While I don't have any problem with mounting the roll bar to the shelf with
backing plates, whoever owned my parts car decided to weld the mounting pads
to the rear shelf. Bad idea. The welds probably made the bar very solid
for some years, but by the time I got the car the welds had rusted and the
bar could almost be ripped out by hand. In fact I did remove some of it
without cutting any metal away by ripping it out.
I have never gone as long as I have with this car without installing a roll
bar in any of my Fiat or Datsun roadsters. I often wondered what good it
would do in an accident, and can see the very good logic on the fact that a
roll bar that will go under your soft and hard tops probably won't protect
your knoggin in a roll over accident. It might help to keep a high 4WD
bumper from hitting your head as hard as it might should one rear-end you.
I had not considered the side impact issue, but that is an interesting point
if the bar is wide enough.
The problem I have is that I want to use the factory installed mounting
holes and still keep the sliding room for my Miata seats. I know I will
loose some of the seat back movement, but that is OK. I have decided to
build extensions of the mounting plates that are formed to bolt to the holes
behind the seats and follow the shape of the metal from the holes to the top
of the rear shelf and onto the top of the rear shelf. There the bar will be
welded to the adapter/foot. I will add rear braces to fit the 8 attachment
holes per side at the rear of the shelf and a horizontal bar with threaded
inserts for the shoulder harnesses. In the end I suspect the only part of
the roll bar from my parts car that I end up using will be the heavy round
bar itself. The rest will be ground off and tossed out.
The best use I ever found for the roll bars was that they made it very easy
to push the cars around if you did not want to (or could not) start the
engine for a short move, or while adjusting valves. As I remember they were
also useful for holding 25" color TV picture tubes (in the box) between the
windshield frame and the roll bar.
Tom
69 2000 - Mr. Hyde
Portland
http://www.datsun2000.com
-----Original Message-----
From: owner-datsun-roadsters@Autox.Team.Net
[mailto:owner-datsun-roadsters@Autox.Team.Net]On Behalf Of Richard Hugi
Sent: Friday, January 14, 2005 2:56 PM
To: datsun-roadsters@Autox.Team.Net
Subject: RE: Roll Bar Question
Geeeze, I know I'm gonna get in trouble with someone here, but who can
predict what kind of accident that might happen to them? I think that
bolt-in roll bar offers protection to some degree, but there are so many
variables involved. It might be as strong as a hard top on a car, the
failure will most likely not occur in the connection, remember, the bearing
points are only as strong as the metal it is connected to. If your 40 year
old chasse is suffering from metal fatigue there would be no way to predict
what would happen. I would expect that "welded-in" backing plates would
increase the area that experiences the trauma. And don't forget, one thing
that I've seen the most failures with at the track is in the seat
connection. Too many people neglect that assembly. There are only four
1/4" studs holding in your seat, and in a violent rollover can leave your
body flailing about with the weight of you strapped in. My track car has
3/8" bolts into 1/4" steel reinforcement plates welded to the cage. A
harness does little good in a rollover if your seats aren't an integral
unit.
Richard
2 years Formula Dodge "Wheel to Wheel"
3 years street stock CSRA "door to door"
3 years open track Trans Am Replica
1 Really nasty roll that left me with having experimental spinal surgery and
ended my career as a Furniture Maker. Yes, Weld those Roll bars to the frame
otherwise tuck your head down between your legs and kiss your ass good bye
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