Last weekend one of my mates race cars suffered a diff failure at
Phillip Island, when we removed it we found the problem was all the
carrier to crown wheel bolts had come out.
Amazingly neither the crown wheel or the pinion were damaged but the LSD
and the casting are beyond repair.
It was last out about 2.5yrs ago for a rebuild.
When it was rebuilt the bolts were loctited and torqued to the correct
spec then secured with the stock locking tabs.
According to a few people that we spoke to who use the same diff in the
same type of race car this a common failure on this model diff when
fitted to race cars with sticky tyres.
The diff is a Toyota T series out of an AE86 Sprinter and it was fitted
with a Kaaz LSD.
My theory is the LSD "chatters" causing the bolts to vibrate out but at
this point in time that's just my theory, no one we have spoken to has
any idea why this happens, one suggested that the use of Loctite could
affect the torquing of the bolts?
After its rebuilt we are thinking about drilling the bolt heads and
using lock wire plus removing the diff after every 4th race meeting to
inspect it.
Thoughts anyone and again sorry for a car related post:-)

--
Daryl

On 9/07/2023 10:30 am, Daryl wrote:
> Last weekend one of my mates race cars suffered a diff failure at
> Phillip Island, when we removed it we found the problem was all the
> carrier to crown wheel bolts had come out.
> Amazingly neither the crown wheel or the pinion were damaged but the LSD
> and the casting are beyond repair.
> It was last out about 2.5yrs ago for a rebuild.
> When it was rebuilt the bolts were loctited and torqued to the correct
> spec then secured with the stock locking tabs.
> According to a few people that we spoke to who use the same diff in the
> same type of race car this a common failure on this model diff when
> fitted to race cars with sticky tyres.
> The diff is a Toyota T series out of an AE86 Sprinter and it was fitted
> with a Kaaz LSD.
> My theory is the LSD "chatters" causing the bolts to vibrate out but at
> this point in time that's just my theory, no one we have spoken to has
> any idea why this happens, one suggested that the use of Loctite could
> affect the torquing of the bolts?
> After its rebuilt we are thinking about drilling the bolt heads and
> using lock wire plus removing the diff after every 4th race meeting to
> inspect it.
> Thoughts anyone and again sorry for a car related post:-)

Must have some horrendous chatter if it can shake bolt loose that have
been torqued, loctited *and* held in place with locking tabs.

I have zero experience with Toyota diffs other than swapping centres at
the request of the paying customer :), but I've rebuilt more 8 and 9
inch Fords than you could poke a stick at and never had a problem with
bolts coming loose.

Some people might tell you that using a thread locking compound will
require a reduction in torque values, but the same people will probably
*also* tell you that the best way to get a decent valve seal is by hand
lapping :) I've used locking compound on *many* occasions and never
needed to change torque values, but there are locking compounds and then
there are locking compounds.

The best locking compounds you can buy are made by Loctite, and the two
most suitable for an application like this would be "Threadlockers" in
either Blue 242, or Red 271. The main difference between them is that
the blue provides a removable fit whereas the red is permanent and will
bond so tight that the fastener will usually break before it can be
removed. In fact the correct recommended procedure for removing any
fastener where Red 271 has been used is to use a blowtorch to soften the
compound and release the grab.

My advice, for what it's worth, is to buy a new set of bolts and use Red
271 on perfectly clean and dry threads ensuring the bolts are torqued to
either the manufacturer's or bolt makers specifications. Ensure that the
ring gear fits the hemisphere *perfectly* and that there is no lateral
movement. A ring gear that is not a snug fit on it's hemisphere is a
recipe for disaster. Put your locking tabs in place and secure them
properly and you should be good to go after the compound has had
sufficient time to cure.

Lastly, lock-wiring.

A *lot* of the time spent during the first 12 months of my
apprenticeship was spent lock-wiring components, as virtually everything
on aircraft uses the stuff. I still even have the lockwire pliers here,
and it was a job I came to hate as it was a pain in the arse. I don't
bother with it myself these days as I find it to be a largely
unnecessary practice in the automotive world, but if you're planning on
giving it a try then I would suggest you use very good quality bolts and
very good quality wire.

My preference would be to use stainless aircraft grade wire as it's far
less likely to break and get caught in anything in service, and if
possible use bolts that have been pre-drilled by the manufacturer. If
you have to drill your own bolt heads then don't even contemplate the
idea without a drill guide and the correct cutting fluid as it's a very
delicate process.

--
--
--
Regards,
Noddy.

On 9/7/2023 4:18 pm, Noddy wrote:
> On 9/07/2023 10:30 am, Daryl wrote:
>> Last weekend one of my mates race cars suffered a diff failure at
>> Phillip Island, when we removed it we found the problem was all the
>> carrier to crown wheel bolts had come out.
>> Amazingly neither the crown wheel or the pinion were damaged but the
>> LSD and the casting are beyond repair.
>> It was last out about 2.5yrs ago for a rebuild.
>> When it was rebuilt the bolts were loctited and torqued to the correct
>> spec then secured with the stock locking tabs.
>> According to a few people that we spoke to who use the same diff in
>> the same type of race car this a common failure on this model diff
>> when fitted to race cars with sticky tyres.
>> The diff is a Toyota T series out of an AE86 Sprinter and it was
>> fitted with a Kaaz LSD.
>> My theory is the LSD "chatters" causing the bolts to vibrate out but
>> at this point in time that's just my theory, no one we have spoken to
>> has any idea why this happens, one suggested that the use of Loctite
>> could affect the torquing of the bolts?
>> After its rebuilt we are thinking about drilling the bolt heads and
>> using lock wire plus removing the diff after every 4th race meeting to
>> inspect it.

Rebuilding the diff at regular intervals is what you should have been
doing all along. 2.5 years in a high performance application is way too
long.

>> Thoughts anyone and again sorry for a car related post:-)
>
> Must have some horrendous chatter if it can shake bolt loose that have
> been torqued, loctited *and* held in place with locking tabs.
>
> I have zero experience with Toyota diffs other than swapping centres at
> the request of the paying customer :), but I've rebuilt more 8 and 9
> inch Fords than you could poke a stick at and never had a problem with
> bolts coming loose.
>
> Some people might tell you that using a thread locking compound will
> require a reduction in torque values, but the same people will probably
> *also* tell you that the best way to get a decent valve seal is by hand
> lapping :) I've used locking compound on *many* occasions and never
> needed to change torque values, but there are locking compounds and then
> there are locking compounds.
>
> The best locking compounds you can buy are made by Loctite, and the two
> most suitable for an application like this would be "Threadlockers" in
> either Blue 242, or Red 271. The main difference between them is that
> the blue provides a removable fit whereas the red is permanent and will
> bond so tight that the fastener will usually break before it can be
> removed. In fact the correct recommended procedure for removing any
> fastener where Red 271 has been used is to use a blowtorch to soften the
> compound and release the grab.
>
> My advice, for what it's worth, is to buy a new set of bolts and use Red
> 271 on perfectly clean and dry threads ensuring the bolts are torqued to
> either the manufacturer's or bolt makers specifications. Ensure that the
> ring gear fits the hemisphere *perfectly* and that there is no lateral
> movement. A ring gear that is not a snug fit on it's hemisphere is a
> recipe for disaster. Put your locking tabs in place and secure them
> properly and you should be good to go after the compound has had
> sufficient time to cure.
>
> Lastly, lock-wiring.
>
> A *lot* of the time spent during the first 12 months of my
> apprenticeship was spent lock-wiring components, as virtually everything

Ah, more bullshit. Darren, you *didn't qualify* for an AME
apprenticeship. Needed year 10 passes, it's at *technician level*
remember? You squibbed out on your *year 9 exams*, ran away, DNS. That
means you *didn't even qualify* for an automotive apprenticeship.

> on aircraft uses the stuff. I still even have the lockwire pliers here,
> and it was a job I came to hate as it was a pain in the arse. I don't
> bother with it myself these days as I find it to be a largely

It's the sort of job you would give an apprentice. That means *you*, as
a *trades assistant*, would have only been handing the mechanic the
tools and/or the wire. Did you knock those pliers off when you got the
flick Darren?

> unnecessary practice in the automotive world, but if you're planning on
> giving it a try then I would suggest you use very good quality bolts and
> very good quality wire.
>
> My preference would be to use stainless aircraft grade wire as it's far
> less likely to break and get caught in anything in service, and if
> possible use bolts that have been pre-drilled by the manufacturer. If
> you have to drill your own bolt heads then don't even contemplate the
> idea without a drill guide and the correct cutting fluid as it's a very
> delicate process.

--
Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)

On 9/07/2023 4:18 pm, Noddy wrote:

> Lastly, lock-wiring.
>
> A *lot* of the time spent during the first 12 months of my
> apprenticeship was spent lock-wiring components, as virtually everything
> on aircraft uses the stuff. I still even have the lockwire pliers here,
> and it was a job I came to hate as it was a pain in the arse. I don't
> bother with it myself these days as I find it to be a largely
> unnecessary practice in the automotive world, but if you're planning on
> giving it a try then I would suggest you use very good quality bolts and
> very good quality wire.
>
> My preference would be to use stainless aircraft grade wire as it's far
> less likely to break and get caught in anything in service, and if
> possible use bolts that have been pre-drilled by the manufacturer. If
> you have to drill your own bolt heads then don't even contemplate the
> idea without a drill guide and the correct cutting fluid as it's a very
> delicate process.

If conditions are that bad, I'd use aircraft bolts, they are stronger
than the average automotive bolt, partly because they only have a short
threaded length, and they are made to a higher standard (and a higher
price). They are drilled for use with castellated nuts. Personally I'd
use split pins rather than wire, but I don't know how practical that
would be in a diff.

On 9/07/2023 5:14 pm, Keithr0 wrote:
> On 9/07/2023 4:18 pm, Noddy wrote:
>
>> Lastly, lock-wiring.
>>
>> A *lot* of the time spent during the first 12 months of my
>> apprenticeship was spent lock-wiring components, as virtually
>> everything on aircraft uses the stuff. I still even have the lockwire
>> pliers here, and it was a job I came to hate as it was a pain in the
>> arse. I don't bother with it myself these days as I find it to be a
>> largely unnecessary practice in the automotive world, but if you're
>> planning on giving it a try then I would suggest you use very good
>> quality bolts and very good quality wire.
>>
>> My preference would be to use stainless aircraft grade wire as it's
>> far less likely to break and get caught in anything in service, and if
>> possible use bolts that have been pre-drilled by the manufacturer. If
>> you have to drill your own bolt heads then don't even contemplate the
>> idea without a drill guide and the correct cutting fluid as it's a
>> very delicate process.
>
> If conditions are that bad, I'd use aircraft bolts, they are stronger
> than the average automotive bolt, partly because they only have a short
> threaded length, and they are made to a higher standard (and a higher
> price). They are drilled for use with castellated nuts. Personally I'd
> use split pins rather than wire, but I don't know how practical that
> would be in a diff.

Not practical in this situation as the bolts he's talking about would go
into a blind hole and don't use nuts.

Bolts are ranked in "grades" which refers to their sheer strength, and
all bolt grades are usually marked on the head of the bolt with a series
of lines or numbers to to indicate the grade strength the bolt confirms
to. The more lines or the higher the number, the higher the grade
strength of the bolt and the more suitable it is for severe duty
applications. Across the automotive world a variety of bolt grades are
used ranging from low quality carbon steel bolts for things like door
hinges and other body components, to bolts made from 8740 Chrome Moly
for things like Connecting rods.

It's application dependent, which is different to the Aviation world
where everything tends to be massively over engineered for obvious
reasons. In Daryl's case a suitable aircraft bolt in the right thread
pitch and length would be ideal as it would most likely have a drilled
head for lock wire use, but he'd need to be careful in selecting such a
bolt as differential ring gear bolts are usually specific to the
application and often have shank sections that are sized specifically to
act as locators in the carrier holes to keep the ring gear centred
precisely on the carrier.

Without having seen Daryl's diff in the flesh I have no idea as to
what's causing it's issues, but I've seen similar problems with Jag rear
axles and people using Dana gearsets.

The popular Jaguar independent rear axle used for many years is actually
a British version of an American diff called a Dana 44 which has a
lineage going all the way back to the WWII Jeep. It was used in
countless American cars and trucks over the years and is still used in
some to this day, and my old F100 has one under it's tray. Jaguar, when
designing their Independent rear in the 1960's, decided to make a diff
centre based on that Dana 44 unit and built their independent suspension
components around it. As a result, some Jaguar and Dana diff parts are
interchangeable.

Some :)

In their infinite wisdom, as the British so often do, they decided that
the Dana diff needed some upgrades as they went, so they made some.
Things like thicker bearings, larger ring gear bolts, etc. None of them
were drastic and they were all good ideas in terms of beefing up what
was a pretty basic rear axle assembly, but it caused a few issues for
people years later down the track and one area that was problematic was
ring gear bolts.

The standard Dana 44 rear axle uses 3/8" bolts to hold the ring gear to
the carrier, and Jaguar thought that was insufficient. So they upgraded
the carrier and ring gear to use 7/16" bolts. It worked fine and I'm not
aware of any Jags having bolt related failures, but when people were
looking for a gear ratio swap and wanted to use a Dana 44 gearset they
would fit the 3/8" bolts into the carrier designed to locate with the
jag 7/16" bolts and that's when the problems would arise with results
similar to the issues Daryl complained about. It took a while for people
to catch on, but the solution was to either use a Dana carrier, or bush
the jag unit to take 3/8" bolts and that solved the problems.

The point in all this rambling is that it may be worth Daryl's while to
check the location of the ring gear bolts in the carrier and seeing if
they're locating properly.

--
--
--
Regards,
Noddy.

On 9/7/2023 4:18 pm, Noddy wrote:
> On 9/07/2023 10:30 am, Daryl wrote:
>> Last weekend one of my mates race cars suffered a diff failure at
>> Phillip Island, when we removed it we found the problem was all the
>> carrier to crown wheel bolts had come out.
>> Amazingly neither the crown wheel or the pinion were damaged but the
>> LSD and the casting are beyond repair.
>> It was last out about 2.5yrs ago for a rebuild.
>> When it was rebuilt the bolts were loctited and torqued to the correct
>> spec then secured with the stock locking tabs.
>> According to a few people that we spoke to who use the same diff in
>> the same type of race car this a common failure on this model diff
>> when fitted to race cars with sticky tyres.
>> The diff is a Toyota T series out of an AE86 Sprinter and it was
>> fitted with a Kaaz LSD.
>> My theory is the LSD "chatters" causing the bolts to vibrate out but
>> at this point in time that's just my theory, no one we have spoken to
>> has any idea why this happens, one suggested that the use of Loctite
>> could affect the torquing of the bolts?
>> After its rebuilt we are thinking about drilling the bolt heads and
>> using lock wire plus removing the diff after every 4th race meeting to
>> inspect it.
>> Thoughts anyone and again sorry for a car related post:-)
>
> Must have some horrendous chatter if it can shake bolt loose that have
> been torqued, loctited *and* held in place with locking tabs.
>
> I have zero experience with Toyota diffs other than swapping centres at
> the request of the paying customer :), but I've rebuilt more 8 and 9
> inch Fords than you could poke a stick at and never had a problem with
> bolts coming loose.
>
> Some people might tell you that using a thread locking compound will
> require a reduction in torque values, but the same people will probably
> *also* tell you that the best way to get a decent valve seal is by hand
> lapping :) I've used locking compound on *many* occasions and never
> needed to change torque values, but there are locking compounds and then
> there are locking compounds.
>
> The best locking compounds you can buy are made by Loctite, and the two
> most suitable for an application like this would be "Threadlockers" in
> either Blue 242, or Red 271. The main difference between them is that
> the blue provides a removable fit whereas the red is permanent and will
> bond so tight that the fastener will usually break before it can be
> removed. In fact the correct recommended procedure for removing any
> fastener where Red 271 has been used is to use a blowtorch to soften the
> compound and release the grab.
>
> My advice, for what it's worth, is to buy a new set of bolts and use Red
> 271 on perfectly clean and dry threads ensuring the bolts are torqued to
> either the manufacturer's or bolt makers specifications. Ensure that the
> ring gear fits the hemisphere *perfectly* and that there is no lateral
> movement. A ring gear that is not a snug fit on it's hemisphere is a
> recipe for disaster. Put your locking tabs in place and secure them
> properly and you should be good to go after the compound has had
> sufficient time to cure.
>
> Lastly, lock-wiring.
>
> A *lot* of the time spent during the first 12 months of my
> apprenticeship was spent lock-wiring components, as virtually everything
> on aircraft uses the stuff. I still even have the lockwire pliers here,
> and it was a job I came to hate as it was a pain in the arse. I don't
> bother with it myself these days as I find it to be a largely
> unnecessary practice in the automotive world, but if you're planning on
> giving it a try then I would suggest you use very good quality bolts and
> very good quality wire.
>
> My preference would be to use stainless aircraft grade wire as it's far
> less likely to break and get caught in anything in service, and if
> possible use bolts that have been pre-drilled by the manufacturer. If
> you have to drill your own bolt heads then don't even contemplate the
> idea without a drill guide and the correct cutting fluid as it's a very
> delicate process.
>
>
>
>
>
I was also thinking drilling the bolts could be a problem, don't know if
predrilled bolts for that application exist but I'll see what I can find.
Just tonight I mentioned the diff issue to my son's mate who is a
mechanic who worked on a race team ( I think he said it was next level
down from V8 Supercars) and he said that they experienced the same
problem and they solved the problem by tac welding the bolts to the
carrier but I didn't ask what diffs they were using.
It only takes a couple of hours to refit inspect and refit so that's
probably the safest way to make sure nothing comes loose.

--
Daryl

On 9/7/2023 5:14 pm, Keithr0 wrote:
> On 9/07/2023 4:18 pm, Noddy wrote:
>
>> Lastly, lock-wiring.
>>
>> A *lot* of the time spent during the first 12 months of my
>> apprenticeship was spent lock-wiring components, as virtually
>> everything on aircraft uses the stuff. I still even have the lockwire
>> pliers here, and it was a job I came to hate as it was a pain in the
>> arse. I don't bother with it myself these days as I find it to be a
>> largely unnecessary practice in the automotive world, but if you're
>> planning on giving it a try then I would suggest you use very good
>> quality bolts and very good quality wire.
>>
>> My preference would be to use stainless aircraft grade wire as it's
>> far less likely to break and get caught in anything in service, and if
>> possible use bolts that have been pre-drilled by the manufacturer. If
>> you have to drill your own bolt heads then don't even contemplate the
>> idea without a drill guide and the correct cutting fluid as it's a
>> very delicate process.
>
> If conditions are that bad, I'd use aircraft bolts, they are stronger
> than the average automotive bolt, partly because they only have a short
> threaded length, and they are made to a higher standard (and a higher
> price). They are drilled for use with castellated nuts. Personally I'd
> use split pins rather than wire, but I don't know how practical that
> would be in a diff.
>

They don't have nuts, the bolts pass though the carrier directly into
the back of the threaded crown wheel.
Don't know if we can get higher grade bolts but I will see what I can find.

--
Daryl

On 9/7/2023 8:43 pm, Noddy wrote:
> On 9/07/2023 5:14 pm, Keithr0 wrote:
>> On 9/07/2023 4:18 pm, Noddy wrote:
>>
>>> Lastly, lock-wiring.
>>>
>>> A *lot* of the time spent during the first 12 months of my
>>> apprenticeship was spent lock-wiring components, as virtually
>>> everything on aircraft uses the stuff. I still even have the lockwire
>>> pliers here, and it was a job I came to hate as it was a pain in the
>>> arse. I don't bother with it myself these days as I find it to be a
>>> largely unnecessary practice in the automotive world, but if you're
>>> planning on giving it a try then I would suggest you use very good
>>> quality bolts and very good quality wire.
>>>
>>> My preference would be to use stainless aircraft grade wire as it's
>>> far less likely to break and get caught in anything in service, and
>>> if possible use bolts that have been pre-drilled by the manufacturer.
>>> If you have to drill your own bolt heads then don't even contemplate
>>> the idea without a drill guide and the correct cutting fluid as it's
>>> a very delicate process.
>>
>> If conditions are that bad, I'd use aircraft bolts, they are stronger
>> than the average automotive bolt, partly because they only have a
>> short threaded length, and they are made to a higher standard (and a
>> higher price). They are drilled for use with castellated nuts.
>> Personally I'd use split pins rather than wire, but I don't know how
>> practical that would be in a diff.
>
> Not practical in this situation as the bolts he's talking about would go
> into a blind hole and don't use nuts.
>
> Bolts are ranked in "grades" which refers to their sheer strength, and
> all bolt grades are usually marked on the head of the bolt with a series
> of lines or numbers to to indicate the grade strength the bolt confirms
> to. The more lines or the higher the number, the higher the grade
> strength of the bolt and the more suitable it is for severe duty
> applications. Across the automotive world a variety of bolt grades are
> used ranging from low quality carbon steel bolts for things like door
> hinges and other body components, to bolts made from 8740 Chrome Moly
> for things like Connecting rods.
>
> It's application dependent, which is different to the Aviation world
> where everything tends to be massively over engineered for obvious
> reasons. In Daryl's case a suitable aircraft bolt in the right thread
> pitch and length would be ideal as it would most likely have a drilled
> head for lock wire use, but he'd need to be careful in selecting such a
> bolt as differential ring gear bolts are usually specific to the
> application and often have shank sections that are sized specifically to
> act as locators in the carrier holes to keep the ring gear centred
> precisely on the carrier.
>
> Without having seen Daryl's diff in the flesh I have no idea as to
> what's causing it's issues, but I've seen similar problems with Jag rear
> axles and people using Dana gearsets.
>
> The popular Jaguar independent rear axle used for many years is actually
> a British version of an American diff called a Dana 44 which has a
> lineage going all the way back to the WWII Jeep. It was used in
> countless American cars and trucks over the years and is still used in
> some to this day, and my old F100 has one under it's tray. Jaguar, when
> designing their Independent rear in the 1960's, decided to make a diff
> centre based on that Dana 44 unit and built their independent suspension
> components around it. As a result, some Jaguar and Dana diff parts are
> interchangeable.
>
> Some :)
>
> In their infinite wisdom, as the British so often do, they decided that
> the Dana diff needed some upgrades as they went, so they made some.
> Things like thicker bearings, larger ring gear bolts, etc. None of them
> were drastic and they were all good ideas in terms of beefing up what
> was a pretty basic rear axle assembly, but it caused a few issues for
> people years later down the track and one area that was problematic was
> ring gear bolts.
>
> The standard Dana 44 rear axle uses 3/8" bolts to hold the ring gear to
> the carrier, and Jaguar thought that was insufficient. So they upgraded
> the carrier and ring gear to use 7/16" bolts. It worked fine and I'm not
> aware of any Jags having bolt related failures, but when people were
> looking for a gear ratio swap and wanted to use a Dana 44 gearset they
> would fit the 3/8" bolts into the carrier designed to locate with the
> jag 7/16" bolts and that's when the problems would arise with results
> similar to the issues Daryl complained about. It took a while for people
> to catch on, but the solution was to either use a Dana carrier, or bush
> the jag unit to take 3/8" bolts and that solved the problems.
>
> The point in all this rambling is that it may be worth Daryl's while to
> check the location of the ring gear bolts in the carrier and seeing if
> they're locating properly.
>

That is something I will be checking, I did wonder if there might have
been a bit of slack around the bolt holes allowing some movement that
rattled the bolts loose.
Since the old diff carrier/LSD was damaged the replacement will be new
so less likely to have any clearance but still worth checking.

--
Daryl

On 9/07/2023 10:07 pm, Daryl wrote:
> On 9/7/2023 4:18 pm, Noddy wrote:

>> My preference would be to use stainless aircraft grade wire as it's
>> far less likely to break and get caught in anything in service, and if
>> possible use bolts that have been pre-drilled by the manufacturer. If
>> you have to drill your own bolt heads then don't even contemplate the
>> idea without a drill guide and the correct cutting fluid as it's a
>> very delicate process.
>
> I was also thinking drilling the bolts could be a problem, don't know if
> predrilled bolts for that application exist but I'll see what I can find.

They'll most likely be around, but whether they solve the problem or not
is anyone's guess. The wire really isn't that strong and can be snapped
fairly easily. If the forces acting on the bolt are enough to bend
locking tabs then they'd most likely break the wire and defeat the purpose.

> Just tonight I mentioned the diff issue to my son's mate who is a
> mechanic who worked on a race team ( I think he said it was next level
> down from V8 Supercars) and he said that they experienced the same
> problem and they solved the problem by tac welding the bolts to the
> carrier but I didn't ask what diffs they were using.

I've heard of people doing that but I'd be *real* careful about doing
it. If they're grade 8 bolts, and I suspect they are, then they've
already gone through a heat treating process and welding will interfere
with that. Another point to bear in mind is that most differential
carriers are made of cast steel, and it's difficult to get a decent weld
"bite" without generating a fair amount of heat. Enough in fact that I
would suspect it would be relatively easy to cause some run out.

> It only takes a couple of hours to refit inspect and refit so that's
> probably the safest way to make sure nothing comes loose.

Me personally I'd try the Red 271 threadlocker, as it's pretty strong
stuff, and if that didn't work I'd be looking at why.

You mentioned that while the carrier was rooted the ring gear was
undamaged, but I'd be checking to see if it actually was. If this is the
same ring gear that's been re-used each time the problem occurred then
the first thing I'd be checking is that the threads in the bolt holes
haven't been flogged in some way and are preventing the bolts from
getting a full purchase. Failing that and the bolts are locating in the
carrier holes correctly with everything else being a good fit then it's
really difficult to understand why the thing keeps coming apart. Not
unless you're subjecting it to *way* more torque than it's capable of
handling and it's suffering from some serious distortion in service.

As far as the bolt welding goes it's not something I would ever do, but
if you have no other choice and are forced to resort to it as a last
ditched effort to solve the problem then I would recommend that if the
locking tabs are just a number of simple flat metal strips that secure
between a pair of bolts then I would refit them and weld the bolt heads
to the lock tabs themselves rather than to the carrier directly. I would
tig them in place using Silicone Bronze as it would give the highest
possible strength for the lowest amount of heat, and theoretically the
bolts should be locked in position between each welded pair without risk
of the carrier being damaged or the weld not holding to the cast steel
due to poor penetration.

--
--
--
Regards,
Noddy.

On 9/7/2023 11:43 pm, Noddy wrote:
> On 9/07/2023 10:07 pm, Daryl wrote:
>> On 9/7/2023 4:18 pm, Noddy wrote:
>
>>> My preference would be to use stainless aircraft grade wire as it's
>>> far less likely to break and get caught in anything in service, and
>>> if possible use bolts that have been pre-drilled by the manufacturer.
>>> If you have to drill your own bolt heads then don't even contemplate
>>> the idea without a drill guide and the correct cutting fluid as it's
>>> a very delicate process.
>>
>> I was also thinking drilling the bolts could be a problem, don't know
>> if predrilled bolts for that application exist but I'll see what I can
>> find.
>
> They'll most likely be around, but whether they solve the problem or not
> is anyone's guess. The wire really isn't that strong and can be snapped
> fairly easily. If the forces acting on the bolt are enough to bend
> locking tabs then they'd most likely break the wire and defeat the purpose.
>
>> Just tonight I mentioned the diff issue to my son's mate who is a
>> mechanic who worked on a race team ( I think he said it was next level
>> down from V8 Supercars) and he said that they experienced the same
>> problem and they solved the problem by tac welding the bolts to the
>> carrier but I didn't ask what diffs they were using.
>
> I've heard of people doing that but I'd be *real* careful about doing
> it. If they're grade 8 bolts, and I suspect they are, then they've
> already gone through a heat treating process and welding will interfere
> with that. Another point to bear in mind is that most differential
> carriers are made of cast steel, and it's difficult to get a decent weld
> "bite" without generating a fair amount of heat. Enough in fact that I
> would suspect it would be relatively easy to cause some run out.
>
>> It only takes a couple of hours to refit inspect and refit so that's
>> probably the safest way to make sure nothing comes loose.
>
> Me personally I'd try the Red 271 threadlocker, as it's pretty strong
> stuff, and if that didn't work I'd be looking at why.
>
> You mentioned that while the carrier was rooted the ring gear was
> undamaged, but I'd be checking to see if it actually was. If this is the
> same ring gear that's been re-used each time the problem occurred then
> the first thing I'd be checking is that the threads in the bolt holes
> haven't been flogged in some way and are preventing the bolts from
> getting a full purchase.

We will certainly be checking that but more than likely it won't be an
issue because the last time I spoke to Les the plan is to change the
ratio from a 4.1:1 to a 4.3:1.

Failing that and the bolts are locating in the
> carrier holes correctly with everything else being a good fit then it's
> really difficult to understand why the thing keeps coming apart. Not
> unless you're subjecting it to *way* more torque than it's capable of
> handling and it's suffering from some serious distortion in service.

Its possible, the cars engine has way more power than a stock AE86 that
the diff is out of but its about 400kg lighter, R spec tyres have a lot
more grip than normal road tyres plus it does get driven very hard and
overall the car is very quick.
>
> As far as the bolt welding goes it's not something I would ever do, but
> if you have no other choice and are forced to resort to it as a last
> ditched effort to solve the problem then I would recommend that if the
> locking tabs are just a number of simple flat metal strips that secure
> between a pair of bolts then I would refit them and weld the bolt heads
> to the lock tabs themselves rather than to the carrier directly. I would
> tig them in place using Silicone Bronze as it would give the highest
> possible strength for the lowest amount of heat, and theoretically the
> bolts should be locked in position between each welded pair without risk
> of the carrier being damaged or the weld not holding to the cast steel
> due to poor penetration.
>
>

Sounds like a good idea.

--
Daryl

On 9/07/2023 2:18 pm, Noddy wrote:
> On 9/07/2023 10:30 am, Daryl wrote:
>> Last weekend one of my mates race cars suffered a diff failure at
>> Phillip Island, when we removed it we found the problem was all the
>> carrier to crown wheel bolts had come out.
>> Amazingly neither the crown wheel or the pinion were damaged but the
>> LSD and the casting are beyond repair.
>> It was last out about 2.5yrs ago for a rebuild.
>> When it was rebuilt the bolts were loctited and torqued to the correct
>> spec then secured with the stock locking tabs.
>> According to a few people that we spoke to who use the same diff in
>> the same type of race car this a common failure on this model diff
>> when fitted to race cars with sticky tyres.
>> The diff is a Toyota T series out of an AE86 Sprinter and it was
>> fitted with a Kaaz LSD.
>> My theory is the LSD "chatters" causing the bolts to vibrate out but
>> at this point in time that's just my theory, no one we have spoken to
>> has any idea why this happens, one suggested that the use of Loctite
>> could affect the torquing of the bolts?
>> After its rebuilt we are thinking about drilling the bolt heads and
>> using lock wire plus removing the diff after every 4th race meeting to
>> inspect it.
>> Thoughts anyone and again sorry for a car related post:-)
>
> Must have some horrendous chatter if it can shake bolt loose that have
> been torqued, loctited *and* held in place with locking tabs.
>
> I have zero experience

.... and that's where the truth ended.

On 11/7/2023 1:41 am, Clocky wrote:
> On 9/07/2023 2:18 pm, Noddy wrote:
>> On 9/07/2023 10:30 am, Daryl wrote:
>>> Last weekend one of my mates race cars suffered a diff failure at
>>> Phillip Island, when we removed it we found the problem was all the
>>> carrier to crown wheel bolts had come out.
>>> Amazingly neither the crown wheel or the pinion were damaged but the
>>> LSD and the casting are beyond repair.
>>> It was last out about 2.5yrs ago for a rebuild.
>>> When it was rebuilt the bolts were loctited and torqued to the
>>> correct spec then secured with the stock locking tabs.
>>> According to a few people that we spoke to who use the same diff in
>>> the same type of race car this a common failure on this model diff
>>> when fitted to race cars with sticky tyres.
>>> The diff is a Toyota T series out of an AE86 Sprinter and it was
>>> fitted with a Kaaz LSD.
>>> My theory is the LSD "chatters" causing the bolts to vibrate out but
>>> at this point in time that's just my theory, no one we have spoken to
>>> has any idea why this happens, one suggested that the use of Loctite
>>> could affect the torquing of the bolts?
>>> After its rebuilt we are thinking about drilling the bolt heads and
>>> using lock wire plus removing the diff after every 4th race meeting
>>> to inspect it.
>>> Thoughts anyone and again sorry for a car related post:-)
>>
>> Must have some horrendous chatter if it can shake bolt loose that have
>> been torqued, loctited *and* held in place with locking tabs.
>>
>> I have zero experience
>
>
> ... and that's where the truth ended.

Does that mean Darren is actually capable of telling the truth, however
rarely?

Nah, Darren must have misspoken! His very nature is to lie, lie, lie.

--
Xeno

Nothing astonishes Noddy so much as common sense and plain dealing.
(with apologies to Ralph Waldo Emerson)