Braking shimmy

belle34, Nov 13, 7:43pm
wondering what would cause the sensation like unbalanced wheel when braking under load., as when braking going down the steep hills outside of Dunedin. with ordinary braking on the flat doesnt cause it.
1badbox, Nov 13, 7:46pm
front brake rotors need replaced.
sr2, Nov 13, 7:56pm
Not necessarily. If they are within spec they may just need a skim, a very quick job with an on car disc grinder.
franc123, Nov 13, 8:44pm
Get the brake rotors checked and measured, one of the above suggestions will need to be carried out depending on how worn they are. Sticky calipers causing partial binding of the brakes (and therefore subjecting the rotors to more heat build up for longer) will aggravate the problem, its possible for both front and rear brakes to be affected. Get it all checked properly.
kazbanz, Nov 14, 6:13am
belle my. What is the hear/make/model?
Some cars are known for warping disks when they get hot.
whqqsh, Nov 14, 6:58am
most models these days discs are cheap, it's hardly worth skimming, for a few extra dollars go new. Especially as some skimming firms want you to have the car jacked up & wheels off anyway, or they charge extra.
sr2, Nov 14, 7:21am
If you replace the rotors you'll still need to jack the car up and remove the wheels?
intrade, Nov 14, 7:27am
braking shimmy is caused by worn shockabsorbers, that tv add is actuarly not fully bullox like most tv ads about worn shocks and stopping distance . paired with severly worped discs could lead to what you would call braking shimmy
intrade, Nov 14, 7:38am
do the bounce test on shocks to see if nothing is there it will bounce 3 or more times should bounce 1 and a half time maximum on front shocks.if ok-ish
this video is correct bounce test tests for fully dead shocks and if you get the shimmy from braking i would guess shocks are probably dead .
https://www.youtube.com/watch?v=BiW0ISi8N-w
mals69, Nov 14, 7:56am
Would make sense your deduction with more weight being on the
shocks going downhill - still the King round here !
whqqsh, Nov 14, 7:58am
but why pay 3/4 the cost of new getting old ones skimmed if half the work is already done?
pandai, Nov 14, 8:22am
How much is a set of discs? My discs were $28.75 each to machine on the car, new parts quoted at $190+gst each
rsr72, Nov 14, 8:37am
. and/or worn tie-rod bushes.
whqqsh, Nov 14, 9:00am
I got quoted 120-160 for the fronts alone (mobile service with car jacked up & wheels off) $200 a pair new, Brembo from Autostop
belle34, Nov 16, 8:17am
thank you all for your help, will drop off at workshop this week. It is an au Fairmont. the shocks are ok,
scuba, Nov 16, 12:54pm
If you do any towing get quality pads and make sure you bed them in properly. hell. do that regardless, cheaper in the long run
kokako14, Nov 16, 1:45pm
Had a rental car that did this a couple of weeks ago, took it back to the company and simply advised by the lady in the office I should be changing down gears when I am going down hills. It was an automatic, never knew that.
After some discussion, they agreed to give me another car. I told them they should service their vehicles
aj.2., Nov 16, 2:11pm
Automatic driver here, and yes going down hill , switch off the overdive, helps give a bit of engine braking, and if on very steep down hill , go to lower gear.
That way you don't ride the brakes so much.
I have seen smoke pouring out of one tow wagon with a heavy boat behind it, I was sure glad he was in front of me. Did not want him to follow behind , then come crashing into me.
But brake Shimmy is just that , out of true bake disc. and worn pads as well.
kokako14, Oct 9, 12:12pm
Bit hard to select a lower gear when you only had the choice of P - R - N - or D.