churm@ihuxf.UUCP (b.r. churm) (09/03/85)
We have been having a discussion here at my office concerning a problem that some of us are having in the GM A-frame cars. If there is any one out in the net that has had this problem or knows what this is, we would appreciate your comments. Currently there are two cars involved. Both 1982 GM A-frame issues. One is a Buick Century the other a Pontiac 6000. Both have about 30K miles on them, give or take a few thousand. The problem is intermittent and occurs while braking. It occurs under all types of braking conditions. What happens is that when the brakes are applied a thunk, thunk sound occurs from the back of the car. It sounds somewhat like the sound you have when you get a flat tire. The brakes have been checked and are OK, (ie. not enough wear to justify replacement). We are dumbfounded as to what this is and how to repair it; outside of totally overhauling the rear braking system with no guarantee of correction. Has anybody else with the GM A-frame model had this problem? Did you get it fixed and if so what was fixed? Any comments or suggestions on how to deal with the problem would be most appreciated since both cars are out of the warranty period and we would like to avoid any unnecessary expensive repairs. Thanx in advance. Brian Churm ihnp4!ihuxf!churm AT&T Network Systems
clewis@mnetor.UUCP (Chris Lewis) (09/05/85)
In article <2688@ihuxf.UUCP> churm@ihuxf.UUCP (b.r. churm) writes: > >Currently there are two cars involved. Both 1982 GM A-frame issues. >One is a Buick Century the other a Pontiac 6000. Both have about >30K miles on them, give or take a few thousand. > >The problem is intermittent and occurs while braking. It occurs >under all types of braking conditions. What happens is that >when the brakes are applied a thunk, thunk sound occurs from the >back of the car. It sounds somewhat like the sound you have when you >get a flat tire. Are you sure it's the back? Sometimes the noises can be misleading. Have you got disk brakes on the back? Did you check the front brakes too? We had a similar problem on an X-body, and it turned out that the surface of both rotors of the disk brakes were breaking up. The thunks were teeth-rattling. On a rear-wheel car I have, I was getting substantial klunking from a combination of thin rotors (possibly warped) and partially seized pistons. Another thing I can suggest is that maybe something is wrong with the rear axle/bearing assembly. I once had a similar problem on a rear-wheel car, but the noise was more of a cruuuuunch-cruuunnch which we originally thought was brake or differential problems - but, the axle bearings were shot. (you might be able to tell by raising a rear wheel off the ground and trying to see if the wheel will move with the suspension staying still - particularly side-to-side slop instead of vertical) Are the thunks related to tire speed or engine loading? -- Chris Lewis, UUCP: {allegra, linus, ihnp4}!utzoo!mnetor!clewis BELL: (416)-475-8980 ext. 321