Bad brake judder;new parts

[Timbuick]

prior to buying my GN, the Powermaster failed. The vendor eventually replaced it with a vacuum kit (Aggressive performance) which seems to work fine. Addtionally he replaced the roters and pads. Problem is, the car judders noticably back thru the pedal braking at any speed.
Wondering what it may be;
overtight bearings or maybe a caliper issue.
Its really uncomfortable to drive with this issues especially braking at speed.

 

[DR BOOST]

is there any noticeable KA-ching, wang ,or pfft when is judders or does it buzz, shudder and judder in sequence.

 

[Timbuick]

Nothing metallic sounding at all. Just a really obvious judder at the pedal. As I slow down to very slow, I can feel the vacuum rise and pump the pedal a touch more against my foot as I brake to a stop.
Thing is, the brakes were much the same with the Powemaster, so then it was assumed that the roters wee warped, but I have new ones on now,

 

[Tony Shoaff]

Nothing metallic sounding at all. Just a really obvious judder at the pedal. As I slow down to very slow, I can feel the vacuum rise and pump the pedal a touch more against my foot as I brake to a stop.
Thing is, the brakes were much the same with the Powemaster, so then it was assumed that the roters wee warped, but I have new ones on now,

The new rotors maybe be warped. Brake shutter when braking or just while driving??

 

[DR BOOST]

they are not shuddering, they are juddering.

Pay attention Tony.

 

[Tony Shoaff]

they are not shuddering, they are juddering.

Pay attention Tony.

Someone took my money and I cannot afford to even pay attention

 

[Timbuick]

I'm easy, shudder/judder!!
Anyway, only whilst braking. Car drives out really nicely, doesn't pull to either side and even when braking, pulls up square. The shjudder is so bad that my passenger can notice it under heavy braking.

 

[Tony Shoaff]

The rotors are warped.

 

[DR BOOST]

+1

 

[Timbuick]

Guys, surely not twice?
I drove the car with the failing powermaster and original rotars and noticed the judder. As condition of sale, the vendor replaced the rotars with brand new ones. i have the old ones too. These new rotars juddered right out of the box. Just wondering if the wheel bearings were too tight, wouldn't that cause the rotars to spin off centre and drag against the calipers when applied?

 

[Tony Shoaff]

The rotors are warped or the wheel is getting ready to fall off because of a bad bearing??? How much did the rotors cost?? The cheaper they are the more likely to be warped. Take it back to the vendor that did the work. Good luck.

 

[Timbuick]

Guess, i'll need to take it all apart and check everything. Don't think the wheels are going to fall off just yet. Once had a car with worn out bearings and you could hear it a mile away!

 

[GN owner]

Another thing to look at is whether the back brake drums are out of round due to overheating!

 

[mousemobile]

Warped!

The rotors are warped. They can be warped due to sitting on the shelf improperly, machining out of tolerance, or just from braking.

The stock rotors are really too small and too light (not enough thermal mass).

You can have the rotors trued up. Just remove minimal material.

I warped the rotors on my Regal. They shook the car hard during braking. Truing them up fixed it. Until I used the brakes hard, then they warped again. I just lived with the judder (for years). Now I'll change to 12" front brakes and elimate the problem.