I just moved to delaware from philly and when i went to get my 97 cavalier inspected they test the brakes by having you drive onto a grid at 5mph and then have you hit the brakes hard and some how this test the psi of each brake because you can actually see the results on the screen for each wheel. I changed the shoes adjusted them and also replaced both wheel cylinders and I also blead the brakes and found that the master cylinder is sending the fluid back to the rear brakes fine. It failed again. The drums don't look bad so i'm not sure what to do next.

any help will be appriciated.

Interesting to fail before and after?? How much difference did the test show? The new wheel cylinders rule out a stuck piston and they bled out satisfactory you said.

What's missing is what if anything was done to the drums? If they were turned(machined) or even new there is some time before the shoes properly wear into the surface and perform their best -- longer with a turned drum. Both are safe ways and turning is fine if within spec. The return springs are a question if not replaced. The force to return to shoes must be overcome by the fluid pressure and is expected and they should be the same. An old spring could have lost some force and that brake would have more braking force. There is also a question of parking brake being free when it should be free. Cables do get sticky and not return properly and you might not notice but that brake could be warmer and be stronger or weaker depending on the exact circumstance.

There needs to be a break in period for a strict test. It's not fair to expect these new shoes and drums to be peak right away. I don't know how sensitive this test is but it seems like it may be too sensitive or not really getting the whole picture at just 5mph.??

I suppose you should replace the springs if you didn't and look at the shoes and you can see that they are only showing wear at some percentage of the arc of the shoe which should be equal on both sides.

Hey - it's nice to know if something is wrong and I'm sure you want it to be right but again I worry about this test.

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Real Story: My own (I have several of similar cars) 88 Town Car went in for the state's inspection and failed for slightly over on emissions. This was in my sight and we are not allowed to drive the vehicle ourselves for the testing. The tech couldn't get the feel of my gas pedal and I swear he had the car going 100mph on the dyno with no resistance as I could see the tires stretch like dragsters do!!!! He got it to pass and how nice that within a week my back brakes were all screwed up and covered with axle oil (seals blown) that were fine before this freaking test. You should never let a drive wheel go that fast without resistance as it causes problems up to and including blowing up the differential! Thanks a bunch Massachusetts for taking a safe car and making it unsafe defeating all objectives of testing. The tech was about the age of the car and wasn't used to driving a boat and that's the excuse.

I just don't think the system for this is good enough for such a wide variety of vehicles they have to test. What do you do?

T
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Tom Greenleaf - MetroWest, Boston