Which stud on a SIII transfer box

G

Greg

Guest

• Sep 17, 2006

• #1

One of the 4 studs that hold the top cover plate on has been stripped and I
need to Recoil it, I think the thread in the casting is 5/16" UNC (the nut
is 5/16 UNF) but would be grateful of confirmation before forking out for
one of these expensive kits.
Greg

 

O

Oily

Guest

• Sep 17, 2006

• #2

"Greg" <[email protected]> wrote in message
news:[email protected]...
> One of the 4 studs that hold the top cover plate on has been stripped and
I
> need to Recoil it, I think the thread in the casting is 5/16" UNC (the nut
> is 5/16 UNF) but would be grateful of confirmation before forking out for
> one of these expensive kits.
> Greg
>
>
I think you will find the stud is 5/16" whitworth/BSF not UNC/UNF

Martin

 

J

JD

Guest

• Sep 17, 2006

• #3

Greg wrote:

> One of the 4 studs that hold the top cover plate on has been stripped and
> I need to Recoil it, I think the thread in the casting is 5/16" UNC (the
> nut is 5/16 UNF) but would be grateful of confirmation before forking out
> for one of these expensive kits.
> Greg

I am pretty certain the thread in the casting is 5/16 Whitworth.
JD

 

D

Dougal

Guest

• Sep 17, 2006

• #4

JD wrote:

> Greg wrote:
>
>
>>One of the 4 studs that hold the top cover plate on has been stripped and
>>I need to Recoil it, I think the thread in the casting is 5/16" UNC (the
>>nut is 5/16 UNF) but would be grateful of confirmation before forking out
>>for one of these expensive kits.
>>Greg
>
>
> I am pretty certain the thread in the casting is 5/16 Whitworth.
> JD

Even Land Rover are very unlikely to have mixed BS threads on one end
with Unified on the other. Therefore if you have UNF at the outer end
the other is most likely to be UNC. Similarly BSF outer end, BSW inner.

Get the stud that you intend to use and check it.

You don't actually need the special insertion tool to put in a
Helicoil - although it is much easier if there are several to be done.
For a one-off a piece of bar of the thread minor diameter, slotted
across the end to take the tang will do. You do need to take care that
the Helicoil doesn't get wound up like a spring outside the hole. This
way you're only buying the tap and inserts.

Could you borrow a tool?

There is another insert design - Keensert - which uses standard taps
(as opposed to the specials used with Helicoils). They don't do BSW,
though. They can be less of a fiddle to install and the kits may be
cheaper (no real knowledge, just a guess)
http://www.specialty-fasteners.co.uk/cgi-bin/sfc.cgi?usr=78334&page=view&pid=INS-KNS-KNS1

 

J

JD

Guest

• Sep 17, 2006

• #5

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

> JD wrote:
>
>> Greg wrote:
>>
>>
>>>One of the 4 studs that hold the top cover plate on has been stripped and
>>>I need to Recoil it, I think the thread in the casting is 5/16" UNC (the
>>>nut is 5/16 UNF) but would be grateful of confirmation before forking out
>>>for one of these expensive kits.
>>>Greg
>>
>>
>> I am pretty certain the thread in the casting is 5/16 Whitworth.
>> JD
>
> Even Land Rover are very unlikely to have mixed BS threads on one end
> with Unified on the other. Therefore if you have UNF at the outer end
> the other is most likely to be UNC. Similarly BSF outer end, BSW inner.
>
> Get the stud that you intend to use and check it.
>
> You don't actually need the special insertion tool to put in a
> Helicoil - although it is much easier if there are several to be done.
> For a one-off a piece of bar of the thread minor diameter, slotted
> across the end to take the tang will do. You do need to take care that
> the Helicoil doesn't get wound up like a spring outside the hole. This
> way you're only buying the tap and inserts.
>
> Could you borrow a tool?
>
> There is another insert design - Keensert - which uses standard taps
> (as opposed to the specials used with Helicoils). They don't do BSW,
> though. They can be less of a fiddle to install and the kits may be
> cheaper (no real knowledge, just a guess)
>
http://www.specialty-fasteners.co.uk/cgi-bin/sfc.cgi?usr=78334&page=view&pid=INS-KNS-KNS1
You're probably right - its most likely UNC not Whitworth, although I would
not bet on it. But in this size the two are effectively interchangeable.
JD

 

G

Greg

Guest

• Sep 17, 2006

• #6

"JD" <[email protected]> wrote in message
news:[email protected]...

> You're probably right - its most likely UNC not Whitworth, although I
would
> not bet on it. But in this size the two are effectively interchangeable.

I actually checked the stud against a 5/16" whitworth plug tap and it's the
same 18tpi, but so is UNC, only the thread form is different and that's
subtle (55 instead of 60 degrees and slightly different crest and root) so
I'll have to find those Whitworth thread gauges and see if I can tell the
difference. Aren't standards a wonderful thing!.

Greg

 

J

JD

Guest

• Sep 18, 2006

• #7

Greg wrote:

> "JD" <[email protected]> wrote in message
> news:[email protected]...
>
>> You're probably right - its most likely UNC not Whitworth, although I
> would
>> not bet on it. But in this size the two are effectively interchangeable.
>
> I actually checked the stud against a 5/16" whitworth plug tap and it's
> the same 18tpi, but so is UNC, only the thread form is different and
> that's subtle (55 instead of 60 degrees and slightly different crest and
> root) so I'll have to find those Whitworth thread gauges and see if I can
> tell the difference. Aren't standards a wonderful thing!.
>
> Greg

Yes - trouble is there are too many of them. As I said, in that size, for
practical purposes UNC and Whitworth are interchangeable - neither the stud
nor the helicoil will have been made with small enough tolerances that they
won't interchange, even if a little tight.
JD

 

O

Oily

Guest

• Sep 18, 2006

• #8

"JD" <[email protected]> wrote in message
news:[email protected]...
> Greg wrote:
>
> > "JD" <[email protected]> wrote in message
> > news:[email protected]...
> >
> >> You're probably right - its most likely UNC not Whitworth, although I
> > would
> >> not bet on it. But in this size the two are effectively
interchangeable.
> >
> > I actually checked the stud against a 5/16" whitworth plug tap and it's
> > the same 18tpi, but so is UNC, only the thread form is different and
> > that's subtle (55 instead of 60 degrees and slightly different crest and
> > root) so I'll have to find those Whitworth thread gauges and see if I
can
> > tell the difference. Aren't standards a wonderful thing!.
> >
> > Greg
>
> Yes - trouble is there are too many of them. As I said, in that size, for
> practical purposes UNC and Whitworth are interchangeable - neither the
stud
> nor the helicoil will have been made with small enough tolerances that
they
> won't interchange, even if a little tight.
> JD

And as I said (I don't know why I bother) the thread is Whitworth, if you
don't believe me put your thread gauge on the other end to see if it's B.S.F
or U.N.F and try a 1/2" or 1/4"Whit open ended spanner on the nut and see
which one fits.

Martin

 

G

Greg

Guest

• Sep 18, 2006

• #9

"JD" <[email protected]> wrote in message
news:[email protected]...

> Yes - trouble is there are too many of them. As I said, in that size, for
> practical purposes UNC and Whitworth are interchangeable - neither the
stud
> nor the helicoil will have been made with small enough tolerances that
they
> won't interchange, even if a little tight.

Yes I think it'll make little difference, the real problem will be getting
the tap in without having to remove the whole seat box 8-(.
Greg

 

O

Oily

Guest

• Sep 18, 2006

• #10

"Greg" <[email protected]> wrote in message
news:[email protected]...
> "JD" <[email protected]> wrote in message
> news:[email protected]...
>
> > Yes - trouble is there are too many of them. As I said, in that size,
for
> > practical purposes UNC and Whitworth are interchangeable - neither the
> stud
> > nor the helicoil will have been made with small enough tolerances that
> they
> > won't interchange, even if a little tight.
>
> Yes I think it'll make little difference, the real problem will be getting
> the tap in without having to remove the whole seat box 8-(.
> Greg
>
>

The transfer case is quite thick on the top, can you use a longer stud to
reach any good threads left in? If it is stripped all the way through then
you might be able to tap it out to 3/8" Whit or UNC using a short tap under
the seat box without drilling as 3/8" is only 3/4 of a millimetre either
side bigger for the thread depth. A short socket head setscrew will miss the
casing on the front holes (unless you want to keep it looking original make
a two diameter stud). You can remove the rear power take off cover and
bearing housing to catch any swarf. Save a lot of messing about.

HTH Martin

 

G

Greg

Guest

• Sep 19, 2006

• #11

"Oily" <[email protected]> wrote in message
> And as I said (I don't know why I bother) the thread is Whitworth

Yes you're quite right, the outer end is 22tpi so BSF, thanks for pointing
me in the right direction.
Greg