Dual tow hooks and tie down design for D3/LR3

[bbyer]

This is a proposed design for a pair of rear tow hooks and shackle tie downs for my LR3. The rear right side assembly is illustrated; the left side is of course the mirror image of the right side.

Given that the 3 has an excellent factory centre rear tow hook, I agree that there can be the view that this design is a solution to a non existent problem. I have however seen comments that at times, there can be a requirement for dual tow points. Regardless, I put the design forward for comment as my primary concern is not whether dual tow hooks are needed but if the design will put an undo moment on the frame and hence twist the frame.

The actual tow hooks are off the shelf early Jeep (1987 to 1995 YJ Wrangler) ½” bolt type, @ 2-7/8”OC, and the pair of shackle holes will take 5/8" and near 1" pins.

Each assembly secures to the box frame near each muffler using the existing 24.3 mm ID holes in the box frame just forward of the two vertical metal bracket plates on the outside of each frame section near the muffler.

The plate material is primarily 3/8" A-36 mild steel so the real concern not failure of the bracket assembly but whether the box frame would twist from sidewards pulling forces. A 3/8" spacer plate is located between the bottom of the box frame and the top of the three box shaped steel pieces that the pulling bits are attached to.

The idea is that the plate is to help evenly distribute rearward pulling forces up to the bottom of the box member rather than have all the forces act on the 24.3mm ID hole that runs thru the box frame.

I have posted PDF’s of the proposed design below and also in my gallery, actually JPG's as the gallery appeals not to be designed for PDF's.

In my gallery, there are descriptions related to each picture. The reason for posting these is to get comment regarding the design, in particular if built and installed, whether actually tugging on the hooks would do more harm than good. My thinking is that with a hook on each side and a strap type bridle, that as long as the pulling forces are shared, that no damage should result to the frame. At any rate, that is the question.

[Tank]

The only comments I have is that when using a bridle front or rear you should use a strap that is long enough to keep the angle formed well below 90 degrees, ideally less than 45 degrees.
It seems that your shackle holes are are in in the vertical axis, which is good as it allows the shackle to align itself with the line of pull, shackles attached to holes that are horizontal place undue stress on the shckle as it jams against the pin hole or bracket, shackles (D or Bow) are designed to only be pulled straight ahead and not sideways in a horizontal pin position, Regards Frank.

[bbyer]

I appreciated your comments re the bridle design.

For the bridle, I was intending to use a 30 ft length of non-elastic 3" recovery strap with fabric loops at both ends.

By my calculations, then the two 15 ft long legs yields an internal angle at the "central" tow point of somewhere between 15 and 20 degrees between the two strap section where they return back to the proposed Land Rover attach points.

If I understand that correctly then, at least I have that part of the thinking correct.

At least with the bridle, the chances of the frame being twisted at the attach points is somewhat reduced and that is a major concern of mine as I am certain that with the centre mount Land Rover rear attach point that there would be no twisting action so I do not want to make things worse.

Thanks Bruce

[101RRS]

Given that the 3 has an excellent factory centre rear tow hook, I agree that there can be the view that this design is a solution to a non existent problem. I have however seen comments that at times, there can be a requirement for dual tow points.

Hi Bruce,

I guess for me your above comment seems very relevant however I do accept other points may be required.

On my 101 I did almost exactly the same as you describe. ARB here sell "tow hooks" rated at 4500kg/10,000lb (there is not indication whether this is safe working load or min fail load) that look basically the same as the ones you used. I bolted one to each front spring hanger and I have used them in anger.

While the use of one hook is strong enough for winching I was concerned that when snatching my 101 if fully loaded and bad conditions the snatch might go close to the max load of these hooks so hence the two. Pulling just on one side of the chassis is not such an issue in the 101 (the winch pulls from one side only) but could be on other vehicles.

For a bridle I use two tree protection straps (one is not rated enough in my view - particularly for a snatch) but ARB do sell a plasma rope bridle for about $90. It is rated at about 10000lb - again a bit light for me but it has given me the idea of getting a piece of heavier grade plasma and getting it made into a bridle - this will provide extra strength and allow for a bit of wear abrasion.

I did consider a wire rope bridle but it would be a bit cumbersome to carry around and left on all the time runs the risk of getting caught on undergrowth etc.

So - based on my experience what you proposing would work well but as I understand it the single original ring at the front is OK.

Based on your logic for doing what you have designed - what about the rear of the car? Afterall most recoveries are to pull backwards out of a bog not through it. I have just put on a Mitch Hitch on the rear of my RRS and will be using one of these to recover it backwards - noting the hitch is only rated at 3500kg so I will be supervising any snatch recovery to ensure the minimum of force was used.

[bbyer]

A 101, that is kind of special. I doubt that there are any here in Canada at all. We do occassionally see ex MOD Defenders in rather distorted shapes however. The Royal Army has a tank training facility here in Southern Alberta and some Defenders tend to get slightly run over. As such, those units make it to the auction and are snapped up - for the serial number plate I suppose.

I suspect that the ARB and Smittybilt hooks are from the same factory in Taiwan, at least that is where the Smittybilt box says theirs are made.

I note that Curt appears to have about the same hook, two bolts holes however, but at least the 10,000 lbs is marked and as you said, whatever that means.

I have seen other similar hooks, but without any marking so I suppose those ones are from the knockoff factory in China proper.

Actually, my plan is for the tow assemblies to be mounted on the rear to the frame between the muffler and the spare tyre location - hence dual rear tow points.

Re the front, I expect that I will just remain with the single LR point as doing anything up front that does not hang down alot is tough to figure out. Also as you said, rear tows are the most common, particularily here where one tends to slide off the road due to snow etc.

Also I have visions of installing a bash plate up front so that makes the factory front tow point a bit more readily accessible.

As to strap loading, I wondered if since I was planning on using a single strap but anchored at both ends, should I assume that the strap load is effectively not divided as the forces all come together at the V. I had not really thought of that, hence two individual shorter straps, (four end loops rather than two), as you do it, make more sense and are more safe. This towing / recovery business is tricky - one has to think a bit.

[101RRS]

I suspect that the ARB and Smittybilt hooks are from the same factory in Taiwan, at least that is where the Smittybilt box says theirs are made.

The ARB ones are made in either the PRC or Taiwan


Actually, my plan is for the tow assemblies to be mounted on the rear to the frame between the muffler and the spare tyre location - hence dual rear tow points.

Silly me :o - did not read you original post correctly :(.


As to strap loading, I wondered if since I was planning on using a single strap but anchored at both ends, should I assume that the strap load is effectively not divided as the forces all come together at the V. I had not really thought of that, hence two individual shorter straps, (four end loops rather than two), as you do it, make more sense and are more safe. This towing / recovery business is tricky - one has to think a bit.

I only use two straps as a bridle as the tree protection straps are only ever used for winching so are only about the half the strength (about 3500kg) required for snatching. Ideally the bridle should have the same rating as the rest of the gear being used eg maybe up to 10,000kg for a heavy snatch of a heavy vehicle to about 9000lb for a winch with a 9000lb winch. You do not need to make the bridle double the size of your other gear - I just use two tree truck protectors as that is what I have and it then give me about the correct rating that I need.

Garry

[bbyer]

I was just looking on the ARB site and see that they have two lengths of tree strap, 3 m and 5 m.

I would think then that a pair of the 5 metre lengths would work quite nicely for a bridle?

[101RRS]

In due course I will change over to a length of plasma rope - much stronger, lighter and easier to store.

Garry

[bbyer]

I have heard the word plasma, as related to rope but that is about all. Is there a link to I guess a supplier where I could read up on what it is?

I am not exactly at the leading edge of anything here other than digging out of snow drifts - that I am good at, and normally before I am stuck - the digging is just to get at the door handle.

That is however alot better than tangling with crocs just to get at your overnight submerged Rover - some not so nice pictures coming out of Rockhampton on our TV's these days.

[101RRS]

Here is something that might answer your questions.

Plasmarope.com.au - Fibre winch ropes (http://www.plasmarope.com.au/)

The US is the place to buy it.

Pics just coming through of the main street in Toowoomba is interesting and unfortunately loss of life.

[camo388]

[QUOTE=bbyer;1403263]A 101, that is kind of special. I doubt that there are any here in Canada at all. We do occassionally see ex MOD Defenders in rather distorted shapes however. The Royal Army has a tank training facility here in Southern Alberta and some Defenders tend to get slightly run over. As such, those units make it to the auction and are snapped up - for the serial number plate I suppose.

There is a 101 in the Alberta Land Rover Enthusiasts club.
Check us out at www.alre.ca (http://www.alre.ca) and come out to a meeting. Web site gives details.
Your tow hooks idea looks OK but will you have a sleeve through the frame to prevent the frame from crushing/tearing? Jate rings on a 110 have the bolt inside a sleeve to help take the load but also to avoid destroying the frame.
Other than being quicker to hook up, the hooks are a weak point. I would use a side plate with a lug to take a shackle. This is a personal reference from experience gained from pulling oilfield trucks to job sites.

Bruce

[bbyer]

So now I have a 101 to watch for - and just when I thought I had spotted most of the Land Rovers in the Edmonton area.

The sleeve is a good idea and I will figure out how to incorporate that. I had thought about it, but discarded the idea as I assumed the two lower 1/2" bolts would tend to carry the twisting forces.

The 7/8" bolt can be downsized to 3/4" or maybe even 5/8" with no decrease in safety so I will give the addition of a sleeve some thought.

Hook vs clevis, or lug for clevis, has also been on my mind. The bow shackle is clearly a better attachment method, but all I could figure out was a design where the bow tended to hang down, (unless tied up), or had to be carried loose and then attached when needed - hence the fixed hook.

Thanks and yes, I have been watching the www.alre.ca (http://www.alre.ca) site for the last few months. Last fall, I drove past the pub where the meetings are held - lived about two blocks from there when I was younger - like five years old. And yes, you may see me some Wednesday evening the the first of the month.

I have been admiring the club grill badge and wondering how to mount it on an LR3.

[camo388]

The 101 lives in Medicine Hat, so you are not likely to see it often. The owner sometimes trailers it up to Edmonton for driving events with the club.
The shackle does present a problem of storage or left hanging low when not needed.
If you don't expect to pull or be pulled very much the hooks will likely be more than enough. With oilfield trucks a very strong pulling point is mandatory and used often.
I mounted my badge to a plate that I could fasten to the grill guard. I don't have much faith in a plastic grill.

[Tombie]

Those hooks are a pita at the back.
The catch on all sorts of things.

Personally, recover from the hitch or centre point.

You're reinventing the wheel!
Or....
Putting a belt on, whilst wearing braces!

[bbyer]

Yes, if anything is bothering me, it is just that, the belt and suspenders sort of thing and is this really necessary, or worse, it the whole concept a bad idea.

If there is a reason for the dual pull points, it is just that - dual.

Here we tend to slide off perfectly good roads into ditches full of snow. If we are lucky, only our egos are bruised, and with the 3's skid plates, the engine and rad tend to remain where Solihull first put them.

If I were pulling someone out of aforementioned ditch, I would use the centre tow loop, however if I were the one in the ditch, it just seemed to me that being pulled via a bridle off the two hooks would better distribute the strain on the frame and also reduce the tendency for the vehicle to flip on its side - something that happens here as the vehicles rarely stop nice and level like, nor is the path back up the slope necessarily all flat and smooth. And yes, the idea is that the pulls will hopefully never be used.

Your comment re catching on something is a concern I am still looking at.

I am actually impressed at how clean it is under the rear, (and also the front), of the 3 and the idea of actually putting something under there that catchs on whatever does bother me.

In other words, the removable trailer hitch to me makes good sense so any design that fouls the underneath is by definition, far from ideal.

I do have a variation of the design where I have put 45 degree slopes on the leading surfaces of most of the metal bits that hang below the frame in an attempt to get stuff to not catch - but the hook is still a hook, even it it is horizontal and the thin spring metal guard is not much help really.

Also in the alternate design, for lashing down, I have deleted the dual shackle attachment tab and substituted a kind of longtitudinal "JATE" ring that swings left or right up against the bottom of the assembly to provide better clearance and flexability.

I certainly appreciate your comments as that is why I put the post up. I also have concerns as to the design, so the more comments I see, the more thought I can put into the design.

As I said in a previous post, recovery procedures and equipment are not as simple as they may first look to be.

[camo388]

Now you have got me looking at every 4x4 or oilfield truck I see and trying to judge good/bad features of each tow point.
On the whole I would think you want to be towed out using a low point so that the tow will partly lift the weight of the vehicle out of the deep snow/mud to reduce drag. Some vehicles have high tow points (jacked up utes) so in effect you would be pulling them down as you try to tow.
With this in mind you might want to consider only using the tow hooks and eliminate the lower lashing eyes. True you will reduce the catch point by very little but are the lashing eyes going to be of any use if deformed?

Bruce

[bbyer]

I enjoyed your post. Looking at every truck that goes by as regard to tow hook location is about what I have been doing as well.

About the best setup I have seen on the heavy trucks is where they run two lengths of about 1", (25mm), wire rope from front to back and clamp the cable to all the axles. Then when the truck is stuck and they hook on to a Cat D10, that the axles bring the truck along with the cable. I guess this is a reaction to the more common situation where the axles remain mired in the mud and the truck turns into a skid unit.

Not only on Oilfied, but I have also noted the wire rope cable setup to be fairly common in the City here on transit mix trucks. I think it has something to do with the media making a fuss when dynamite is used in the City to unstick the undercarriage from the mud.

I agree with your comments re the lashing down arrangement and have per attached, revised the lashing attachment to be a swinging forged metal loop rated at 11,000 lbs, but the idea is that the loops are for tieing the 3 down, not for towing.

Regarding clearance, the intent is that the lashing loop be tied up sideways and not hang down except for lashing. The lashing requirement is a result of me watching how our local tow truck operators tie down sick BMW's to their flat bed haul away trucks. Chains between the spokes of the wheels seems to be favored over chains from the deck to the wheel A arms or whatever Beamers have. I expect some variation of that is used on the LR Sports as well. There do not seem to be enough 3's around that I have seen any being dragged away but I assume much the same "technique" would be used.

Getting the tow hooks as low as practical is a trade off between creating something that hangs up on whatever and having the hooks so high up that the body is lifted off the frame, or as you said, sucked further down into the mud or snow.

An initial design of mine had the tow hooks bolted under the frame where the lashing loops now are. That had the advantage of reduced twisting action on the frame, but really created a hang up concern - as in dangerous.

I would not say that what I have designed is yet "the solution" in either regard by the way. My concern began is a result of watching the local tow truck operators. They have these big "fish hooks", (J shaped hooks), that they like to throw over anything that a J hook will catch on. If not the wheel rims between the spokes, then whatever parts of the rear wheel / axle / A frame bits they can find, seems to be an accepted procedure. I am trying to provide a dual alternative - not easy it seems.