Looking for bolts.

[northwest]

Incidentally, they are screws if the thread goes all the way to the head and bolts otherwise.

 

[Dcal]

What are you expecting to tow?
We need a but of perspective here.

The tow bar is designed to transfer the forces from the object being pulled and spread them reasonably evenly into the structure of the vehicle.

A single 12mm 8.8 bolt will take over 4 ton in tension and more than that in shear or double shear.
These are loads at yield, the ultimate just before failure will be even greater.

I'd assume there will be a mixture of tension and shear connection between the tow bar and the vehicle.
10.8 and 12.9 bolts will only increase the factors of safety but high tension bolts can fail quite spectacularly if grossly overloaded. (Don't know how you could do in in this application other than by over torquing and you would know that while installing the tow bar as the bolts would go soft)

Before you pull a tow bar off a vehicle you will get a lot of warning.
The bolt holes would elongate and the thing would be rattling about long before it lets go.
The manufactures know what they are doing and design in huge factors of safety on things like this.
You would need to be incompetent to install a tow bar that falls off (not installing all the bolts, or smaller sizes, or not tightened, or hugely over tightened, or wrong grade bolts (4,8 anyone?) or a mixture of all etc) and even then there would be warnings.

Most disconnections are from quick the release section of the tow bars not being installed correctly by owner.

Has anyone ever seen a correctly (or incorrectly) installed tow bar being pulled right off a vehicle?
Towing competitions and stunts excepted.

 

[gordon stephenson]

Hello Damian, Not got anything in mind at the moment for towing, but I am thinking of getting another caravan, The Westfalia tow bar is original VW fitment with permanent, non detachable hockey stick type ball, This thing is so strong and heavy it takes some believing that it is for a car, And with eight 12mm bolts screwed horizontally directly into the chassis, It will be absolutely solid. This a small detail of just two of the bolt positions, Don't know why the thick spacers are needed, but that is the original design.

 

[Dcal]

That's just what I was thinking.

There is nothing to worry about, the whole thing is so overdesigned to account for muppets and misuse and to survive a high speed accident when everything will be wrecked (but probably still hold togeather) that I personally would have no problem using the bolts @anto44 has offered.

I'm not suggesting this for anyone else (just my personal opinion) and if someone wants to overthink it and will feel safer using "better"'bolts that's fine.
I don't think the bolts will be the limiting factor, and I'm absolutely sure you will install the towbar correctly and use it within a fraction of it's capabilities.

 

[gordon stephenson]

Upon receiving the tow bar I was absolutely amazed at the weight and construction of the thing, It just seems so massively over engineered, Having worked in heavy industry all my life and being involved with many types of lifting gear etc, There is no way on earth that this would fail with a "mere" 3.5 tonne towing limit, I realise that this bar will also act as protection in the event of a rear collision, As the factory bumper bar (behind the plastic cover) has to be removed to fit the tow bar,

 

[Farside]

It is clear nobody in this thread has tried recutting/cutting threads on a high tensile bolt.

Oh, yes I have.
Never again. Mug's game, and you can't be sure how strong it is now.

 

[bricol]

What are you expecting to tow?
Has anyone ever seen a correctly (or incorrectly) installed tow bar being pulled right off a vehicle?
Towing competitions and stunts excepted.

Seen two that were badly installed - not tightened up properly, so the whole thing was flapping about. And another caught exiting a field after a car trial. Not quite aligned afterwards!

I reckon most get close to failing when the anchor points rust away.

Thing is, with a modern, decent car, you can get quite a moment through the brackety - not many seem to be braced forwards, so it all comes down to the fixings into the rear crossmember - when you see the height and length of some of these "euro gooseneck" things, I wonder about the forces reacting into the shell. Bear in mind it's not once, it many times, over many years, so fatigue lift needs thinking about too - so no unneccessary stress raisers.

The load path through the one I recently fitted to the back of my Challenger is interesting. As a non-EU vehicle, I don't need an approved tow bar - so mine isn't
I reckon under a full bore take-off it's doing a stirling job

 

[arther dailey]

Looking at pic Gordon reckon thats for a 7.5 ton lorry ! that would rip your chassis to pieces before it broke

 

[northwest]

Oh, yes I have.
Never again. Mug's game, and you can't be sure how strong it is now.

LMAO You only ever try this once. I was told not to do it, the outcome was explained to me and I was told in graphic detail what would happen to me if I ever used such a modified article.

Didn't stop me trying it though, but as you say, only the once!

 

[gordon stephenson]

Sorted now with correct VW 12mm 10.9 bolts from another forum member, As said before this tow bar is massively over engineered and being attached by the eight 12mm bolts, correctly fitted and torqued up it's going nowhere,

 

[marlinspike]

Well that was a novel and unexpected resurrection of the thread ....

I fear the postage costs will be prohibitive, my friend, but I will bear you in mind when I next build a house.

 

[Paul.]

Well that was a novel and unexpected resurrection of the thread ....

Short lived too, we don't allow spammers

 

[anto44]

@gordon stephenson did the towbar fall off yet?

 

[gordon stephenson]

@gordon stephenson did the towbar fall off yet?

No, (thanks for the bolts) Tow bar solid, Sold the Touareg to a friend, who tows quite a lot, I have the Touareg Escape model now with factory fitted auto electric tow bar, trying to decide now if a gearbox oil and filter change is worth a cash for sometimes jerky changes,

 

[anto44]

No, (thanks for the bolts) Tow bar solid, Sold the Touareg to a friend, who tows quite a lot, I have the Touareg Escape model now with factory fitted auto electric tow bar, trying to decide now if a gearbox oil and filter change is worth a cash for sometimes jerky changes,

Change the oil and filter if you don't know when they were last done

 

[gordon stephenson]

Change the oil and filter if you don't know when they were last done

I think that I have read, there are two levels of oil change, One that only changes a proportion of the oil? Any knowledge about this?

 

[mike os]

afaik the dsg only has one potion... make sure its serviced as required or it can get very expensive.

this is one item i used to go main stealer or specialist for.... if they dont get the filter and seals back in properly you can end up needing a new clutch ...

no idea on that particular model but the golf and passat its a pita

 

[Johnnybravo]

Why please explain your logic, Bricol?






12.9 is the tensile strength of the material the bolt is made from not the thread length, cap head screws bolt or set screws are all 12.9.

Set screws are generally 10.9 not 12.9

 

[zzr1200]

Set screws are generally 10.9 not 12.9

That's not what our old supplier stated when we asked for the tensile strength of the setscrews, manufacturers paperwork also confirmed this...

 

[Johnnybravo]

That's not what our old supplier stated when we asked for the tensile strength of the setscrews, manufacturers paperwork also confirmed this...

Depends on the type of set screw. Hexagon head set screws are invariably 10.9, whilst socket head cap screws are invariably 12.9. Given the OP was looking for Hexagon head set screws it’s fairly safe to say that they are normally 10.9 . Only special application are normally supplied as 12.9