Kai M. Radicke wrote:
> Brian @ Power British wrote:
>
> > It is quite common for you to not be able to open the
> > doors when the car is completely up on jackstands.
> > The TR-6 is a notoriously flexible chassis and even
> > beautiful, unmolested chassis are subject to the same
> > condition you describe. It will go back to the way it
> > was when back on the ground without any fuss. If you
> > want to close the door completely, jack up from the
> > rear of the car onto the cross-tube where the stud that
> > holds the spare tire comes through. Put a piece of
> > wood on the jack to avoid damaging threads on the
> > stud.
>
> Is there any way to strengthen the TR4A / TR250 / TR6 chassis so it doesn't
> flex and twist as much? And I'm speaking of procedures that are short of
> welding the doors shut Dukes of Hazzard style (although I thought about
> that).
>
> In extreme cases, upon landing of a TR6 back onto earth, the chassis will
> flex so much that the upper tips of the doors will get creased and banged up
> (ask me how I know).
>
> CTM Engineering in the UK < http://ctmengineering.hypermart.net/ > lists a
> reinforcing kit for the chassis, but without diagrams I am wondering what
> areas it applies to.
>
> Cheers,
>
> --
> Kai M. Radicke -- kradick1@ic3.ithaca.edu
> '74 Triumph TR6 -- http://www.pil.net/~felix
Kai,
Unlike the early TR-2/4 chassis, there's little you can do to the chassis of a
'6 due
to the nature of it's design without adding significantly to it's weight. The
weak
spot is in front of the diff, where the frame rails are only 18" or so apart.
Forces
of the springs are transmitted into the rear crossmember aft of this narrow
spot, thus
the rear of the chassis torques around this narrow area and you get a lot of
flexing.
There is much less flex in the earlier 4cyl. TR chassis because the rails are
set
wider apart. The early chassis is not only lighter and less complicated, but
also has
more torsional strength as a result.
To address the problem on the '6, I prefer to reinforce the bodyshell rather
than the
chassis. Looking at the bodyshell, you'll notice that the front inner fender
meets
the top of the rocker box section for about 14" overlap that is spot welded
together
forming a strong section that is very resistant to flexing, but looking at the
rear,
the overlap is only about 4" (9" if you count the triangular gusset). This
area is
very prone to flexing and this is where extra bracing must be added. To do so
is
complex and really can only be done properly when the bodyshell is torn down for
floor/rocker replacement. I like to section the B pillar along the seam where
the
door seal goes and add an inner layer of 18ga. sheet that parallels the rocker
box and
extends both forward along the rocker and up the B post about 12" in each
direction.
The piece should also extend all the way down to the bottom seam of inner and
outer
rocker and back to the start of the rear wheelwell. Add a small (about 2"wide x
8"tall) diagonal piece from the rearmost edge of the new sheet to the backside
of the
B post leaving enough room to clear the flange on the rear fenders. Finally,
box in
the normal triangular gusset by adding another flat piece of 18ga. sheet as a
backer
to close it in completely. This gusset is normally covered by a vinyl piece
with
cardboard glued to one side to fill in the natural hollow of the stock gusset.
You're
simply replacing the cardboard with welded sheet steel. When all the plates are
welded in and ground smooth, you really can't tell in a finished car that any
mods
exist unless you look inside the wheelwell and catch the small diagonal
reinforcement. (Which does a great deal for strength around the pillar, so I
recommend you live with the visual cue it's there.)
While this is certainly a very elaborate repair requiring a fair amount of
fabrication
and metal finishing, you'll be delighted with how much more solid the car feels
and
sounds going down the road.
Cheers!
Brian Schlorff '61 TR-4 '64 TR-4 '72 TR-6 '79 Spit
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