Are there any Howrse hacks that will get you free passes without downloading?

Unfortunetly, No. None have been successfully recorded to hack through Howrse.com and still continue to play.

If you do find a hack, it has been proven that within 6 hours, Howrse will either sanction you or delete your account due to hacking their system.

(They have a hack tracker)

This is for the good on Howrse, if there was a safe and non downloadable hack, everyone would be using them. No hack is safe.