Tow Balls - Why So Awkwardly Complex?

[Lionelgee]

Hello All,

I went to fit a 3.5 Tonne tow ball to my vehicle. I found that the tow ball nut is tapered. The nut is 32.5 mm and only fits "tow ball nut spanners" one way. They should also be torqued to 250 Nm.

According to an online conversion a 32.5 mm socket is 1 inch and 4/16ths; accessed 26th April 2020 Conversion mm to inch and inch to mm with fraction (https://en.libraindustriale.com/unit-convert)
This may convert down to 1-1/4 inch socket.

This I learnt from experience:

I only have a 32 mm and a 33 mm socket, and these are impact sockets
I have two torque wrenches - neither of them el-cheapos and they both only go up to 200 Nm
There is no ability for tow ball nut spanners to read torque
There is no notification which way the taper should go? Is it thickest side to the tow tongue? Or is it the thinnest side of the taper to the tow tongue?
The car parts supplier I went to only has on stock torque wrenches that go up to 200 Nm.

I found only one supplier of 32.5 mm sockets on eBay and that was available in England. The Imperial version is more readily available at 1-1/4 inch in Australia.

So how many people buy the specialist Tow ball nut spanner and have a guess what the torque setting is? Or they grab a big shifting spanner, or a set of stillsons. To the extent that there may be more non-manufacturer's specification towballs fitted travelling on the road then there is up to specification ones.

So off I go with special tow ball nut spanner in hand to have a guess about taper directions - my guess is thicker to tongue, and what I can crank out on a cheap single purpose pressed spanner. This will have to last until I can take the tow ball into a specialist to see if they have a torque wrench that goes up to 250 Nm and has a 32.5 mm socket and get them to test my work.

Next time I follow someone towing a trailer I will wonder how close to manufacturer's specifications their towball is fitted to?

P.S. I now have a 350 Nm torque wrench and a 1-1/4 inch deep socket on their way via Australia Post.

Kind regards
Lionel

[W&KO]

I keep it simple, plus have never seen a tapered nut.

I have only ever used a shifter, did it up as tight as I could with my body weight, use next size up shifter when removing.

Spring washer under the nut

30 year and never had an issue.

Oh, i doubt tow bar fitter get a torque wrench out.

[Blknight.aus]

big shifter and a spring scale...

9.8n to the KG

multiply out with the distance from the center of rotation and heave on with a spring scale, use a pipe on the spanner to get to an easy to work out number.

you'll also find that 250nM is a touch light on for the bolt size on the bottom of the ball.

IIRC it should be nearer 400nm.

Ive also never seen a tapered nut on a tow ball. Whered you get this thing from.

If the nut is a security nut (one designed to resist standard sockets by maing them "cam" off) you may not get away with a near enough fit of a normal socket and will need the specialist tool.

good luck

[Slunnie]

I think you're over thinking it.

Just put a big shifter or whatever on it and do it up really tight. It's a big bolt, you wont break it, you just don't want it to come loose.

It's a bit like wheel nuts, just do them up tight using the wheel brace supplied, you don't have to put a torque wrench on everything even if everything has a torque specification.

[loanrangie]

Big shifter on nut, position right boot on receiver, pull and lean back - job done.

[INter674]

Big shifter on nut, position right boot on receiver, pull and lean back - job done.

Naa...3/4 rattle gun plus big socket 🤤

[ramblingboy42]

I've never heard of it Lionel.

what vehicle is it on?

I have seen tapered nuts in the mining game but bloody big ones and require hero impact guns to remove them.

[scarry]

Two 15" shifters,one for the nut,other for the flat on the ball.
Do up bloody tight recheck after 50Km with van on,then recheck every so often.

Move on to something thats worth worrying about[biggrin]

[101RRS]

Sorry not following this thread - all the tow balls I have purchased over the last 35 years have been a simple bolt up affair - simple thread, big spring washer and a bit nut - nothing special.

Where did this unique ball come from - why not buy a "normal" tow ball from the likes of Supercheap et al.

Garry

[Lionelgee]

Sorry not following this thread - all the tow balls I have purchased over the last 35 years have been a simple bolt up affair - simple thread, big spring washer and a bit nut - nothing special.

Where did this unique ball come from - why not buy a "normal" tow ball from the likes of Supercheap et al.

Garry

Hello Garry,

The tow ball I bought is a Hayman Reese 3.5 tonne rated flat side I bought along with the tongue from Pedders. The HR tow ball came in an indistinct brown box. I read the label on the same tow ball at Repco. The box featured fitting instructions, including their recommended torque setting.

The tow ball tool came from AutoBarn.

Why do I think the nut is tapered? Because the sales reps at both Repco and AutoBarn measured them with a vernier calliper. The only thing both places had in stock that would fit the nut was the tow ball tool. The tool will allow the nut to fit the spanner in one direction only. It will not pass through both sides. It fits flush with the end of the nut - however the nut cannot pass through the tool. This side goes upwards towards the tongue. Allowing the spanner to be withdrawn downwards once the nut is tight.

So nothing unique about: the tow ball; the tow nut; or the tow nut spanner. They are all commonly available from the majority of auto-parts suppliers.

Kind regards
Lionel

[101RRS]

Ok thanks - never had that issue - I just use a big shifter or stilsens to tighten the nut - I have never had one that is tapered.

Cheers

Garry

[trout1105]

Most reoutable tow hitches have retaining slots to hold the ball itself and all you have to do is to crank up the retaining nut against the spring washer as hard as you can (preferably using a 24inch shifter or stilson) end of story and it will NEVER come loose[thumbsupbig][thumbsupbig]

Why do people get "Technical" or way "Overthink" such simple procedures[bigwhistle]

[Lionelgee]

Hello All,

Well according to Bruno Latour, I have made a big mistake. I have questioned something that everyone takes for granted as something common place that just simply works in everyday life. This is described as "Blackboxing".

Where Blackboxing ...

Is the way scientific and technical work is made invisible by its own success. When a machine runs efficiently, when a matter of fact is settled, one need focus only on its inputs and outputs and not on its internal complexity. Thus, paradoxically, the more science and technology succeed, the more opaque and obscure they become.

As cited in, Latour (1999). Pandora's hope: essays on the reality of science studies. Cambridge, Massachusetts: Harvard University Press. p. 304.

I made the mistake of lifting the curtain and I took a peek inside the blackbox.

It's all good folks tow balls are just tow balls.... Nothing to see here .... moving right along...

Kind regards
Lionel

[Lionelgee]

Why do people get "Technical" or way "Overthink" such simple procedures[bigwhistle]

Hello Trout,

Two reasons at first spring to mind: 1) Autism Spectrum 2) PhD Candidate... = I think too much.

Oh and 3) probably trying to do the "right" thing - which links back to 1).

Plus 4) faith that someone studied an Engineering degree and wrote some technical specifications that should be followed so a product does not fail... Okay link this back to 1) as well.

Kind regards
Lionel

[gromit]

Sounds like it's a poorly made nut, very slightly larger at one end rather than deliberately tapered.

Use a 1 5/16" AF deep socket or large adjustable.
You could use the 33mm socket as on that diameter .5mm bigger shouldn't be an issue.

I wonder if you could get to 250Nm with the pressed steel spanner ? Maybe a long tube on the end and turn the spanner till it bends ?

Never heard of a torque wrench being used but 250Nm tells me it needs to be tight.


Colin

[W&KO]

Hello All,

I made the mistake of lifting the curtain and I took a peek inside the blackbox.



Thought it was a Brownbox that the tow ball come in [emoji6]

Either way i see you point and assume this the first time you’ve fitted a tow ball and hooked up a trailer.

The tow-ball is only a very small part of the towing and probably the easiest.

From memory you’ve mention getting a car trailer with a 3.5T ATM. Towing with 3.5T there is a whole lot more to learn than getting the ball 100%.

I’d personally ditch the tow ball you purchase and just get a standard towball that a shifter fits. Spin the nut on and do up as tight as you can.

[Lionelgee]

Thought it was a Brownbox that the tow ball come in [emoji6]

Either way i see you point and assume this the first time you’ve fitted a tow ball and hooked up a trailer.

The tow-ball is only a very small part of the towing and probably the easiest.

From memory you’ve mention getting a car trailer with a 3.5T ATM. Towing with 3.5T there is a whole lot more to learn than getting the ball 100%.

I’d personally ditch the tow ball you purchase and just get a standard towball that a shifter fits. Spin the nut on and do up as tight as you can.

Hello W & KO,

No - an incorrect assumption; this is just the first time I have made the mistake of reading the label and instructions. Previously I have used either a nice big shifting spanner or an equally long set of Stillsons.

No none of the other installations of tow balls or tow bars fell off or did anything bad. Each application was successful.

Towing - as a former Horticulture/Agriculture TAFE Trade teacher I used to teach people to tow and reverse trailers and large farm machinery. This was back in the day that there was a "tractor licence" and an independent tester would award a ticket like a fork-lift licence gets tested now. Having worked in five local government shires in Queensland, within parks & gardens, I have also towed quite a range of things behind me all day in different vehicles.
I also have a UD classification on my Queensland Driver's Licence. - now a defunct classification apparently.

Today, I just made the mistake of looking into the blackbox.

Kind regards
Lionel

[Graeme]

Sounds like it's a poorly made nut, very slightly larger at one end rather than deliberately tapered.
I would add that the stamped spanner probably isn't meant to be tapered so when put together with the particular nut it appeared as a design feature.

I use an 18" shifter.

[martnH]

Just weld the nut on.

[Lionelgee]

Hello All,

I neglected to mention - not being happy with the amount of leverage offered by the new special tow ball tool - I used the new tool in conjunction with my old Record T channel sash clamp, which I fitted to the flats of the tow ball. This gave me a 1500 mm long lever to clinch down onto the tongue with. I think I got the nut good and tight.

Kind regards
Lionel

[Slunnie]

Hello Trout,

Two reasons at first spring to mind: 1) Autism Spectrum 2) PhD Candidate... = I think too much.

Oh and 3) probably trying to do the "right" thing - which links back to 1).

Plus 4) faith that someone studied an Engineering degree and wrote some technical specifications that should be followed so a product does not fail... Okay link this back to 1) as well.

Kind regards
Lionel

Don't forget that everything has a tolerance specification and if its not written or measurable then you're free to make it up. So bolts, tighten them up until just before they go loose again. :lol2: You won't get a tow bar that tight without putting the car in a vice.

Edit... I am joking.

[onebob]

Don't forget that everything has a tolerance specification and if its not written or measurable then you're free to make it up. So bolts, tighten them up until just before they go loose again. :lol2: You won't get a tow bar that tight without putting the car in a vice.

Edit... I am joking.

“tighten them up until just before they go loose again” [emoji23]🤣 I’m lovin’ the humour in this thread.

[JDNSW]

I'm reminded of many years ago reading the maintenance instructions for a mud pump (high pressure piston pump circulating drilling fluid on a mobile drilling rig used for drilling holes up to 300m). The torque specification for tightening the nut holding the piston on, from memory about 2" thread, "36inch pipe wrench with four foot cheater". Not too different from me loosening the wheel nuts on the County one time after the tyre place fitted a wheel!

[PhilipA]

I must be trying too hard.
Moved the daughter and SIL's camper trailer to Saratoga from Avalon so had to switch towballs from my Mchitch to normal.
He had a new towball.
Tightened it up with my shifter. Time came to undo and the lock washer had distorted so much it bit into the thread of the towball.

All I can think is that the lock washer was so crap and not sprung steel that it distorted. now he needs a new lock washer and maybe towball as the thread was damaged pretty severely.
So buy a quality lock washer from a nuts and bolts place.
Regards PhilipA

[4bee]

Don't forget the smear of grease on the ball each time it is used. Dry balls can apparently loosen up with movement friction. No kid.


Remember, grease your balls. Some may even find it a pleasant experience.:Thump::Rolling:

[ramblingboy42]

many an apprentice had the treatment.......I don't believe it was pleasant......especially when they used what we call "gotcha grease" those with a past in mining maintenance should know that one.

[Bigbjorn]

many an apprentice had the treatment.......I don't believe it was pleasant......especially when they used what we call "gotcha grease" those with a past in mining maintenance should know that one.

At ED's shipyard in Brisbane it was the custom to "grease" new apprentices. A mixture of heavy grease, Stockholm tar, and machine shop swarf was the favoured treatment. Management put an instant stop to this when a highly aggrieved and influential mother of a 16 y.o. new apprentice went to court for damages and won a substantial award against the company. Sackings all around and warnings of instant dismissal and police charges of assault in future.

The apprentice's family were prominent in the Anglican Church and Freemasonry and wealthy.

[4bee]

With a background like that Brian, WTF was he doing wanting to be a Shipwright? Plumber, Sparky, Carpenter etc.[biggrin]

[Bigbjorn]

With a background like that Brian, WTF was he doing wanting to be a Shipwright? Plumber, Sparky, Carpenter etc.[biggrin]

He was a boilie and his family owned a specialist and prosperous engineering works. His father did not apprentice family at his works preferring they got a grounding in the outside world where they were not the bosses' son, nephew, etc.

[Graeme]

"36inch pipe wrench with four foot cheater"3/4" socket breaker bar with a length of water pipe to tighten and loosen the bolts on my tractor's rear duals after loosing all bolts except 1 from the left wheel some years ago.

[ausGeoff]

I've always used the "standard" tow ball spanner ($12 at any auto shop) and the ball's never come loose.
50 year's worth of towing caravans and trailers around the Eastern states. The split lock washer is essential.
Foot against the tow bar, and throw your weight into the spanner. I've never worried about torquing.

[jh972]

I would add that the stamped spanner probably isn't meant to be tapered so when put together with the particular nut it appeared as a design feature.

I use an 18" shifter.
Yes, no one has mentioned the degree of taper. It's likely not meant to be tapered at all, and is just cheaper manufacture.

[theelms66]

Don't forget the smear of grease on the ball each time it is used. Dry balls can apparently loosen up with movement friction. No kid.


Remember, grease your balls. Some may even find it a pleasant experience.:Thump::Rolling:Some couplings have friction pads located in the ball receiver to aid stability/anti sway . I think these are to remain dry to be effective, not very common though.

[trout1105]

Don't forget the smear of grease on the ball each time it is used. Dry balls can apparently loosen up with movement friction. No kid.


Remember, grease your balls. Some may even find it a pleasant experience.:Thump::Rolling:

I Never grease up the towball because it will pick up grit/sand and will prematurely wear down the ball, The balls are usually brass anyway and don't need lubrication.
If the ball comes undone due to "Friction" then it wasn't tightened up enough in the first place[thumbsupbig]

[theelms66]

Brass balls are only on monkeys

[Rick Fischer]

All sounds a bit Nuts! ;0)

As I recall from when I was a youngling apprentice being beaten around the head over torque wrenches, I was also taught that in the main spanners are designed (length) so as to be able to only apply the maximum safe torque to the nut or bolt size of the spanner. So when in doubt for something like this, find the correct size open ender or ringy and swing off it. [bigsmile1]

Cheers

RF

[4bee]

Seems not all Tow balls are brass & plenty are steel. I can see where your application would require a brass one & no grease.

There is plenty on Google that advise a light greasing of the ball.


I guess it is a matter of choice. You do what suits you best & I will do likewise.

Job done.

[Homestar]

I stopped using tow balls years ago - use a DO35 hitch or pintle on my stuff - when I borrow a trailer from work I put up with them, but that's not often.

[4bee]

Brass balls are only on monkeys


Probably on Pawn Shops as well, especially if they are outside.[smilebigeye]

[JDNSW]

I Never grease up the towball because it will pick up grit/sand and will prematurely wear down the ball, The balls are usually brass anyway and don't need lubrication.
If the ball comes undone due to "Friction" then it wasn't tightened up enough in the first place[thumbsupbig]

Interesting! I have been using a wide variety of towballs for almost sixty years. I have never seen a brass one. Cast iron (used to be very common in Imperial sizes), yes, turned steel, yes, chromed, yes, painted yes, rusty, yes, greasy, yes. But I have never seen a brass one.

And I always grease mine, not to prevent it unscrewing - as noted above, it should be tight enough that it is not going to come undone even if dry - but to minimise wear. And it should be cleaned off and regreased regularly because of the grit issue.

Note that the coupling will wear as well as the ball, and some couplings have an adjustable pad to take this up. I should also note that while I have never seen a brass ball, bronze couplings used to be fairly common, although I don't recall ever seeing one in metric sizes.

[DirtDigger]

Hello All,

I went to fit a 3.5 Tonne tow ball to my vehicle. I found that the tow ball nut is tapered. The nut is 32.5 mm and only fits "tow ball nut spanners" one way. They should also be torqued to 250 Nm.

According to an online conversion a 32.5 mm socket is 1 inch and 4/16ths; accessed 26th April 2020 Conversion mm to inch and inch to mm with fraction (https://en.libraindustriale.com/unit-convert)
This may convert down to 1-1/4 inch socket.

This I learnt from experience:

I only have a 32 mm and a 33 mm socket, and these are impact sockets
I have two torque wrenches - neither of them el-cheapos and they both only go up to 200 Nm
There is no ability for tow ball nut spanners to read torque
There is no notification which way the taper should go? Is it thickest side to the tow tongue? Or is it the thinnest side of the taper to the tow tongue?
The car parts supplier I went to only has on stock torque wrenches that go up to 200 Nm.

I found only one supplier of 32.5 mm sockets on eBay and that was available in England. The Imperial version is more readily available at 1-1/4 inch in Australia.

So how many people buy the specialist Tow ball nut spanner and have a guess what the torque setting is? Or they grab a big shifting spanner, or a set of stillsons. To the extent that there may be more non-manufacturer's specification towballs fitted travelling on the road then there is up to specification ones.

So off I go with special tow ball nut spanner in hand to have a guess about taper directions - my guess is thicker to tongue, and what I can crank out on a cheap single purpose pressed spanner. This will have to last until I can take the tow ball into a specialist to see if they have a torque wrench that goes up to 250 Nm and has a 32.5 mm socket and get them to test my work.

Next time I follow someone towing a trailer I will wonder how close to manufacturer's specifications their towball is fitted to?

P.S. I now have a 350 Nm torque wrench and a 1-1/4 inch deep socket on their way via Australia Post.

Kind regards
Lionel
No Mate. Never ever seen a HR tapered tow nut. I use 11/4 standard impact socket and a breaker bar .tighten up hard. No need for torque wrench. You are somehow overcomplicating it.? Why.

[4bee]

No Mate. Never ever seen a HR tapered tow nut. I use 11/4 standard impact socket and a breaker bar .tighten up hard. No need for torque wrench. You are somehow overcomplicating it.? Why.


I suppose it could be down to worn dies on the press.

[pedro54]

On a 3.5T towball the thread is 7/8" UNF, spanner size is 1 5/16", though I have used 3'4" Whitworth simply because I have it.

Below is an extract from a table of various spanner spanner sizes I created as I needed to fit nuts on an old machine tool. I you look on Ebay most of the large spanners can be found over time at reasonable prices.



Jaw Size Millimetres

Jaw Size Inches
Spanner Metric
Spanner
AF
Spanner
British
Common Nut/Bolt
(*=non-preferred)


32

1.26
32mm


M22*


33.02

1.3


3/4 W; 7/8 BSF



33.34

1.313

1-5/16 AF

7/8 UNF


34
1.339
34mm







Peter

[JDNSW]

On a 3.5T towball the thread is 7/8" UNF, spanner size is 1 5/16", though I have used 3'4" Whitworth simply because I have it.

Peter

That is a big spanner! Sure the three feet doesn't refer to the handle length?

The toolboxes in my 2a and tractor both have 3/4"W spanners (with the jaws eased slightly with a file) that live there for the purpose of removing and refitting balls - which live in the respective toolboxes when a pin rather than a ball is being used.

[slug_burner]

I am most surprised that fastener torque for heads and other mechanical components aren’t just listed as; FT, 4 foot cheater bar, just put your foot up against it and pull like hell on your 15” shifter, like purgatory with a 18” shifter or longer.

Come on people, what we do and what is written might be two different things but give Lionel a break.

Don’t bust his balls (ha ha!). I can just see the Hayman Reese representative in the dock saying, “we instructed the purchaser to do it up F..king Tight (FT) my Lord”

[Slunnie]

I am most surprised that fastener torque for heads and other mechanical components aren’t just listed as; FT, 4 foot cheater bar, just put your foot up against it and pull like hell on your 15” shifter, like purgatory with a 18” shifter or longer.

Come on people, what we do and what is written might be two different things but give Lionel a break.

Don’t bust his balls (ha ha!). I can just see the Hayman Reese representative in the dock saying, “we instructed the purchaser to do it up F..king Tight (FT) my Lord”

I bet more mechanics could feel FT better than they could 250Nm. :lol2:

[Blknight.aus]

I maaaay have been known to accept being told "do it up FT, it doesn't matter" as a challenge to see what fails first my FT or the yield strength of any part of the assembly thats about to get FT'd.

I have on more than one occasion taken said busted part back to the advisor and gone "No, FT is apparently too T and this is now F, got a replacement for me?"

[Slunnie]

I maaaay have been known to accept being told "do it up FT, it doesn't matter" as a challenge to see what fails first my FT or the yield strength of any part of the assembly thats about to get FT'd.

I have on more than one occasion taken said busted part back to the advisor and gone "No, FT is apparently too T and this is now F, got a replacement for me?"

Tightened until it loosened! :lol2:

[rick130]

I Never grease up the towball because it will pick up grit/sand and will prematurely wear down the ball, The balls are usually brass anyway and don't need lubrication.
If the ball comes undone due to "Friction" then it wasn't tightened up enough in the first place[thumbsupbig]Brass is brittle, it'd snap quickly under a minor shock load and not something I would use in that situation.

And as for the old grease vs no grease, I've always been firmly on the side of greasing.
Never seen wear from using grease, and when I was an apprentice we were towing a 1 tonne rated tilt trailer all the time for work.
I was also one of those weirdo's that lubricated a cattle crush.
I wanted the bloody thing to work with minimal effort the next time we were drafting/weighing/tagging/marking!
I had to fight the ex-FIL on that one, but I was the one using the crush, he always had farm hands having to put up with a partially seized machine during a draft.

[PhilipA]

My Mc Hitch "ball" says not to grease it. I use grease in the UJ on the McHitch as the trunnions are sealed. The chrome coating on the ball is plenty to stop wear and lets face it they are cheap even if they do wear over say 5years.

Grease if used on dirt is a magnet for dust and then becomes grinding compound so IMHO never use it if travelling on dirt.

I do not se grease anywhere where dust is likely eg the rear door lock , side door locks etc

Never had a D2 rear door lock fail, jamb, stick etc even on GRR and long dust hauls.
I use dry teflon lube.
Regards PhilipA

[Graeme]

I use dry teflon lube.
A lubricant none-the-less and similar to my use of silicon spray but perhaps better, just not grease.

[rick130]

Massive point pressure on a tow ball so I use a grease with lubricating solids, e.g. Moly as the hydrodynamic film will fail and galling will start.
Never had an issue with wear, the film at the base of the ball stops contaminants working higher into the wear areas IMO.

[trout1105]

Massive point pressure on a tow ball so I use a grease with lubricating solids, e.g. Moly as the hydrodynamic film will fail and galling will start.
Never had an issue with wear, the film at the base of the ball stops contaminants working higher into the wear areas IMO.

The tow ball itself isn't an issue when using grease, Its all the "Crap" that gets stuck up in the hitch itself that can cause problems.
Tow balls are cheap and easy to replace, The hitch itself Not so much.
The Only place I put grease when towing is in the bearing buddy's [thumbsupbig]

[onebob]

Tightened until it loosened! :lol2:

Made me smile too.. An old Fitter and Turner I encountered during my apprenticeship days (50+years ago) used the term TTPS

Two Turns Past Stripped [emoji6]

[Blknight.aus]

Made me smile too.. An old Fitter and Turner I encountered during my apprenticeship days (50+years ago) used the term TTPS

Two Turns Past Stripped [emoji6]

AKA,

crank it till she snaps then back off half a turn

[POD]

Correct torque for this application is 'two grunts and a sigh'. Which is a little bit less than 'tighten it up til you strip the thread then back it off a 1/4 turn'.

I would be more worried that the threads were cut by a machine shop that couldn't even get the flats on the nut parallel.

[gromit]

Correct torque for this application is 'two grunts and a sigh'. Which is a little bit less than 'tighten it up til you strip the thread then back it off a 1/4 turn'.

I would be more worried that the threads were cut by a machine shop that couldn't even get the flats on the nut parallel.

Nuts are normally machined from bar stock but may be they are forged (which would explain the slight taper).

Strange that the nut has an Imperial hex size, so I guess still an imperial thread ?


Colin

[PhilipA]

Ah made me remember my only "failed to proceed " when my D2 **** its fuel manifold at El Questro.
Called NRMA who organised the Kununurra RACWA agent to tow us in.
The truck arrives and has a very grotty towbar insert.
The McHitch depends on the towball sitting flat on the flange so the driver must have used the turn it until it loosens philosophy. It has to be down flat so the pin can pass through the groove as in the photo. The ball is stainless steeel.
I wondered why later when they bought my camper to the caravan park on the tilt tray.
Any way I wanted the car moved to the Thrifty dealership and while talking to the first mob , they said "oh we have been trying to get you a new towball "
I said why and was handed the towball in which the top small thread was stripped. I said no worries we can helicoil it.
Er no the big thread on the bottom was also stripped.
This took real talent.
I carry a spare now.

Regards PhilipA

[JDNSW]

Nuts are normally machined from bar stock but may be they are forged (which would explain the slight taper).

Strange that the nut has an Imperial hex size, so I guess still an imperial thread ?


Colin

It is a while since I have bought a new towball, but I am sure I have bought one in the last ten years - and I have never seen one with metric sizes. I suspect the reason is either that the thread is specified in ADRs, or simply that the ones sold on the Australian market are made in China (or Taiwan) for the US market (which still runs largely on Imperial threads and spanners).

[gromit]

It is a while since I have bought a new towball, but I am sure I have bought one in the last ten years - and I have never seen one with metric sizes. I suspect the reason is either that the thread is specified in ADRs, or simply that the ones sold on the Australian market are made in China (or Taiwan) for the US market (which still runs largely on Imperial threads and spanners).

John,
I don't think it's really a Metric nut. They probably sell a 'Metric' sized spanner because an Imperial dimension would confuse the majority of people....

Shank is Imperial https://www.couplemate.com.au/tow-balls/
7/8" UNF is 1 5/16" head size.




Colin

[4bee]

From memory I thought 'One Piece Turned Steel Balls' came out when Metric was introduced. Could be wrong but that's what I thought.

My initial post said "a smear of grease" not handfulls. There be a difference, yer know. [bighmmm]