D21 rear brake issues

[RJT]

Hi there.
I'm having some issues with the rear brakes grabbing and wearing the pads prematurely (i.e. 6 months), plus creating a lot of heat which I'm sure isn't great for the wheel bearings..
I did a rear calliper rebuild not long ago, checked it all out last night while replacing the pads and the pistons and slides are all moving freely but they're still grabbing once they're bled.
I replaced the brake master cylinder 6 odd months ago when i changed the pads last, wondering if I didn't bleed that up properly maybe? Braking performance is still fine.
Any help would be appreciated.
Cheers, Rhys.

[derk]

I replaced the brake master cylinder 6 odd months ago when i changed the pads last,

have you checked the pushrod length on the new M/C to make sure there's some freeplay so the M/C piston can return fully

[RJT]

Good point! I never thought of that!
Thanks for that, I'll check it!
Seems it only really started when I changed the master cylinder so kinda makes sense.

[RJT]

have you checked the pushrod length on the new M/C to make sure there's some freeplay so the M/C piston can return fully

Worked a treat in the end, thanks. Still getting a bit hot at the rear end but presuming the wheel bearings are fried.
Just another job to add to the list.

[RJT]

Ok so adjusting the freeboard in the pedal seemed to work but turns out it didn't. Still a lot of drag on the brakes!
I tried adjusting the brake booster pushrod (nearly at min adjust) and has helped a little more but I'm still not happy.
Any other ideas would be greatly appreciated. Getting pretty off it now!
Cheers, Rhys.

[ChurchurDan]

You didnt get a master cylinder for a rear drum brake terrano or navara by accident? They have a residual pressure valve in the rear circuit to maintain a little pressure in the drum brake circuit. This will prevent the callipers returning correctly.

[MihiT]

Do they have a load proportioning valve for the tray? Did you bleed in the correct order (farthest wheel to nearest)?, is there a vacuum leak to the booster? Some crap in the lines (especially if previous cylinder had corrosion in it)?, are your wheel bearings pre-loaded correctly?

Just some thoughts.

[RJT]

Bled Correctly (up until recently was apprentice in motor trade). No blockages as it bled up fine. The previous master cylinder bust a seal, no corrosion. No proportioning valve. No vacuum leaks that I've noticed. No movement in wheel bearings and when rear rotors are removed can easily spin the axles.
It's got me stumped!

[RJT]

You didnt get a master cylinder for a rear drum brake terrano or navara by accident? They have a residual pressure valve in the rear circuit to maintain a little pressure in the drum brake circuit. This will prevent the callipers returning correctly.

Good question that. Though I got the master cylinder from BNT via my rego # so I'd have thought they would give me the right one off that.
It definitely makes sense if that's the the case! Maybe I need to try again with a new master cylinder.
Thanks for that!!!