PeteH Posted October 20, 2021 Report Share Posted October 20, 2021 The Age (1971) would suggest that a UN thread form is likely, In fact, enlarging the photo would suggest a flat thread. Although the mystery remains as to why the TPI is inconsistent with UNF. IE; 28TPI (UNFS) as opposed to 18TPI (UNF)?. Pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 20, 2021 Author Report Share Posted October 20, 2021 Well, it's not UNF. I borrowed a 9/16 UNF die and thankfully practiced on a spare column which although it has better splines had badly worn threads - these professional quality dies cut without even knowing they're doing it; my cheapies would have told me that there was untoward resistance but once it flew to the bottom there was no doubt that the thread is different, and a check with the nut reveals it won't even come close to fitting. The original is a fine thread of approx 10 turns, the new cut is coarser and about 7. Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 20, 2021 Report Share Posted October 20, 2021 1 hour ago, Colin Lindsay said: Well, it's not UNF. I borrowed a 9/16 UNF Quote thats half a story so what TPI was on your die nut if its not 28 you get what you have there are not that many 9/16 x 28 commonly about in tool boxes Pete Link to comment Share on other sites More sharing options...
NonMember Posted October 20, 2021 Report Share Posted October 20, 2021 2 hours ago, Colin Lindsay said: Well, it's not UNF. No, I think several people had said so right at the start. It's closer to UNEF ("extra fine") but seems to be even finer still as that's 24TPI. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 20, 2021 Author Report Share Posted October 20, 2021 40 minutes ago, Pete Lewis said: thats half a story so what TPI was on your die nut if its not 28 you get what you have It says: 9/16 UNF WB HS and then as I've found already, 'Goliath'. Link to comment Share on other sites More sharing options...
PeteH Posted October 20, 2021 Report Share Posted October 20, 2021 That`s 28TPI. If you look at the photo`s I posted and count the threads it`s exactly 10 threads, and my thread gauge (28tpi) is a "fit". 9/16 UNF is 18TPI. Colin`s estimate of 7 threads would give 19 TPI. I suggest it`s probably 18TPI. Pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 20, 2021 Author Report Share Posted October 20, 2021 I swapped over steering wheels this evening; the original is standard but I've a nice leather-covered Herald wheel (I think it's an Alexander cover?) and much more comfortable; I put the socket on and found the nut wasn't even tight. That's now been remedied. However still looking for the definitive answer, today's mission cost me two packets of biscuits (anyone tried the fully-coated Hobnobs yet?) so a return visit on Friday will cost me the same at least. 28Tpi in what thread? Link to comment Share on other sites More sharing options...
PeteH Posted October 20, 2021 Report Share Posted October 20, 2021 1 minute ago, Colin Lindsay said: 28Tpi in what thread? I would suggest it to be UN. The age of the Vehicle, coincided with the change from BSF/BSW etc; to Unified Threads ( the 1948 international ISO standard agreement was slow to implement). The pitch will be the same But the form is 60deg with a Flattened top profile. Pete Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 20, 2021 Report Share Posted October 20, 2021 the guy on the US TR forum used a 9/16unf x 28tpi die to spin downn 6 columns to clean up threads and it worked very easy and nicely you only have to look to see its is something special the dia is confirmed as 9/16" the 28 TPI is confirmed what else is there to do its been solved enough times on this post we dont have a shadowgraph but that would confirm the angle for once Pete 1 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 21, 2021 Author Report Share Posted October 21, 2021 18 hours ago, Pete Lewis said: the dia is confirmed as 9/16" the 28 TPI is confirmed what else is there to do its been solved enough times on this post Begging your pardon, M'Lud, but it's been debated, discussed, suggested, and bandied about but only in one post (your reference to the US forum) does it say it's 9/16 28 tpi, and that's been queried with more recent posts suggesting UNS, UNFS, BSF, BSP, 60 degree threads, 60 degree threads with special thread form, even UNEF, so call me dim-witted, slow learning or just downright stoopid but nowhere does it say definitely and positively go for 9/16 UNF 28tpi, and as an amateur man-in-the-garage home-mechanic type that's what I need. Link to comment Share on other sites More sharing options...
NonMember Posted October 21, 2021 Report Share Posted October 21, 2021 1 hour ago, Colin Lindsay said: that's been queried with more recent posts suggesting Unfortunately, Colin, many people don't read Pete's very sage advice before posting what Google threw up for them. All those following posts were "according to this" (bloke down the pub) type posts which failed to account for the facts already presented. The 9/16" and the 28TPI are both demonstrably correct because you can (and people have) measure them on an actual column. Everything else is speculation from web sources. I remember getting in an argument with a chap on the Internet who insisted that my 2.5PI "could not" have a knob called "choke" because Wikipedia told him chokes were used on carburettors. I offered to show him the car, he said that wasn't "real verification" because Wikipedia couldn't cite it. Personally, I live in the real world and consider hard physical evidence of more value that some post on some web page by some bloke I've never met. Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 21, 2021 Report Share Posted October 21, 2021 Hi Colin Beg as much as you wish its free, but apart from the angle be it 55 or 60deg is the only unknown had i stiil been working we used a shadowgraph this magnifies things like threads and blows them up giant size so you can use your old school protractor to solve the X factor anyone got one ??? Pete Link to comment Share on other sites More sharing options...
PeteH Posted October 21, 2021 Report Share Posted October 21, 2021 At the risk of repeating myself. I have measured the Pitch against my Thread Gauges. I Miked up the o/d of the threads. Result 9/16 o/d and 28TPI. That is on the Column removed from my 13/60. (it now has a PAS unit). I am of the opinion that the thread form will be 60deg, implying UN??. I have searched online, and can only find reference to this size on Australian E-Bay. Where it is described as UNFS, the S representing special. In 60 years I have never actually come across the Thread combination before. But the physical evidence is that it Exists!. https://www.ebay.co.uk/itm/152292227571 BTW, haven't seen reference to "shadowgraphs" For many a Year. Although I did make animal shadows with my hands on the wall of the kids and later grand-kids room to entertain them. Pete Link to comment Share on other sites More sharing options...
RogerH Posted October 21, 2021 Report Share Posted October 21, 2021 Hi Folks, my brain hurts. UNS is a normal thread form. It is designed for those special occasions. 9/16 X 28 tpi what is wrong with that. There are dozens and dozens of thread forms - some used more than others. The Overdrive switches (on the TR2-6) are 5/8" diameter X 13tpi if you look at every thread table in the universe it does not exist. But it does !!! Most people use M16 X 2mm it fits. it works but it is wrong Roger 1 Link to comment Share on other sites More sharing options...
Peter Truman Posted October 21, 2021 Report Share Posted October 21, 2021 Question, whats the engineering reason why Triumph would use such an odd ball thread, is the thread angle of the UNS thread such that it is less likely to come undone? Or only being a thin, 1/2 nut is the UNS thread structurally stronger. Ref the Aus eBay sale as the offending die it’s local, I’m tempted to buy it to see how it actually runs down the steering shafts thread! 1 Link to comment Share on other sites More sharing options...
NonMember Posted October 21, 2021 Report Share Posted October 21, 2021 5 minutes ago, Peter Truman said: Question, whats the engineering reason why Triumph would use such an odd ball thread Pure speculation follows: Assuming the thread is made on a good material, the finer thread will produce better clamping force for a given torque, and allow more threads on a thin nut, plus it's less prone to undoing by itself. As the steering column did not, originally, have a lock, specifying a nice low tightening torque is good. The only really good reason for using coarse threads is if the material you're making the thread in isn't all that strong, or fine grained. UNF threads in aluminium strip quite easily, for example. The steering wheel attachment fixes an alloy hub with fine pitch splines onto a good high tensile steel shaft, by a thin steel nut. I suspect the clamping force to tightening torque ratio is a factor. Link to comment Share on other sites More sharing options...
KevinR Posted October 21, 2021 Report Share Posted October 21, 2021 https://www.tkelasguhuy.com/index.php?main_page=product_info&products_id=810833 Link to comment Share on other sites More sharing options...
chrishawley Posted October 21, 2021 Report Share Posted October 21, 2021 I apologise for any previous reference I made to Whitworth. I'm glad this erroneous statement was quashed promptly. It's obviously wrong despite what the factory manuals say. Manuals say that GT6/vit is 9/16th Whit, 2000/2.5 says 17/16th Whit and late Spit as 9/16 UNF - which I now know can't necessarily be trusted. So I spoke to the machinist in the Unit next to me. 40 years experience. old skool. Pointed me in the direction of the Unified constant pitch series of threads as specified under ASME B1.1. Lo and behold Unified 9/16 28 tpi is a designated part of the 'constant' series. So it's a recognised standard, just an obscure one. No idea where to get tap/die for that size. 1 Link to comment Share on other sites More sharing options...
KevinR Posted October 21, 2021 Report Share Posted October 21, 2021 1 hour ago, chrishawley said: No idea where to get tap/die for that size. See the link I posted above Link to comment Share on other sites More sharing options...
PeteH Posted October 22, 2021 Report Share Posted October 22, 2021 Available in Australia and the USA (so far), then?. Merlin tools (Loughbrough) May have them? according to this add?. https://gbr.grandado.com/products/9-16-28-right-hand-thread-die?gclid=EAIaIQobChMIp8v_pbPd8wIVh-_tCh343AFOEAQYAiABEgJEUPD_BwE&variant=UHJvZHVjdFZhcmlhbnQ6NTc5MDIyMzU Pete. Link to comment Share on other sites More sharing options...
RogerH Posted October 22, 2021 Report Share Posted October 22, 2021 13 hours ago, chrishawley said: e. No idea where to get tap/die for that size. https://www.tracytools.com/ Look at UNS Roger Link to comment Share on other sites More sharing options...
RogerH Posted October 22, 2021 Report Share Posted October 22, 2021 14 hours ago, Peter Truman said: Question, whats the engineering reason why Triumph would use such an odd ball thread, is the thread angle of the UNS thread such that it is less likely to come undone? Or only being a thin, 1/2 nut is the UNS thread structurally stronger. Ref the Aus eBay sale as the offending die it’s local, I’m tempted to buy it to see how it actually runs down the steering shafts thread! The OD inhibit switch had this thread (5/8" 13tpi) . Prior to the WW2 metric threads on the continent were all over the place and not formalised fully. But, how did they end up with a thread that didn't exist ANYWHERE. Possibly patent protection for the switch manufacturer As mentioned - UNF have a better clamping effect due to their shallower thread angle. UNS is simply UNF in specialist situations. Another oddity is the 5/16" stud (6 off) in the rear suspension trailing arms. Everybody says it should be UNC. But NO!!! UNF with its low torque and clamping effect will work better Roger Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 22, 2021 Author Report Share Posted October 22, 2021 19 hours ago, NonMember said: I live in the real world and consider hard physical evidence of more value that some post on some web page by some bloke I've never met. I hope you realise the irony of that statement. 1 Link to comment Share on other sites More sharing options...
Pete Lewis Posted October 22, 2021 Report Share Posted October 22, 2021 6 hours ago, RogerH said: Another oddity is the 5/16" stud (6 off) in the rear suspension trailing arms. (tr and the big saloons /stag) Everybody says it should be UNC. But NO!!! UNF with its low torque and clamping effect will work better thats another good case of gorilla ingress as listed 5/16x24 unf with only 12/14 lbft ie just a nice light handed nip and just to say how silly some WSM clues from triumph are way out it shows the big saloon steering wheel nut as 1, 1/16" x 20tpi whit thats enormous when they use the same nut as the small chassis cars so some clown has mixed up the AF size from the shaft diameter whilst the nut is same the spline and taper is up a size you cant trust anyone Ha !!! Pete Link to comment Share on other sites More sharing options...
Colin Lindsay Posted October 22, 2021 Author Report Share Posted October 22, 2021 1 hour ago, Pete Lewis said: you cant trust anyone Ha !!! Pete You can trust experience, which is why I know it's NOT 9/16 UNF in the thread that I tried. Next column, please... Link to comment Share on other sites More sharing options...
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