Brake Booster Removal - 73 Twin-Cam Special

[jlmullen2]

Hi Everyone, I have what I hope is a simple question relating to removing the brake boosters on my 73 Twin-Cam. Does anyone have any photos or suggestions on how and where to connect the hard brake lines after you remove the boosters?

In looking over the parts diagram for the dual brake system, I see two lines running from the MC back to the boosters. These are for the front & rear brake systems which then go into the boosters. The two lines then exit the boosters and go to the PDWV (Pressure Difference Warning Valve). The lines exit the PDWV and go to the front and rear brakes. It seems the PDWV is the simplest place to connect the lines which went to the boosters. Is this correct or is there a better way to do this?

Thanks

[BDA]

I think you're right. The front goes into one side of the PDWV and out to the front brakes. Ditto with the rear. It doesn't matter which one you put where since the m/c bore is the same for both. You will have to know that when you adjust the PDWV (by bleeding the front or the rear) so the light goes off.

I was taught to bleed the brake furthest from the m/c first - which would be the front! 

[Grumblebuns]

Larry,

The boosters on my 73 TCS have been removed by the PO. I'll take a look today and see how he bypassed them. I'm curious myself since I started to remove the boosters on my other TCS 20 plus years ago and never completed the job.

Joji Tokumoto 

[Arizona]

When I removed my boosters I also removed the PDWV. Not sure why I did that but it makes bleeding the system easier. I should have run lines directly from the master cylinder to the front brakes, like the Federal S2, thus eliminating the long run to the rear and back. I guess there's no real reason to do that but it seems a more elegant solution.

[Grumblebuns]

Looking at the layout of the brake lines to and from the boosters,  the best way, in my mind, to jumper the brake boosters is to fabricate new brake lines from the outlet of the PDWV  (item 7) and tie in directly to the female connectors leading to the brakes as Larry proposes. I've attached a couple of illustrations from the parts manual showing the dual system brake system. The second shows the proposed jumpers. I believe that I have the flow path right, if anyone sees any errors please correct me.
 
In the case of my TCS, the PO had run a new brake line from the MC to the front 3 way junction and disconnected the original line running to the PDWV. The PDWV and boosters were removed and a installed jumper from the intermediate connection of the line along the left side rail to the junction with the brake light switch.

[EuropatcSPECIAL]

 
Welcome Larry
all the best
Stuart

[espurin]

Hi,
I temporarily removed Power boosters to rebuild them.  Two brake lines are connected to work.

[jlmullen2]

Thanks to all who responded, it seems I'm on the right track as far as replumbing the system without boosters. After I deal with rerouting the lines and hook them up to the PDWV, I'll be having the original MC sleeved down to retain adequate feel at the pedal.

By the way, where did you get the adapter to fit the original hard line to the rearmost port on the PDWV? I believe it's a 3/8-24 to a 7/16-20. I've looked around and could not find this adapter.

Thanks again foe all the help.

[espurin]

I ordered the adapter to Dave Bean Engineering ( http://www.davebean.com ) four years ago.