16 replies to this topic

[Pairaminis]

I've searched Haynes, Rover Workshop Manual, TMF FAQ and Torque Printout, other forums, and Google and can't seem to find this info.

 

Anyone know the torque for the 5/8 nut on the rear subframe support pin (the one that goes through the trunions at the front of the subframe and has the two funny holes on the end) and the 5/8 nut on the end of the permanent bolt that holds the trunions and rubber bushings on the rear of the subframe?
Jack

 

[geoff-d]

I Think Its F T

[Lincsminbin]

I recently had my rear subframe off and stripped down.  Like you I struggled to find specific torque values for putting things back together.

 

In the end went with a combination of the Haynes Manual and the Mini workshop manual found here:  http://www.renegadem...shop_Manual.pdf

 

The Haynes has the radius arm pivot shaft nut(s) as 53 lbf ft / 72 Nm

 

As the other bolts don't seem to be specified I went for the 'General' settings from the workshop manual (list below), but in summary I used:

 

1) Subframe support pin (7/16 unf - The big pin with the flat head with 2 holes in) - 75 Nm

2) Trunion to body bolt (front / sills and boot) (5/16 unf) - 25 Nm

3) Radius arm bracket bolt (5/16 unf -) - 25 Nm

 

I by no means know if these are the 'correct' values, but they felt right when tightening things up, and nothing has fallen off over the last 3 weeks

 

GENERAL (Extract from Workshop Manual)

Bolt M6 10 Nm ...................................

Bolt M8 25 Nm ...................................

Bolt M10 45 Nm ..................................

Bolt M12 80 Nm ..................................

1/4 UNC/UNF 9 Nm ..............................

5/16 UNC/UNF 25 Nm .............................

3/8 UNC/UNF 40 Nm ..............................

7/16 UNC/UNF 75 Nm .............................

1/2 UNC/UNF 90 Nm ..............................

5/8 UNC/UNF 135 Nm

[Cooperman]

I've never used a torque wrench on those nuts. Just 'FT' normally does OK.

[Lincsminbin]

I've never used a torque wrench on those nuts. Just 'FT' normally does OK.

Got to admit I agree with you, but I have a strange attachment to torque values, I think a lot of it stems from my need to justify the cost a of my torque wrench to the other half!

[Pairaminis]

Thanks Lincsminbin.  I think 75Nm must be pretty close since that's about the same as the big nut on the end of the the radius arm pivot shaft.

Jack

[Steve220]

Plus it allows the right amount of torsional stress to be put on a fastener so it doesn't snap or come lose.

[A-Cell]

Key thing is to ensure the nut bottoms out on the shoulder of the pin, similar principle to the front suspension tie bar big nut. Then the tolerances give the correct load on the rubbers. Hence 'fully tight'. The size of the thread gives a required torque of 75Nm according to the Rover workshop manual, quoted above by Lincsminbin.

[Spider]

I'm not sure what type of Nut was used for that in the UK, however on the Aust Production, it was a Nyloc Nut, being a self locking Nut there is no specified tighten Torque.

[Lincsminbin]

Ah, that's interesting to know. It is indeed a Nyloc nut, I'm learning all sorts about fasteners owning the old minbin. Do Nyloc nuts not have a specific torque value, is it always just 'tight'?

[sonikk4]

Something to remember unless the nut is original never assume its the correct one. So you may find a Nyloc fitted but it may have been something else. Always worth checking.

[humph]

I asked the same question, here is the thread http://www.theminifo...y-trunnions-be/

 

This jist of it was that they bolts are shouldered so the nut is tightened until it hits the shoulder and stops.

[Spider]

Ah, that's interesting to know. It is indeed a Nyloc nut, I'm learning all sorts about fasteners owning the old minbin. Do Nyloc nuts not have a specific torque value, is it always just 'tight'?

 

Nylocs don't and can't be 'torqued' as their initial friction can't properly be taken in to account. I just do them tight as appropriate for the diameter of the fastener.

 

<Edit: Another 'thing' with most Nylocs (not all, but probably 95% of them) is that they are single use only, but I do know many of us use them more than once. The reason for this is that the 'thread' is 'cut' in to the Nylon component as so it (theoretically) looses some / all of it's self locking capability.  I'll just say that I tend not to re-fit them more than about 2 or 3 times, depends on how they feel when going back on.

 

If you want a higher performance Self Locking Nut, look for Coneloks (Trade Name) >

Edited by Moke Spider, 13 January 2015 - 10:19 PM.

[F1L8EY]

Im sorry but as an aircraft engineer I disagree with the above made comment. (sorry if that comes across as curt) 

 

A nylock or any"stiff nut" can be torqued. when a nylon is new thus has not been run down a thread yet, this is when its designed friction loading will be applied to its full value. (so a nylon for example that has been run down the thread and torqued many times will be let effective as you might have cut more nylon out or stretched the tolerances, if its old don't expect it to do as good a job) 

 

the resistance needed Or torque to run a stiff nut down a treaded bar is called the run down torque and can be measured by a torque wrench by increasing the torque slowly until it fails to break and moves the nut. or with a gauge torque wrench. 

 

once the rundown torque has been measured you can add it to the desired torque for the size nut required. So using the above mentioned figures as an example if the rundown torque on an M6 nut was 2Nm and the desired torque is 10Nm you should torque the bolt to 12Nm. 

 

there are many types of stiff nut, the most common you will see are nylons in a car environment. when i put my mini back together i shall incorporate some principles like wire locking on the important nuts to aid safety. 

 

hope this helps, and sorry again if it came across as rude

[Spider]

Bhaha,,, no, not rude at all. Good info in fact.

 

This is a sheet my fastener supplier passed on to me a few years back,while is is pretty much along the lines of what F1L8EY has said, the last paragraph is why I said what I did above;-

 

 

Nyloc is a registered trade name of Forest Fasteners.
 

A Nylock nut resists turning. Usually nuts are free spinning, but Nylock nuts have a plastic patch that causes resistance to nut turning. This resistance is called "prevailing torque". Prevailing torque is the torque required to turn the nut. None of the prevailing torque goes toward tightening the bolt.

Nylock nuts fall within a group of nuts called 'lock nuts" Lock nuts come in all types and sizes. Typically there are the "Nylock" or elastic stop nuts, and the "all-metal" lock nuts.

The rule of thumb is to add the prevailing torque to the torque value when applying torque to a Nylock nut. This is because the prevailing torque doesn't contribute to bolt tightening. It is just friction that needs to be overcome.

For example, a Grade 5 1/4-28 bolt in tension lubricated zinc plating, with a torque of 10.5 lb. ft. produces a clamping load of 2,511 pounds.

If we use a use a Nylock nut that takes 2 lb. ft. of torque to turn, then 2 lb. ft. of torque is used in turning the nut leaving only 8.5 lb. ft. for bolt tension. Our clamping load is reduced to 2,009 pounds.

If, however, we take our original torque of 10.5 and add the 2 that the Nylock requires and set our torque wrench to 12.5, our clamp load is 2,511 pounds. The same as it was without the nylock.

You can use your torque wrench to measure Nylock nut torque and then add this value to the bolt's required torque.

Prevailing torque calculation should be done with your nut and your bolt using your thread lubricant. Published prevailing torque charts may give you an idea of how much torque is used up by the nut's locking feature, but in actual conditions, the results will vary. There is an interaction between the bolt threads, nut locking feature, and the thread lubricant (whether liquid or plating) that makes each prevailing torque calculation unique.

 

I hope that I don't appear Rude in presenting this view.

 

<Edit: To correctly 'torque a fastener with a torque wrench, as stated in the above and for good reason, lubricaant needs to be used to overcome the friction created between the threads of the fasteners and also the face to material friction, otherwise what are we 'torquing'? Are we doing it to a desired 'friction' value or to stretch the fastener? From my own experience when lub is added to a Nyloc, much (and in some cases, all) of it's self locking feature has gone. I think the only way of setting fastener 'tightness' when using self locking fasteners is by measuring the stretch of the fastener.

 

Out of curiousity, In the Aircraft Industry, do they state to 'Torque' Dry or Lubed?   And what are the materials being fastened together?>

Edited by Moke Spider, 14 January 2015 - 06:47 AM.