Drilling the chassis

I know that before-n-after, when doing their waxoyl service, enlarge the drain-holes in the chassis. I assume that as long as the holes are not on an edge/corner and are not too big then all is well, common sense required I think.

Regards. Mark.

Dont forget if putting bolts through the chassis it normally has a tube inside to stop the sides crushing in. Richard

Good point. Should the tube be welded in? Is welding a good idea (great generator of rust)?

Fred

In message , Fred Labrosse writes

As JATE rings are strong enough why bother?

A JATE ring can pivot on its single bolt, if you make it a two bolt fixing it can no longer pivot, and the force associated will be transferred into the mounting bolts and then to the chassis. The weakest link being the chassis !

I think that you'll find that they are 10 mm (3/8") bolts.

You're probably going over the top as a decent 10 mm bolt in double shear has quite some capacity anyway.

There is a down side to two bolts if I interpret your idea correctly - they will prevent the 'Jate' ring from swivelling which is one of its advantages.

As someone else comments the frame is usually 'tubed' at the attachment point. There is usually some scope for enlarging the holes before fouling the inside of the 'tube'. At least 12 mm should be possible. Bear in mind however that there is limited metal in the 'eye' of a genuine Jate ring and that the enlarged hole required for the bigger bolt will weaken the Jate ring. If you are designing you own 'Jate' ring or using one of the copies this might not be an issue.

Are they indeed? Somebody not long ago commented on the fact that you should always use two of these for serious recovery.

Which I think is one of the problems with it: moves about when you drive normally, damaging the rust proofing of the chassis, crushes what ever you use for recovery between it and the chassis (unless you use a shackle, yet another thing flying in case of a break somewhere, etc).

Which solves the problems above.

But the effort is anyway transferred to the chassis, only differently. Yes, you are right, having 2 mounting bolts mean that there will be a torque applied to the chassis. Is that a problem? I don't know.

Fred

I'm not sure this is an advantage (see my other post). Can you explain?

Good point.

Fred

The reason for this is to avoid distorting the chassis and turning the right angles into something else - imagine putting three tonnes of stress on one chassis rail and having that rail move towards you while the other side stays stuck in the mud and doesn't move - the result is a parallelogram shaped chassis and an expensive replacement job - the result's about the same as hitting a concrete bollard straight on one of the chassis rails at around 30MPH - one buggered chassis.

JATE rings are rated to an 8 tonne load - believe me - they're plenty strong.

I've never seen one swivel far enough to catch what was attached to it between the ring and the chassis - the chassis where they attach is curved, and the tube they bolt though is suspended about half an inch below the chassis member proper.

With JATE rings you just do the bolt up tight enough to *just* pinch the chassis tube between the ends of the ring and it won't swing unless a genuine force is exerted on it, like a rope or a rock - no swinging loose, no knocking lumps out of the chassis rail.

P.

Point taken.

They would if mounted on my 110 as suggested at .

Ok.

Fred

It mimimises the loads in the bolt and chassis, always applies the load to the Jate ring in its strongest direction and avoids bending the Jate ring. As the load direction changes (which it can do) these conditions remain true.

A swivelling Jate ring applies only the towing load to the chassis at the attaching bolt. Each arm of the Jate ring carries half the load in tension. The Jate ring is not subject to (lateral) bending. Always assuming that you are pulling in the logitudinal direction of the chassis.

I'm going to apply a very worst case example of what may be your design as an illustration. It would be easier if we could have pictures but, here goes ...

Say that your 'Jate' ring was attached vertically and at right angles to the chassis. We'll assume that it looks like a shackle hanging down and what you see below is a side view.

The two attachment bolts A and B are vertically above each other and 2 units of measure apart. The towing load is applied horizontally at point C, a further 3 units of measure below B. The forces on the 'Jate' ring are shown below.

x A x ------ 3/2 T ------> x x Bolt A x x x x x x x x

Bolt B is carrying two and a half times the load it would see if the load was applied directly to it, and bolt A one and a half times. The chassis obviously also sees these loads at the contact points. The chassis in addition to seeing a nett force T in the direction of the tow is also subject to a torque applied about a point between bolts A and B. This torque does not exist (for all practical purposes) with a swivelling shackle/Jate ring.

But, possibly the most disadvantageous point is that you are not using the design of the Jate ring to best effect. No force is being applied in tension along the side arms. All that is happening is that you are bending the side arms.

Paul is correct in suggesting that it is preferable to pull equally on each chassis rail. His description of the result is a little OTT in the circumstances that you would normally encounter but you get the point. A three ton pull would have a very different (practically negligible) effect compared with a 30mph collision into a concrete block!

To stop the Jate ring rattling about just do as Paul suggests - nip up the bolt until it stops swinging freely. If you want to mess around further you could fit plastic washers or 'wave' washers between the inside of the Jate ring and the chassis but it's hardly worth the chew.

You shouldn't hazard your best tow rope by attaching it directly to your 'Jate' ring or anything else for that matter. It something is going to get nipped make sure that it is something that will survive.

As far as chipping the cosmetic covering of the chassis is concerned - if you are that worried you shouldn't be considering off-road recovery!

Dougal

Yes, I see your point, but this is not quite what I had in mind but more something like:

(keeping thesame letters as yours. This is almost like a JATE in the sens that theeffort will be more or less in line with it, but would spread it acrossmore bolts.

Yes, indeed.

I don't really care about cosmetic, just about the effect of damaged rust proofing.

Fred

OK. A lot of effort for little gain in my view.

You ought to tube the chassis at whichever A or B is not the existing tubed point. By having A and B aligned in the direction of pull you avoid the worst load multiplying effects.

You will lose ground clearance locally roughly to the extent of distance B-C.

I you want a good solid rear tow point why not use the existing holes in the centre of the rear crossmember. NATO hook? Just ensure that you have good quality bolts SAE grade 8 / metric 10.9, compatible high strength (preferably hardened) nuts, hard washers and a good spreader plate behind. The crossmember etc. obviously need to be in good condition - or is that the problem?

It's more accessible than the Jate ring points - less likely to require digging for access. Just think what will be accessible when the back end is stuck in a bog. It's central, too. It then leaves the Jate ring points free for attaching a bridle if that's your inclination.

(... and Bowyer seems to have got his pictures and captions all mixed up!)

Dougal

That's the kind of input I need. I am just going over the top (probably) or...

Yes, and this is not that obvious as the tube should really be welded, otherwise it's not very useful.

Agreed. but not that much (an inch or two, and given the curve in the chassis at these points, not a big problem).

No it's fine (although I just discovered yesterday that it starts rusting (just bought the car) and the missing rear step has probably been removed not very nicely as the holes are funnel shaped and rusty).

I already have one on the tow kit, which I want to remove because so far I only used it as a plow thing rather than a tow bar ;-). Maybe I can reuse parts of it to kip the tow ball and nato hook. I'll have a look.

Quite right indeed... This is something I always wondered about JATE rings.

Yes.

Thanks for all that.

Fred