Bud wrote:
>As Ed McMahon used to say "You are CORRECT sir!"
>
>I looked in my old 68-76 manual for 510, 610 and 710 and it confirms
>exactly what you said. I had a 1972 510 wagon and I could have sworn it
>was IRS (and have probably claimed it was to Lee Janssen) but after
>looking at the book I realize how flawed my memory is. I have the
>article that spurred the search for the 510 springs and they erroneously
>refer to the springs as being from a wagon...makes it hard to find them
>when they don't exist. Some guy from Wisconsin bought that wagon from
>me at 10:30 at night on his way through town, gave me cash and was
>driving it home by 11:00. He said he and other racers like them because
>of the dual point ignitions, but I think they were also just great
>little machines.
>
>The pictures in the manual show a semi trailing arm independent rear
>suspension (sedans and hardtops) that looks amazingly like the rear
>suspension of the TR6 except that it uses tube shocks. I mean it looks
>like you could weld a TR6's frame members right to that Datsun rear
>suspension.
>
>This might support some of Keith Ehrlich's recent research which favored
>tubes over levers for handling since the 510s sedans were famous for
>their handling. Of course they had McPherson struts on the front which
>helped too.
That was my recollection as well, that the wagons were solid axle with leaf
springs. I had several buddies that autocrossed 510's and 240Z's and
during that time I became nearly as familiar with "dimers" as I am with
TR6's. 510's are capable of impressive feats of roadholding, and yes,
their rear suspensions are virtually identical in concept to the TR6. The
semi-trailing arms are fabricated out of steel, not aluminum, and you can
unbolt the axle shaft from both ends, leaving the hub where it belongs, in
the semi-trailing arm. The coils are situated in the semi-trailing arms
just as a TR6 and the spring is controlled by a tube shock.
Racers elongate the holes in the trailing arm brackets to allow adjustments
of camber and toe. The outboard bracket gets "slotted" horizontally for
toe and the inboard bracket gets a vertical slot to adjust camber.
With regard to the tube shocks, before you are tempted to use the 510 as an
"example of a TR6 IRS with a tube shock conversion," the shocks on a 510
have an eye mounting on the lower end and a stud mounting on the upper end.
The stud that the lower end of the shock fits onto protrudes out of the
semi-trailing arm at a curious angle. The axis of that stud, and therefore
the axis around which the shock rotates as the suspension moves through its
designed arc is parallel to the pivot axis of the entire semi-trailing arm.
Actually, the way it's designed allows very little angular displacement of
the shock, if any. Rather, it's more a matter of the semi-trailing arm
"rotating" in relation to the shock. The point is, engineers DESIGNED it
that way. And it works.
Due to many constraints and obstacles, it is not possible for us to
engineer a conversion to fit a TR6 that takes all that into account.
Whatever folks have come up with in the way of a tube conversion has
emulated the position of the 510's tubes, but if you limit your thinking
along those lines, you will NEVER end up with a tube shock kit that is
really worth a damn.
There IS another answer...
Have you ever looked real close at the suspension on a formula car?
Food for thought.
Pete Chadwell
1973 TR6
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