Brake Rod rattle

[3bassets]

I just took my 29 Model A coupe' on a shake down run with my new touring engine. I heard a banging knocking sound and got worried, the faster I went the faster the noise got, the rougher the road the louder the banging. When it was really making noise, I applied the brake pedal under power and the noise stopped. I tried this at all speeds and by applying the brake pedal it stops. Checked under the car and all looks to be in order and brakes are adjusted.

Any ideas?