Chassis Reinforcement V 1.2

[Rabbit16v@attbi.com (Rabbit16v)]

I am considering doing this also in my MK1 project.  I would like to go from
the strut towers through the firewall and in between the doors and seat
somwhere in the armrest area.  Or, as I am thinking about this, tie it into
a 4 point rollbar by bringing another bar across the roof line at the upper
door jamb and down the a pilar to the floor after switching to about a 45
deg angle after clearing the dash (going downward).  Then the bars through
the firewall can hook to these bars.  I'd also like to tie the rear 2 points
of the 4 point bar into the rear shock towers.  I think this would make the
MK1 nice and rigid, and sturdy enough for about 250hp with a quaife and
slicks.  There would be a bar the goes between the two bars right behind the
front seats but I am thinking I need another bar between the two coming from
the strut towers.  Of course there will be a strut bar (upper and lower and
rear upper) so maybe I won't need the front bar.  If it is setup up this
way, then the crumple zones would still be there from the strut towers
forward and the shock towers back.  I want to do this once so that if I
decide to go with more hp (20v!!!) I won't have to go through the car again
and reinforce the chassis.  The car will be ran on the strip and weekender
driving.  I'm planning on doing most of the work myself and would like to
get a good idea of what diameter of pipe to use.  The motor is a 2.0L 16v
shaved (40thous) 2.0L head, ported, polished, new valves, HD springs, 268
cam, balanced bottom end with lightened flywheel, AGB trans with quaife,
bolt kit, etc. and a 50ish shot of nitrous.  I will start out with the 88
Scirocco car harness striped down to the necessities of a 78 MK1 and a
chipped motronic setup.  I think the updated harness is a really good idea
since the wiring in most MK1s are not too good (and I'm not a fan of the
older fuse boxes) and that it would create a good solid base to upgrade to a
stand alone system in the future.   I don't know what type of problems I am
going to run into and I may just scrap the idea of the half cage all
together but I think after hearing about others twisting their car with
250ish hp that it would probably be a good idea.  Especially with how hard
it is to find a good MK1 these days!

As far as the vectors are concerned, if the motor twists at the axis, and
the axis being the passenger and trans mounts, then isn't the stress put on
the area between the strut towers and the firewall?  Isn't this where a lot
of the cracking begins on the MK2s?  Well, that is what my logic tells me
but I may be wrong.  If anyone has any ideas or help, please LMK as, for the
most part, this project won't be started until at least February.

Dave

----- Original Message -----
From: "Scott F. Williams" <sfwilliams@comcast.net>
To: "Josh20V" <mkii@nycap.rr.com>; <scirocco-l@scirocco.org>
Sent: Tuesday, December 24, 2002 12:19 PM
Subject: RE: RE. chassis reinforcementv.1o1


> > But bringing the tube through the fire wall, running it on the
> > floor past the seats, up into the rear of the car where you have
> > a hoop (along the lines of a normal roll bar), and it all ties
> > into the rear shock towers = still not a good idea.....because?
>
> <armchair mechanical engineer mode on>
> I don't really think there's any danger with this set up. However, I don't
> see how it is going to protect your chassis from stress induced by the
> engine's torque. Think about how the engine is mounted. The engine rotates
> forwards and backwards about the axis created by the side mounts, right?
> That's why A1s with big power tend to rip up the rad support and the rear
> transmission mount.
>
> Meanwhile, the thrust vectors would travel parallel to the direction of
your
> proposed chassis reinforcements. So, what would you be protecting? Your
> tubes would help a little bit with impact-related stress, though.
Torsional
> stiffness would not likely be increased much, however, because the tubing
> would not be boxed together. Rather, you'd have long cantilevers which are
> easy to distort.
>
> For what it's worth, I should have around 300hp between my engine and a
> 100shot of nitrous. All I'm doing for the time being is the Ron
> Wood/Potterman/Neal Tovsen/vaporware rad support brace and I'm not
> particularly worried about it at all. I'm also depending on my progressive
> nitrous controller, minimal tire traction, and driving technique to not
> shock the driveline too badly. You've got turbolag to "help" you out.
> </armchair mechanical engineer mode off>
>
> P.S. If you're this concerned about the power turning your car into a
> pretzel, what are you doing about your transmission? That'll be the first
> thing to break, methinks.
> --
> Scott F. Williams
> NJ Scirocco nut
> '99 Subaru Impreza 2.5 RS
> Mazda 323 GTX turbo "assaulted" vehicle
> Golf GTI 16v "rollycar"
> ClubVAC: "Roads found. Drivers wanted."
>
>
>
> _______________________________________________
> Scirocco-l mailing list
> Scirocco-l@scirocco.org
> http://neubayern.net/mailman/listinfo/scirocco-l
>