At least you offer food for thought and an opportunity for users to make
a decision for themselves... and maybe those with factory technical
information at their disposal could try to look up such engineering
information. Maybe someone who has access to Triumph service bulletins
could find something regarding this.
The original post that started this thread suggested that jacking the
car would potentially thrust a mounting stud through the cross
member... I debated this...and would again.
A following post suggested that the bushings were not "designed" to take
such a load... and I debated this and would again.
I would suggest that anyone with a manual, or a stripped IRS frame
sitting in the garage... look at the IRS layout... and study what would
happen when you lift the differential... remembering that the car
weighs 2240 lbs.... I would assume less than 1/2 of that at the rear...
In my opinion... The load is well spread across two separate cross
members attached to the frame. The load is not placed on the mounting
studs. The bushings are solid and are not going to be damaged. The IRS
differiential casing is quite a solid piece.
And lets not forget... when you jack one side of the frame at a time...
this is ALSO putting loads on the very same cross members. Jacking a car
is going to put strains on the frame...
The only area that now makes me uncomfortable... having put increasly
more thought into this due to the thread... is my assumption that people
would have solid frames.
I've held the opinion that if jacking the car by the diff should break
the mounting studs... or, for that matter, any of the cross members...
it would be a good thing... because it's better to know now, than while
driving... (If it should give way while jacking, it's not a safety
issue, as suggested by Gernot, because A. you're not under the car while
jacking it up and B. even if one of these items snaps, the car would not
come crashing down.)
...but living in California, I tend to forget that many of you have IRS
frames that you could put fingers or even hands through the rust
And while it is easy for me to say, "hey, if your frame is so screwed up
that jacking your car is going to cause it to snap... then it's time to
do a frame off and fix it..."
Well... I suppose... while it's not safe to drive on rotting frames...
maybe it's just something you've got to do... if you're going to enjoy
the car at all... While I would enter, you're not only placing yourself
in danger, but those around you... particularly those in the path of
your moving car...but, generally, when things like mounting studs
give-way... it leads to a clonk or a thump, rather than an accident. (I
would hope you would inspect the critical areas regularly, and beef 'em
up when necessary!)
Having heard all the threads... if your frame is borderline... or
worse... by all means... avoid the diff... Maybe you'll get a few
more miles. Particularly if you baby it up, as suggested by Steve
Chandler, with TWO jacks being raised relatively simultaneously.
Or just avoid the differential altogether, because John's having had to
write it down 100 times for his headmaster-mechanic, has weighed your
opinion against it. At least it would be a decision based on some
(So there's no confusion here, I never suggested you LEAVE the car
supported by the diff... the idea was that you could jack the
differential up with a floor jack, and then lower the car down onto jack
stands on the frame rails! There may be a "cross the pond"
misunderstanding in english... as the term "jack", etc., has different
meanings, I recall.)
I would like to hear from qualified sources, specifically where/why
damage would be done in lifting a TR 4A/TR 6 type rear end by the
differential...so that I can look at it for myself, and come to
understand it. I enjoy such input.
The point of all my posts regarding this matter have been based on the
Disinformation should be routed... through informed debate... to give
readers the opportunity to determine what is right for them, without
being prejudiced by misguided theories, particularly those that incite
I simply felt visions of damaged bushings from an occasion car-jacking
and mounting studs breaking through the cross-member were not
And any post that would suggest that I am blind to safety concerns is
not warranted, nor appreciated.
> On April 5, Justin Wagner wrote
> >Honestly, I would just let this ride... but when I think of some
> >percentage of the newsgroup falling for some misplaced theory about the
> >dangers of jacking a car by the differential... I feel a need to say
> This isn't a flame but I've got to say one last thing on the "misplaced
> about the dangers of jacking a car by the differential" as this relates to
> rear independently sprung Triumphs. Then I'll shut up. If the vehicle
> manufacturer itself insisted that its directly employed service staff
> jacked Triumph cars using load spreaders to the chassis extensions there
> was a supremely sound reason for it. I used exactly the same argument to my
> foreman that the bushings were strong enough to take the temporary
> additional local load.
> It elicited the response, quote "don't bl***y argue! The bushings are for
> DIFF load - NOT for jacking! If you jack the car, you use a *#%! spreader"
> I was then shown a grubby page from an Engineering Procedures Manual.
> While I can't remember the verbatim transcript, it was to the effect that
> "no car is to be lifted using a jack directly imposed on the differential
> housing of vehicles fitted with independent rear suspension. Such
> initiatives impose unnecessary loads on the differential housing and their
> related mounting accessories."
> I suppose I should have remembered the exact wording because apart from
> losing my bonus for the week, I had to write it out 100 times - in true
> schoolboy fashion.
> >When it's an issue of how to pronounce tomato or potato, feel free to
> >leave it alone. But when it's an issue such as "using gasoline as a
> >cleaner", or in this case, the safe-lifting of a Triumph, please join in
> >with a voice of reason.
> Is this an adequate voice of reason?
> John Macartney
> Now in the same museum as the cars he sold when they were new