What if we were all Hercules ?

[Zeuk in Oz]

Apologies for the navel - gazing, but a conversation I had with Kristian (BigKriss) on Saturday at the Sydney Oran Park meet has been on my mind.

We were talking about tools, specifically breaker bars and extensions on rachets compared with air tools etc etc.

I found that when I was lying under my car the other day torquing the loaded thrust arm bushings to 127 Nm (if my memory serves) it was just about the limit of what was possible in such a confined space.

Are components made to be just about unremovable without special tools because that is the optimum or because if components were put together more tightly no mortal could remove and replace them ? Would we have better cars if we were strong enough to work on them ?

What I am getting at is every time I work on the car I feel that were I 20% weaker I would not get the job done.

Is this "near the physical limit" mechanical work intended or deliberate ?

Could vehicle manufacturers construct a vehicle that your proverbial 100 lb weakling could work on without serious exertion ?

Or does the flaw lie in the quality of our tools ? Or perhaps that we use steel nuts and bolts - when we could perhaps use some more high - tech but easier to work with material ?

Don't really know if I have expressed myself well enough but I hope you get the idea !

[Kalevera]

99% of the job is using the right tools, from a professional standpoint where time matters.

Take, for example, the removal or installation of an E30 iX all wheel drive transfer case. While hardly the most difficult mechanical work I've done, I wouldn't wish it on anybody. Even with a lift, transmission jack, and an endless array of sockets, extensions, and universals, it took me nearly an hour to engineer a method of removing the upper two bolts mating the transmission to the transfer case the first time I did one of these. Had the car been on jack stands in my garage at home, with a limited selection of extensions and joints, it would've taken me days.

Most of this stuff is routine. Once you've had a successful go of it, there's no more guessing about it with fast learners. Just as the forum is comprised of those who've done it, and those who haven't. Most procedures don't require much beyond typical hand tools to get it done. That doesn't mean it gets done quickly, but for me, part of the definition of enthusiasm has always been about enjoying the work.

best, whit

[wingman]

Yes I see your point. I think of the Paris to Dakar. A crew of two big blokes change a wheel. No torque wrench out there so it's "as tide as you gan Sven" (apologies to the Swedish members). Same place a crew of two slight ladies change a wheel " as tight as...." you get the picture. Whose wheel stays on the longest?

I think there is a balance between components that can do the job versus cost effectiveness. Take an F1 car apart and you'll find the strongest and lightest bits available. With a road car the kind of torque settings would be much lower so as to not break the components. Granted that there are far less stresses on them in Chatswood than at Silverstone.

Where am I going with this? I think they set it all as tight as the components can handle and not to prevent 100lb weaklings from working on them. Our cars could be better but we couldn't afford them.

[DanDombrowski]

As a mechanical engineer I can tell you that for the most part that the torque of a bolt or system is determined based on the strength of the material. More specifically, you usually want the nut on a bolt to be slightly past the yield point of the material, to where it just slightly deforms. I have a feeling that its somewhat of a coincidence that the torque of a bolt is near what most humans can do.

I've never seen any 'maximum human assembly' torque in any of the design manuals I've used. If anything, the only way something would be specified based on that would be if something went into production, the workers couldn't assemble it, and they evaluated weather or not a lower torque would suffice.

[Robin-535im]

As a mechanical engineer I can tell you that for the most part that the torque of a bolt or system is determined based on the strength of the material. More specifically, you usually want the nut on a bolt to be slightly past the yield point of the material, to where it just slightly deforms. I have a feeling that its somewhat of a coincidence that the torque of a bolt is near what most humans can do.

I've never seen any 'maximum human assembly' torque in any of the design manuals I've used. If anything, the only way something would be specified based on that would be if something went into production, the workers couldn't assemble it, and they evaluated weather or not a lower torque would suffice.
I agree with you on the relation to material strength, but I'd suspect that there is a relationship between maximum torque settings and the "human perspective", I'll call it.

Now for small fasteners, forget the human factor, it's probably minimimum size that will do the job given the loading and material strength.

But for big fasteners, it is indeed curious that you never come across a nut that a grown man can't wrench with hand tools... washing machine, air conditioner, swingsets, cars, etc., I can't think of a case where it's too big for manual operation.

Of course, when you get down to it, the ME at GM desigining a bracket has a list of common fasteners in his AutoCAD toolbox and gets penalized big bucks for choosing an exotic fastener when a common one will suffice, so maybe it's supply and demand that makes the bolts on our cars all man-sized. There's no (legitiimate) market for huge nuts (!) so they don't get built en masse, there's a culture at the design shops to use familiar approaches, and the Big Nuts just don't make it into designs.

[Zeuk in Oz]

it is indeed curious that you never come across a nut that a grown man can't wrench with hand tools... washing machine, air conditioner, swingsets, cars, etc., I can't think of a case where it's too big for manual operation.

Thank you, that is what I was trying to say ! :)

[stx133]

did a project last year using 1.5" dia bolts torqued to 1200 Nm. had a torque multiplier ratcket and a few big boys, coulpe of hours and job done. economy of scale. use 2 big bolts or 6 smaller bolts, for a car it is a no brainer. in heavy industry 20 large bolts or 60 smaller bolts, starts getting messy...

[McWatters]

No you are all wrong wrong wrong.... Every car company hires Steriod injected empoyees. Where do u think all the body buffs go.
god

cheers

J.McWatters