Since nobody else has jumped in, I'll give my two cents worth. I believe my vacuum wipers use 1/4" on my only car with them. I don't have a booster on any old vehicles now, but I seem to recall that the hose was 1/2" or so. I do remember a shop bulletin saying never tap into brake booster line to add a vacuum accessory. Safety first! smile

Last edited by 40casey; 09/02/2012 9:28 PM.

1940 Chevy 1/2 ton pickup "KC"
A day without sunshine is like, well, ..... dark!