Datsun Roadster Forum-311s.org

Are your rear disc brakes swap working fine with OE Datsun master cyl? I’ll be using Mustang 8.8 diff with factory discs. I’d prefer to keep the Datsun MC (actually is a new ‘68-‘73 510 MC from Raybestos.

I’m wondering if I’m going to have residual pressure issues with the disc rear and or any issues from the rather small fluid capacity of the Datsun rear reservoir.

All you folks with the RX7 rear end, if you're still using the Datsun MC is your rear disc braking fine?

After way too many years since purchase, I hope to install my RX7 rear end this spring. I'll save this thread and report my findings. (yea, sorry, they won't be the most timely results/reports).

I am sure others will chime in.

From the parts diagram and from personal experience, the RPV is removable and is not required for a disc brake rear: -


P/N 22, 23 and 24

Nissanman, what's RPV stand for?
Interesting!

Residual Pressure Valve.
It maintains hydraulic pressure to rear drum brake cylinders to keep the shoes in close proximity to the drums.

You would want smaller caliper pistons in the rear than you have in the front so that the rears do not lock first (and possibly an adjustable bias valve)

The stock front calipers each have two 2.125" pistons, so you would want calipers smaller than that in the rear. The 3/4" master would be good in that case. I used some ATE rear calipers about 25 years ago that had two 1.25" pistons and they worked fine w/o a bias adjust. (remember the rear of the roadster is light, so too much rear braking effort will lock the rears prematurely-which is not desirable)

If you are using some other caliper in the front, just make sure the rears are a bit smaller as a start.

If the 3/4 bore master is big enough for the fronts, it should work for the rears, but you may need to modify or eliminate the RPV as mentioned above.

In reality, there is minimal benefit to rear discs on a light little Datsun roadster.

JT68 wrote: ↑Sun Mar 10, 2024 9:45 am
In reality, there is minimal benefit to rear discs on a light little Datsun roadster.

one benefit is disc brakes are self adjusting