Contractions vs. full forms...

[Douglas Bigham]

Can anyone direct me toward research concerning the grammaticality of
contracted forms vs. full forms?  For example:

There's two white cars in my yard.  vs. *There is two white cars in my yard.
?I suggest that you're early tomorrow. vs. *I suggest that you are early
tomorrow.

Of course these are non-standard for "There are two white cars..." and "I
suggest that you be..." but the contracted forms are also acceptable to my
(and alot of people's) ears while the full forms are not.  So, yeah, has
anyone worked on this before?

-dsb
Douglas S. Bigham
Southern Illinois University - Carbondale