Identifying trailer stud thread and pitch for a locking wheel nut

[Gin]

Probably a question for Vyv but since others may have a similar need, now posted as a new thread on here.

I have a braked, double axle, galvanised boat trailer of about Y,2000 vintage which has 4 stud steel wheels (PCD: 14cm- rounded up, and 'S' distance 10cm, again rounded up) on 13 " rims.

My trailer is in a secure compound but we have a public footpath so I want to defend myself against thieves removing the wheels- so I want to replace one nut (not bolt) on each wheel with a locking nut of unique design.

That's the simple objective, but finding a suitable locking nut/key set is not quite so simple as I cannot easily identify whether the studs are metric or imperial and my only guide is what I have obtained from a removed nut. i.e. the hex head takes a 3/8" AF socket ( I did not have a 19mm to hand); the internal ID of the removed nut measure 10.35mm and with some difficulty I think the thread TPI is about 17 per inch.

So, I have a real mess of different measurement standards which I realise is not helpful coupled with which the locking nuts available on the market seems to be exclusively either:-

10mm x 1.25 pitch ( seems too small a pitch to me, and my eyeball count, above, seems more like standard 10mm) or 3/8" UNF TPI 17 ( which seems more likely but doesn't look like a fine thread to my uneducated eye).

However, just to further confuse, the trailer has a manufacturers very faded badge which I think says' CM trailers'- an American firm, who I have contacted and they say they have no UK dealers, so how and where this trailer was constructed and whether it used UK suspension units I cannot say.

Before I go ordering sample threads or hacking around the country for what is on offer, I wonder if someone can make head or tail of this can of worms?

 

[Motor_Sailor]

If you used an imperial socket instead of 19mm, it would have been a 3/4AF, not a 3/8th.

7/16th UNF is quite a common American wheel stud size. (20tpi)

 

[Gin]

Probably correct, for I borrowed said socket and failed to check its ID.

I did a little research and the 7/16" seemed a possibility but rightly or wrongly I have discounted that as this trailer, seemingly, was constructed in the UK- a conclusion only arrived at as it it would make no sense to import such a heavy product.

Most likely a simple and standard fitment which, as yet, eludes me

 

[colhel]

. i.e. the hex head takes a 3/8" AF socket ( I did not have a 19mm to hand); the internal ID of the removed nut measure 10.35mm and with some difficulty I think the thread TPI is about 17 per inch.

possibly you meant 3/4" AF ? 10.3 ID could show M12 x 1.75 but not the 17 TPI (equivalent would be 14.5 TPI) . Might be worth trying the nut on an M12 if only to rule it out. 17TPI is so close to 1.5 pitch I wouldn't rule it out, but the 10.35 is tad small but possibly M12 x 1.5

 

[Gin]

My eyeball squint down the nut may be out, so my estimate of the TPI may be well out also, but I would hope not.

I do have a standard M12 in my garage and the web is simply too large to even consider a match to the removed nut, so it must be something smaller.

Do bear in mind that my best best efforts may fall well short of precision!

 

[colhel]

How accurate is your 10.35?

 

[Gin]

Chinese, digital vernier scale

 

[colhel]

okay. So if it was 10.5mm I'd say M12 x 1.5, if it was 10mm I'd 7/16"UNF.
I would check the stud OD, if that measures 11.8-11.9 ish M12x 1.5 if it measures 11mm, 7/16"

 

[Gin]

Thanks, that's the next step then, at the weekend

 

[Sandro]

Find a bolt that fits, but accurately fits, your nut, then use the bolt as a gauge when going shopping for the security nut.

Sandro

 

[William_H]

Of course a simple alternative might be to jack up the trailer and take the wheels home. This means you can protect the rubber from UV damage and also provide security for the trailer it self. Here in Oz theft of boat trailers is quite common so most people have a coupling lock anyway.
On the same subject my Oz made Ford has alloy wheels and one peculiar nut on each wheel. There is a matching socket for this nut stashed away for wheel changes. The car is 7 years old and I wonder if they still do this on new cars. Alloy wheels used to be an expensive option but now almost universal. Likewise car radio/tape player used to have a security code. Now days no body bothers to steal a car radio so security codes are not put in. (thank goodness, so inconvenient)
So does your trailer have allow wheels and what is the risk of theft. A profound question.
good luck olewill

 

[PaulRainbow]

Now days no body bothers to steal a car radio so security codes are not put in. (thank goodness, so inconvenient)

Car radios are still coded. But rather than you having to put a code in if the battery goes flat etc, the radio is coded to the cars VIN

 

[Gin]

Find a bolt that fits, but accurately fits, your nut, then use the bolt as a gauge when going shopping for the security nut.

Sandro

Yes, indeed, that is Plan 'B'

 

[Gin]

Of course a simple alternative might be to jack up the trailer and take the wheels home. This means you can protect the rubber from UV damage and also provide security for the trailer it self. Here in Oz theft of boat trailers is quite common so most people have a coupling lock anyway.

good luck olewill

Steel wheels and unlikely to be stolen but thieves respond to opportunity or vandalism not need so for the sake of a few pounds I would like to make a theft a little more challenging- no storage space in my garage for another 4 wheels, sadly.

The trailer itself has a coupling lock and is now parked behind others, so making the theft of the whole rig unlikely especially as the compound is magnetically locked too.

 

[Jim@sea]

In order to make my boat trailer safe over the winter, I undid the castle nut in the centre of the hub and removed the hub (with the wheel still on) and took it home. That way if anyone wanted to steal the trailer they would have to turn up with the brake drum, with part of a bearing inside, a wheel and tyre etc. Its surprisingly easy to remove the wheel and hub, a large socket and a pair of plyers to remove the split pin. 5 minute job.

 

[JumbleDuck]

Why not remove a nut, take it to Indespension (other trailer parts suppliers are available) and say "Have you got a locking version of this?"

Do thieves steal trailer wheels?

 

[<152587>]

Most trailers use left hand thread on the nearside wheels so standard automotive nut lock would not be suitable.

 

[Graham_Wright]

Take a nut to your local fixings and fasteners dealer and ask them to size it. Nuts, screws and bolts have quite wide tolerances and quite a lot will interchange.

 

[lw395]

The best way to measure thread pitch is a gauge like this:
http://www.ebay.co.uk/itm/Degree-Du...302656?hash=item3f7dba5340:g:7xEAAOSwlMFZLDiG

I have a dual one which does metric and imperial.

But unless it's really obscure, I expect to find a bolt to fit in either my workshop or a mate's.
Then I'd go to my local breaker's yard with the bolt and ask if they've got any locking nuts to fit. But these days most cars seem to be bolts instead of studs and nuts.

 

[JumbleDuck]

Most trailers use left hand thread on the nearside wheels so standard automotive nut lock would not be suitable.

Most? The only trailer I have ever met like that is the one for my Hunter 490, which has old Rubery-Owen suspension units. The Insdepension units I bought for the Drascombe trailer last year are right hand thread for both sides.