ebodyboy

!984 SE - - Fresh fluid every 2 - 3 years and only 56k miles. No issues first 35 years. Parked last 5. Lifted front wheels to remove for quick checkup. Very difficult to rotate both. Right barely with one hand - left barely with two. Changed fluid and bled lines - - as usual. Test drive around city for about 15 minutes with lots of accels and brakes. Got back and checked wheels for heat. Very hot at left side and quite hot at right. I knew it would still be an issue as car slowed rather quickly when foot off accel pedal. Ideas? Calipers? Master C? Prop Valve? Front hoses? etc? Should point out that rear brakes not dragging - and - no trapped line pressure, so, I am leaning towards bad front caliper seals. Anyone else experience this?

KansasCityREPU

iTrader: (9)

When was the last time the rubber brake lines where replaced? The rubber inside the line collapses/restricts. You won't see it on the outside. What happens is that the pressure from the master is great enough to push the fluid to the caliper, but there is very little pressure to have the caliper release. This causes the pads to stay engaged with the brakes not pressed.

peejay

Any time I had issues with RX-7 front brakes dragging, it was because of rust buildup in the caliper bore, between the dust boot and seal.

The fix is to remove the piston, dust boot (little clip holds it in), carefully remove the seal without damaging it, and clean out all the rust from that area with a.die grinder. The hardest part is reassembling it, because you have to install the seal and dust boot first, then try to get the caliper piston inside the dust boot. Compressed air to blow the seal open and over the piston is very helpful but it can be done without.

I have never actually replaced the seals, I reuse them.

peejay

This is easy to diagnose... open the bleeder screw, if that releases the brake, then the problem is either hoses or improperly adjusted master cylinder.

There should be a little free play at the pedal pushrod, should be able to wiggle it. Checking the brake booster adjustment is trickier. After verifying that it isn't the easy rod to get to at the brake pedal, you loosen the master cylinder from the booster and see if that frees up the brakes.

All assumes that opening the bleeder released the brakes in the first place.

LongDuck

Piston and caliper bores are rusty, most likely. Rebuild front calipers and you're good for another 40 years. Highly unlikely to be lines, Master Cylinder or proportioning valve. These cars are not that complex. You might also check your wheel bearings to be sure there's no slop or play. Sitting for 5 years is likely to show problems with rust welded parts that haven't moved in awhile.