Enhanced rear springs buttons

[PeteH]

Plastic Batton Rounds. Serious "crowd control" devices, and subject of much controversy. However less deadly than the alternative.

Pete

[Colin Lindsay]

3 hours ago, PeteH said:

Plastic Batton Rounds. Serious "crowd control" devices, and subject of much controversy. However less deadly than the alternative.

Pete

Yep. One of the 'rubber bullet' range. They used to be used a lot, then usage dwindled due to controversy. The current version is called an AEP - Attenuated Energy Projectile - but made of softer material. I doubt you could make suspension bushes from them these days, even if they were ever used again.

(BTW I hope no-one finds the post insensitive or offensive; it's just something that actually happened - sort of 'swords into ploughshares' kind of recycling!)

[Unkel Kunkel]

19 hours ago, DVD3500 said:

I would have thought a lighter color would be better but what do I know I have a degree in French and German so I must be qualified to talk about everything... 😄

 

If there was a rule that talking required qualifications, I would be rendered  mute. 

I’ll ignore it..Here is my (totally unqualified)  explanation: 

Many  polymers have a weakness, they degenerate in UV B light - sun light. = photo-oxidative generation.

There are various ways of protecting against this  -adding a pigment is one to act as an UV absorber and screener.

I agree - at first sight it does seem counterintuitive to have an absorber of  UV light  such as a black pigment but it means that UV light is restricted to the very outermost very thin layer where it’s energy is effectively “used  up”  and dissipated  resulting in the  the inner structure screened.

This characteristic will be there  no matter if the polymer is cut, turned or moulded i.e you don’t have to coat it or paint some sort of UV protection  onto it.

Carbon black is cheap.It also contains other compounds such ethers and other organic groups , hydroxyls, quinones, ethers which help by combining  with some of the destructive oxidative products - “free radicals” effectively   “ mopping them -up” and stabilising.

( Titanium dioxide - the “white of the “whitest”  of practically all “white paint” everywhere  made  is used sometimes in polymers where  the natural white colour is required.)

 

 

[NonMember]

24 minutes ago, Unkel Kunkel said:

Here is my (totally unqualified)  explanation

You're actually pretty much spot on. The problem with "white" polymer is that it's really quite translucent, so the UV propagates all the way through and degrades it to the core. Adding carbon as a black pigment makes it nearly opaque, and only the very surface degrades. Since carbon does not degrade in UV, it's perfectly safe for it to absorb the UV energy. It will warm up slightly and dissipate the energy in forms that are harmless.

[rlubikey]

On 17/10/2022 at 15:16, cliff.b said:

Has anyone had experience of any material other than polyurethane? I'm sure I read somewhere about teflon buttons, but can't find it now.

Sorry I'm late to the party. Yes, I made some of these - well, a friend with a lathe did! I was going to use PTFE because it has the lowest friction, as any fule kno! Then a tribologist said that oil-impregnated nylon would be the ideal material, so I used something with a trade name "Nylon 66" made by company I can't remember but bought from RadioSpares. Here's my drawing - SwingSpringButton.pdf

Cheers, Richard

[cliff.b]

This is all interesting stuff so many thanks for the responses.

One thought, it makes sense to me that it is an advantage for these to be "slippy" but I'm thinking the original rubber ones probably weren't. Doesn't rubber grip? Or does it depend on the compound? 

[rlubikey]

My thinking is that the original rubber buttons undergo shear stress / deformation and there's no slip involved. The relative movement of the spring leafs must be quite small under normal suspension conditions, but I have to admit I haven't checked! I think they're making pattern part buttons out of the same material as track rod boots, engine mounts, bonnet cones etc. hence why they're failing in no time.

Richard

[DVD3500]

15 hours ago, Wagger said:

So, what is an Earshplittinmountinboomertube?

 

>/D

 

[cliff.b]

2 hours ago, rlubikey said:

My thinking is that the original rubber buttons undergo shear stress / deformation and there's no slip involved. The relative movement of the spring leafs must be quite small under normal suspension conditions, but I have to admit I haven't checked! I think they're making pattern part buttons out of the same material as track rod boots, engine mounts, bonnet cones etc. hence why they're failing in no time.

Richard

Yes, that makes sense, but raises a further question.

Is a "slippy" replacement optimal or is the original rubber under a shear force a design feature which contributes beneficially to the performance of the spring 🤔

Not that it really matters as the new rubber ones all appear to be rubbish so the only issue is what the best replacement is.

[rlubikey]

The thing about a sliding action is that it will be subject to wear. Perhaps this is why Triumph added the rubber buttons - if I'm right and it's shear only then there's no wear!

When I get round to fixing the oil leak in my diff, I will examine the spring and check my Nylon 66 buttons for wear. If there is any I will be interested in looking at the polyurethane buttons, since I presume they are manufactured as elastomers and work in shear like the rubber originals. (Are all polyurethanes elastomeric? I don't know.)

Richard

[Unkel Kunkel]

3 hours ago, rlubikey said:

My thinking is that the original rubber buttons undergo shear stress / deformation and there's no slip involved. The relative movement of the spring leafs must be quite small under normal suspension conditions, but I have to admit I haven't checked! I think they're making pattern part buttons out of the same material as track rod boots, engine mounts, bonnet cones etc. hence why they're failing in no time.

Richard

Forget rubber - within little time they will be  squeezed flat, torn , or squashed so as not properly in their locating holes.It is just not a suitable material to use in this situation.

Using another material also has the bonus that it can compensate for a degree  of spring “sag”.

( They can also made too thick, though).

A tangent,  but  of some relevance - Prof John Charnley’s first artificial hips at Wrightington  were “Teflon” ie PTFE .

Welcomed as miraculous, they did have one very significant problem -  they wore out rather quickly, sometimes in as little as a year as patients enjoyed their new mobility and freedom from pain.

A  rep from Hoescht had been visiting nearby textile factories in the area  with UHMPE  samples ( promoting its use in bearings and gear trains in looms etc)  and persuaded  Charnley’s chief technical advisor to wear test a sample in their lab.

Charnley, who was becoming quite despondent  over the hip failure rate at this time, agreed.

Both were surprised that in the severe wear test in which the PTFE  was  finished in less than a day, the UHMWPE just kept  going,  hardly worn well after a week.

Hence UHMWPE.

A very talented orthopaedic surgeon, a lot of the original work on the  stainless steel femoral “ball” that joins the spikey bit ( that fits into the femur - thigh bone part of the “ball and socket”  joint) was  done on a lathe  in his garage. The lathe was financed from royalties from several previous successful inventions.

(After the prototypes,  manufacturing was undertaken by Thackrays   in Leeds )  

[Colin Lindsay]

11 minutes ago, Unkel Kunkel said:

A very talented orthopaedic surgeon, a lot of the original work on the  stainless steel femoral “ball” that joins the spikey bit ( that fits into the femur - thigh bone part of the “ball and socket”  joint) was  done on a lathe  in his garage. The lathe was financed from royalties from several previous successful inventions.

(After the prototypes,  manufacturing was undertaken by Thackrays   in Leeds )  

Good job he wasn't a Triumph owner, we'd have ended up with trunnions.

[rlubikey]

8 minutes ago, Unkel Kunkel said:

Forget rubber - within little time they will be  squeezed flat, torn , or squashed so as not properly in their locating holes.It is just not a suitable material to use in this situation.

With the current offerings maybe, but with a suitable (as per Triumph original) grade of rubber ...? I'm no expert so will of course bow to superior knowledge, but rubber is used in spring eyes, Austin Mini suspension and - designed by the same person - Moulton bicycle rear suspension. All work in shear, and with the weight of the vehicle applied. I seem to recall my factory original rear spring buttons were all present and recognisable when I dismantled 12 or so years ago. I replaced with Nylon 66 because it seemed like a good idea at the time.

UHMPE - Ultra-high-molecular-weight polyethylene - does seem to be highly suitable for this sort of application.

Cheers, Richard

[Unkel Kunkel]

21 minutes ago, Colin Lindsay said:

Good job he wasn't a Triumph owner, we'd have ended up with trunnions.

Up until Charnley, it was generally held that the “  oil” in the joint, the synovial fluid.. (the EP 90  continuing the analogy! ) was the most significant limiting factor to consider in  joint replacement and this would present  such a major problems for any possible joint replacement  as to make it  unworkable.

He was the first to look at the problem in a very different way -   forgetting trying to provide some sort of system  for synovial fluid, oil/  EP90 whatever and  focus first on the  coefficient of  friction of the respective wearing surfaces and then work from there.

Charnley’s “trunnions” would presumably be of some sort of self- lubricating polymer construction presumably  oil-less.That’s not an entirely absurd idea.

[daverclasper]

On 17/10/2022 at 13:26, 68vitesse said:

I just cut some from a sheet of polyurethane.

Regards

Paul

So just flat?, as appose to turning for the locating shape. Can someone explain please?

On 18/10/2022 at 19:56, Unkel Kunkel said:

It is very  frustrating to turn on a lathe - I made quite a pile of failures to get a few accetable ones.

 

[daverclasper]

7 hours ago, Unkel Kunkel said:

I agree - at first sight it does seem counterintuitive to have an absorber of  UV light  such as a black pigment but it means that UV light is restricted to the very outermost very thin layer where it’s energy is effectively “used  up”  and dissipated  resulting in the  the inner structure screened.

Maybe a daft idea, thought could black boot polish (or something similar) help to preserve my tired window rubbers , that do see the sun often?

[cliff.b]

This thread has become far more interesting and educational than I expected 🙂

[PeteH]

I rebuilt the ones on mine after a good clean, left the existing Buttons there, and coated the leaves liberally in Copperslip.

Pete

[Unkel Kunkel]

37 minutes ago, daverclasper said:

Maybe a daft idea, thought could black boot polish (or something similar) help to preserve my tired window rubbers , that do see the sun often?

No, it might  be absolutely fine but there are quite a few ingredients  in there and probably some variation with different manufacturers   - several solvents such as  naptha, turpentine  etc might be a bit much for aged rubber -it would be those rather than the waxy stuff ingredients like guar gum, gum arabic etc..

I would tend to stay with  propriety products  of which there are many.

listening  to other people’s  experiences can be very useful - someone, somewhere will swear by Kiwi or something 

[Unkel Kunkel]

1 hour ago, daverclasper said:

So just flat?, as appose to turning for the locating shape. Can someone explain please?

 

The top hat or Jesuit hat shape should stop them sliding out though the 2 lower outer ones need to be positioned carefully before weight is on the spring or they can come out  of place whilst the spring is “hanging”.

The bump seems to be of different diameters.The “hat” brim  is the width of the spring.

Some “”replacement”  springs don’t seem to  have them at all.

Loads of things tried with laminated springs over a century : A hollow central bolt with  a grease nipple to squeeze grease between the leaves on ancient Fords, grease - filled gaiters enclosing the spring  the spring, people greasing the spring  then spending a long and messy  time winding “ Denso”tape  round them.

They used to squeak in the summer otherwise

[Colin Lindsay]

36 minutes ago, Unkel Kunkel said:

people greasing the spring  then spending a long and messy  time winding “ Denso”tape  round them.

They used to squeak in the summer otherwise

I still do that!

[Unkel Kunkel]

25 minutes ago, Colin Lindsay said:

I still do that!

I haven’t come across that for quite a while.

I offer my admiration and respect for wrestling with that stuff!

Or are you referring to squeaking in the summer months ?
That could be joint related..

[Colin Lindsay]

12 hours ago, Unkel Kunkel said:

I haven’t come across that for quite a while.

I offer my admiration and respect for wrestling with that stuff!

Or are you referring to squeaking in the summer months ?
That could be joint related..

My joints creak rather than squeak, and when they do I usually utter something rather more substantial than a squeak, too.

I first wrapped a spring many years ago, it was an old spring, probably sagging badly, and it stiffened it up superbly. Ever since then, any leaf spring I refurbish, I grease the leaves quite heavily then wrap both sides in Denso and secure with wire twists; plastic ties become too brittle. It's more to keep rust from the bolts and nuts for future dismantling than any attempt at improving the suspension. I end up greased to the elbows, like a Vet looking for a cow, but whether or not there's any benefit remains to be seen. Keeps me happy, though.

 

[68vitesse]

4 minutes ago, Colin Lindsay said:

It's more to keep rust from the bolts and nuts for future dismantling

 

I just used stainless steel nuts and bolt with a stainless spacer tube, much simpler and cleaner.

Regards

Paul

[Dave the tram]

This thread made me think - the area I’ve paid least attention to on my Mk 3 GT6 (swing spring) is rear suspension, apart from fitting Gaz shockers and routine maintenance like trunnion greasing. I’ve long been puzzled by a noise I get when I jack the rear. As it gets negative camber but before the wheel leaves the ground I hear a loud metallic bang, as if something was under tension then slips. It’s not associated with tyre slipping on the ground. Perhaps spring leaves binding then releasing. I’ve now wondered if this could be linked to a less noticeable noise on rare occasions on rebound after bumps. Stiffening the shockers made it less frequent but I’ve noticed it more after stripping the interior out for renovation so no sound insulation. Think I need to look at the thread on spring refurb and make the rear end my next project. Anyone recognise this description of the noise?

Dave