How tight should my nuts be

[Bernie Cook]

I read with interest the letters about the various styles and sizes of wheels from the mexican hat variety to the latest AMG product but one thing is missing from all these missives.

"How tight should the wheel nuts be when you've finally fitted your latest?"

I expect that the foot/lbs would differ with each size of wheel and to whether the wheel is steel or alloy. It would be nice to know though.

 

[jimmy]

Alloy wheels = 110 lbs/lbs

 

[silverclk230]

if you have locking wheel nuts then use a torque wrench and copper ease (or similar) on the threads. I used to "guess" the torque and conequently overtightened the nuts, McGuard type locking wheel nuts can fall to bits when you try and remove them.

 

[miro]

Too tight

still tight

About here is good

This is too loose

 

[concordepilot19]

Be careful with the units. My manual says 110 Newton Metres (NM) which is about 81 Foot Pounds (ft lb). Check your owners manual.

 

[jimmy]

Be careful with the units. My manual says 110 Newton Metres (NM) which is about 81 Foot Pounds (ft lb). Check your owners manual.

Ahh, yes it is either 110 lbs or NM!

 

[Ian B Walker]

80 foot lbs according to the book and please use copper slip on the threads, I once had to drill out a bolt through over tightening and it wasnt funny

 

[inetd]

Depends on what part of town you're in

(I couldn't resist)

 

[GordonTarling]

Whilst we're in a jovial mood, some engineers use the following methods of judging torque -

Count the number of white knuckles - 2 is tight enough, 3 is tighter, 4 is too tight.

Tighten the bolt until it shears and then back it off 1/4 turn

If it gives you a hernia, it's over-torqued.

Judge the length of the exertion 'grunt'

 

[glojo]

I was about to query the specified torque setting for the E-class 211. My manual states they should be 130nm which is more than tight. It is blooming tight!

I have just taken a wheel nut off and no way is it at that setting, more like the 110nm that everyone is discussing. My torque wrench is a half inch calibrated Teng, so I am fairly confident it is accurate. I am worried about

a) tightening the nuts to this degree
b) Expecting anyone to undo them
c) I do not think I have the strength to apply the pressure(or can stand the pain )
d) Will the threads cope?

There are a number of 211 owners on this forum, is it possible for someone to check their manual (in the hope it is a different edition) and check what settings are recommended for their wheels please?

Regards,
John

 

[SL300-24]

Hi John,
The manual for the w211 does say 130nm. My E320 cabrio says 110nm. Having had wheel nuts break on my 129SL I would make sure that you use copperslip on the bolts and do not exceed the recommended torque settings.

 

[Ian B Walker]

whoops dup post

 

[big x]

Ahh, yes it is either 110 lbs or NM!

and that is why some of the problems occur....

I see the EU are going to have another go at banning imperial measurements
in things like tyres,wheels and plumbing supplies that are still widely used in Europe.


adam

 

[Sp!ke]

Talking of wheel bolts....

I had one bolt on the W123 that just wouldn't budge. I tried a 1/2" breaker bar on it and snapped the bar.

Then I was told that Machine Mart do a 12v Impact Driver which not only was cheap, it also works.

£20 later, I came home and gave it a try and hey presto the nut came off with ease. It was so easy my 6 year old could have undone it. What a brilliant little tool.

Put this on your Christmas present list, worth every penny in my book.

http://www.machinemart.co.uk/product.asp?p=060810610

 

[l5foye]

A couple of years ago, one wet morning, I got a puncture just outside a branch of Kwik-Fit. I decided to get it fixed there. While in the waiting area, I noticed a lots of signs stating that this branch had ISO 9002 approval. With tongue in cheek, I asked the manager what it meant. He said' Sir, it means we do everything by the book'. I asked' Does that mean you torque the wheel nuts on'. Of course, sir was the reply. I then pointed out that my wheel had not been torqued on. The manager then called the fitter in and demanded to know why a torque wrench had not been used on my car. The fitter replied- As you f..... well know, there hasn't been a torque wrench around this place for years!!!!. The manager turned to me and said Sir, there is no charge for fixing your puncture.

 

[Roger Jones]

Can't swear 100% to this, but I believe the torque settings quoted by MB are for dry fitting. Settings for lubricated fitting are reckoned to be significantly lower and I've seen an online calculation that they are 50% of dry-fitting numbers.

Ah yes:

http://www.rockcrawler.com/techreports/fasteners_torque/index.asp#

where it says "Notice that the torque required for a lubricated fastener is LESS THAN HALF that of an unlubricated fastener."

 

[glojo]

Can't swear 100% to this, but I believe the torque settings quoted by MB are for dry fitting. Settings for lubricated fitting are reckoned to be significantly lower and I've seen an online calculation that they are 50% of dry-fitting numbers.

Hi Roger,
Thanks very much for the link. It has really made things interesting at best, but also quite worrying. When I undone the wheel nuts they were all DEFINITELY less than 110nm. I say this simply because my torque wrench is set at 110. All bolts were easily loosened, all bolts were lubricated with a whitish coloured grease?? The manual for our vehicle clearly states 130 nm, but makes NO mention of lubricated or not. In my lay persons opinion the 130 is way, way over the top, and there is no way that my wife would EVER slacken off anything torqued down to that degree?

I think it fair to say I am concerned over what to do. Safety is obviously paramount.

Regards for now,
John

 

[Roger Jones]

I've quoted some info from an MB tech data handbook on another thread. Most of the torque figures are 110Nm, but there is 130Nm for alloys for a W126 labelled "special protection" (don't ask, as I don't know what that means). And you can see some much higher settings in this table:

http://www.etyres.co.uk/vehicle-makes-models/tyres-mercedes-benz.htm

I am inclined to ask MB to confirm that their figures are for dry settings. If I get an answer, I'll report in. I may also ask them about their recommendation viz. dry or lubricated fixing.

By the way, on another forum, someone who seems to know what he's talking about has called into question the validity of the calculations shown in the link I provided. I shall continue to search for some definitive answers. I have no such technical expertise.

 

[Satch]

It is a bit scary once you realise that it is nearly impossible to set any bolt to an accurate torque figure without highly specialist equipment. If you really get bored over Christmas, off you go:

http://www.boltscience.com/

 

[Parrot of Doom]

I always just do them all up in a star pattern (ie not sequentially), and then tighten them fully by pushing down and grunting a bit.

Never had any come loose yet.