Why do modern car engines have different types of bolt type heads like Torx etc?

I'm afraid that 'why o why' threads always end this way.

Tend to agree, in all of the the less well off who manage to keep old(ish) bangers on the road will be ignored. I suspect that this will create a major unrest when they suddenly find that they are isolated and denied the services that they are used to. The political fallout could be large.

If you want to mix and match heads, look no further than a Myford 254. The change wheel studs are BSF/Whit as is the tool post nut; the bolt which secures the drive belt and change wheel cover, and the carriage lock are 1/2" AF; the rest are metric.

Edited By Chris Pearson 1 on 27/07/2023 18:26:48

There is one great advantage in having UK sources of oil and coal (including new Oil and new coal) is that you SAVE the transport costs and emissions bring it from far off places for as long as we need it to allow the green steps to be safely taken.

Anyway, how much of the worlds emissions do we contribute? Quite a low % I would guess.

There IS tax on aviation fuel. How much depends on the usage. With the recent duty change centered on red diesel the situation with jet fuel in the UK got complex. If you have a company turbine helicopter and say fly to a trade show yourself you pay excise duty on the fuel because it's classed as private. If you take a co-worker with you you don't duty because it's business.

https://www.gov.uk/guidance/fuel-used-in-private-pleasure-craft-and-for-private-pleasure-flying-excise-notice-554

My club bought from the local builders' stockists a set of flanged nuts for the studs holding the portable track sections to each other.

A very good idea... Would be even better if the hexagons, though metric, are not the standard ones for any ISO-M threads (M10 or M12 but not 17 or 19mm a/f). I found similarly with other building fastenings I used for parts of my workshop installations.

Over the years I have equipped my Myford ML7, which I had bought second-hand with few accessories, and found the new fittings needs an odd mixture of spanners! The basic machine is consistently BA and BS but the additions like the rear tool-post stud and its two Tee-slot nuts, and the steady's clamp-nut, seem to be Standard Somewherehandy.

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Years ago I worked for an electronics company that serviced a lot of small Royal Navy equipment. The cases often bore warning labels about mixed thread standards.

I think private flying is beside the point, road and rail users pay tax on fuel, railways even pay various levies on electricity (one website states this increases electricity costs by 40%,commercial aviation fuel is not taxed. Hardly a level playing field. I can appreciate that there would be an incentive for airlines to fill up abroad if we were the only country to tax aviation fuel, but there are ways round this.

What has Malthus got to do with bolt heads?

This topic has been taken for a good walk!

JA

I have seen comments here on different bolt heads due to access restrictions, but I don't think I have seen any informed comment on the torque-handling capabilities of the different head forms. Particularly important when you are taking the d****d things out when you have to fight both the original tighening torque plus the corrosion that's occurred in the years since it was put in in the factory...

I know that security is one reason for the odd heads you sometimes find. Sometimes misplaced ideas of security. I spent some time working in a pretty secure Government establishment. To help with resetting forgotten passwords (fairly common - their technical people were pretty switched-on but the staff they supported dwelt on a planet slightly to one side of our own) there was a "super-secure" PC in a custom cabinet with some kind of specially trusted network connection. To reduce the chance of hardware tampering, there was a clear polycarbonate cover so you could see all the components and which was secured with "security bolts". The guy in charge was very proud of this. I had to tell him that I had bought a set of bits off eBay the previous weekend for a tenner that included the bits necessary to undo his security bolts.

I plead guilty to contributing to thread deviation, M'lud.

In mitigation, I claim to have suggested the best engineering reasons for mixing threads and heads on the same modern engine.

I don't believe it's done simply to screw-up home mechanics, because different heads are found far deeper inside the engine than maintenance normally goes. Things like the bolts holding water-pumps and the alternator together, those fixing the oil pick-up to the engine block inside the sump, fixings inside the cam-block, and those connecting cranks to the crankshaft, or that anti-harmonic thingy. Anyone on the forum ever completely dismantled an entire engine?

The engine in one of my early cars, a Talbot/Chrysler Sunbeam, or maybe a Horizon, contained a wild mixture of US, imperial and metric bolts. I think this resulted from the dreadful mess the British car industry was in at the time, where part of the answer was seen as collaboration between previously independent manufacturers in the same group. Chrysler owned what had been Rootes in the UK and Simca in Europe. Building on existing assets Chrysler UK produced a number of cars, as did others, from parts sourced from around the world. Not sure how long this went on, but many of the 'British' cars I drove during the seventies and eighties had both Imperial and Metric thread types, indicating mixed heritage. Due to being in terrible financial trouble makers couldn't afford to design new cars and engines from scratch, and had to make the best of what they already had. In the long run, not good enough, when foreign competitors have brand-new production facilities and haven't trashed their relationship with lenders, staff, and government!

Pretty sure this kind of financial pressure doesn't explain why universally metric modern engines mix hex, torx and other heads. As far as I know all modern engines are made with lots of different heads, reason unclear.

Dave

As the old saying goes “ you could write a book” just about Torx

… for convenient reference though; the Wikipedia page provides a reasonable summary:

**LINK**

https://en.wikipedia.org/wiki/Torx

MichaelG.

Industry seems to manage pretty well using 8 mm heads on M6 fasteners, and 10 mm hexagons on M8 fasteners, in high volume production situations. Maybe they use better quality spanners and sockets?

You can bet thta some one will have done their sums to compare the strength of the hexagon against that of the thread.

I wore out a cheap 7/16 socket, but not the Britool one that replaced it

You get what you pay for, ultimately.

Howard

I’ve not read the whole thread so apologies if someone else has mentioned it but apparently some Japanese motor bikes have five sided head bolts.

Torx Plus (IP) not the 5 sided are quite simply the best internal fasteners, they're amazing, there's probably a long list of reason manufacturers haven't switched over to using them as a norm, hex fasteners are decided by manufacturer quality and the quality of sockets used on them too, I've given a few of my sockets a rough measure.

The top photo is a Snap Flank drive FDX 16mm socket, these are made to precise tolerances, and show exactly 16mm.

The second photo is a middle of the road 14mm impact socket that shows 14.2mm

The third photo is a 12mm Taiwanese blue point socket showing 12.2mm.

The fourth photo is a standard snap on flank drive 16mm showing 16.14mm

If you're even semi serious about mechanical work it's best to keep every possible fastener type socket to hand, a good selection of Snap On ratchets never hurt anyone either.

I apologise, I need to wait to be upgraded to Moderater status before making random off topic comments and calling people nutters, luckily Neil likes me 😂 so it won't be long.

Dave & Pete

Apologies not accepted.

I rather like watching topics being taken for a good walk. It is one of the beauties about "Tea Room" topics.

Perhaps this is a future subject.

JA

Godwins law says that all internet discussions eventually get round to Adolph Hitler and the Nazis. The civilised members of this forum have avoided that so far!

Now look what you have done, Duncan

MichaelG.

Dave, the further into an engine you get, the less likely it is to find unusual fasteners. I wouldn't consider 12point male heads to be unusual for things like conrod bolts.

The worse offenders for this German, as they seem to have a competition for who can use the most different fasteners, seemingly scattered around at random.