Need info/advice re torque wrench for motorhome

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CycleTourer

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#319932 15-Jun-2025 13:24

I apologise in advance for the low-level nature of this post, I know many posters here have significant knowledge about vehicles. I am however, a "weak and feeble woman" (to quote Queen Elizabeth I) who doesn't have much knowledge (although I have changed many car tyres over the years), so I'd be grateful for some help.

I recently bought a motorhome on a Fiat Ducato base. I'll be travelling long distances in it on my own, so have organised a spare wheel (it didn't come with one) and I want to buy a torque wrench so I can be sure wheel exchanges are being done properly (no matter who does them).

I'd never heard of torque wrenches a few months ago and I'm having trouble evaluating them online. I see there are some with 1/2" drive and others with 3/4" drive. What is the drive and how can I tell which one is right for my motorhome? If it makes a difference, I believe the wheel bolts (not conventional studs with wheelnuts to hold the wheel on) are 14mm.
It seems I'm also going to need to buy sockets to go with it, is that correct?
I know I should buy one whose range has my figure (180Nm) a bit below the top end, makes perfect sense. But what length should I be looking for? (I have in mind to get a length of pipe as an extender, if necessary. I'm not at all sure if I can achieve 180Nm even with an extender, but I figure it won't hurt.)
And finally, given that I don't want to spend thousands on this thing, but definitely want to be able to trust it, what brands should I be looking at and are there suppliers that would be good to go to (or alternatively, avoid!)? I intend getting it checked during my annual tyre condition check at a tyre shop that I know I can trust, and I know to always reset it to zero after use.

Many TIA 😃

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#3384317 15-Jun-2025 13:50

1/2" has a bigger square stud that plugs into 1/2" sockets that you can get from Repco or in a full socket set. You'll want this for wheels. You'll likely snap a 3/8 tightening a wheel.

I've got a 1/2" Fuller adjustable torque wrench - just find one that has a nice wide torque range topping out just above what you'll need for say a wheel hub.

Yes a pipe for an extension is a good idea and likely to save you a bunch of money and be more compact to store.

tweake

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#3384319 15-Jun-2025 14:28

double check the specs. 14mm afaik is usually around 150nm.

honestly i think 3/4 drive might be better way to go. basically you want the longest torque wrench you can get. a normal 1/2 drive one might be to short and make it hard for you, 150 or 180nm is going to take a lot of effort. and NO you CANNOT use a cheater bar. torque wrenches must have your hand on the handle in the right place or it throws the torque figure out.

also check you do not have left hand threads on one side of the vehicle. most of the affordable torque wrench only work in one direction. so if you have left hand bolts you will need a two way torque wrench or a left and right hand ones.

i would not get to concerned with accuracy. the cheaper ones are fine and wheel bolts/studs have a quite a bit of redundancy built in. over tight is not a problem, but being under tight is.

i would also recommend anti seize on the bolts/studs. corrosion is the worse thing, as you will tighten up on the rust and end up with a loose bolt/nut. better to be lubed and go a bit tighter than be loose.

also make sure you have a decent jack that will handle rough ground (pays to have blocks as well) and that you can handle the weight of the wheel.

the one thing thats saved me a few times is a decent sized air compressor. if its got a slow leak, you can pump it up and get into the nearest town.

mudguard

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#3384320 15-Jun-2025 14:31

I think one issue is most places are going to use an impact wrench to the nuts up. So even if you buy a lovely torque wrench, you will still have to undo them with a breaker bar or tyre iron, then do them back up and check with the torque wrench.

I go through tyres more quickly than most due to the kms I do and have done a few spare changes on the side of the road, sometimes it takes my full weight standing on the tyre iron so I'd say mine get done up well over the 103NM the factory suggests.

I should go measure how much I can do them up with a standard tyre iron.

180NM is a lot, so if double check you can undo that yourself.

Or put in battery impact wrench. I have a Ryobi one I use for car parts and stubborn wheel nuts.

mudguard

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#3384321 15-Jun-2025 14:37

tweake:

i would also recommend anti seize on the bolts/studs. corrosion is the worse thing, as you will tighten up on the rust and end up with a loose bolt/nut. better to be lubed and go a bit tighter than be loose.

I strongly disagree. The last place you want to out anti seize is on the wheel studs. Wire brush any rust off. You won't get an accurate torque measurement either.

If you are rotating the tyres you won't have an issue with stuck bolts. If it's being parked up for a decade, maybe.

RunningMan

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#3384323 15-Jun-2025 14:48

Even the cheaper torque wrenches from the like of Super Cheap will be good enough for doing wheel nuts - https://www.supercheapauto.co.nz/search?q=torque+wrench&lang=en_NZ As long as you look after it (reset it to zero after use and be gentle with it) then it should be fine.

Drive size is the size of the square bit that clips into the back of a socket. 1/2" means each side of the square is 1/2". 1/2" is a pretty common general purpose drive size for use on cars. You could go to 3/4" - this is more common with truck mechanics working on stuff that needs to be tighter (so tools are stronger), but everything that goes with it will be more expensive - sockets, extensions etc. 1/2" drive should be OK for 180Nm torque.

The longer the handle, the easier it will be for you, but generally you'd normally use a cross brace or speed brace to nip the nuts up, then use the torque wrench for the final tightening.

Check the wheel bolt size - it may be the bolts are 14mm, but the head is likely bigger, perhaps 19 or 21mm - this is the socket size you will need.

You'll probably also need an extension between the socket and torque wrench to clear the edge of the wheel. This sort of thing https://www.supercheapauto.co.nz/p/toolpro-toolpro-extension-bar-1-2-drive-125mm/221298.html

Ultimately, it probably depends on what, if any, tools you currently have. If you've already got a 1/2" socket set then you'll have a socket and extension already, just need to buy the torque wrench itself. Alternatively, there this sort of kit with the wrench, a short extension and selection of sockets - just make sure that you know what size socket is needed.

tweake

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#3384339 15-Jun-2025 14:51

mudguard:

I strongly disagree. The last place you want to out anti seize is on the wheel studs. Wire brush any rust off. You won't get an accurate torque measurement either.

If you are rotating the tyres you won't have an issue with stuck bolts. If it's being parked up for a decade, maybe.

its a hugely debated topic. but even with greased studs your never going to overtighten them to the point of failure (grease adds about 10%ish more) even if your only loosely within spec. the torque spec is not super critical, as long as you go over not under.

the problem is not stuck bolts. its doing them up loose thats the problem. because they are dry and sticky, you can very easily loose half the torque. i would much rather over tighten than risk being loose. you will never loose a wheel because the bolts where to tight.

mudguard

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#3384340 15-Jun-2025 14:55

tweake:

mudguard:

I strongly disagree. The last place you want to out anti seize is on the wheel studs. Wire brush any rust off. You won't get an accurate torque measurement either.

If you are rotating the tyres you won't have an issue with stuck bolts. If it's being parked up for a decade, maybe.

its a hugely debated topic. but even with greased studs your never going to overtighten them to the point of failure (grease adds about 10%ish more) even if your only loosely within spec. the torque spec is not super critical, as long as you go over not under.

the problem is not stuck bolts. its doing them up loose thats the problem. because they are dry and sticky, you can very easily loose half the torque. i would much rather over tighten than risk being loose. you will never loose a wheel because the bolts where to tight.

10% of 180 is almost 200NM. Snapping a stud could be a complete PIA.

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tweake

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#3384342 15-Jun-2025 15:03

mudguard:

10% of 180 is almost 200NM. Snapping a stud could be a complete PIA.

which is still well under for a high grade 14mm. (the 180nm is really high for the usual grade they use, so its either less than that or they are using high grade).

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#3384346 15-Jun-2025 15:10

CycleTourer:

I'd never heard of torque wrenches a few months ago and I'm having trouble evaluating them online. I see there are some with 1/2" drive and others with 3/4" drive. What is the drive and how can I tell which one is right for my motorhome? If it makes a difference, I believe the wheel bolts (not conventional studs with wheelnuts to hold the wheel on) are 14mm.
It seems I'm also going to need to buy sockets to go with it, is that correct?
I know I should buy one whose range has my figure (180Nm) a bit below the top end, makes perfect sense. But what length should I be looking for? (I have in mind to get a length of pipe as an extender, if necessary. I'm not at all sure if I can achieve 180Nm even with an extender, but I figure it won't hurt.)
And finally, given that I don't want to spend thousands on this thing, but definitely want to be able to trust it, what brands should I be looking at and are there suppliers that would be good to go to (or alternatively, avoid!)? I intend getting it checked during my annual tyre condition check at a tyre shop that I know I can trust, and I know to always reset it to zero after use.

Many TIA 😃

1/2" drive (bigger knob, stronger, fits the wheel nut better
2 sockets depends on your wheel nut. either buy a set or bring in your nut. every wheel nut different so best to get a set.
you can't use torque wrench with a pipe extender. get one around 50cm.
get the cheapest from supercheap auto or repco when they have a deal or anyone.

mudguard

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#3384354 15-Jun-2025 15:26

tweake:

mudguard:

10% of 180 is almost 200NM. Snapping a stud could be a complete PIA.

which is still well under for a high grade 14mm. (the 180nm is really high for the usual grade they use, so its either less than that or they are using high grade).

Why risk it though? When cars come with anti seize on the studs then I'll consider it. I've a got thirty year old car in the garage and the worst I've seen on the stud was a it of rust that was cleaned up with a wire brush.

tweake

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#3384428 15-Jun-2025 16:23

mudguard:

Why risk it though? When cars come with anti seize on the studs then I'll consider it. I've a got thirty year old car in the garage and the worst I've seen on the stud was a it of rust that was cleaned up with a wire brush.

why risk not doing it? thats what makes the debate so interesting.

if you can keep the studs like new, then thats fine. but real world almost no one ever does and they get dirty and rusty. the only time i've had any issues was with doing a flat tire change with dry, dirty, slight rust, studs and one came loose. in many decades of grease or anti-seize on a small fleet of vehicles, i have never had a problem or heard of one. the antisieze/grease keeps them clean and rust free.

part of the issue in the debate is many people blame broken studs on over tightening. but its far more common to break studs from nuts coming loose. i would guess in my experience 99% fail due to being loose.

CycleTourer

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#3384429 15-Jun-2025 16:26

Wow! Thanks so much for all these great replies, folks. Lots of stuff to digest here. Really good to know what "drive" means. And also the good sizes to go for. It turns out I may have access to a full 1/2" socket set with extensions and everything!

tweake:

also check you do not have left hand threads on one side of the vehicle

Oh -- something else I didn't realise -- huge thanks for this! I can't check since the van isn't here right now but would e.g. this one fit the bill on that score? It mentions that it's "reversible".

The likelihood the wheel bolts are stuck is pretty low, I'd say -- the van is only 4 years old. The older tyres (2021s) are being replaced tomorrow so I'll get a good handle on that situation at least for those.

In terms of impact guns being used on them I've had a policy for decades, of specifying they are not to be used. I always get pushback, and nearly always get told that "ours don't go above blahblahblah" and I just push back until they agree to do them by hand. I've had boyfriends who couldn't undo wheelnuts even jumping up and down on the wheelbrace! I nearly always travel alone, and only weigh 60kg...

I've had the 180Nm figure checked and it is correct, but thanks for the queries on that.

Huge thanks again, everyone 😀

tweake

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#3384433 15-Jun-2025 16:53

CycleTourer:

would e.g. this one fit the bill on that score?

I nearly always travel alone, and only weigh 60kg...

I've had the 180Nm figure checked and it is correct, but thanks for the queries on that.

Huge thanks again, everyone 😀

that one doesn't go high enough. check the specs for the range. try to get one that can go far higher (for a 180nm you want one that go up to 300+) a quick look shows your going to have to go up to a 3/4 drive to get one long enough. thats going to be VERY important for someone who is "light weight". from a big guy, that torque is going require some serious muscles using a 1/2 drive.

i highly recommend trying one out at that setting and also go and lift the tires involved. especially as euro bolt ones are a pain to line up. i suggest go get a guide pin made. its just a pin with a rounded end that you screw into the top bolt hole, so you lift the tire up on it, which holds it in place while you fit the rest of the bolts.

k1w1k1d

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#3384435 15-Jun-2025 17:05

The first issue you will have is undoing the wheel bolts. Doesn't really matter what your gender is, they will probably be a struggle, especially if they have been tightened up with an air impact wrench at a tyre shop.

I would suggest getting a 1/2" flex head power bar/breaker bar and an impact socket of the correct size. Then get a length of pipe that fits over the end of the bar to increase the leverage. Supercheap have a ToolPRO 668314 1/2" drive 750mm bar for $50.99.

Then get a 1/2" torque wrench to use with the socket to tighten the bolts.

Bung

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#3384436 15-Jun-2025 17:08

5 years ago Mehrts posted "A few years ago I bought a Mechpro branded torque wrench from Repco, it's the exact same as that Craftwright unit from Bunnings which was linked a few posts above." @Mehrts are you still happy with the Mechpro?

Repco currently $55, Bunnings $59. The Repco one has a 21mm socket to suit the Ducato bolts.

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