The bottom plate provides two attachment points for the composite factory front belly pan (or the aftermarket aluminum belly pan) on the later cars.

The plate also provides additional crossmember rigidity which may improve chassis rigidity.

 

I would think the lower plate would add a lot of rigidity to the cross member regardless as to wether the rack is solid or rubber mounted. Without the lower plate the cross member is esentially a C-channel, which will flex much easier then when the lower plate is installed. With the lower plate installed it makes the cross member function similar to a piece of boxed Tubing instead of C-channel.

 

Bottom plate keeps the bolts from rocking. The flange on the edge of the top plate is too small a surface to reliably support the bolts. If they move, you risk snapping the ears off the rack. That plate is also the 'skid plate' for the rack. It keeps the big rocks from damaging that delicate aluminum housing. I wouldn't ever think of leaving that plate out. But that's just me, a conservative retired engineer thinking on the internet.

 

Hmmm...I suppose with the big heavy wheels I have on the '86.5, I might as well put the plate back on.

When I do the lightweight '85, I'll probably leave it off, though.

 

dr bob make a very good and valid point here. especially since you still have the rubber bushings installed not only have you gone from double shear to single shear but with the rubber bushings by eliminating the lower plate you have also put the bolts in bending. I don’t think I would consider running with no lower late with solid bushings much less with rubber ones.

 

OKay, OKay.

I see the light, and will leave them on.

It looks like it's the tie rods which are bad. They aren't too expensive.

 

A very easy solution to fix the steeringrack is the use of conical washers.It´s the simplest way to reduce the play.

 

Conical washers add extra clamping force when the bolts are tightened through the plates, but do they do anything to keep the rack centered on the bolts? Perhaps better bolts and higher tightening torque required?

The currently-available aluminum (or Delrin) rack bushings take minutes more to install. and do a great job of locking the rack in place when used with just a flat washer as a shim. No guesswork, no new fasteners required.