Blooming Series half-shafts.

Thank goodness for that
> little yellow knob.
yes indeed got me home on 2 occasions that i can think of !!

In message <[email protected]>
Alex <[email protected]> wrote:

> On Wed, 09 Aug 2006 06:48:01 +1000, JD <[email protected]>
> wrote:
>
> >Alex wrote:
> >
> >> Bust another half-shaft today, nothing strenuous, just a quick
> >> move-off and it snapped when i lifted off to change into 2nd. Why do
> >> Series half-shafts snap so often, and how the hell am I going to stop
> >> them when i fit the bigger engine?
> >>
> >> Alex
> >
> >It is rare to snap half axles on SWBs with the original engines but common
> >on lwbs. As others have suggested the answer is to fit a Salisbury rear
> >axle - these are virtually indestructible. The impression I have is that
> >axle quality suffered from the late sixties to the end of the seventies,
> >but I have no hard evidence of this. One contributing factor apart from
> >driving style is excessive free play in the drive train, and another is the
> >fitting of larger than standard tyres (maybe this is why lwbs break axles
> >more often).
>
> Interesting, the two 88's I've had that have snapped halfshafts are
> both late 60's, and both were fitted with 7.50x16 tyres. But i've
> never snapped a LWB one. As for free play in the drive train, I did
> have the propshaft come loose on this vehicle a couple of weeks ago,
> which necessitated crawling underneath and removing it entirely in
> order to continue my journey.
>
> Alex

I have to say that in many years of trialling I never broke a
half-shaft on an 88" - though I did do a front diff once playing
silly buggers (twice actually, I did the Stage I's as well).
109's with a Rover rear axle will snap as easily as a very easy
thing, but a Sailsbury is almost indestructable - hence why
Sailsbury's were fitted I presume. I've always had 7.50's on
my 88's - so I don't think that is a problem as such. I have
a Sailsbury on my 88" currently (because I happened to have a 109
rolling chassis sitting around), and would heartily not recommend
it for laning or trialling - the bottom of the Sailsbury makes a
very effective ground anchor!

If you want to break an 88" rear shaft then driving off a kerb
(or rock, or mound etc) such that one wheel is free to spin,
however breifly, is a good way of doing it.

As said above, I'm firmly of the opinion that driving style, on
or off-road, is the key. I can well remember going to my first
inter-club trial (at Trentham) and whatching bog standard Series
motors thrashing toyed-up 90's. After a while I twigged why -
a careful right foot is far more effective than a V8 or agressive
tyres.

Just my 2p.

Richard

--
www.beamends-lrspares.co.uk [email protected]
RISC-OS - Where have all the good guys gone?
Lib Dems - Townies keeping comedy alive

On or around Thu, 10 Aug 2006 09:03:29 +0100, beamendsltd
<[email protected]> enlightened us thusly:

>As said above, I'm firmly of the opinion that driving style, on
>or off-road, is the key. I can well remember going to my first
>inter-club trial (at Trentham) and whatching bog standard Series
>motors thrashing toyed-up 90's. After a while I twigged why -
>a careful right foot is far more effective than a V8 or agressive
>tyres.
>
>Just my 2p.

There's a good deal of truth in that. also fat tyres only make sense in
very soft conditions, when they might make the diffence between sinking and
not-sinking. all the rest of the time, normal-width tyres work better.
--
Austin Shackles. www.ddol-las.net my opinions are just that
"For millions of years, mankind lived just like the animals. Then
something happened which unleashed the power of our imagination -
we learned to talk." Pink Floyd (1994)

Alex wrote:
> Bust another half-shaft today, nothing strenuous, just a quick
> move-off and it snapped when i lifted off to change into 2nd. Why do
> Series half-shafts snap so often, and how the hell am I going to stop
> them when i fit the bigger engine?
>
> Alex

There used to be available, as I remember, a replacement hub which
absorbed shock (a bit like the springs in the driven plate of a clutch,
I guess) in the transmission. If they're still around and not too
expensive, it could be a quick and easy way to prevent weakening or
fracture of half shafts. Never heard of a freewheeing version for the
front, though

While on the subject, btw, can anyone tell me the reason for the dire
warnings about damage to transmission if using 4wd with the hubs set to
freewheel? I can't see why when in freewheel the hubs should lock the
front half shafts whether driving or driven in either direction. If
this is the problem, however, is it the case with all makes? - I use
superwinch.

Arthur
(and "Mikey", my '67 SIIa SWB)

In message <[email protected]>
"ArthurC" <[email protected]> wrote:

> Alex wrote:
> > Bust another half-shaft today, nothing strenuous, just a quick
> > move-off and it snapped when i lifted off to change into 2nd. Why do
> > Series half-shafts snap so often, and how the hell am I going to stop
> > them when i fit the bigger engine?
> >
> > Alex
>
> There used to be available, as I remember, a replacement hub which
> absorbed shock (a bit like the springs in the driven plate of a clutch,
> I guess) in the transmission. If they're still around and not too
> expensive, it could be a quick and easy way to prevent weakening or
> fracture of half shafts. Never heard of a freewheeing version for the
> front, though

Free-wheeling hubs for the front of Series vehicles are two-a-penny,
there were some automatic ones, as per the Series I, but they didn't
work in reverse. All the rest are just variations on a theme.
There is/was a kit available for Defenders that involved a mod
to the transfer box. In fact, the very, very early 110's had selectable
4wd as per Series motors and freewheeling hubs are in the parts book.

>
> While on the subject, btw, can anyone tell me the reason for the dire
> warnings about damage to transmission if using 4wd with the hubs set to
> freewheel? I can't see why when in freewheel the hubs should lock the
> front half shafts whether driving or driven in either direction. If
> this is the problem, however, is it the case with all makes? - I use
> superwinch.

Because there would be some very interesting loads in the transfer
box, which it was not designed for, plus I *think* the front diff
would very confused with no load at all on the half-shafts with the
prop being driven, but then that might just be me!

>
> Arthur
> (and "Mikey", my '67 SIIa SWB)
>

Richard

--
www.beamends-lrspares.co.uk [email protected]
RISC-OS - Where have all the good guys gone?
Lib Dems - Townies keeping comedy alive

On 11 Aug 2006 08:57:56 -0700, "ArthurC" <[email protected]> wrote:

>While on the subject, btw, can anyone tell me the reason for the dire
>warnings about damage to transmission if using 4wd with the hubs set to
>freewheel?

IIRC the warning was only about using low ratio if the front wheels
weren't driven. Because the rear half shafts were a known failure
point having the greater torque delivered to them rather than shared
between front and back was too much. This is why the Range Rover moved
to permanent 4wd.

The other issue was the yellow knob. This is essentially a sprung
loaded release mechanism to engage a dog clutch and was designed for
use on the move. If free wheeling front hubs are in use then the front
transmission drive train is stationary. Engage the clutch via the
yellow knob, on the move, and all this has to be accelerated to road
speed instantaneously.


AJH

> IIRC the warning was only about using low ratio if the front wheels
> weren't driven. Because the rear half shafts were a known failure
> point having the greater torque delivered to them rather than shared
> between front and back was too much. This is why the Range Rover moved
> to permanent 4wd.
>
> The other issue was the yellow knob. This is essentially a sprung
> loaded release mechanism to engage a dog clutch and was designed for
> use on the move. If free wheeling front hubs are in use then the front
> transmission drive train is stationary. Engage the clutch via the
> yellow knob, on the move, and all this has to be accelerated to road
> speed instantaneously.
>
>
I'd wondered if the rear half shaft loading was the issue, but in this
case, the rear half shaft loading would also be too high if in low
transfer one of the front wheels lost traction and all torque was
delivered to the back. This is practically what 4wd is for and will
occur frequently off road, so it would seem strange if it was
guaranteed to cause damage. If, on the other hand, all wheels retain
full traction, then the front/rear windup would surely put even more
stress on the transmission.

As an aside, I've often thought that the torque due to windup must be
quite large. I wonder if this is what sometimes causes the initial
damage in some cases of half shaft failure and it's only a shock (such
as a careless left foot or spinning wheel) that finishes it off. I'd
always assumed that eliminating windup was the main reason for moving
to using a centre diff, and if you've got a centre diff you might as
well have permanent 4wd as well.

I agree that the dog clutch will have a nasty shock if engaged with the
vehicle in motion but the front transmission stationary, so I can
understand the yellow knob warning. However, the shock would be even
worse if the yellow knob were to be pressed down when the vehicle is
stuck with the rear wheels spinning, which must be a likely reaction
for anyone, who, for example, loses traction on a snowy road.

Maybe, as another contributor has suggested, there's a potential
problem with the axle. Although the pinion and crown wheel are
designed to drive in either direction, maybe there's a problem if the
pinion is driven, but the crown wheel is unloaded and rattles back and
forward between driving and driven tooth engagement. Can any diff
experts comment?

> > There used to be available, as I remember, a replacement hub which
> > absorbed shock (a bit like the springs in the driven plate of a clutch,
> > I guess) in the transmission. If they're still around and not too
> > expensive, it could be a quick and easy way to prevent weakening or
> > fracture of half shafts. Never heard of a freewheeing version for the
> > front, though
>
> Free-wheeling hubs for the front of Series vehicles are two-a-penny,
> there were some automatic ones, as per the Series I, but they didn't
> work in reverse. All the rest are just variations on a theme.
> There is/was a kit available for Defenders that involved a mod
> to the transfer box. In fact, the very, very early 110's had selectable
> 4wd as per Series motors and freewheeling hubs are in the parts book.
>

Sorry, the last sentence was meant to be a joke - although you could in
principle have a freewheeling hub which shock absorbed when locked, it
seemed a bit unlikely.

> >
> > While on the subject, btw, can anyone tell me the reason for the dire
> > warnings about damage to transmission if using 4wd with the hubs set to
> > freewheel? I can't see why when in freewheel the hubs should lock the
> > front half shafts whether driving or driven in either direction. If
> > this is the problem, however, is it the case with all makes? - I use
> > superwinch.
>
> Because there would be some very interesting loads in the transfer
> box, which it was not designed for, plus I *think* the front diff
> would very confused with no load at all on the half-shafts with the
> prop being driven, but then that might just be me!
>

I can't see the problem with transfer box loading. The transfer box
gears are ahead of the dog clutch, so the transfer gears only see the
combined load and don't know anything about whether the load is from
the front or back or both. The dog clutch looks too simple to worry
about whether the front output is loaded or not. I've never heard of
any problems with running with the front prop disconnected, which would
look the same to the box as the front axle freewheeling.

Seems you're more likely to be on the right track in suspecting the
pinion and crown wheel driving the front diff (see my other reply).

Back on the history track, the old Rover 75s and 90s (closely related
to 4 cyl and 6 cyl Land Rovers) had a freewheel which disengaged the
transmission on overrun, thus saving fuel and engine/transmission wear
when going downhill or stopping. The lack of any engine braking,
combined with single circuit brakes must have been a bit lethal, and
Rover dropped it in favour of an overdrive. I think, but am not sure,
that this change coincided with the 75 becoming the 80 and the 90
becoming the 100 and 110 (twin carb).

"ArthurC" >>
>>
> I'd wondered if the rear half shaft loading was the issue, but in this
> case, the rear half shaft loading would also be too high if in low
> transfer one of the front wheels lost traction and all torque was
> delivered to the back. This is practically what 4wd is for and will
> occur frequently off road, so it would seem strange if it was
> guaranteed to cause damage. If, on the other hand, all wheels retain
> full traction, then the front/rear windup would surely put even more
> stress on the transmission.
>
> As an aside, I've often thought that the torque due to windup must be
> quite large. I wonder if this is what sometimes causes the initial
> damage in some cases of half shaft failure and it's only a shock (such
> as a careless left foot or spinning wheel) that finishes it off.

You've got it spot on there. Many farmers would tow large loads with series
vehicles which needed low ratio to manouvre and also to start off from
junctions and to climb roads. They were just so underpowered at that time.
The torque loading from all this was massive, especially when turning with a
heavy load where the wheels could not slip. The half shafts just couldn't
take this for very long and were/are a regular failure item.
Sometimes they ultimately failed when driven quite gently up a slight grade
in 2wd.


I'd
> always assumed that eliminating windup was the main reason for moving
> to using a centre diff, and if you've got a centre diff you might as
> well have permanent 4wd as well.

Yes, the Defender was a major step forward and is still ahead of the game in
this respect when compared with all other comparable vehicles. Same goes for
the Discovery and Range Rover in all models although others have caught up
in drive train design in this class, such as Toyota and Mercedes but the
Toyota does lock the centre diff by default in low range for some reason.


Huw

On 11 Aug 2006 12:06:23 -0700, "ArthurC" <[email protected]> wrote:

>I'd wondered if the rear half shaft loading was the issue, but in this
>case, the rear half shaft loading would also be too high if in low
>transfer one of the front wheels lost traction and all torque was
>delivered to the back.

I think the issue was more to do with using low ratio on a firm
surface with a heavy load or trailer, it was to share the load between
all halfshafts. On soft going traction is the limit on firm surface
it's engine torque, clutch slipping or driveline failure. The half
shafts were the known weak point and IIRC the manual stressed that low
ration 4wd was only for off road use but we all used it when towing
heavy loads.

> This is practically what 4wd is for and will
>occur frequently off road, so it would seem strange if it was
>guaranteed to cause damage. If, on the other hand, all wheels retain
>full traction, then the front/rear windup would surely put even more
>stress on the transmission.

Yes I am sure wind up does cause high stress on the half shafts but it
was always the long one on the rear that broke and always with
characteristic fatigue lines (and it leaves a sort of cone at the
break). As I said spinning the rear wheel in mud and then suddenly
lifting off to brake it on engine overrun and pulling the vehicle to a
halt with the handbrake was the counter point to stressing it whilst
under load. These combined to fatigue the halfshaft.
>
>As an aside, I've often thought that the torque due to windup must be
>quite large. I wonder if this is what sometimes causes the initial
>damage in some cases of half shaft failure and it's only a shock (such
>as a careless left foot or spinning wheel) that finishes it off. I'd
>always assumed that eliminating windup was the main reason for moving
>to using a centre diff, and if you've got a centre diff you might as
>well have permanent 4wd as well.

All sounds reasonable but off course you still get wind up when the
diff lock is used.
>
>I agree that the dog clutch will have a nasty shock if engaged with the
>vehicle in motion but the front transmission stationary, so I can
>understand the yellow knob warning. However, the shock would be even
>worse if the yellow knob were to be pressed down when the vehicle is
>stuck with the rear wheels spinning, which must be a likely reaction
>for anyone, who, for example, loses traction on a snowy road.

Or in the mud. The thing is releasing the throttle when things start
to grate with a stuck vehicle is a lot faster than bringing the
vehicle to a stop when the yellow button has been pressed in
anticipation of a muddy bit.
>
>Maybe, as another contributor has suggested, there's a potential
>problem with the axle. Although the pinion and crown wheel are
>designed to drive in either direction, maybe there's a problem if the
>pinion is driven, but the crown wheel is unloaded and rattles back and
>forward between driving and driven tooth engagement. Can any diff
>experts comment?

I don't know but I do have experience of another 4wd tractor where the
lower 3 gears were for crawling and not full power use. The manual
plainly states that the diff will not take full engine torque in these
low gears. The manufacturer safeguarded the diff, half shafts and
housings by using shear rivets from crown wheel to carrier.

AJH

ArthurC wrote:
> Alex wrote:
>> Bust another half-shaft today, nothing strenuous, just a quick
>> move-off and it snapped when i lifted off to change into 2nd. Why do
>> Series half-shafts snap so often, and how the hell am I going to stop
>> them when i fit the bigger engine?
>>
>> Alex
>
>
> While on the subject, btw, can anyone tell me the reason for the dire
> warnings about damage to transmission if using 4wd with the hubs set to
> freewheel? I can't see why when in freewheel the hubs should lock the
> front half shafts whether driving or driven in either direction. If
> this is the problem, however, is it the case with all makes? - I use
> superwinch.
>
> Arthur
> (and "Mikey", my '67 SIIa SWB)
>
Think of the kinetic energies involved with a free but stationary shaft being
instantly brought up to speed - something would give, somewhere. Probably the
dog clutch.

Karen

--
"Sometimes I think I have a Guardian Idiot - a little invisible spirit just
behind my shoulder, looking out for me ... only he's an imbecile" - Jake Stonebender

beamendsltd wrote:
> In message <[email protected]>
> "ArthurC" <[email protected]> wrote:
>
>> Alex wrote:
>>> Bust another half-shaft today, nothing strenuous, just a quick
>>> move-off and it snapped when i lifted off to change into 2nd. Why do
>>> Series half-shafts snap so often, and how the hell am I going to stop
>>> them when i fit the bigger engine?
>>>
>>> Alex
>> There used to be available, as I remember, a replacement hub which
>> absorbed shock (a bit like the springs in the driven plate of a clutch,
>> I guess) in the transmission. If they're still around and not too
>> expensive, it could be a quick and easy way to prevent weakening or
>> fracture of half shafts. Never heard of a freewheeing version for the
>> front, though
>
> Free-wheeling hubs for the front of Series vehicles are two-a-penny,
> there were some automatic ones, as per the Series I, but they didn't
> work in reverse. All the rest are just variations on a theme.
> There is/was a kit available for Defenders that involved a mod
> to the transfer box. In fact, the very, very early 110's had selectable
> 4wd as per Series motors and freewheeling hubs are in the parts book.
>
>> While on the subject, btw, can anyone tell me the reason for the dire
>> warnings about damage to transmission if using 4wd with the hubs set to
>> freewheel? I can't see why when in freewheel the hubs should lock the
>> front half shafts whether driving or driven in either direction. If
>> this is the problem, however, is it the case with all makes? - I use
>> superwinch.
>
> Because there would be some very interesting loads in the transfer
> box, which it was not designed for, plus I *think* the front diff
> would very confused with no load at all on the half-shafts with the
> prop being driven, but then that might just be me!
>
>> Arthur
>> (and "Mikey", my '67 SIIa SWB)
>>
>
> Richard
>
Not two a penny in Australia - they are really expensive for what they are. Last
time I purchased some in the UK I bought direct from Mayflower in Tavistock for
some £12 or so, in around 1970.

Karen

Karen

--
"Sometimes I think I have a Guardian Idiot - a little invisible spirit just
behind my shoulder, looking out for me ... only he's an imbecile" - Jake Stonebender

"ArthurC" <[email protected]> wrote in message
news:[email protected]...
>
> > IIRC the warning was only about using low ratio if the front wheels
> > weren't driven. Because the rear half shafts were a known failure
> > point having the greater torque delivered to them rather than shared
> > between front and back was too much. This is why the Range Rover moved
> > to permanent 4wd.
> >
> > The other issue was the yellow knob. This is essentially a sprung
> > loaded release mechanism to engage a dog clutch and was designed for
> > use on the move. If free wheeling front hubs are in use then the front
> > transmission drive train is stationary. Engage the clutch via the
> > yellow knob, on the move, and all this has to be accelerated to road
> > speed instantaneously.
> >
> >
> I'd wondered if the rear half shaft loading was the issue, but in this
> case, the rear half shaft loading would also be too high if in low
> transfer one of the front wheels lost traction and all torque was
> delivered to the back. This is practically what 4wd is for and will
> occur frequently off road, so it would seem strange if it was
> guaranteed to cause damage. If, on the other hand, all wheels retain
> full traction, then the front/rear windup would surely put even more
> stress on the transmission.
>
> As an aside, I've often thought that the torque due to windup must be
> quite large. I wonder if this is what sometimes causes the initial
> damage in some cases of half shaft failure and it's only a shock (such
> as a careless left foot or spinning wheel) that finishes it off. I'd
> always assumed that eliminating windup was the main reason for moving
> to using a centre diff, and if you've got a centre diff you might as
> well have permanent 4wd as well.
>
> I agree that the dog clutch will have a nasty shock if engaged with the
> vehicle in motion but the front transmission stationary, so I can
> understand the yellow knob warning. However, the shock would be even
> worse if the yellow knob were to be pressed down when the vehicle is
> stuck with the rear wheels spinning,

It would only be worse if the freewheeling hubs had been put back in fixed,
otherwise it would be the same as the first case scenario, i.e. no load but
stationary front drive train.

which must be a likely reaction
> for anyone, who, for example, loses traction on a snowy road.
>
> Maybe, as another contributor has suggested, there's a potential
> problem with the axle. Although the pinion and crown wheel are
> designed to drive in either direction, maybe there's a problem if the
> pinion is driven, but the crown wheel is unloaded and rattles back and
> forward between driving and driven tooth engagement. Can any diff
> experts comment?
>
If there is so much play in the meshing of the crown wheel and pinion that
they rattle with no load, then the diff would be knackered anyway.

Martin.

On or around 11 Aug 2006 12:06:23 -0700, "ArthurC" <[email protected]>
enlightened us thusly:

>I agree that the dog clutch will have a nasty shock if engaged with the
>vehicle in motion but the front transmission stationary, so I can
>understand the yellow knob warning. However, the shock would be even
>worse if the yellow knob were to be pressed down when the vehicle is
>stuck with the rear wheels spinning, which must be a likely reaction
>for anyone, who, for example, loses traction on a snowy road.

but only people who don't bother to read the instructions...
--
Austin Shackles. www.ddol-las.net my opinions are just that
"Nessun maggior dolore che ricordarsi del tempo felice nella miseria"
- Dante Alighieri (1265 - 1321) from Divina Commedia 'Inferno'

> >
> >I agree that the dog clutch will have a nasty shock if engaged with the
> >vehicle in motion but the front transmission stationary, so I can
> >understand the yellow knob warning. However, the shock would be even
> >worse if the yellow knob were to be pressed down when the vehicle is
> >stuck with the rear wheels spinning, which must be a likely reaction
> >for anyone, who, for example, loses traction on a snowy road.
>
> Or in the mud. The thing is releasing the throttle when things start
> to grate with a stuck vehicle is a lot faster than bringing the
> vehicle to a stop when the yellow button has been pressed in
> anticipation of a muddy bit.
>
Best thing is to depress the clutch momentarily whilst pressing yellow knob
if driving off road with rear wheels spinning but I would think most if not
all would judge the conditions and already be in 4 wheel drive with the
front hubs in fixed before getting into such a position.

Martin

Oily wrote:

> Best thing is to depress the clutch momentarily whilst pressing yellow knob
> if driving off road with rear wheels spinning but I would think most if not
> all would judge the conditions and already be in 4 wheel drive with the
> front hubs in fixed before getting into such a position.

It's a simple rule really - if you're going off road the hubs go in
regardless of whether you think 4WD is going to be needed.


--
EMB