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Is it legal to fit a Tow Bar yourself?

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Post Options Post Options   Likes (0) Likes(0)   Quote Alan L Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 2020 at 9:06pm
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Seriously - I would not get too hung up on the torque values on a tow bar. Tight is tight sort of thing. It is not an engine head etc, or crankshaft.
If you give us the size of the bolts(diam) and as a bonus pitch - but not real necessary, and any markings stamped in the bolt  head, it will be reasonably simple to come up with a general number.
A torque wrench is not the usual thing you would use for frozen bolts. Heat and a breaker bar. Not what a T wrench is designed for. It is designed to tell you how much leverage on a bolt, not how to apply maximum effort on a stuck bolt/nut.
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Post Options Post Options   Likes (0) Likes(0)   Quote kitno Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 2020 at 10:42pm
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Agree with Alan L, a torque wrench is not critical for such an application. 3-400mm of leverage should get your bolts tight enough.
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Post Options Post Options   Likes (0) Likes(0)   Quote smudge Quote  Post ReplyReply Direct Link To This Post Posted: 17 Oct 2020 at 10:46pm
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As Alan says above a torque wrench wouldn't help to undo bolts, you only use them so you can tighten the bolts to the correct torque setting. That torque setting depends on the size and tensile strength of the bolt. For instance if the bolt is 10mm and has 8.8 embossed on the head and it has a 1.5 pitch then that bolt can be tightened to a recommended torque setting of 49Nm (Newton metres). I got that info from Steelmasters torque table which you will find in a Google search. There are other factors to take into account such as oiled threads etc. You would use at least an 8.8 rated bolt for a  towbar.

If you don't understand that stuff then my advice would be to get a towbar fitted. 
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 18 Oct 2020 at 8:33am
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Unlike other above.. If you are not very familiar with how much force u need to reach a given torque on a wheel nut ,  and other critical suspension stuff..
 Use a torque wrench.
Reasoning is we see wheel nuts fall off, studs snap, suspension failures all because a wild guesstimate that is either way high or way low.
Even I had an issue when professionally got new spring nut hangers for our boat a few yrs ago (old threads).
Spec for 1/2" is 65lbs
 Get home put torque wrench on... between 18 and 25lbs.

If want to get an idea how good your 'guesstimates are..
 Loosen and tighten up your whell nuts on the car.
 Head down to the local type shop (WHO SHOULD have a calibrated torque wrench) and chech the torque against actual hand book specs..
 9 out 100 will be way way off

'play' with suspension, tow bars etc stuff, invest in a torque wrench to finish .. even if a cheap one  and look after it.

Have seen a lot of failures over the yrs, blamed on "chinese bolts" and all asorts stuff, yet inspect the failure and it goes back to inccorect torques , that time and/ or previous times.
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Post Options Post Options   Likes (0) Likes(0)   Quote Big -Dave Quote  Post ReplyReply Direct Link To This Post Posted: 18 Oct 2020 at 8:28pm
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Now we have rattle guns, battery powered, otherwise know as 'the dug a dug'
With one of these you can pull the trigger and over tighten just about anything..
My son got one that does about 400 nm, I've pointed out to him that it all but strips bolts and spreads spring washers..

Fiz, 3/4 torque wrench?, now just how many people, including yourself, have a 3/4 socket set? Makes me wonder if you really should be undertaking this job..
you can't fix an idiot with duct tape, but it does muffle them for a while...
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Post Options Post Options   Likes (2) Likes(2)   Quote v8-coupe Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 2020 at 7:33pm
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Maybe people are over thinking this.
Use common sense.
I have built and installed tow bars, rear and front, built trailers and cars without ever using a torque wrench.
1/2" ratchet and T-bar is all I ever used/needed plus a good set of ring spanners, never crescents.
The only time I ever used a torque wrench was when rebuilding the engines for my cars.
Never had anything fall off because of a bolt/nut coming loose or shearing off.
This includes engine/spring mounts, suspension and steering components, clutch components, modified wheel hubs et al.
Maybe I have just been lucky for the last 43 odd years.
Take care.
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Post Options Post Options   Likes (0) Likes(0)   Quote Big -Dave Quote  Post ReplyReply Direct Link To This Post Posted: 19 Oct 2020 at 9:02pm
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Originally posted by v8-coupe v8-coupe wrote:

Maybe people are over thinking this.
Use common sense.
I have built and installed tow bars, rear and front, built trailers and cars without ever using a torque wrench.
1/2" ratchet and T-bar is all I ever used/needed plus a good set of ring spanners, never crescents.
The only time I ever used a torque wrench was when rebuilding the engines for my cars.
Never had anything fall off because of a bolt/nut coming loose or shearing off.
This includes engine/spring mounts, suspension and steering components, clutch components, modified wheel hubs et al.
Maybe I have just been lucky for the last 43 odd years.
Take care.



Ditto
you can't fix an idiot with duct tape, but it does muffle them for a while...
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 2020 at 7:49am
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V8 coupe..

you/ we have used torque wrench , have a very good idea of how much force to put on what size/ type and length of spanner to achieve a ball park torque.

 Something we tend to take for granted.
But as tyre shops often find, accident inspectors discover far too often on wheel nut, suspensions, those people who have never or rarely been familiar with using a torque wrench get it very wrong , tight or loose far too often.

And that is where the over thinking comes in.. people doing things with out a clue, in all innocence and things go horribly wrong.
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Post Options Post Options   Likes (0) Likes(0)   Quote fish-feeder Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 2020 at 8:21am
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Even so called professional tyre fitters don't get it right all the time. I had 10 out if 24 wheel studs stretched by a tyre out fit.... Using a rattle gun without torquing afterwards,just going full nang with a rattle gun....idiots
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Post Options Post Options   Likes (0) Likes(0)   Quote Bounty Hunter Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 2020 at 8:54am
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Originally posted by fish-feeder fish-feeder wrote:

Even so called professional tyre fitters don't get it right all the time. I had 10 out if 24 wheel studs stretched by a tyre out fit.... Using a rattle gun without torquing afterwards,just going full nang with a rattle gun....idiots

had similar experience here - my opinion of tyre places is, broadly speaking, very low...
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Post Options Post Options   Likes (0) Likes(0)   Quote Steps Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 2020 at 8:57am
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Even so called professional tyre fitters

 Yep .. few yrs back, dont know if beauRepairs still has it in their employment contract.. All wheels had to be put on and checked with a torque wrench.. instant fired.
 They had too many stud failures..

 And there is my example in previous post..'professional workshop replacing my hangers  on my trailer.. 18 to 25 lbs  not 65 lbs when I checked at home..
He left that workshop not long after, and was only a couple months at the next one.


 Back in the day, workshops , and on block coarses , the young employees/ apprentices where put on a bench with fixed studs and nuts of varing size. They had to torque over and over and hand with different wrenchs, drives , they checked with torque wrench till they got the correct ball park feel.
 I havnt seen such a setups , even in the back of a workshop for over 30/40yrs.

 it only take one under trained (employers ffault) or lazy "professional " to give a workshop a bad name

 Professional mean they get paid... no more than that..
Tradie means they are qualified.
Most are good tradies, some are beyond that "craftsmen"
And other , like who fitted my hangers, qualified and should take up needle work or dig drains by hand.

 I have the utmost respect for most tradies and their apprentices
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Post Options Post Options   Likes (0) Likes(0)   Quote pjc Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 2020 at 9:47am
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Originally posted by Bounty Hunter Bounty Hunter wrote:

Originally posted by fish-feeder fish-feeder wrote:

Even so called professional tyre fitters don't get it right all the time. I had 10 out if 24 wheel studs stretched by a tyre out fit.... Using a rattle gun without torquing afterwards,just going full nang with a rattle gun....idiots


had similar experience here - my opinion of tyre places is, broadly speaking, very low...
more important us the retorque after 50)100kms.apparently with steel nuts on mags they tend to loosen over a short period.
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Post Options Post Options   Likes (0) Likes(0)   Quote Fraser Hocks Quote  Post ReplyReply Direct Link To This Post Posted: 20 Oct 2020 at 10:40am
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Yea have to agree I was a little surprised.  I was hunting to buy a Mercedes Sprinter campervan last year.  I wanted a tow hitch and am a dab hand with a welder, and own a multi-process welder. 

I asked for a quote on a tow hitch and was told id have to take the van to Christchurch (I live in Queenstown so a huge drive) and it was going to cost over 3k. 

I ended up speaking to NZTA who gave me all the details, but essentially the code states that the tow hitch should be "fit for purpose"  No additional details around construction or strength.  I ended up purchasing a van that already had a tow hitch fitted, but if left to my own devices I would have highly over-engineered a suitable tow hitch.

The van came with an 1 1/4 Reece hitch.  The bar is very heavily built.  Iv considered cutting the 1 1/4 hitch off and replacing with a more standard 1 1/2 hitch, but really haven't had the need yet. 


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