Locking Nuts v. FLanged Nuts

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_grilledcheese_

_grilledcheese_

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Quick Question -

I don't have very much experience when it comes to working on cars. But my brother and I are doing a little interior work on a project he has on the go.

We have had to replace the drivers seat due to some irreparable damage.

What are the best type of fastening nuts for replacing a car seat. I've done a little research online and there seems to be a number of advantages to both Locking and Flanged nuts.

Does anyone have any preference??

- Chang
 
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My vote is for Nylocks with locktite. They will never let go.
 
halfafish said:
My vote is for Nylocks with locktite. They will never let go.
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as someone who deals with these on a daily basis, NEVER use locktite on Nylocks. We have ran into multiple instances on our platforms we work on where the locktite actually destroys the nylon insert resulting it the erosion of the nylon and thus, loosening of the nut. So we have re-engineered everything to use simply nuts with Red or Blue Locktite depending on the the location of the nut.
 
1st, you do need a large washer between the nut and the floorboard. Whether that washer is integral to the nut, or a separate part, it really does not matter. 2nd, while there is nothing wrong with blue Loctite and regular old nuts, the nylon locking nuts or "nylocks" are pretty nice.
 
69_340_GTS said:
1st, you do need a large washer between the nut and the floorboard. Whether that washer is integral to the nut, or a separate part, it really does not matter. 2nd, while there is nothing wrong with blue Loctite and regular old nuts, the nylon locking nuts or "nylocks" are pretty nice.
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FYI, Nylocks have a maximum manufacturers recommended replacement/life span of 5 years. After 5 years, the nylon becomes brittle and starts to degrade, thus loosening up and eventually failing. Not something I'd want to retain a seat. something thats not as life/safety critical, then yes. And for your own sake, never re-use a Nylock. EVER. they are meant for one time tightening only.
 
dukeboy_318 said:
FYI, Nylocks have a maximum manufacturers recommended replacement/life span of 5 years.
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What manufacturer? The life will depend on many factors. Most critical for nylon or similar plastics is UV exposure. I don't think there is much UV exposure under the car. Also, if you care to spend a little extra money, the Mil-Spec nylon insert locknuts can be re-used, because they use a better grade of nylon in them. Yes, some holding value diminishes with repeated use. But they are not going to fall off.
If you're really worried about this, just use Top-Lock or Flex-Top nuts (all-metal nuts with deformed threads). I'm pretty sure Ma Mopar used something like that.
 
69_340_GTS said:
What manufacturer? The life will depend on many factors. Most critical for nylon or similar plastics is UV exposure. I don't think there is much UV exposure under the car. Also, if you care to spend a little extra money, the Mil-Spec nylon insert locknuts can be re-used, because they use a better grade of nylon in them. Yes, some holding value diminishes with repeated use. But they are not going to fall off.
If you're really worried about this, just use Top-Lock or Flex-Top nuts (all-metal nuts with deformed threads). I'm pretty sure Ma Mopar used something like that.
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As a defense contractor working on the engineering side of projects that can only use mil-spec parts, the bolded is false. We source from a variety of manufacturers, all mil-specs have a replace recommendation at 5 years. and it says right on the spec sheet, 1 time use only.
 
Chrysler used flange nuts, and so should you.
With proper torque, the loctite is simply redundant and being undercar, I'd use anti size instead.

I used flange nut wherever possible. Look at most oem nuts and bolts, they're flanged because it spreads it the loads.
 
Stock type "sems" nuts with the built in captured washer, and serrations on the edge of the washer so it bites into the floor pan worked well enough for chrysler when these cars were new. So well in fact that i have snapped many a seat track stud taking them out because they corroded themselves in there, and having to drill and weld new studs in on the tracks. No need to reengineer it. If you you really want a secondary safety, use loctite, or drill the seat mount stud past where the nut will sit and pin the stud with a cotter pin, then if the nut loosens it cant rattle all the way out. If you dont like nylocks, you can buy locknuts that are threaded, then squeezed to a slight oval for a locking feature. Then you can use them multiple times, and not worry about them loosening up, and not need loctite on them either.

Multiple places on our mopars where these ovaled nuts are located because of high heat, vibration, and general worry about them loosening up. Trans crossmember thru bolt nuts, engine mount bracket to engine ears mount nuts, the nuts for the large bolts that attach the disc and drum brake spindles to the lower ball joints. None of these are nyloc nuts, or use a lock washer either, however they all are a squeezed ovaled mechanical locking nut. Aviation terminology (jap nut). Dont over think it guys.
 
dukeboy_318 said:
As a defense contractor working on the engineering side of projects that can only use mil-spec parts, the bolded is false. We source from a variety of manufacturers, all mil-specs have a replace recommendation at 5 years. and it says right on the spec sheet, 1 time use only.
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What Mil spec says they can only be used once? And is it because of what an engineer put on a drawing, or does the spec itself tell you not to reuse them? I do not have any specs in front of me, but I will when I'm at work Monday, and I'm going to let you know what MS-21044 and NASM-17830 says. So is McMaster-Carr lying to the world about re-usability?
McMaster-Carr
 
69_340_GTS said:
What Mil spec says they can only be used once? And is it because of what an engineer put on a drawing, or does the spec itself tell you not to reuse them? I do not have any specs in front of me, but I will when I'm at work Monday, and I'm going to let you know what MS-21044 and NASM-17830 says. So is McMaster-Carr lying to the world about re-usability?
McMaster-Carr
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It's listed in our program requirements and limitations specs, not the supplier. McMaster Carr is one of our suppliers however.
 
I saw nothing in MS-21044 and NASM-17830 about the re-use of this type of nut. I suppose someone, somewhere, decided that re-using them was a bad thing. It might be, for certain applications. But you're not installing and un-installing a seat very often anyways, right?
 
Loctite won't do anything that the nylon insert isn't already doing. Plus, given the fact that we don't know for sure if the chemicals in it will harm the nylon, I'd stay away from it.
 
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