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Hooked
bare metal cafe racer
Joined: 01 Sep 2017
Posts: 356
Location: Aotearoa (New Zealand)
Sun Jul 07, 2019 6:40 pm quote
chandlerman wrote:
Hooke's Law or Newton's Law of Restitution (Elasticity). I don't remember enough of the difference between the two.

Either way, I had the dampener sorted in no time at all without any helper but my knee
Donít know the law... but if you push fast then you both overcome inertia and get momentum on your side.
Hooked
bare metal cafe racer
Joined: 01 Sep 2017
Posts: 356
Location: Aotearoa (New Zealand)
Sun Jul 07, 2019 6:42 pm quote
pheasant plucker wrote:
chandlerman wrote:
Hooke's Law or Newton's Law of Restitution (Elasticity). I don't remember enough of the difference between the two.

Either way, I had the dampener sorted in no time at all without any helper but my knee
Donít know the law... but if you push fast then you both overcome inertia and get momentum on your side.
And itís been a while since physics... but the thing with springs is they resist with constant force. The spring constant =k
Banned
2:6
Joined: 11 Jan 2007
Posts: 7401
Location: San Francisco
Sun Jul 07, 2019 9:01 pm quote
pheasant plucker wrote:
pheasant plucker wrote:
chandlerman wrote:
Hooke's Law or Newton's Law of Restitution (Elasticity). I don't remember enough of the difference between the two.

Either way, I had the dampener sorted in no time at all without any helper but my knee :D
Donít know the law... but if you push fast then you both overcome inertia and get momentum on your side.
And itís been a while since physics... but the thing with springs is they resist with constant force. The spring constant =k
not constant force, but proportional to the length of displacement. F=K*d
Ossessionato
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 2079
Location: Chicago. Well, Evanston, but that's almost Chicago
Mon Jul 08, 2019 6:00 am quote
autojack wrote:
chandlerman wrote:
Either way, I had the dampener sorted in no time at all without any helper but my knee
I'll admit I've got more lengths of 2x4 than I have friends.
And 2x4's don't drink all your beer, either.
Ossessionato
1976 Super (x 2), 1974 Primavera (x 2), 2006 Fly 150
Joined: 26 Sep 2013
Posts: 4674
Location: So Cal
Wed Jul 10, 2019 10:52 am quote
I realize I may be the last person on the forum still using a castellated clutch nut. But if there are any others out there, do yourself a favor and BEVEL THE EDGE of the nut removal tool.

The tool works OK with the engine out, but I spent a whole frustrating afternoon trying to get the teeth to to grip the nut with the engine in the scoot. Thereís basically no way to put enough leverage on it. It just slips off.

Beveling the edge of tool lets it sits deeper in the teeth. The nutíll twist right off. Then throw it away and get a shouldered nut.

633F562A-3AF8-448E-B12A-83CB2D465C31.jpeg

Ossessionato
05 Stella, '62 VBB, 76 Sprint V, 63 GL
Joined: 16 Jun 2011
Posts: 2079
Location: Chicago. Well, Evanston, but that's almost Chicago
Wed Jul 10, 2019 11:13 am quote
The tool barely fits into the six spring clutch on my sprint, so I'm feeling kind've dumb I didn't think of this myself. In general, I only use the damn tool to remove castle nuts, but I haven't have flange nut that will fit in there yet and I forgot to see what SIP had when I ordered my new axle & cruciform last night.
Veni, Vidi, Posti
74 50s x2 78 P200 84 Cosa 58 AllState 68 Sprint 80 50special + projects
Joined: 22 Nov 2010
Posts: 6882
Location: seattle/athens
Wed Jul 10, 2019 11:22 am quote
Yep, I still use them and I jumped on this when I saw it here:
Ginch wrote:
SFvsr wrote:
Bevel the edge of the clutch nut tool. Clutch design changed over the years and some clutch nut tools go deeper into the castellated nut than others, mostly because the tool bottoms out on the clutch before it seats completely into the nut.

In the picture, the tool on left is unmodified. The tool on right has been put to a grinder.
Enthusiast
58 VB1T, 81 100 Sport
Joined: 06 May 2019
Posts: 67
Location: Long Beach, CA
Thu Jul 11, 2019 9:11 am quote
SoCalGuy wrote:
I realize I may be the last person on the forum still using a castellated clutch nut.
Been out of this vespa thing for a bit, so I'm picking up new things these day in the past I have always used the castle nut, and personally never had any issues. Although I know others do. I always used a new nut + cage when removing/replacing.

I understand the advantage of using a shouldered nut for ease of using a standard socket, and I would think more even distribution of force. What about locking it down without the cage? Split-ring or toothed lock washer is sufficient? Same factory torque specs as the castle nut?
Veni, Vidi, Posti
74 Super, 75 Super, PX project, LML off-roader and new to 2018, '66 Blue Badge Smallframe
Joined: 30 Nov 2011
Posts: 6884
Location: Victoria, Australia
Thu Jul 11, 2019 2:29 pm quote
[quote="GeekLion"]
SoCalGuy wrote:
What about locking it down without the cage? Split-ring or toothed lock washer is sufficient? Same factory torque specs as the castle nut?
This type of nut is supposedly single-use. I read that the threads, compared to a normal nut, is very slightly different. That means that they deform just a little, enough to grip the male thread. I have re-used them however and never had one come loose from the clutch over the last 10 years.
Quote:
K-nuts are developed by the aerospace industry.

The goal was to be able to fasten the components of an airplane with a nut that is vibration proof and lighter while being more resistant to corrosion.

That is why they're often called jet nuts!

https://k-nuts.com/
Molto Verboso
Joined: 26 Oct 2015
Posts: 1463

Thu Jul 11, 2019 4:32 pm quote
SoCalGuy wrote:
I realize I may be the last person on the forum still using a castellated clutch nut. But if there are any others out there, do yourself a favor and BEVEL THE EDGE of the nut removal tool.

The tool works OK with the engine out, but I spent a whole frustrating afternoon trying to get the teeth to to grip the nut with the engine in the scoot. Thereís basically no way to put enough leverage on it. It just slips off.

Beveling the edge of tool lets it sits deeper in the teeth. The nutíll twist right off. Then throw it away and get a shouldered nut.
I dug through by tool box of Vespa specific tools today to find my custom made socket. I didnít have the correct socket at the time, so I made one. I think I made it sometime around the turn of the century? I also found a couple of the correct sockets as well. I must have had the same issue as everyone else, because apparently I sanded down a taper on it so that it would fit. I guess that should tell you the last time Iíve used one of those castellated nuts!

9A4E4376-F356-4D3A-BDE7-31FCCD258252.jpeg

Veni, Vidi, Posti
74 50s x2 78 P200 84 Cosa 58 AllState 68 Sprint 80 50special + projects
Joined: 22 Nov 2010
Posts: 6882
Location: seattle/athens
Thu Jul 11, 2019 5:42 pm quote
Me too, about 10 years ago the first time I needed one and I didn't want to wait a week for the special tool. I had an extra clutch nut and discovered that it fit perfectly with the other one so I welded a short fat bolt on it and pulled the clutch shortly after. Works well if you are in a jam, but the steel is not hardened and it won't last like the real deal.

clutch nut.jpg

Enthusiast
58 VB1T, 81 100 Sport
Joined: 06 May 2019
Posts: 67
Location: Long Beach, CA
Thu Jul 11, 2019 7:22 pm quote
Ginch: Thanks for that info and link. I have one of these nuts I got from SIP/DRT a while back but never used, #11351940. Scootermercato sells what appears to be the same oneÖ both retail approx $10. SIP has another option without the washer for 1/3 the price.... I'm sure there are others out there
I wonder if these are actually true ďJet NutsĒ as they come with a toothed lock washer. Or are they simply machined ďflange nutsĒ with NO self locking characteristics...


Some more detailed information about the Jet/K nut and how it achieves the self locking through Eliptical offset on part of the threads., As you said Ginch!

Jet-Nut / K-Nut - from wiki
A jet nut,[1] also known as a k-nut,[1][2][3] is a special type of hex locknut that is commonly used in the aerospace and automotive racing industries.[3]
It has a flange on one end of the nut, the hex is smaller than a standard sized hex nut, and it is shorter than a standard hex nut. It achieves its locking action by using an elliptical offset on the un-flanged end of the nut.[4]

Elliptical offset nuts
Elliptical offset nuts is a catch-all category that encompasses designs known as oval locknuts[1] or non-slotted hex locknuts,.[3] The salient feature is that the threadform has been deformed at one end so that the threads are no longer perfectly circular. The deformed end is usually shaped into an ellipse or obround triangle. These are known as one-way nuts as the nut may be easily started on the male fastener from the bottom non-deformed portion, but are practically impossible to start from the deformed end. As the male fastener reaches the deformed section it stretches the threads of the nut elastically back into a circle. This action increases the friction between the nut and the fastener greatly and creates the locking action. Due to the elastic nature of the deformation the nuts can be reused indefinitely.

Reusing Locking Nuts
The FAA has issued guidelines on the reuse of locking nuts. Specific recommendations have been published for larger sizes (7/16-20 and up), but the general rule is that you should not be able to turn the nut by hand once the locking portion engages the male threads. If you can turn the nut with your fingers, it must be replaced. When in doubt, replace!


On a slightly different note: digging into thread locking/bolt lossening on Boltscience.com. Interesting stuff for a Geek if you want to dive in deep! Basicly they say that split-ring washers do NOT help secure a nut, and actually cause it to fail sooner than just a plain nut alone. This is only preliminary research. Not thinking specifically for the clutch, just general purpose info for those who want to dig deeper. I think I shall

IMG_5599.jpg

jet nuts for clutch.jpg

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