Inconsistent braking shudder

Of course this is correct.
The wheel pressure has to be evenly applied to the rotor - its the wheel nuts that hold it on - not rust.
That said - most people over tighten wheel nuts...

 

After the front rotors and pads were changed by garage the car still shuddered. You replaced the rear rotors and pads - and the car still shuddered. The exact point of shuddering is hard to define - it's like when you change a tape the car feels faster!!!

The garage hasn't done a proper job - probably skimmed or cleaned your disks/ rotors and used cheap pads. And then maybe you slammed the brakes on for a few hundred kays???

Shuddering while braking always comes from the front.

 

Comming from a guy who burns his car out over a 13 buck air filter, I would be surprised if you knew the difference between the radiator and oil cap. I see you giving a lot of advice, but no real information comming out. Well apart from negative bullshite anyway, I got a wicked idea. Worry more about common sense and basic life skills, a wise man once said " it's better to have the masses think you are a fool, rather than open your mouth and remove all doubt".

 

Hahahahaha wheel nut determine you rotor calibration, be sure to let holden know that. The more I read the more I realise you're a 13yr old kid or a mid 40s housing comission rat, grasping at nonsense straws or retarted , made up folk tales.

 

Actually old boy - I know nothing apart from common sense.
You crank on the old wheel too tight using an air gun and boom ... the rotor is too tight in places and irregular.

If you can't get the nut undone with a cross brace the garage has over tightened.

That is total sense. Don't you get it?

I'm actually 56 years old.

And have spent 28 years in submarines cleaning.

 

What do you mean by 'calibration'? do you mean the thickness of the rotor?

 

The guy that drives the long commodore is onto it.
"Brake rotors "warp" on the VT-VZ because 99% of the time when done by a shop the wheel nuts are done up with a rattle gun and not torqued correctly. The Commodore is very sensitive to wheel nut torqueing and the sequence that they are torqued. I think we will see an update in a couple of weeks saying your shudder is back."

Air tools no good.

 

Rear wheel imbalance makes the car sway, not shudder.
So the garage has done a crap job.

 

Hi mate,
I'm not a mechanic although I do a lot of work on my dirt bike so have a basic mechanical level. I've had heavy shudder when braking in my VX and thought it would naturally be the rotors warped, even though they were replaced only about 12 months ago and I'm not a hard driver. Couple of days ago I took my car down to Bob Jane's to get a simple tyre rotation and have a quick look at the bushes/tie rod ends. When I got the car back my severe shudder had completely stopped. Tyres were not balanced, just a simple rotation. Point that you mention about the nuts being over tightened was I had to get Bob Jane's to rotate the tyres cause I could not get the nuts off. Simply too tight. I asked what they would torque the nuts back to and they said they go to 110, which I was able to get off easily enough with a cross-bar. So given that tyres were simply rotated, and the nut pressure on the rotors was reduced, this in my case, reduced the shudder from severe to very mild on occasion now.

I've just replaced the front bushes on the control arm, and although replaced one of the inner bushes, it really looked in good shape so I'm not going to replace the other one, because of the effort to get it bugger out. I'm thinking though the brake caliper pins may have needed cleaning and greasing, and this may have caused the calliper to not function 100%. Could be wrong, but can't harm in cleaning it. Back to BJ tomorrow for a wheel alignment after the caster bush replacements.

thoughts?

 

Don't go to Bob Jane for your wheel alignment.....They can only differenciate between green and red....Majority of them can't understand the basics of suspension set ups

Nuts being too tight has nothing to do with the shudder.... But it is good you can undo them with a cross brace

 

It will entirely depend on the technician themselves re the alignment. Bit of a broad statement saying that Bob Jane can't do a proper alignment.

As for the nuts being too tight, well, I will disagree there too. It can, and does, quite often contribute to vibration due to not being torqued correctly and in the wrong sequence. It was a tech bulletin distributed by a few rotor manufactures and Repco too I believe, not long after the VT was released. 110 is the correct number, but they also have to be done in 2 stages if you follow Holden's manual.

 

I never saw the bulletin and I quite often get bulletins about wheel nut tightness. That being said, you would buckle a rim, before you warped the rotor around the bolt up face bolting the rim up incorrectly.....Just compare the metals for both items and the thickness to see how any one could come to that conclusion

I'll also add in, the rotor sits fairly flat to the wheel bearing face, as the brake pads hold it in position, therefore adding more weight to the theory of it being difficult to warp it by incorrectly doing wheel nuts up

 

You'd be surprised. It's called "Installed Runout". Both DBA and Bendix talk about it on their websites as well.

 

I've mentioned how it would be near impossible for this to occur, so it'd be nice for you to explain how it could, given what I have mentioned

 

And I've mentioned that it is possible and highly likely to occur, especially on the VT-VX. They are particularly prone to it. Rather than wasting more time, here are a couple of links.

http://www.centricparts.com/files/technical guides/brake-rotor-installation-tips.pdf

https://www.bendix.com.au/news/why-...ake-components-when-installing-new-brake-pads

 

I agree, not cleaning the rotor mounting surface can cause issues....The beginning of these instructions start with cleaning of the mating surface, as this is the main cause.....Yes there is a mention of incorrect wheel torque, however it doesn't explain to me, how a thick steel mating surface (ie the rotor centre) can bend before a thin metal wheel centre, or alloy one.

Am I being painful....Possibly, but to me, a wheel centre is weaker than a rotor centre and common sense says, thinner metals will bend before thicker metals.....And I have seen this occur, when people forget to remove centre locating rings, prior to fitting a standard wheel back onto a car.....

 

Incorrectly torqueing a wheel will cause the rotor to distort. As little as 0.1mm of runout will be felt in the steering or the brake pedal at speed. If you rattle up one wheel nut, it clamps that position to the hub, if you go around the wheel nuts in a circle, the metal will roll onto the hub and by the time you get to the last nut the metal in the rotor has stretched enough to distort it. Exactly the same principle as a torqueing a head. There is a sequence for a reason, to get he clamping force even on all bolts so that the mating surfaces have complete and even contact.

 

You're missing the metal thickness and type differences I've been on about. So we'll leave it at that as you obviously don't understand

 

So by your logic, a head doesn't need to be torqued in any particular sequence because the metal is pretty thick?

Metal thickness makes no difference. A rotor can and will distort if the wheel nuts are not torqued correctly. Steel is flexible no matter how thick it is.

 

A rotor centre is about 3" thick and is held against a wheel bearing face which is about 3" thick as well....The rotor is held fairly flat by pads which are long and wide enough to hold about 1/4 to 1/3 of the rotor against this 3" thick surface.....You are trying to tell me, a steel wheel centre which is about 1/4" thick (and being generous) can bend 3" thick steel and not bend this 1/4" thick steel in the process.....Defys logic....

And yes metal is flexible......Logic says, the thinner metal will bend before the thicker metal......Same applies with other sorts of metals....The weaker metal will give before the stronger metal......Hence why bolting a head up, it has to be done in sequence.....The block metal is stronger than the head metal.....Otherwise, you'd hear of block warpage, more than head warpage