Recovery Points - Cutting Chassis

[jp4294]

Hey guys,

I've got a 1999 GU and it doesn't have recovery points...yet. Now, I'm planning on using it the way it's supposed to be used so recovery points are a must as far as I'm concerned.

My dilemma:
Got a TJM steel bullbar which needs to come off in order to access the ends of the chassis rails if I'm to open them up to get washers and nuts in. However, I was having a look around today and wondered if you can cut the end of the chassis rails right off? There's nothing attached to them and as far as I'm concerned they don't do anything in terms of the structure of the chassis.
By doing this, I'll be able to easily slide the nuts and washers in without removing the bullbar.
Has anyone done this or know if this is a big no no in terms of safety, legality, anything else?

Here's a picture to show what I mean.
Green = area covered by bullbar
Red = cuts
Yellow = bullbar mounts
73628

[MB]

G’day mate, please do look up a Vendor on here called ‘Outback Recovery’ I believe it is. They will mount up easily below your chassis rail (W/SW) of your lowest yellow arrow pictured above. Cheers!


Sent from my iPhone using Tapatalk

[PeeBee]

MB I think you had something like this done to your rig when the Millweld bar went on? I would think the ends of the 'box section' will need to be capped to retain the shape rigidity, as you are cutting fairly close to the load points for the mounts and the chassis rails are quite lightweight. Strictly speaking you are also altering the chassis so it should be a 'certified modification', but thats up to your interpretation at the end of the day until you get caught that is!

[mudnut]

http://www.nissanpatrol.com.au/forums/showthread.php?12616-Outback-Ideas-Recovery-points&highlight=outback+recovery

[MB]

G’day mates, never suggested otherwise. There should be no reason why a standard TJM bar trek plan should need such? Old mate John on here makes an awesome compliant recovery point/s to mount below any TJM, ARB or most !


Sent from my iPhone using Tapatalk

[PeeBee]

The mounts with the rusty hole witness marks look very accessible or am I not seeing something? Does the TJM bar slide over the chassis rails? I can't see why Johns mounts won't fit straight up.

[MB]

Back on ‘charge’ apologies for delay PeeBee Phil mate :-) John’s recovery points mount inline with all chassis’s underneath and bolts x 3 connect them with lateral force not front pull off I guess is the benefit/term :-)


Sent from my iPhone using Tapatalk

[PeeBee]

So bolts in shear/double shear, not tensile loading?

[MB]

Tensile = Snap doesn’t it?


Sent from my iPhone using Tapatalk

[PeeBee]

Shear is load across the diameter of the bolt, tensile loading is the load pulling on the bolt in the axis of length. A bolt under tension will stretch before breaking, however a bolt under sher will deform in the line of load then shear or cut off, like a whipper snipper cutting thru grass. Good night, going to bed.

[MB]

Correct I believe mate :-) ?


Sent from my iPhone using Tapatalk

[MB]

I believe I’ve also heard of blokes using HT engine valves as Bobcat ramp locator pins, bad idea :-( Personally trialled HT and Mild bolts in lateral force tests on paddock trailer suspension and find HT shears off/snaps every time. We’ll have to get a recommendation off TD as to what bolts best suits his kit/lateral pull design:-)


Sent from my iPhone using Tapatalk

[Plasnart]

HT only for straight pull forces is my understanding. Weak in shear.

[PeeBee]

HT only for straight pull forces is my understanding. Weak in shear.

Plassy, generally correct. depends on thread form, actual avail root diameter, and type of load, temperature, environment to name a few. Its a myth that putting high strength bolts , being a higher tensile rating will improve strength of a joint - depends whats physically happening. like what Mark suggests, high tensile bolts are generally harder and more brittle, due to the granular config within the material during manufacture, be it from heat treatment or the manufacturing methods like heat tempering or forging. It is possible to torque up a HT bolt to get a higher joint pressure and this is typically the application. They are less likely to strip the bolt thread than the parent metal, which is a danger and why torque settings are important. Also, the nuts are a matched part of the system and the nuts are slightly softer than the bolt to ensure one part of the system is elastic to a degree to give deformation grip, and also fail if the torque is exceeded, thus protecting at least one side of the system.

For example most normal assy's of manufacture are configured with grade 4.6 bolts or less as they are more forgiving of overload, more elastic and less prone to break due to their plasticity. Structural is usually defined in the GR8.8 range and are harder, higher tensile load capacity but less elastic due to the grains or plates in the material being longer and also the materials in the bolts add positive attributes but at a cost to other areas - generally you get a slightly higher shear rate from a HT bolt, but nothing like the magnitude of the retained tensile load. Moving higher you hit the 10.9 and 12,8 ranged and then exotic bolt materials and bolt diameters with specifics around thread form heat treatment - we lay people would rarely see these, more a specific application and design related.

Apologies for the long winded response, you opened a door into a design past and this is what I know about.

[jp4294]

Thanks for all the input guys. I saw John's "T" shaped ones but my bullbar has a flange/folded section of metal that runs vertically along the the bullbar mount (left of the mounting holes (yellow arrows) in the picture I posted) so I think that might get in the way. Not sure about grinding a bit out of that in terms of structural rigidity for the bar? I'll try post a photo when I get a chance..

[mudski]

This might help the OP out...
http://www.nissanpatrol.com.au/forums/showthread.php?14223-Fitting-GU-Recovery-plates

[BillsGU]

Iron Man recovery points are the only ones I know of that will fit both sides on early GUs. The one on the passenger side comes with nuts that are welded to wires so they can be fitted from holes to the rear of the chassis and then engage with bolts that fit through one side of the left hand chassis only. No need to muck about with the end of the chassis rails. Talk to your nearest Iron Man rep.

[katwoman]

http://www.nissanpatrol.com.au/forums/images/imported/2017/11/31.jpg
http://www.nissanpatrol.com.au/forums/images/imported/2017/11/32.jpg.............


Sent from my iPhone using Tapatalk