bolt but if it makes sense, try it in a few spots to see how it works.

Here's what I've done in the past and what I'll do when I paint my car this fall. Ace Hardware has a nice supply of thin nylon washers as well as a bunch of other connectors/fasteners that has saved my butt more than once.

I paint the nylon washer with some rattle-can paint that closely matches the cars color. I place that washer between the lock washer and the paint and it's kept the paint from getting gouged.

Good luck with your car!

[=Enigma=]

I paint the nylon washer with some rattle-can paint that closely matches the cars color. I place that washer between the lock washer and the paint and it's kept the paint from getting gouged.

You do realize that renders your lock washer nearly useless right?

Here's an image of the type of bolt I'm referring to:

Note that this type of bolt usually has a serrated mating surface, which is why I asked the question in the first place. Something is telling me that it is unwise or unacceptable to use this type of bolt with a lockwasher. Anyone?

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[pcs]

Hi Guys from the land down under,

These flange bolts are great for spreading the load ,such as when a panel has a slotted bolt hole. They should stay tight due to their design.

pcs:)

[Carl Beck]

Hi Adam:

Given that you said you are using it against a painted surface, using a flange bolt with a lock washer should be no problem. It might be a problem if establishing a specific and/or critical torque on the bolt is necessary for it to do its job.

If it's a body bolt or one with a relatively low torque spec. (say something below 25 lb/ft) I don't see any problem.

FWIW,

Carl B.

[ezzzzzzz]

One note if you use the lock washer and wish to remove the bolt. When turning the bolt out the lock washer will be grabbed by the serrations on the flange and turn with the bolt. That will gouge the mating surface even if only for a small amount. I'd use nothing or nylon washers for this.

[240ZX]

Using a nylon washer, as mentioned earlier, pretty much negates a bolt's ability to maintain a torque setting, since the washers are of a relatively soft material. Again, if used in an area requiring low torque specs you're probably fine. Applying a small dab of low strength Lok-Tite on the threads is also a recommendation.

[BD240Z]

You do realize that renders your lock washer nearly useless right?

Nope, not true. The lock-washer still compresses and maintains the outward pressure on the bolt.

Since you've decided to use flange-bolts, try one in an inconspicuous area and then remove it to see what happens. A few tests might answer your question.

Good luck with your car.

[240ZX]

Nope, not true. The lock-washer still compresses and maintains the outward pressure on the bolt.

Since you've decided to use flange-bolts, try one in an inconspicuous area and then remove it to see what happens. A few tests might answer your question.

Good luck with your car.

Either split or star type lock washers do their locking job by bighting into the surfaces they bear against. If you add a nylon washer between the lock washer and the bearing surface, painted surface in this case, then the lock washer will not bight....unless of course it penitrates the nylon washer, in which case you have defeated the purpose of put a nylon washer on to begin with. Lock washer do not lock via providing outward pressure!

[John Coffey]

I'd like to use them with lock washers to prevent the marring of the painted surfaces they will make contact with.

Split lock washers most of the time mark or scratch the surface they are tightened against.

Either split or star type lock washers do their locking job by bighting into the surfaces they bear against.

Nope, by the time the bolt has turned enough to allow the spring or star lock washer to bite into the material, the bolt has already lost tension. Per the AN935 spec the spring lock washer works (what little it actually does) by maintaining tension on the bolt during heat cycles and very small cyclical loads.

BTW... the number one most effective way to keep a bolt or nut from losening is to use a NEW fastener and torque it to spec in a clean and properly threaded hole/nut. The number two way is to use an elastic stop nut or a very specifically designed locking bolt. Spring lock washers are about the worst form of locking device ever developed.

[240ZX]

For anyone that is seriuosly interested in learning more up to date information on lock washers and locking devices should visit the following website.(www.boltscience.com/pages/vibloose.htm) It provides a clear expalination on how these devices work.

And John, I always respect your knowledge and input but this time I believe you need to update yourself on lock washers. Technically speaking lock washer lock via adding friction to prevent lossening of a fastener...not by spring force as you suggest.

[=Enigma=]

Given that you said you are using it against a painted surface, using a flange bolt with a lock washer should be no problem. It might be a problem if establishing a specific and/or critical torque on the bolt is necessary for it to do its job.

Carl, can you explain why you think this would present a problem? The painted pieces are suspension parts so proper torque will be critical. In fact, most of the suspension parts will be assembled using the flanged bolts since I couldn't find any non-flanged cap screws in the right sizes in 10.9 grade.

One note if you use the lock washer and wish to remove the bolt. When turning the bolt out the lock washer will be grabbed by the serrations on the flange and turn with the bolt. That will gouge the mating surface even if only for a small amount.

Yup, I thought of this but I am really more concerned with using the flanged bolts without a washer which would scrape and possible tear, crack or wrinkle the paint on the way in. I'm hoping to minimize the number of places rust can start on my freshly painted parts.

On that note, would it make more sense to use flat washers to achieve my goals? Would I need to worry about the bolts working themselves loose or not holding their torque settings if I use flat washers? Most of the bolts are 10.9 grade and will be torqued to spec.

Split lock washers most of the time mark or scratch the surface they are tightened against.

Yep, again I'm not too worried about this but I felt like the flange on the bolt would do more damage. Can't get around the marring the lock washer will do unless you don't use 'em.

Maybe I'm overthinking this whole thing. It wouldn't be the first time, and certinaly won't be the last. I'm just glad the damn fasteners finally arrived, even they're not gold chromate colored like I thought they would be...... Oh well, I'm not going for a strictly pure stock look anyway and they are zinc plated.

Thanks for the comments guys.

Adam