Steering Shimmy Under Brakes

[klrevo]

hey guys,

had a search came up with a fair few threads, but couldnt reeeeally find anything particular to my problem.

So just an idea on the setup, its a pajero with hilux diff under the front, cheezy five link front with panhard, ifs spacers, and 35"s.

the problem being is that the car drives fine, steers fine, it drives really well on road, EXCEPT for when say coming down a hill you feather the brakes to maintain your speed its gets this crazy steering wobble. this is what iv done so far, panhard is super tight, bushes are fine, theres no play when i check for wheel bearings, the tyres arent that old, like 2000km so were balanced pretty recently. Its done it for a while, was real bad with the old tyres 33"s cos they were out of balance so they use to throw it into a wobble that you had to stop to get rid of. So theres no wobble anytime except when under brakes.

is there something else i should check??? theres a bit of play in the steering dampener bush? is this enough to do this though? can a wobble like this be caused by the steering box???

cheers fellas,

dean.

[liftkit8]

Could well be from warped rotors.
generally if you feel the pedal pulse - its the rears, and if you feel it through the steering wheel its the front, just a tip.

[thehanko]

definitely sounds the same as when i have ever had warped rotors. you just easy on the break going down hill and it can be anything from a slight wobble to a scary one.

either get your rotors machined - they will also have to machine your pads, or replace your rotors if they are cheap enough to not warrant machining them.

sometimes you cannot machine them as they are to 'thin' already.

you generally cant see that they are warped you just fell it under brakes.

then stopp riding your breaks once its fixed as if they are warped it generally means they are getting too hot or they can just be shitty ones like ford falcon ones - they always warp!

[klrevo]

okay yeh,

under light brakes, there is definitely a pulse through the pedal. the fronts are slotted rotors, but seeing as its through the pedal could well be the rears.

sometimes the wobble continues for a short while (seconds), after initiated by the braking, this still caused by warped rotors??? will get it checked out, hopefully just machine up the rotors then

cheers fellas.

dean

[thehanko]

light pedal pressue shows it up alot for some reason. its usually the front rotors as they do 70% of the work, more work = more friction = more heat = warped rotors. do you feel it through the steering wheel as well? if so its frot rotors. id say 99% sure

[hulsty]

I had the exact same problem, fixed it last week. Mine had a very slight pulse under light brakes, but under some circumstances the steering wheel would shimmy really bad and the front LH wheel would bounce up and down like the shocks were rooted. Fitted new rotors and wheel bearings and been fine since!

cheers

[chunks]

either get your rotors machined - they will also have to machine your pads,

You don't machine the pads, just the rotors.

[klrevo]

yeh theres definitely a wobble in the steering wheel that comes in after the braking, can get pretty bad.

guess ill swap rotors then, can you get slotted rotors machined??? iv had normal rotors machined before, and yeh never had the pads done but just not sure if you can machine slotted rotors???

cheers fellas,

dean.

[chunks]

Yes slotted can be machined, you just have to slow the lathe down a bit. Not a big deal though

[thehanko]

I have had warped pads many times due to the heavy trailers i tow for work, and ford has had to fix them under warrenty, they have always said they need to machine the pads as well as they dont sit as flush, maybe only on really bad cases, but this must be true as they ended up replacing the pads free of charge as they had machined them so much they were responsible for the replacment??? not sure but have had the same story everywhere ive been.

[klrevo]

yeh i can agree with the ford scenario. dad had the last 5 series of fords or so over the last 20 odd years for work cars cos his work places have had ford leases and theyre not too bad at customer service just shit at making cars.

even up until his BA mkII, the front ends on them were hopeless, the last two BA;s he had had the whole front end swapped over to the xr6 turboi gear because that ended up being cheaper than continuosly swapping front rotors, calipers and pads.

ill get mine checked out hopefully its just that,

dean,.

[lay80n]

I have had warped pads many times due to the heavy trailers i tow for work, and ford has had to fix them under warrenty, they have always said they need to machine the pads as well as they dont sit as flush, maybe only on really bad cases, but this must be true as they ended up replacing the pads free of charge as they had machined them so much they were responsible for the replacment??? not sure but have had the same story everywhere ive been.

You dont machine the pad,s you just replace them if they are stuffed.
You machine the rotors to remove excess runout or warping, unless the rotors are too close to their minimum thickness or they are of a non machineable type, then you replace them. When i was working for holden we did heaps of brake shudder work, commodores are pretty bad for it.


Layto....

[thehanko]

hmmm, wonder why they keep telling me they do the pads, had it from ford and a aftermarket place. ford was under warrenty so no benfit for them to spin any rubbish.

but yeah pretty much every falcon and commo i know of has had it at some stage.

your car feels so much nicer when its done, its feels like new all over again

[RAY185]

hmmm, wonder why they keep telling me they do the pads, had it from ford and a aftermarket place. ford was under warrenty so no benfit for them to spin any rubbish.

but yeah pretty much every falcon and commo i know of has had it at some stage.

your car feels so much nicer when its done, its feels like new all over again

You'll find that when they say they "machined" your pads, they just meant they resurfaced them with emery tape to remove the glazed face of the pad and possibly shamfered the leading and trailing edge of the pad.

[thehanko]

makes sence, makes me look a little less wrong too but only a little