bad calipers?

[Guest 1onesy]

I have a 85 riv with 4 wheel disc and I wasn't satisfied with the braking.So I installed new power boost,master cylinder,proportion valve,rear calipers,bled it and had pressure tested.Still I'm not confident with it.It seems that the front brakes are not grabbing well enough.Should the rear wheels lock up before the fronts do?

[Guest simplyconnected]

Rear wheels do very little brakeing compared to the fronts. About 90% front and 10% rear brakes (like a 10-speed bike). That's why rear pads last so long. The only way to adjust the ratio is with an adjustable proportioning valve (which you probably don't need).

You said they aren't grabbing. What does that mean? Are they spongy (like they have air in the line? Or, do they feel like wet rotors? Do they 'pull' squeal or chatter? Did you break-in the pads yet? Did you change all the pads? Did you mix DOT3 and DOT5 fluid?

Why did you change all those components, were they ALL bad at the same time? The calipers that do the most work, you left alone. We need a lot more info, described in detail.

[Guest 1onesy]

Why do the rear wheels do so little?The car used to be equipped with the hydroboost system which I changed over to the power boost.The hydo's kept going bad on me and they were very expensive to replace.When I swapped it I also had to change the master cylinder because it called for a different one.The brake lines then did not fit into there previous holes on the m.cylinder so I swapped them,does this make a difference?If so how do I get them to fit where they belong?

[Guest simplyconnected]

Is your master cylinder a dual feed? If so, it makes a big difference if you crossed the lines going to the proportioning valve. Brake lines are cheap. If you need a longer one (or both) go to the auto parts store and buy new ones. (Bring your old lines to compare fittings.) They probably have a bending tool they will loan, for free. Brake lines bend fairly easy. Take your time.

Over the years, different cars used hydro (usually powered from the power steering pump). Cadillac used them, so did late model Mustangs (because of space issue). I don't know that it makes much difference which one you use, they both asssist the master cylinder.

Another change; automakers got serious about using metric. Now we have both thread systems at the parts store and they are NOT compatable with each other. They both function equally but separately.

Did you ever pull hard on the emergency brake, going about 30 mph? Even if your rear brakes lock, it still takes forever for the car to stop (compared to using front brakes). The rear wheels drag behind and are incapable of digging-in like the fronts, because of "weight transfer."

Sounds like, when you swapped brake lines, the proprotioning valve now sends excessive pressure to the rear brakes, causing them to lock before the fronts can work. Swap them back then bleed the lines.