First highway run... brakes shake BAD when stopping

Discussion in 'The whoa and the sway.' started by BamaWildcat, Mar 26, 2005.

  1. I've been re-habbing my parents old car that didn't move for 10 years. I've been through a bunch of problems, but I finally have the car to what I thought was a driveable state. Driveshaft fixed, motor tuned good, insured etc.

    The last time I drove the Buick on the highway (Jan), I found out I needed driveshaft work, and the brakes pulled to the right. Because of that, I went through the whole brake system. I have a new Master Cylinder, rebuilt every wheel cylinder, and installed new brakes shoes in the rear. The front shoes were in good shape.

    So now, I do not have a pull to the right after all that brake work, but I do have a bad shake when I brake from highway speeds of 50-30 MPH. It doesn't seem to come from any one wheel, and was so bad my dash ordament (a little plastic bobble dog) was vibrating all over the place.

    I would like any suggestions of what could cause this bad shake. I did have an issue with my new rear shoes making the drums way tight, but I thought I cured that when I loosened the e-brake cable. The drums were visually inspected by Meineke but not turned or measured.

    Any tips?

    Thank you!
     
  2. BadBrad

    BadBrad Got 4-speed?

    I'd say the un-turned drums are suspect. No way a visual inspection by shop monkey will guarantee a round drum. Maybe the dude was hungover.
     
  3. 45569Skylark

    45569Skylark Well-Known Member

    It doesn't seem as though you have front disk brakes. On cars with disk brakes shaking usally means warped rotors. I haven't delt with drum brakes in awhile. It is possible the drums are warped causing the vibration during braking. Maybe someone else will have a different idea.
     
  4. sbbuick

    sbbuick My driving scares people!

    I had a '61 LeSabre that had warped drums. They were so bad that the car wouldn't stop well at all. You can't visually inspect drums!
     
  5. Truzi

    Truzi Perpetual Student

    Could be that bobble dog is bad juju.

    Seriously, though, have the drums turned. Its cheap. If they are out of round, the brake shoes/pads are in effect grabbing tighter at times, not so tight at times b/c they are expecting a nice consistent surface.
     
  6. 1979SHX

    1979SHX derevaun seraun

    You mentioned the e-brake cables being too tight....better check those drums. Probably warped.
     
  7. Keith Seymore

    Keith Seymore Well-Known Member

    You can also separate the front from the rear to help isolate the problem.

    Make a stop using the emergency brake only to see if its in the rear brakes.

    Use a pair of vise grips to pinch off the rear brake hose (above the rear axle) and see if it is just as bad with the front brakes only.

    Naturally, you'll want to do this somewhere where there is not a lot of traffic!

    K
     
  8. I dropped the Wildcat off at a tire/brake place today for them to take the reigns of my brake problem. This is not the place that "visually inspected" the drums, so maybe they can fix it. :grin:
     
  9. 1979SHX

    1979SHX derevaun seraun

    Be sure to let us know what he found.
     
  10. Here is what they found...

    The new tire place called me and told me my rear drums were both warped. I think the guy said they would wobble like an inch or some arbitrary measurement.

    I took them the rear drums off my parts car, which were a PITA to get off... reminder: do not park a parts car 1 foot from a building if you ever plan on working on that side. :rant: They turned just fine and once placed on the good car, he came home.

    Before the brakes ever shook, they pulled to the right. Once the store got the shakes out of them, I had them go down that path. They just pulled the drums off, inspected everything again, said it was safe, and that the tires and suspension were "tight." Since I have new hoses, booster, and master cylinder, I have decided to put new wheel cylinders on the front. I rebuilt my wheel cylinders all the way around, but some had pitting, and I honed them (lightly) which the book says is a big no-no. So this week on go the new front wheel cylinders.
     
  11. 69LARK455

    69LARK455 awww sheeeiit!!

    my old truck used to shake like crazy and pull to the left when I stepped on the brakes, had a warped left front rotor that I just never bothered to replace...
     
  12. New wrinkle

    Today I found a new wrinkle, maybe even my problem.

    I installed my brand new Bendix made in the USA front wheel cylinders and went out to see if that fixed the problem. I have basically put on a brand new brake system except for springs, front shoes, and drums. The drum have been turned.

    Using my in-laws gravel driveway as a skid-pad, I tried to get it to pull to the right. I stopped hard, and walked out and four four skid marks in the gravel. Stop moderately, and notice my right front tire leaves a skid mark and others do not. Do this again and again, and notice a pattern. Braking at the same speed on the gravel as the highway makes the front right leave a skid.

    This leads me to believe I have some sort of adjustment problem on my right front side so it is braking stronger than all the others. I adjusted both wheels with the adjuster until they had even drag, but is the self adjuster mechanism suppost to limit the adjustment wheel to a click at a time?

    My self adjust actuator sits about 3/16 above the star wheel with no contact. Is that right?
     
  13. 1979SHX

    1979SHX derevaun seraun

    The adjuster needs to be in constant contact with the star wheel. Otherwise, it won't hold its adjustment and will keep tightening up. Sounds like you found your problem.

    It could have been bent easily when the brakes were taken apart/replaced.

    Reid
     
  14. nailheadina67

    nailheadina67 Official Nailheader

    Shaking while stopping can be amplified by loose front end parts.......particularly rubber bushings and center link. I've had warped drums on mine in the past and they will pulsate but they never shook the car. Be careful having them turned.......if they take off too much, they will warp again as soon as you heat them up. If they are oversized more than .050" at the very most, expect them to warp again. :bglasses:
     
  15. If you are bored this weekend, or just a board fanatic, check out this short movie of my shoes pushing out and see if anything looks wrong to you. It can't hurt to ask.

    Link
     

    Attached Files:

  16. 462CID

    462CID Buick newbie since '89

    It doesn't look out of the ordinary to me, Joe

    But a word of warning- you can pop the pistons out of a wheel cylinder doing that. Without the drums to resist the shoes, they can go too far

    On car that sit for so long, I'd have the brake fluid changed- not topped off, completely removed and replaced with new fluid
     
  17. Found the problem.

    I CANNOT believe I overlooked it so many times. :Dou:

    When I installed new back brake shoes, I had no idea there was a primary and a secondary shoe until Joe Naab pointed it out. From that point on, I "knew better". Since I started rebuilding the brakes, the car pulled to the right. To try and correct the pull, I replaced about every part in the front except for the shoes because they looked brand new.

    I've been racking my brain over this pull for way too long. Since last week, I've had the car on jackstands so I could try to lick this. I've had the car down to a brake place TWICE. Today I happen out, and pull the hub. I look at the guts for the 400 millionth time, and you know what I notice?

    The right wheel has two long shoes on it! :Dou:

    No short and long. I look on my parts car, and as it should, it has one long, and one short. So I take the brakes apart, put a long and short on each side, and I think the pull is gone! I will have to test it tomorrow on the highway, but the long driveway test did not result in a pull to the right.

    I am so happy!!!!!!

    This problem has been going on for so long I am glad to have licked it!

    Funny thing was, with all the brake work I did with the fronts (new hoses, wheel cylinders, turning drums), I never mixed the parts left to right. That means the previous owner put the shoes on wrong (longs on one side, shorts on the other). Geez, who would do such a thing?

    My father. :laugh: Now ya'll remember I didn't know that there were primary and secondary shoes, so I guess I know where I got the lack of knowledge from. :pp

    I am truly happy.
     
  18. r0ckstarr

    r0ckstarr Well-Known Member

    Congratulations. Glad you found the problem.

    Cool video too. I was always told not to work the brakes until the drum was on, so ive always wondered what it looked like inside the drum. :TU:
     
  19. Brian,
    I had known of the caution not to pump the brakes with the drums off, but since I had the help of a monitor hooked to my camcorder, I could see when to stop. :laugh: I never did push the brakes to the floor, just enough to see the mechanism working.
     

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