Vibration under Brakes

[mpau009]

Would anything other than a warped disc be to blame for cronic shuddering under brakes? The discs look almost new all round to me, less than 1mm of lip, and good stock pads. They are fine around town and on the motorway etc, but if i touch the brakes at anything over 150k it feels (and sounds) like there is someone with a jackhammer in the back, or like old skool ABS, but by the time it slows to 120 its like having normal brakes again..

Would this be something that can be solved by having the rear discs skimmed, or should i have a look for an OEM replacement set?

Any pointers as to what i should check first would be good, could something be loose? Or would this be something upsetting the ABS system?

Id kinda like to get it sorted before i go and remove the speed cut.:thinking:

[bradc]

What happens if you are at normal speeds and you slam the brakes on hard enough so that the ABS kicks in? Is it the same sort of feeling or something different?

[Subaru ETA]

not going over 150 would probably solve it /pan

if you feel it through the car and brake pedal but NOT through the steering wheel, its the rears.

Through car, pedal and steering wheel, its the fronts. legnums are bad for getting brake shudder through the fronts..

a skim of the effected rotors and resurfacing the pads should fix it. (willing to do a cashy is your interested)

[mpau009]

Ill do a couple of brake tests tomorrow when the roads are drier, but i havent really noticed it around town. Its also not only hard braking that it shows up, a week ago, i was on a long empty (closed:scholar:) straight getting some info for the MAP2, when i backed off i let it cruise down to 170, then gently applied the brakes.. the vibration was awful, like driving on one of those rumble edge lines, it was actually worse than if you just brake heavily.

I think it would be worth getting the rears skimmed, but does that actually fix it if it has been warped? i thought it only fixed grooves and stiff like that?

Whatever it is, it cant be too drastic since its only apparent at high speeds... right?:thinking:

And David i'm always keen for a cash job, i might see if i can pop around during the week and get you to see if theres anything noticably out of place.

[Subaru ETA]

yup pop over if you can, you have my number...

the rotors could have as much as much as 1mm of lateral runout wich you cant see and it will give it a horriable shudder (well it does on the heaps of **** i have to work on :P)

[Subaru ETA]

ill ask on behalf of mike...if you grab your rear caliper can you wiggle it around? you can onmikes but cant on mine so i was thinking it was that...

mine has shims on the pads and his dont

[mpau009]

ill ask on behalf of mike...if you grab your rear caliper can you wiggle it around? you can on mikes but cant on mine so i was thinking it was that...

mine has shims on the pads and his dont


I was just about to ask:P It does seem a bit weird that you can wiggle the slidey bit, i can imagine how it might be causing the shuddering.

[mpau009]

So everyone knows, this is the bit that wobbles aka "slidey bit".


(pic stolen from another thread).

[bradc]

you mean the bar or the caliper?

[Subaru ETA]

the caliper. if you grab ityou can move it around even tho tho the slides are tight as ****

[mpau009]

/pan

Figured out what all the shuddering was about..

I got my two rear GSD3's replaced on monday, after the whole shouldv got a wheel alignment thing. They found that i had a small picture hook type nail in one. Not leaking too bad, but i guess enough to throw out the wheel balance.

Havent really pushed it past 140, but nothing so far.

Also i passed my 3 100k-0 stop tests for my cert with flying colours, actually improving to the last test. All under 2.4 seconds, best was 2.12.

[Gly]

sweet who did you go with for you cert?

[mpau009]

sweet who did you go with for you cert?

Norwest Motor Mechanix, Alex Gee. The cheapest (by $55) and closest for me. $340, for suspension only. Turned up in a beat up rusty van, but was really thorough, noted everything and anything, took over an hour. But the photos he took got lost:thinking: , so iv got to send some of mine:pimp2:

Same guy who did my STR back in the day. Hopefully i should have the plate by monday.