924Board.org

anthonimartini · Joined: 17 Feb 2020 Posts: 240 Location: portland oregon

i just acquired a complete 1980 NA with the m471 5 lug brake system that i intend to swap into my 77 martini. but im unsure of which master to use. my 77 master works great so id like to use that to keep it simple and cheap. i have no idea the condition of the 1980 master and i dont really want to spend 200 bucks on a new one if i dont have to. i did just rebuild the entire car. so im bled dry on funds.

i was planning on using the 5 speed with lsd in my martini as well but the guy delivered the 1980 on a dolly and left it in first gear..... the input shaft and torque tube sheared off....
_________________
ive saved alot of 924's
current:
79 MochaSchwartz 931
83 944
87 924S
Instagram @anthoni.jpeg
formerly known as turbellion, lost password.

!tom · Posted: Thu Aug 06, 2020 4:26 am Post subject:

You should be fine using either master cylinder. Just make sure the brake routing matches the master cylinder you use.

Early cars connect the left front / right rear to one chamber in the master cylinder, and the right front / left rear to the other. Late cars connect the left front / right front to one chamber and the left rear / right rear to the other.

The cars that came with the fronts connected together and the rears connected together have different volume capabilities for the fronts vs. the rears, and won't work correctly if plumbed directly to a car that originally had the other system.

So, the arrangement needs to follow the master cylinder. So, if you keep the same master cylinder, you don't need to do anything on that end; just swap the brakes (plus spindles up front, and backing plate and E-brake cables on the rear).
_________________
78 924 NA
5-lug