Drilling the chassis

All,

I'm planning on fitting decent anchor points. JATE rings seem fine, but I
was thinking of something similar but over engineered ;-), something like a
JATE with two bolts (and bigger bolts than the M8 (?) currently used for
the towing eyes and usually sold with "traditional" JATE rings).

Anybody has anyting to say about drilling additional holes and enlarging
existing ones in the chassis of a defender?

TIA,

Fred

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


"MVP" <mr.nice@*nospam*softhome.net> wrote in message
news:[email protected]...
> On Thu, 05 May 2005 11:36:27 +0100, Fred Labrosse <[email protected]>
> wrote:
>
>>All,
>>
>>I'm planning on fitting decent anchor points. JATE rings seem fine, but I
>>was thinking of something similar but over engineered ;-), something like
>>a
>>JATE with two bolts (and bigger bolts than the M8 (?) currently used for
>>the towing eyes and usually sold with "traditional" JATE rings).
>>
>>Anybody has anyting to say about drilling additional holes and enlarging
>>existing ones in the chassis of a defender?
>>
>>TIA,
>>
>>Fred
>
> 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.
> --
> _________________________________________
> 1984 110 CSW 2.5(na)D - leaving soon
> 3.9 V8i LPG auto Disco - coming soon
> www.4x4info.info
> www.mvp-fine-art.co.uk
> www.markvarleyphoto.co.uk
> charity calendar project -
> http://www.4x4info.info/calendar/
> _________________________________________
>
>
>
> ................................................................
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>

Richard wrote:

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

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

Fred

In message <[email protected]>, Fred Labrosse
<[email protected]> writes
>All,
>
>I'm planning on fitting decent anchor points. JATE rings seem fine, but I
>was thinking of something similar but over engineered ;-), something like a
>JATE with two bolts (and bigger bolts than the M8 (?) currently used for
>the towing eyes and usually sold with "traditional" JATE rings).
>
>Anybody has anyting to say about drilling additional holes and enlarging
>existing ones in the chassis of a defender?


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 !
--
Marc Draper

Fred Labrosse wrote:
> All,
>
> I'm planning on fitting decent anchor points. JATE rings seem fine, but I
> was thinking of something similar but over engineered ;-), something like a
> JATE with two bolts (and bigger bolts than the M8 (?) currently used for
> the towing eyes and usually sold with "traditional" JATE rings).
>
> Anybody has anyting to say about drilling additional holes and enlarging
> existing ones in the chassis of a defender?
>
> TIA,
>
> Fred

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.

Marc Draper wrote:

> In message <[email protected]>, Fred Labrosse
> <[email protected]> writes
>>All,
>>
>>I'm planning on fitting decent anchor points. JATE rings seem fine, but I
>>was thinking of something similar but over engineered ;-), something like
>>a JATE with two bolts (and bigger bolts than the M8 (?) currently used for
>>the towing eyes and usually sold with "traditional" JATE rings).
>>
>>Anybody has anyting to say about drilling additional holes and enlarging
>>existing ones in the chassis of a defender?
>
>
> As JATE rings are strong enough why bother?

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

>
> A JATE ring can pivot on its single bolt,

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).

> if you make it a two bolt
> fixing it can no longer pivot,

Which solves the problems above.

> and the force associated will be
> transferred into the mounting bolts and then to the chassis. The weakest
> link being the chassis !

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

Dougal <DougalAThiskennel.free-online.co.uk> wrote:

> Fred Labrosse wrote:
>> All,
>>
>> I'm planning on fitting decent anchor points. JATE rings seem fine, but
>> I was thinking of something similar but over engineered ;-), something
>> like a JATE with two bolts (and bigger bolts than the M8 (?) currently
>> used for the towing eyes and usually sold with "traditional" JATE rings).
>>
>> Anybody has anyting to say about drilling additional holes and enlarging
>> existing ones in the chassis of a defender?
>>
>> TIA,
>>
>> Fred
>
> 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.

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

>
> 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.

Good point.

Fred

Fred Labrosse wrote:

> Marc Draper wrote:
>
>> In message <[email protected]>, Fred Labrosse
>> <[email protected]> writes
>>>All,
>>>
>>>I'm planning on fitting decent anchor points. JATE rings seem fine, but
>>>I was thinking of something similar but over engineered ;-), something
>>>like a JATE with two bolts (and bigger bolts than the M8 (?) currently
>>>used for the towing eyes and usually sold with "traditional" JATE rings).
>>>
>>>Anybody has anyting to say about drilling additional holes and enlarging
>>>existing ones in the chassis of a defender?
>>
>>
>> As JATE rings are strong enough why bother?
>
> Are they indeed? Somebody not long ago commented on the fact that you
> should always use two of these for serious recovery.
>

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.

>>
>> A JATE ring can pivot on its single bolt,
>
> 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).
>

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.

--
1992 200 TDI Disco - heavily modified
1982 V8 Range Rover - heavily corroded
2000 Rover 75 - heavily driven
1993 Lexus LS400 - just plain heavy on fuel

Paul S. Brown wrote:

> Fred Labrosse wrote:
>
>> Marc Draper wrote:
>>
>>> In message <[email protected]>, Fred Labrosse
>>> <[email protected]> writes
>>>>All,
>>>>
>>>>I'm planning on fitting decent anchor points. JATE rings seem fine, but
>>>>I was thinking of something similar but over engineered ;-), something
>>>>like a JATE with two bolts (and bigger bolts than the M8 (?) currently
>>>>used for the towing eyes and usually sold with "traditional" JATE
>>>>rings).
>>>>
>>>>Anybody has anyting to say about drilling additional holes and enlarging
>>>>existing ones in the chassis of a defender?
>>>
>>>
>>> As JATE rings are strong enough why bother?
>>
>> Are they indeed? Somebody not long ago commented on the fact that you
>> should always use two of these for serious recovery.
>>
>
> 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.

Point taken.

>
>>>
>>> A JATE ring can pivot on its single bolt,
>>
>> 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).
>>
>
> 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.

They would if mounted on my 110 as suggested at
<http://www.difflock.com/offroad/bowyer/attached.shtml>.


>
> 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.

Ok.

Fred

Fred Labrosse wrote:

> Dougal <DougalAThiskennel.free-online.co.uk> wrote:
>
>>Fred Labrosse wrote:
>>
>>>All,
>>>
>>>I'm planning on fitting decent anchor points. JATE rings seem fine, but
>>>I was thinking of something similar but over engineered ;-), something
>>>like a JATE with two bolts (and bigger bolts than the M8 (?) currently
>>>used for the towing eyes and usually sold with "traditional" JATE rings).
>>>
>>>Anybody has anyting to say about drilling additional holes and enlarging
>>>existing ones in the chassis of a defender?
>>>
>>>Fred
>>
>>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.
>
> I'm not sure this is an advantage (see my other post). Can you explain?

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
<----- 5/2 T ------ x B x
Bolt B x x
x x
x x
x x
x x
x x
x x
x x
x x
x x
x C x ------ Load T ------>

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.

>>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.
>
>
> Good point.
>
> Fred

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

Dougal <DougalAThiskennel.free-online.co.uk> wrote:

> Fred Labrosse wrote:
>
>> Dougal <DougalAThiskennel.free-online.co.uk> wrote:
>>
>>>Fred Labrosse wrote:
>>>
>>>>All,
>>>>
>>>>I'm planning on fitting decent anchor points. JATE rings seem fine, but
>>>>I was thinking of something similar but over engineered ;-), something
>>>>like a JATE with two bolts (and bigger bolts than the M8 (?) currently
>>>>used for the towing eyes and usually sold with "traditional" JATE
>>>>rings).
>>>>
>>>>Anybody has anyting to say about drilling additional holes and enlarging
>>>>existing ones in the chassis of a defender?
>>>>
>>>>Fred
>>>
>>>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.
>>
>> I'm not sure this is an advantage (see my other post). Can you explain?
>
> 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
> <----- 5/2 T ------ x B x
> Bolt B x x
> x x
> x x
> x x
> x x
> x x
> x x
> x x
> x x
> x x
> x C x ------ Load T ------>
>
> 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.

Yes, I see your point, but this is not quite what I had in mind but more
something like: http://users.aber.ac.uk/ffl/anchorPoint.png (keeping the
same letters as yours. This is almost like a JATE in the sens that the
effort will be more or less in line with it, but would spread it across
more bolts.

>
> 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.

Yes, indeed.

>
> 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!

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

Fred

Fred Labrosse wrote:

> Yes, I see your point, but this is not quite what I had in mind but more
> something like: http://users.aber.ac.uk/ffl/anchorPoint.png (keeping the
> same letters as yours. This is almost like a JATE in the sense that the
> effort will be more or less in line with it, but would spread it across
> more bolts.
>
> 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

Dougal <DougalAThiskennel.free-online.co.uk> wrote:

> Fred Labrosse wrote:
>
>> Yes, I see your point, but this is not quite what I had in mind but more
>> something like: http://users.aber.ac.uk/ffl/anchorPoint.png (keeping the
>> same letters as yours. This is almost like a JATE in the sense that the
>> effort will be more or less in line with it, but would spread it across
>> more bolts.
>>
>> Fred
>
> OK. A lot of effort for little gain in my view.

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

>
> You ought to tube the chassis at whichever A or B is not the existing
> tubed point.

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

> 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.

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

>
> 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?

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.

>
> 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.

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

> 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!)

Yes.

Thanks for all that.

Fred