Hi
It's not as easy as swapping in a rnp as there are several steering
geometries that need to be taken into account. If one of them is not
right,
you will have severe bumpsteer. Bumpsteer is exactly as it sounds, when
you
go over a bump or hit a pothole, the steering wheel and the car will
violently turn in one direction.
Here's the things to consider:
1. Height of rnp in relation****p to steering arm tie rod end.
2. Fore and aft position of rnp in relation to the steering arm tie rod
end.
3. Relation****p between the rnp rod ends and the front control arms. The
rack tie rod ends must follow the same arc as the front control arms.
4. As you found out, the rnp must travel relatively the same distanct. Not
really im****tant as it just means you have a larger turning radius at slow
speeds.
The biggest problem is that you are working in a 3D space and trying to
find
the sweet spot. I just went through that 5 years and don't recommend
trying
it.
Here's my website that discusses more than you ever want to know about
doing
this on a 54 Pontiac.
http://www.cadvision.com/blanchas/54pontiac/rnp.html
Cindy wrote:
> I'm changing the steering system on my 1948 Desoto Suburban (9
> passenger, 4800
> pound vehicle) from the original pitman arm steering to rack and
> pinion steering.
>
> I purchased a rebuilt back-steer rack and pinion (45" long) that was
> for a
> 1995-2005 Chevy Cavalier or Pontiac Sunfire. I built the mounting
> housing, new
> steering shaft, new power hoses from the pump, and new tie rod ends.
> I still
> have to cut one side of the motor mount (1" x 2") off to make room for
> the
> double D U-joint coupler so the rack can turn (not done yet).
>
> I found the travel on the rack is only 2.5" on each side. This does
> not give
> me enough turning angles on the wheels (I need at least 4").
>
> A couple of solutions I thought of are:
>
> * To get a rack from some other vehicle (maybe a truck) that would
> have more
> then 4" travel on each side. Trouble is - I don't know which trucks
> would have
> this type of rack.
>
> or
>
> * To make a shorter steering arm for the existing Desoto but I would
> have to
> find a shop that could do this and I don't know if this would
> compromise safety
> as the tie rod ends and the rack will carry more stress when
> turning.
>
> Would anyone have suggestions on other ways to (safely) resolve this?
> I can
> email pictures of the steering configuration.
--
Eugene Blanchard
Visit my website Hot Rod Kustoms at
http://www.cadvision.com/blanchas
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