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Post by cumulus on Nov 29, 2022 7:09:15 GMT 12
Hi, can you please provide advice on MSS springs. see mssautomotive.comThey design and make springs for a wide range of performance cars and SUVs. In my case I intend fitting them to a BMW M3. Their springs are height adjustable (although I will be setting them to OEM height) via a rotating collar. I note the LVV guidance which states adjustable springs must use "a locking mechanism to prevent loosening". I emailed MSS to ask about this, and got this reply from the founder and head of engineering William Blankson, who wrote: "Thank you for your query. I am aware of the standards in NZ as we have had similar queries in the past. We also have a few customers in NZ since 2016, MSS for VW Golf MK5/MK6 were the products purchased.
In response to your query, we use Trapezoidal threads and the pitch used is particular and also used in Motorsport - these negate additional locking parts for weight saving reasons but most importantly are effective in use. TZ functions by weight and as such when weight is applied it causes an interlocking action that stops the threads from moving under any load - low or high.
The article below explains TZ very well.
blog.igus.eu/self-locking-what-is-it/
All MSS CNC parts uses TZ and a particular pitch for the above reason, thus saves weight, saves cost, has same locking effect.
Hope the above explanation is helpful and useful. Advise on any other queries you may have.
Kind Regards
William Blankson | william.blankson@mss.company Founder | Inventor | Head of Engineering
R5 MSS Limited "Can you confirm that trapezoidal self-locking threads meet the requirement of "a locking mechanism to prevent loosening" and that MSS springs would therefore be able to be certified (all else being ok)? Thanks |
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Post by Chris on Nov 29, 2022 10:31:14 GMT 12
Can you confirm that trapezoidal self-locking threads meet the requirement of "a locking mechanism to prevent loosening" and that MSS springs would therefore be able to be certified (all else being ok)? Thanks I have never seen trapezoidal self-locking threads accepted as a vibration-proof locking device so I would recommend the traditional method of a locknut is used to avoid the issue. If this is not an option, then an application with sufficient evidence would need to be presented to the Technical Advisory Committee to recognise this as a vibration-proof locking device. Hope that helps Chris |
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Post by cumulus on Nov 29, 2022 12:48:40 GMT 12
Ok, thanks for the reply. Given that these springs are used in motorsport and street applications all over the world in a very wide variety of cars and SUVs, I think we can be 100% certain that these self--lockingn threads ARE vibration proof. But how do I go about presenting a case to your committee to prove that? Would a statement (like above) from the designer be sufficient? The MSS springs are not the only springs on the market using trapezoidal self-locking threads. The similar KW struts use it - see blog-int.kwautomotive.net/the-special-thing-about-kw-coilovers-a-closer-look/ and www.kwsuspensions.co.uk/technology/coilovers |
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Post by Chris on Nov 29, 2022 13:14:54 GMT 12
Ok, thanks for the reply. Given that these springs are used in motorsport and street applications all over the world in a very wide variety of cars and SUVs, I think we can be 100% certain that these self--lockingn threads ARE vibration proof. But how do I go about presenting a case to your committee to prove that? Would a statement (like above) from the designer be sufficient? I've never seen an adjustable spring platform without some form of secondary locking device, so, I would not be able to make a statement that these threads are 100% vibration proof. I am not sure how you can prove these meet the bar of vibration-proof as this is not territory that we veer into very often, but I suspect a test report that describes the method of testing and any outcomes observed would be an appropriate start (the testing should replicate the materials used and use real world scenarios that adjustable coil over suspension would be used in) A statement from the manufacturer would not be sufficient on its own but could be included with your application as supporting information. |
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Post by cumulus on Nov 29, 2022 13:31:03 GMT 12
Ok, thanks. I'll email William Blankson and ask him if he has any test report which would be suitable. In the context of this particular product, I suspect the fact that he has sold tens of thousands of these kits all over the world (including in NZ) and hasn't had any reports of issues with the adjuster is proof that it is, in fact, vibration proof (which is easily confirmed by appreciating the engineering behind the design). Does the technical committee not have a general approval for trapezoidal threads based on an understanding of their design? I don't really feel its my job to educate the committee on the workings of trapezoidal threads in general, just the validity of the engineering in this particular application. Your thoughts on that?
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Post by Chris on Nov 29, 2022 13:43:47 GMT 12
Ok, thanks. I'll email William Blankson and ask him if he has any test report which would be suitable. In the context of this particular product, I suspect the fact that he has sold tens of thousands of these kits all over the world (including in NZ) and hasn't had any reports of issues with the adjuster is proof that it is, in fact, vibration proof (which is easily confirmed by appreciating the engineering behind the design). Does the technical committee not have a general approval for trapezoidal threads based on an understanding of their design? I don't really feel its my job to educate the committee on the workings of trapezoidal threads in general, just the validity of the engineering in this particular application. Your thoughts on that? The requirements in the suspension standard and the attachment systems chapter do not cover trapezoidal threads as a suitable mechanical/vibration proof locking device and so the onus is on the applicant to prove they are suitable. I do not know what the TAC members know about trapezoidal threads and as they only meet once a month it is probably going to save you time to provide the appropriate justification with your application. |
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Post by cumulus on Nov 29, 2022 13:50:42 GMT 12
Again thank you for your response, appreciated. I will see what, if any, reports or comments William will make. At the end of the day, I would hope that the fact these are based on sound engineering, already in use in this application, and have been for quite a few years will be seen as sufficient by the committee.
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Post by cumulus on Nov 29, 2022 15:32:53 GMT 12
Hi Chris - somewhat surprisingly I have had a speedy reply from William Blankson, and his comment is that TZ locking capability "is the norm" and should be accepted as a valid locking mechanism by any engineer with a knowledge of these type of threads. I wonder if perhaps it's just a case of the committee "catching up" with technology which is now well established and used world-wide? It might not be "old-school" but it's not "new-fangled" either!
As he says, they have sold many thousands of these products, and other manufacturers like KW also use TZ locking threads on their spring and strut products, which would add many thousands more. MSS has more than 100 dealers in 20 countries, including NZ. I know that KW coil-overs are regularly certified by your certifiers in this country, so I think the TZ locking technology is already accepted. Is there a way for you to find out if MSS springs have been certified here before? If so, then my enquiry is moot. If not, then perhaps I just need to front up to a local certifier with the product and see what they say? Thanks for all your help, cheers.
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Post by Chris on Nov 29, 2022 15:46:22 GMT 12
Hi Chris - somewhat surprisingly I have had a speedy reply from William Blankson, and his comment is that TZ locking capability "is the norm" and should be accepted as a valid locking mechanism by any engineer with a knowledge of these type of threads. I wonder if perhaps it's just a case of the committee "catching up" with technology which is now well established and used world-wide? It might not be "old-school" but it's not "new-fangled" either! As he says, they have sold many thousands of these products, and other manufacturers like KW also use TZ locking threads on their spring and strut products, which would add many thousands more. MSS has more than 100 dealers in 20 countries, including NZ. I know that KW coil-overs are regularly certified by your certifiers in this country, so I think the TZ locking technology is already accepted. Is there a way for you to find out if MSS springs have been certified here before? If so, then my enquiry is moot. If not, then perhaps I just need to front up to a local certifier with the product and see what they say? Thanks for all your help, cheers. To the best of my knowledge, we have never previously accepted "TZ locking" as a suitable mechanical/vibration proof locking device. I am not saying it cannot be accepted, but you will need to convince the TAC that there is reasonable engineering justification to accept it as such. A statement from the person selling the components that "she'll be right" is not enough. However, if this method is accepted, we may include it as an amendment for when we update the appropriate chapters and standards, but until then, TAC approval is your only path forward. |
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Post by cumulus on Nov 29, 2022 16:01:07 GMT 12
Ok, but how can I, as a non-engineer, convince your committee? I have no technical or engineering background in this. I just want to fit a brand of springs which is regarded as "best in class" or close to it, to my car. The car needs a refresh as the current components are nearly worn out, new springs will be safer than the current worn ones. MSS springs are cheaper than OEM and outperform OEM. They are fitted to many high performance cars around the world regularly. I am trusting my safety and the safety of my passengers and other road users with a product which is totally proven over 8+ years and in many different vehicles including Motorsport and off-road applications. The case for this product is strong from both an existing use-case and engineering perspective, but I have no means to "prove" the engineering side of it? How can I proceed?
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Post by cumulus on Nov 29, 2022 16:11:58 GMT 12
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Post by Chris on Nov 29, 2022 16:11:59 GMT 12
As I have said up above, the easiest solution will be to follow the traditional path of a locking nut, and I expect that 4 locking nuts (one for each corner) will probably not cost much more than a TAC application, and certainly a lot cheaper than commissioning an engineer to complete a suitable engineering justification.
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Post by cumulus on Nov 29, 2022 16:19:57 GMT 12
Yes, but the locking nuts will need to be TZ threads, and they wont bind against the height adjuster, but against the thread they both rotate on. That's the point of a TZ thread! I wonder if a small bolt inserted through the adjuster or a short self tapping screw would be considered sufficient to hold it in place? Its not weight bearing (the thread takes a little weight, most of it is on the spring perch) just to prevent lateral movement (which can't happen anyway due to the TZ thread, but still....).
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Post by cumulus on Nov 29, 2022 17:11:04 GMT 12
Actually, I've just realised something. If these springs are set to their maximum height (which is stock OEM height), then they are not adjusted at all, and firmly in contact with, and tight against both the top and bottom spring perches. So they cannot be "loosened" and are mechanically prevented from "loosening" any further than their current position. They could even be used without the adjusters in place, in which case they are not height adjustable at all. Problem solved I think. .If I were to run them without the adjusters then would they even need to be certified at all?
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