Just replaced the rear brake shoes with the result of vibration at 50 to 60
mph which was unrelated to braking or the transmission where I'd like to
learn from your experience what happened.
Balance: Backoff: Adjust: Assemble: Gray Paste: =========================================== 1. Replaced just the brake shoes and tested at 50 to 60 mph where noticeable vibration occurred that wasn't there before the brake job.
2. This noticeable vibration was unrelated to braking events or to coasting
downhill in neutral and was unrelated to road conditions.
3. All four wheels were previously balanced and originally put back in
their original position after the initial repair as were the drums.
4. All six lug nuts on each wheel were torqued to 84 foot pounds using the
classic star pattern. A thin coating of old (partially congealed)
never-seize was applied to the rear hub to drum mating surface.
5. The main deviation from factory protocol was the common practice of
adjusting the star wheel to the shortest position so that the drums go on
easily and then lifting up on the emergency brake handle about a hundred
times to adjust the parking brake to 7 clicks.
6. After an 18-mile test-drive loop, start to finish, to get to the highway
and then to the first exit and back where half was highway and half were
local roads, both drums "sizzled" a wet fingertip, perhaps the driver side
drum more so than the passenger side drum.
7. The brake shoes had a gray pasty appearance, almost of leaking oil but
no oil leaked on the brake shoes.
A. I rotated the tires front to back but they were balanced before so I
don't see how that mattered afterward.
B. I very carefully torqued the six nuts on each wheel to 84 foot pounds,
in a star pattern, with plenty of banging on the wheel assembly to jostle
the seating position, although they were previously torqued to 84 foot
pounds so I don't see how that mattered afterward.
C. I visually inspected the u-joints, wiggling them by hand, but I did not
feel more than about a half millimeter or so of movement, but I don't know
how much they're supposed to move - but they didn't change anyway.
D. I visually inspected the front and rear brakes, where no visual anomaly
was seen, and wiped some of the never seize off, but it was a very thin
E. The only procedure I did very differently was that I explicitly followed
the factory protocol for adjusting the brake shoes just prior to the drum
replacement which was to mic the drum and mic the shoes and set the star
adjustment to 1/2 mm (20 thousandths of an inch) smaller than the drum
F. I also left the parking brake adjustment loose at about 8 or 9 clicks
instead of the 7 clicks (it still held the car on a hill but not as firm as
did the first adjustment if the car was previously moving).
The procedure above "solved" the vibration problem.
The job is done but I would like to learn more about changing brake shoes.
Do you have any idea what specifically had caused the vibration?
- posted 2 years ago