Impact wrench - how much NM.

[princerupert]

I have a hub nut that I cannot get off with my 2ft breaker bar, to do driveshafts/lower suspension arms/track rod ends. I was just going to buy a longer breaker bar, but have been wanting an impact wrench for a while so thought this might be a good as an excuse as any, and will be useful on other suspension bolts I am sure. What I wondered is how much torque I need - would a 400ish NM torque wrench sufficient or should I go up to 700NM? Will 700NM definitely take off a rusty hub nut?



The one I have in mind is the 700NM Kielder KWT-012-51 which you can get with batteries for around £200. It would be for occasional hobby mechanic use only.

[ejenner]

I've got the DeWalt DCF889 which is rated to 418nm. I would say it's been very reliable in every day vehicle workshop use and can recommend it. However, I did try to use it to remove wheel nuts from my taxi which are 27mm and it couldn't do it. They were flipping tight but I just think if this device is going to be your only tool then you should get something more powerful than mine. I've used it for some pretty hefty removals in the past (including hub nuts) but so long as there is something it can't do I would have to say it can't have a 10/10 rating.

For bigger stuff I've got an air compressor and a heavy duty air powered impact gun.

In the end for removing the wheel nuts from my taxi I used my 3/4 drive socket set from Halfords which is for the real bad ass bolts: www.halfords.com/tools/hand-tools/socket-sets/halfords-advanced-professional-21-piece-socket-set-3%2F4in-926360.html

Still had to slide the handle from my trolley jack over the breaker bar which comes in this set and then jump on the end to get those nuts off. Very very tight!

Another slightly naughty recommendation is to rest the breaker bar on the floor and then try to drive the car forward so the breaker bar is pressing against the ground. But that's the sort of thing nobody would ever suggest you do in case of flying pieces of fragmented breaker bar whistling through the air.

[joem83]

I went for this as I already had dewalt tools (now have more lol)

www.amazon.co.uk/Dewalt-DCF899HN-XJ-Cordless-Brushless-Torque/dp/B00VXN7SH6/ref=pd_lpo_60_t_0/260-3921149-7508318?_encoding=UTF8&pd_rd_i=B00VXN7SH6&pd_rd_r=99b13116-658a-4730-97f6-9be577aca5f7&pd_rd_w=upQqj&pd_rd_wg=bRMwr&pf_rd_p=3366510f-1771-44b5-99e2-20c1889506ac&pf_rd_r=NVMV93Q60QWSBPZCCMR1&psc=1&refRID=NVMV93Q60QWSBPZCCMR1

It's a beast, my mechanic uses one with a 9ah 54v felxvot battery instead of the air tools.

I can confirm you would want at least a 5ah battery though as with a 1.3ah battery on it, it seems to have less umph.

[ejenner]

In terms of reliability the DeWalt is great. I went though 3 or 4 cheap electric impact wrenches over an 18 month period. As they had a warranty with them I could keep getting them replaced but it was becoming a waste of time!

[princerupert]

Thanks both. The DeWalt looks great but 175 quid for a battery and charger

Would make it about £125 more expensive than the Kielder, which is a fair chunk of change; but would be very annoyed if I bought the Kielder and it did not get the hub nut loose ...

(Trying to locate a length of scaffold pole to lengthen my breaker bar in the meantime ...)

[Laters]

I was tired of struggling with breaker bars or cheaper impact guns.
A driveshaft nut on the Honda beat every tool thrown at it till I borrowed a Dewalt 899.
First thing I did after it undid the nut was go and order my own.
Had it a while now and its never failed on anything I have needed to use it on.
I have owned a few other cheaper impact wrenches but the dewalt 899 is better by miles.

[ballbagbagins]

May 24, 2021 15:37:17 GMT Laters said:

I was tired of struggling with breaker bars or cheaper impact guns.
A driveshaft nut on the Honda beat every tool thrown at it till I borrowed a Dewalt 899.
First thing I did after it undid the nut was go and order my own.
Had it a while now and its never failed on anything I have needed to use it on.
I have owned a few other cheaper impact wrenches but the dewalt 899 is better by miles.

Another dewalt 899 owner here and again bought for driveshaft bolts on my daily.

[joem83]

May 24, 2021 15:34:05 GMT princerupert said:

Thanks both. The DeWalt looks great but 175 quid for a battery and charger

Would make it about £125 more expensive than the Kielder, which is a fair chunk of change; but would be very annoyed if I bought the Kielder and it did not get the hub nut loose ...

(Trying to locate a length of scaffold pole to lengthen my breaker bar in the meantime ...)

This is all I have to run mine

Charger

Battery

£93 for charger & a 5ah battery.

Apart from the charger (that was in a drill/impact driver set), all mine came from Amazon

So about £253 all in, also mean you can then buy bare tools for anything in the future.

I will be honest, I didnt need anything like the dewalt - but the time I have to spanner is very limited & not having the right tool eats into that. For instance, I needed to swap the front shocks on my S60. 1 side took 30 mins with a cheap impact wrench/hand tools, the other side took 3 hours due to 1 stuck bolt that the impact wouldnt touch - luckily my mate had a compressor & some air impact's - they struggled due to water ingress. So 4hrs to do a 1hr job.

On the same car, it took me over an hour to get 1 stuck wheel bolt out & I bent a 3ft breaker bar! Luckily I had the dewalt the week after and havent had a stuck bolt since lol. I even use it to screw some 3ft ground anchors into solid clay for my sons trampoline - took about 5 seconds lol

[princerupert]

May 24, 2021 16:36:43 GMT joem83 said:

May 24, 2021 15:34:05 GMT princerupert said:

Thanks both. The DeWalt looks great but 175 quid for a battery and charger

Would make it about £125 more expensive than the Kielder, which is a fair chunk of change; but would be very annoyed if I bought the Kielder and it did not get the hub nut loose ...

(Trying to locate a length of scaffold pole to lengthen my breaker bar in the meantime ...)

This is all I have to run mine

Charger

Battery

£93 for charger & a 5ah battery.

Apart from the charger (that was in a drill/impact driver set), all mine came from Amazon

So about £253 all in, also mean you can then buy bare tools for anything in the future.

I will be honest, I didnt need anything like the dewalt - but the time I have to spanner is very limited & not having the right tool eats into that. For instance, I needed to swap the front shocks on my S60. 1 side took 30 mins with a cheap impact wrench/hand tools, the other side took 3 hours due to 1 stuck bolt that the impact wouldnt touch - luckily my mate had a compressor & some air impact's - they struggled due to water ingress. So 4hrs to do a 1hr job.

On the same car, it took me over an hour to get 1 stuck wheel bolt out & I bent a 3ft breaker bar! Luckily I had the dewalt the week after and havent had a stuck bolt since lol. I even use it to screw some 3ft ground anchors into solid clay for my sons trampoline - took about 5 seconds lol

Thanks just ordered this.  For the sake of an extra fifty quid it seems a no brainer.  I might actually have the 205 on the road in the near future with it ...

Quick question:  with all this torque, do you find  yourself snapping more rusty bolts than you used to ...

[Laters]

In all the occasions where I have used the dewalt I have snapped one wheel bolt.
All the other tight stuff its undone. Saying that the bolts I use it on are usually driveshaft nuts or are on the larger side.
I had already tried with the normal extending wheel nut bar and my biggest breaker bar to undo the wheel bolts before trying the impact gun.
Who knows what they tightened the wheel bolts up with but all are getting replaced as there was no need to be as tight as they were.

[joem83]

May 24, 2021 17:29:12 GMT princerupert said:

Thanks just ordered this.  For the sake of an extra fifty quid it seems a no brainer.  I might actually have the 205 on the road in the near future with it ...

Quick question:  with all this torque, do you find  yourself snapping more rusty bolts than you used to ...

I don't think you will regret buying it tbh.

If it's on the smaller side I use my impact driver as it's smaller, but you can put the 899 in low torque mode if you are worried about snapping.

I have found if it's a bit stuck, bump it an ugga dugga tight and then have another go at loosening it - sometimes unfreezes it. I have snapped more bolts with my hands than power tools - the impact part helps shock things free. Some very good videos on youtube about them.


(for refference mine is a type 1)

[ejenner]

I'd say with the 'impact' part of the function of these tools you're increasing your chances of getting the fastener out safely. If you use the gun and it snaps the fastener it's pretty likely you would've done the same thing if you'd tried a hand tool instead.

With the impact wrenches if you're tackling a difficult one then make sure you're square on the head of the bolt, grip the gun tightly and make sure whatever attachment you're using on the gun is the right one for the job. You can also use heat on the fastener beforehand. Something like a brake disc retaining/locating screw with a torx head responds well to a bit of heat.

[slater]

Your in the relms of wishful thinking if you're expecting a 700nm anything to loosen a rusty hub nut. If your after that sort of power over got to go for a proper 1800nm (or whatever they are) Milwalkee or Bosch or somthing decent.

The smaller lighter guns are very useful but don't have the poke for tough jobs.

[ejenner]

that's not really the consensus here so far...

[princerupert]

May 26, 2021 8:37:40 GMT slater said:

Your in the relms of wishful thinking if you're expecting a 700nm anything to loosen a rusty hub nut. If your after that sort of power over got to go for a proper 1800nm (or whatever they are) Milwalkee or Bosch or somthing decent.

The smaller lighter guns are very useful but don't have the poke for tough jobs.

The DeWalt I have ordered is 950 Nm and the consensus seems to be it is awesome and will do everything I need it to ... 

Will find out tomorrow when it arrives I guess ...

[welshpug]

4 foot extension for your little breaker bar, nice and cheap.

[Dez]

Even 950nm isn’t *that* much in the scheme of things though.

To quantify, If I put a breaker bar on a hub nut with a 6ft scaffold pole on it and stand on it I generate double that.
How may times have I done that and it’s pinged the end off the bar (or the end off the driveshaft) rather than undone the nut? Quite a few...

So to expect a 950N gun to undo stuff like pretension hubnuts is unrealistic, especially once you throw a bit of corrosion into the mix. . Given the shear strength of an m12 bolt is about 1500Nm depending on material, it would probably struggle to undo overtightened wheel bolts done up with a windy gun.

And that’s before you get into Battery power tools being nowhere near as powerful as the manufacturers figures would try to make out. It’s all ‘peak torque’ and stuff, not what they can actually do in the real world. For fitters rattling cr4ppy dirty bolts onto stuff or over corroded threads that require a bit of force to wind on, they’re great. But if you want breakaway torque, you need air tools or good old fashioned mechanical leverage.

[princerupert]

If it doesn't get it off I'm going to be upset 

[ballbagbagins]

I very nearly bought a Milwaukee one but the cost was too much for me. They do get brilliant reviews though and they are quite small and light.

[princerupert]

If anyone is better at maths than me, how much torque would a 220 lbs or so man (i.e. me) be putting down by standing on the end of a 2ft breaker bar?