wheel side

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Hi Guys
Just wondering if anyone knows if there is a guide or a chart that lays out
the relationship between large tyres and the stress on the CV joints.
Is there a formula to determine what ratio size V cv joint strain.
I know the bigger the tyres the more strain is placed on the CVs but how
much.
cheers
john 92HDJ80 1HDT
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John
| Just wondering if anyone knows if there is a guide or a chart that
lays
| out
| the relationship between large tyres and the stress on the CV joints.
| Is there a formula to determine what ratio size V cv joint strain.
| I know the bigger the tyres the more strain is placed on the CVs but
how
| much.
I doubt there is such a chart. However how about this for an idea:
The torque that the wheel can transmit is a function of its radius, the
area on the ground and the friction of tread with ground. (Assuming a
constant loading weight.)
Given that taller tyres are aimed at off-road use, tend to have chunkier
treads and are - at the extreme - run at lower pressures, I'd say that
contact area and effective friction also increase more or less with
height.
So I think you wouldn't go far wrong if you used:
S =3D standard tyre radius (measure from hub centre to ground)
T =3D taller tyre radius (ditto)
Peak torque rises as the square of (T / S)
So if your standard tyre measured 400mm from centre to road, and your
taller 450mm, then the ratio would be square of (450 / 400) =3D 1.26
Just a guess, but it seems sensible to me. Any dissenters?
Christopher Bell
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Hi Christopher
Thanks for that,geese you are one for the math.
I am trying to see what extra strain is put on the Cv when using the bigger
tyres like for off roading and is there a point at which the bigger is not
the best but a compromise is better.
I know that anything bigger than 39inch with the Longfield is not
recommended.
I know ill ask them after all they should know.
cheers
john
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Hi John,
I think Christopher's formula sounds about right. I imagine maximum torque
through the cv will probably occur with a combination of turning with the
front diff locked with good traction on both front wheels and shock loading.
Ian and I are both running Longfields with 36.5" tyres and haven't had a
breakage so far. Did break some Milner's cvs before the Longfields went in.
If you go ahead and fit Longfields, bear a couple of things in mind;
First, once you've fitted them it probably won't be the cv joints that fail
- you witnessed the demise of Ian's front crownwheel at Lincomb - the point
of failure moved to the next weakest link in the chain. Though it is
possible to break a front diff with ordinary cvs too - especially in
reverse.
Second, the chrome-molybdenum steel used in the Longfields is specced for
strength not longevity (it is softer and more resilient) so they won't last
as long as OEM cv joints. If you're doing more than a few thousand miles per
year in the 80 they may work out very expensive.
It was a pleasure to meet you at Lincomb, see you next time?
Thanks to Tony and Julian for another excellent weekend.
All the best,
Toby
1990 HDJ80 UK
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Agree with Toby entirely- particularly on longevity- i had a pair of failing Toy CVs and replaced them with Longfield CVs=2C only to take them out a few thousand miles later when i realised i was doing too many road miles. After about 12=2C000 miles they already needed de-burring as they wre going stiff (not a sign of failure=2C but a sypmton of wear). Lonfield do gaurantee against failure due to breakage=2C but DON'T guarantee failure due to wear!

I have broken 2 front crown wheels now though- once with the longfields in and once without- the front diff does seem significantly weaker than the rear- and comparing sizes you can see why.

Whilt's Chris' formula may be correct in the broadest terms=2C in reality 98% of CV breakages occur under shock loading=2C not under constant pressure (unless you get silly- ie nose down=2C full lock=2C front locker and boot it in reverse- and even then Toy CVs will survive- not even Rove AEU252s will survive that!). This is worse when you are lift a wheel (particularly under power)=2C and then the wheel crashes down with the weight of the truck- the shock loading is significant and can break just about any part of the driveline.

I would be happy running Toy CVs up to 36" simex with a fully size truck and up to 38" (extreme tyre- ie bogger) on a lightened challenge truck. Longfields will warrantee any size AFAIK- although they don't recomend over 40"!

I know of one longfield breakage in the field- running 38" boggers and an LS1- am sure ther've been more but don't know of them.
FWIW longfields are made to the same spec by the same factors as Ashcrofts are- but the rover items are bigger!

> From: [Email address removed]
> To: [Email address removed]
> Subject: RE: [ELCO] wheel side
> Date: Thu=2C 8 Oct 2009 14:59:31 +0100
>
> Hi John=2C
>
> I think Christopher's formula sounds about right. I imagine maximum torque
> through the cv will probably occur with a combination of turning with the
> front diff locked with good traction on both front wheels and shock loading.
>
> Ian and I are both running Longfields with 36.5" tyres and haven't had a
> breakage so far. Did break some Milner's cvs before the Longfields went in.
>
> If you go ahead and fit Longfields=2C bear a couple of things in mind=3B
>
> First=2C once you've fitted them it probably won't be the cv joints that fail
> - you witnessed the demise of Ian's front crownwheel at Lincomb - the point
> of failure moved to the next weakest link in the chain. Though it is
> possible to break a front diff with ordinary cvs too - especially in
> reverse.
>
> Second=2C the chrome-molybdenum steel used in the Longfields is specced for
> strength not longevity (it is softer and more resilient) so they won't last
> as long as OEM cv joints. If you're doing more than a few thousand miles per
> year in the 80 they may work out very expensive.
>
> It was a pleasure to meet you at Lincomb=2C see you next time?
>
> Thanks to Tony and Julian for another excellent weekend.
>
> All the best=2C
> Toby
> 1990 HDJ80 UK
>
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Toby
| Second, the chrome-molybdenum steel used in the Longfields is specced
for
| strength not longevity (it is softer and more resilient) so they won't
| last
| as long as OEM cv joints. If you're doing more than a few thousand
miles
| per
| year in the 80 they may work out very expensive.
|
I'm interested in that. My steel book suggests that CrMo steels are
stronger, as in have a higher yield stress, than "ordinary" tool steel,
but also more brittle in that they have less remaining strain to failure
(typically 10% or less).
When they fail does it look ductile (squished or torn) or brittle (well
defined crack)?
Maybe if, as James says, they need de-burring then they are more
ductile. I'd be (professionally) interested if anyone could provide
more information about the steel used.
I certainly remember the rock-crawling folk on the 80s-cool forum saying
that the standard CV joints acted as a "fuse" in the drive-train, and
failed before the more expensive bits.
Also James is right: the worst thing you could do is spin a wheel at
high speed in the air and then crash it down. I saw a Disco's centre
diff destroyed that way once: a Mummy in a hurry charged up a ramp at
speed under full throttle, the front axle got airborne at the top so
that the wheels spun up and then it crashed down. Pop!
Christopher Bell
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They are chrome Moly on the logfields but are treated differently- either they lack heat treating=2C or they HAVE been heat treated. one or the other lol!

Was chatting to bobby longfield about it when i bought a set (ui was importing 4 sets for various people)=2C and was told that they effectively softened the cage compared to standard CVs- this mean that the cage isn't as brittle=2C so dissipates torque transmission better=2C but cannot withstand long wear.


> Subject: RE: [ELCO] wheel side
> Date: Thu=2C 8 Oct 2009 15:55:20 +0100
> From: [Email address removed]
> To: [Email address removed]
>
> Toby
>
> | Second=2C the chrome-molybdenum steel used in the Longfields is specced
> for
> | strength not longevity (it is softer and more resilient) so they won't
> | last
> | as long as OEM cv joints. If you're doing more than a few thousand
> miles
> | per
> | year in the 80 they may work out very expensive.
> |
>
> I'm interested in that. My steel book suggests that CrMo steels are
> stronger=2C as in have a higher yield stress=2C than "ordinary" tool steel=2C
> but also more brittle in that they have less remaining strain to failure
> (typically 10% or less).
>
> When they fail does it look ductile (squished or torn) or brittle (well
> defined crack)?
>
> Maybe if=2C as James says=2C they need de-burring then they are more
> ductile. I'd be (professionally) interested if anyone could provide
> more information about the steel used.
>
> I certainly remember the rock-crawling folk on the 80s-cool forum saying
> that the standard CV joints acted as a "fuse" in the drive-train=2C and
> failed before the more expensive bits.
>
> Also James is right: the worst thing you could do is spin a wheel at
> high speed in the air and then crash it down. I saw a Disco's centre
> diff destroyed that way once: a Mummy in a hurry charged up a ramp at
> speed under full throttle=2C the front axle got airborne at the top so
> that the wheels spun up and then it crashed down. Pop!
>
> Christopher Bell
> ____________________________________________________________
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> systems are scanned for acceptability of content and viruses
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Probably not case-hardened then.
Thanks
CB
They are chrome Moly on the logfields but are treated differently- either they lack heat treating, or they HAVE been heat treated. one or the other lol!=A0
=A0
Was chatting to bobby longfield about it when i bought a set (ui was importing 4 sets for various people), and was told that they effectively softened the cage compared to standard CVs- this mean that=A0the cage isn't as brittle, so=A0dissipates torque transmission better, but cannot withstand long wear.
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Hi Toby
Like wise, good to meet you.
I am just trying to put together the information I saw and heard at the
weekend and from that learn something.
See, the problem is I am so far away and every bang and clang on the way
home is unsettling but yet want to have the fun as well as everyone else.
I have to be cautious but if I can do anything that may help to elevate a
possible breakdown bar of course not going I would be interested.
Is it possible to get stronger diff parts.
I think Ian explained that an older diff with say 200,000 miles on it is
weaker than a new diff so maybe rebuilding the front diff would be a good
idea.
cheers
john92HDJ801HDT
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The first question before your question can be answered is,
What do you want to use it for ?
You cant just punch some No's into an XL spreadsheet and get a straight
forward answer on this, but if your going to run big tyres and drive it
Like its stolen, then stuff is gonna break ;-)
A driver will break way more components than big tyres will.
Darren McRae
-----Original Message-----
From: [Email address removed] [mailto:[Email address removed]] On
Behalf Of john
Sent: Thursday, 8 October 2009 11:29 PM
To: [Email address removed]
Subject: Re: [ELCO] wheel side
Hi Christopher
Thanks for that,geese you are one for the math.
I am trying to see what extra strain is put on the Cv when using the bigger
tyres like for off roading and is there a point at which the bigger is not
the best but a compromise is better.
I know that anything bigger than 39inch with the Longfield is not
recommended.
I know ill ask them after all they should know.
cheers
john
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John
I'd 2nd Darren's ? on how exactly u are going 2b using them
I would say 4 Irish 4x4ing (lots of grass, bog, occasional rock) that u
r fine with the TOY version
Over here a lot of 4x4'ers I meet (running 80's) run the std TOY
birfs/cv's and do not have any issue.
Once you move to LARGE tires sizes (talking 35" ) then u're becoming
more serious. Those "hard-core" guys
I'm on 35" at the moment and don't consider myself on the edge. A lot of
it is do with driving style and not being stupid.
Where I've seen birfs snap is guys (over here) climbing rock ledges
(known as 'waterfalls') and the truck is nearly vertical trying 2 get
grip with a LOT of torque being applied 2 climbing up.
When the tires are spinning, get 'air' and then come down hard on rock -
thats where the 'snaps' occur.
I've run 32" Simex both in Scotland and here with no issues (I'd be more
concerned/careful here as more on rock surface)
As mentioned the bird/cv can act as a 'cheap(er)' fuse so they break b4
something more expensive. In that respect I'd stick to TOY unless u're
gonna get into hard-core ...
Brendan
97 FZJ-80 -220K in Colorado on 35" Toyo
Darren McRae wrote:
On
ger
t
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Could we have this in English please?
----- Original Message -----
From: "Brendan Lally via mail.com" <[Email address removed]>
To: <[Email address removed]>
Sent: Thursday, October 08, 2009 2:14 PM
Subject: Re: [ELCO] wheel side
John
I'd 2nd Darren's ? on how exactly u are going 2b using them
I would say 4 Irish 4x4ing (lots of grass, bog, occasional rock) that u
r fine with the TOY version
Over here a lot of 4x4'ers I meet (running 80's) run the std TOY
birfs/cv's and do not have any issue.
Once you move to LARGE tires sizes (talking 35" ) then u're becoming
more serious. Those "hard-core" guys
I'm on 35" at the moment and don't consider myself on the edge. A lot of
it is do with driving style and not being stupid.
Where I've seen birfs snap is guys (over here) climbing rock ledges
(known as 'waterfalls') and the truck is nearly vertical trying 2 get
grip with a LOT of torque being applied 2 climbing up.
When the tires are spinning, get 'air' and then come down hard on rock -
thats where the 'snaps' occur.
I've run 32" Simex both in Scotland and here with no issues (I'd be more
concerned/careful here as more on rock surface)
As mentioned the bird/cv can act as a 'cheap(er)' fuse so they break b4
something more expensive. In that respect I'd stick to TOY unless u're
gonna get into hard-core ...
Brendan
97 FZJ-80 -220K in Colorado on 35" Toyo
Darren McRae wrote:
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In fairness. I reckon its nearly all down to driving style. We run a
range rover v8 bobtail with 35" simex's and we are using standard
cv's. In 5 years we have only broken 1 cv. I didn't realise the
ashcroft stuff wouldn't last as long. Good thing we have bought any
yet. Brian.
On 10/9/09, Chas <[Email address removed]> wrote:
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Is your bobtail running an auto? i built a bobtail disco with a midly tweaked 300tdi and 35" Simex. It used to blow CVs for a living.
Then decided to upgrade everything (including pegging the diffs=2C hardened h/shafts=2C CVs etc etc) but started with the engine. Plonked in a 4.0 tuned V8 and a HP22 auto. Then ran out of money.
CVs stopped breaking almost completely.
Autos have an amazing ability to absorb shocks through the drivetrain=2C and cushion just about anything. The only thing i've come across that does anywhere near as good are cush drives and slip hubs.
> Date: Fri=2C 9 Oct 2009 15:46:36 +0100
> Subject: Re: [ELCO] wheel side
> From: [Email address removed]
> To: [Email address removed]
>
> In fairness. I reckon its nearly all down to driving style. We run a
> range rover v8 bobtail with 35" simex's and we are using standard
> cv's. In 5 years we have only broken 1 cv. I didn't realise the
> ashcroft stuff wouldn't last as long. Good thing we have bought any
> yet. Brian.
>
> On 10/9/09=2C Chas <[Email address removed]> wrote:
> > Could we have this in English please?
> >
> > ----- Original Message -----
> > From: "Brendan Lally via mail.com" <[Email address removed]>
> > To: <[Email address removed]>
> > Sent: Thursday=2C October 08=2C 2009 2:14 PM
> > Subject: Re: [ELCO] wheel side
> >
> >
> > John
> >
> > I'd 2nd Darren's ? on how exactly u are going 2b using them
> > I would say 4 Irish 4x4ing (lots of grass=2C bog=2C occasional rock) that u
> > r fine with the TOY version
> >
> > Over here a lot of 4x4'ers I meet (running 80's) run the std TOY
> > birfs/cv's and do not have any issue.
> > Once you move to LARGE tires sizes (talking 35" ) then u're becoming
> > more serious. Those "hard-core" guys
> >
> > I'm on 35" at the moment and don't consider myself on the edge. A lot of
> > it is do with driving style and not being stupid.
> >
> > Where I've seen birfs snap is guys (over here) climbing rock ledges
> > (known as 'waterfalls') and the truck is nearly vertical trying 2 get
> > grip with a LOT of torque being applied 2 climbing up.
> > When the tires are spinning=2C get 'air' and then come down hard on rock -
> > thats where the 'snaps' occur.
> >
> > I've run 32" Simex both in Scotland and here with no issues (I'd be more
> > concerned/careful here as more on rock surface)
> >
> > As mentioned the bird/cv can act as a 'cheap(er)' fuse so they break b4
> > something more expensive. In that respect I'd stick to TOY unless u're
> > gonna get into hard-core ...
> >
> > Brendan
> > 97 FZJ-80 -220K in Colorado on 35" Toyo
> >
> > Darren McRae wrote:
> >> The first question before your question can be answered is=2C
> >>
> >> What do you want to use it for ?
> >>
> >> You cant just punch some No's into an XL spreadsheet and get a straight
> >> forward answer on this=2C but if your going to run big tyres and drive it
> >> Like its stolen=2C then stuff is gonna break =3B-)
> >>
> >> A driver will break way more components than big tyres will.
> >>
> >> Darren McRae
> >>
> >>
> >>
> >> -----Original Message-----
> >> From: [Email address removed] [mailto:[Email address removed]]
> >> On
> >> Behalf Of john
> >> Sent: Thursday=2C 8 October 2009 11:29 PM
> >> To: [Email address removed]
> >> Subject: Re: [ELCO] wheel side
> >>
> >> Hi Christopher
> >> Thanks for that=2Cgeese you are one for the math.
> >> I am trying to see what extra strain is put on the Cv when using the
> >> bigger
> >>
> >> tyres like for off roading and is there a point at which the bigger is not
> >>
> >> the best but a compromise is better.
> >> I know that anything bigger than 39inch with the Longfield is not
> >> recommended.
> >> I know ill ask them after all they should know.
> >> cheers
> >> john
> >>
> >> --
> >> European Land Cruiser Owners Mailing List
> >> Further Info: http://www.landcruisers.info/
> >>
> >> --
> >> European Land Cruiser Owners Mailing List
> >> Further Info: http://www.landcruisers.info/
> >>
> >>
> >>
> >
> >
> >
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> >
> >
> >
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> >
>
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Yep. Its an auto. Running ashcroft shaft's and 4.11 diffs with detroit
in rear and truetrac in front. Like you we're running a tweaked 3.9
with a hp22. Also run a disco with tweaked 300tdi manual van on
35"bfg muds as my road car and its all standard drivetrain except for
1.4 transfer box out of a defender and it gets used in the drive it
like you stole it category by everyone i work with and it hasn't broke
a thing in the 2 years i own it. Brian
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