Thread: Recovery point mounting.

Hi Sam - I think there is a difference. From what I understand the shear strength of a bolt is reduced by ~50% at the threaded section, so mounting a recovery point at the head end is far stronger than mounting it at the nut end (where it is threaded).

sam d
I suppose you could turn the bolts around so the nuts are on the other side, or get new longer bolts, I believe the closer to the centre of the vehicle for recovery points the better, I know it is only the thickness of the chassis, but it all helps, I am going to make up a set that go on the inside of the chassis and with the hole for the shackle pin vertical so that the shackle can swivel 180 degrees without placing undue strain on the pins when they are in the horizontal plane, Regards Frank.

Originally Posted by Tank

sam d
I suppose you could turn the bolts around so the nuts are on the other side...

That is what I had intended to do but then realised that the simple sounding job of:

1. Remove nut from bolt.
2. Extract bolt from hole.
3. Insert bolt into hole from opposite direction.
4. Re-attach nut.

sounds waaaay to easy and is the kind of thing that has hidden complications!

I have to mount the recover points on the inside of the chassis though as the steering protector attaches to the outside.

I'll see about fitting the recover point this weekend.

Just completed installing a pair of the Ladas' recovery points on my SI Discovery. Everything was fairly straight forward but a couple of adjustments were required...

I had to ream the bolt holes a little in the recovery points to suit the ½" bolts - 30 sec in the drill press and a few minutes with a file on the slotted hole was all that was required.

I had to replace the bolts for the crush cans on the front of the chassis with slightly longer ones. In fact, since the lower bolt is 12mm longer than the upper one, it looks like you could use the lower one in the upper position and fit a new bolt in the lower position (at least 125mm long).

I was able to stretch the front arm for the steering protector out on each side by 10mm to accommodate the recovery points which are now sandwiched between the arm and the chassis. This requires a decent pinch bar to apply enough force to create the gap. Sam I think you might have been concerned about this but pulling the bolt up tight pulls the flattened face of the arm nicely in against the recovery point.

It's worth noting that both bolt holes are tubed within the chassis rail to prevent any risk of crushing the chassis walls together.

The pictures show the finished job on the driver's side from the side and the front.

Nice work and good explanation GrahamH.

Originally Posted by sam_d

...
Is there any benefit in mounting the recovery point:
on the inside of the chassis rail instead of the outside?
at the 'nut' end of the bolt instead of the 'head' end?

or does it really make no difference?

Cheers!

To the 1st question, no benefit.

But best on the outside if you use a bridle or the recovery load is angled toward the inside. The tension in the bridle will load the bottom bolt in tension plus shear. The shear capacity of a bolt is reduced if the bolt is also in tension.

To the 2nd question, no benefit.

But not as strong if the bolt threads are in the shear plane. If the bolt is long enough the threads may not be in the shear plane, but you may need thick washers under the nut.

From what I can tell from the pics of these recovery points, the shear load on the lower mounting bolt will be nearly double the load attached to the recovery point (assuming a straight pull and simple statics).

So it is prudent to install and use them so that the bolt threads are not in the shear plane and the angle of the recovery load does not place the lower bolt in tension (except for small recovery loads).