how much do rear brakes move on a grocery-getter?

Discussion in 'Wheels, Wings, Mud, and Water' started by chazix, Aug 4, 2017.

  1. chazix

    chazix AK Subscriber Subscriber

    Messages:
    934
    Location:
    Groton MA
    The grocery-getter I have in mind is our third-generation, base-model, automatic-transmission Subaru Impreza. It really is used almost entirely for low-speed local runs. The primary driver, my wife, doesn't do highways, so the car almost never sees speeds much above 40 mph unless I'm driving us on a vacation trip.

    Given that this is a front-heavy car, with (I'm assuming) a front/rear proportioning valve of some kind, is it possible that the rear calipers don't even move under light braking? I'm thinking that the proportioning valve might not reach the threshold of letting fluid flow to the rears.

    As you might guess, my curiosity is prompted by having just needed a comprehensive rear brake overhaul due to the calipers having frozen up.

    (Oh - as you might also guess, we pretty much never use the parking brake.)

    Thanks,

    chazix (a lapsed gearhead)
     
  2. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    31,801
    Location:
    Southern NJ
    Depends on the weight balance of the vehicle but its somewhere around 70% front, 30% rear. Even if you did use the parking brake that doesn't mean the rear calipers won't freeze. The hydraulic piston can freeze independant of the mechanical parking brake bits, especially if you've got the "drum in disc" type of parking brake assembly.

    One thing that really does kill brake parts is moisture in the fluid. Its rarely flushed, and it absorbs water over time. If your calipers are frozen, I'd ask the mechanic to flush the fluid. It has to be bled anyway, flushing it is just an extended bleed to get all of the old fluid swapped out.
     
    roger2, MaxxVolume and stish like this.
  3. MaxxVolume

    MaxxVolume Super Member

    Messages:
    3,513
    Gadget is right on the money....brake fluid (like coolant) should be changed/bled every 2 to 3 years. Brake fluid is hygroscopic (it tends to absorb moisture), and can corrode the brake system from the inside.
     
    roger2 likes this.
  4. HyKlas

    HyKlas AK Subscriber Subscriber

    Messages:
    2,743
    Location:
    SoCal
    The salt on the roads in MA doesn't help either. There's dust boots on the pistons but that isn't a 100% seal...
     
  5. olson_jr

    olson_jr AK Subscriber Subscriber

    Messages:
    12,624
    Location:
    Pilgrim Hills Michigan
    I was doing a Safety Inspection on a car that a customer wanted to buy and found that the rear brake line was rusted out. The person selling the car had bent the line over and crimped it off with a pair of vice grips. I pointed it out and the seller said he had done that over a year before, it was not an issue, but he would fix it if needed to pass an inspection. The guy came back the next day and all he had done was remove the vice grips, pulled the line out of the proportioning valve and put a pipe plug in place of the rear line.

    I told him to go somewhere else for the inspection. But to be honest, when I drove it, I could not tell I only had front brakes.
     
    Last edited: Aug 15, 2017 at 7:32 AM
  6. Shadowdog

    Shadowdog Super Member

    Messages:
    2,396
    Location:
    Flin Flon, Manitoba
    Must have been FWD or a pickup truck as they're so front heavy it makes it really hard to tell. You will if you have to drive it in icy conditions and have to stop going up a hill! Scary if someone is behind you, as just having front brakes going up a slippery hill will do very little to hold you from sliding down the hill. The only thing you could do if you have the room behind you is to get it spun around so your facing down the hill! If it's dry & steep you may have the same issue also. I had a 3/4T truck that would loose a rear axle seal rendering the rear brakes useless so found this out one winter! Brakes were just as good going forward as I never carried much ever.
     
    Last edited: Aug 12, 2017
    roger2 likes this.
  7. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    31,801
    Location:
    Southern NJ
    I lost the rear brakes on my S10 for an unknown amount of time. Not sure what happened exactly but the prop valve "tripped" and valved off the back. I only realized when a safety inspection showed I had no rear brakes. The fix ended up being I had to push the button to reset the valve. It made almost no difference in stopping power or pedal feel. Pickup truck though, unloaded those rear brakes do squat.
     
    John James likes this.
  8. petehall347

    petehall347 the brandy coffee man Subscriber

    Messages:
    23,084
    Location:
    uk.. the middle bit
    now try a motorbike with no rear brake . or a bicycle for that matter .
     
    roger2 likes this.
  9. roger2

    roger2 . Subscriber

    Messages:
    2,895
    Location:
    indiana
    ...on gravel
     
    Last edited: Aug 12, 2017
    petehall347 likes this.
  10. Eric H

    Eric H AK Subscriber Subscriber

    Messages:
    7,095
    Location:
    So. Calif
    I've got a 2000 Civic that's been in the family since new. The rear shoes will go 100,000 miles, the fronts go 15-30k depending on who was driving it.
     
  11. daveg3588

    daveg3588 Toy addict Subscriber

    Messages:
    893
    Location:
    Hamburg, NY
    I'll pipe in having a 2006 Inprezza and a 2010 Forester (119K). In New York road salt, brake maintenance in a must, inspect and lube calipers once a year, regardless of mileage. the 2010 Forester, 5 sp is rear brake biased. Rears only last 30-40 K, fronts 80 K. All wheel drive is 50/50 on the 5sp, 60/40 on the Automatic.
     
  12. gadget73

    gadget73 junk junkie Subscriber

    Messages:
    31,801
    Location:
    Southern NJ
    are the rears considerably smaller than the front? The rear discs on my Towncar are a good inch smaller than the front, they are solid vs vented, and its a single piston caliper vs dual. Pads are thinner and smaller as well. I'm getting some squealing lately and I just had the front brakes apart 2 weeks ago to inspect. All thats fine, guess its time for a gander at the back brakes.
     
  13. chazix

    chazix AK Subscriber Subscriber

    Messages:
    934
    Location:
    Groton MA
    FWIW, I didn't feel any lack-of-stopping-power discomfort when our Impreza's rear brakes were severely dysfunctional. Scary noises, yes! (As perceived from the driver's seat, I thought the noises were coming from the fronts. There go my AK "Golden Ear" creds.)
     
  14. Hajidub

    Hajidub AK Subscriber Subscriber

    Messages:
    4,166
    Location:
    Colorado Springs, CO
    My Honda get's 100K out of the rears and 75K out of the fronts. Of course I drive a MT and downshift a lot. Have replaced pads once since new 2005. BTW, normal braking is 65-75% fronts. Your rear calipers sticking could be due to a ton of things. Brake fluid, MA weather, car sitting with parking brake on for extended periods, mileage vs. last break job.
     

Share This Page