[Roadsters] Rx7 rear end issues ...edited

[Tim .]

If this was actually too much pressure in the line not being released, wouldn't one expect both rear brakes to be affected?

In my case, only the RR is rubbing. Also, I ran the caliper piston all the way back in and have not touched the brake pedal at all.

tim
________________________________
From: futofab <futofab at gsinet.net>
Sent: Wednesday, September 17, 2025 7:04 AM
To: Tim . <tims_datsun_stuff at outlook.com>; Datsun Roadster List <datsun-roadsters at autox.team.net>
Subject: Re: [Roadsters] Rx7 rear end issues ...edited

Check your master cylinder. The large nut on the underside of the duplex brake master, where the brake line attaches, houses a pressure releif valve.

If you have a pressure relief valve for the drum rear brakes, they will maintain about 10psi line pressure when the brakes are released. This may be causing the pads to stay in contact with the rotor.

This is something the 510 owners deal with when converting to rear disc brakes. Typically they remove it or swap in one from the front disc brake circuit which is 2psi.

On 510 disc brake swaps, the brake master from a 79-80? 280ZX is typically used as it is for 4 wheel disc brakes.

Dave Patten
Futofab LLC



Sent from my U.S.Cellular© Smartphone


-------- Original message --------
From: "Tim . via Datsun-roadsters" <datsun-roadsters at autox.team.net>
Date: 9/16/25 6:55 PM (GMT-05:00)
To: Datsun Roadster List <datsun-roadsters at autox.team.net>, "Tim ." <tims_datsun_stuff at outlook.com>
Subject: Re: [Roadsters] Rx7 rear end issues ...edited


I believe I have the rear end from an 82-83 Rx7 with disc brakes and LSD.

I re-built my drive shaft and got rid of the noise I heard with no wheels or brakes mounted (and the car running in gear). Third member bearings and axle bearings spin nice and smooth. I've been told that the axle bearings were replaced by the person who customized this rear end for the Roadster.

With the car on jack stands, I re-assembled the brakes, hung the wheels and ran the car (still on jack stands). I immediately heard a rubbing noise coming from the RR. The noise went away at higher RPMs but there was still something rubbing that caused the rotor to get so hot I could smell it.

Pulled the wheel back off. Brake pads have a little play as does the part of the assembly that holds the piston. Nothing appears to be binding and nothing is sloppy loose.

Parking brake assembly is (basically hanging) loose and does not appear to be applying pressure to the pads.

WTF am I missing?

Thanks
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