Power brake conversion in 1973

porsche735 · 02-23-2010, 02:29 PM

I am planning a power brake conversion for my 1973 911. I have all the necessary parts (new footwell sheetmetal, new pedal cluster, linkage, power brake unit). However, the question I have is "do I need to run a new tunnel line for the vacuum?" There are currently 4 lines in the tunnel, 2 steel lines for gas (1 larger than the other) and 2 other aluminum lines. Can I use one or 2 of those aluminum lines? I don't recall what they went to initially (probably some sort of emissions thing as mine is a 73.5). How are folks doing this?

Thanks in advance for your help!

Chris

E Sully · E Sully's Garage

You really should run a new line in the tunnel. It Is not hard if the tranny is out, but tough if it in in. I would not recommend using the fuel vapor lines. They are not just for emmisions.

zotman72 · 02-23-2010, 03:34 PM

Why would you want to do this task? The '73 has excellent brakes and if you have 3.5 spacing struts, your original master cylinder has no problem with pushing down SC brakes. I did the conversion two years ago for my '74 PCA racecar so I could be technically in class with SCs. It a royal PITA task. The car was not safe either at threshold braking. That said, I used the heater channels to run the vaccum hose to the booster. But then, I did not have heat. Good luck and YMMV.

porsche735 · 02-23-2010, 03:35 PM

Does anyone have a picture of the line at the front and rear of the tunnel? What ID/OD is it? So, there are 5 lines in power brake cars?

Thanks,
Chris

porsche735 · 02-23-2010, 03:39 PM

I have installed 944 turbo front brakes and Carrera rear brakes. I have been told that for enduros, it is VERY helpful to have the power brakes. I have the body all apart right now and am already replacing the front floorpan so I can get in there now. I just need the specs, or I guess I can just put in a line and figure out the plumbing later...

Chris