Brake shudder - how to work out if it's front or rear without pulling off the rotors?

[TumTum]

My VX had a RWC done just before I bought it a few months ago. I reckon the guys who replaced the rotors were half tanked or something because the brake shudder is duh obvious. My local mechanic, who is great, says the discs just need machining and as they're new, they have plenty of life in them so machining them is a no problemo deal. Only issue is he doesn't have the kit to do the job and my local tyre/wheel/battery place can get it done, but they have to take off the rotors and send them to another place locally for the work. I don't have time to take off work atm to fuddle about so am happy to "just get it done" but what to know which rotors out of front/rear would be the duds (or all?). The shudder is noticeable at around 20->50% brake force - any harder and it stops. But at its worst, the steering wheel wobbles. But, under heavier brake force, it stops wobbling and pulls up straight. Probably know what the advice will be that no real way to know until the rotors come off and get tested on the machine? But any advice that might save me a buck or two and some stuffing around would be great.

 

[Pollushon]

Sounds like it's the fronts based on your description, rears won't wobble the steering wheel. Also sounds like cheap **** rotors. I had the same thing with some PBR rotors a while back. Just take it in to a shop that can do it then and there, usually $30 max a side.

 

[Scottm]

I've never had brake shudder with new rotors.. And never had any expensive ones
http://bit.ly/1dtvPr9 - not sure if that link will work but new slotted and drilled rotors on eBay for under 40 deliverd.. Takes 20 min to fit each side if you have no idea what you're doing and can use basic tools

 

[corhijasna]

also probably needs a wheel alignment as well as the rotors

 

[Pollushon]

I've never had brake shudder with new rotors.. And never had any expensive ones
http://bit.ly/1dtvPr9 - not sure if that link will work but new slotted and drilled rotors on eBay for under 40 deliverd.. Takes 20 min to fit each side if you have no idea what you're doing and can use basic tools

Why anyone would want to trust stopping 1.5 tonnes from 30 metres per second using $40 of cheap steel with holes in it is beyond me.

 

[acarmody]

More than likely the hub and wheel wasn't cleaned of all the rust and dust buildup causing the rotors to not sit flush.

 

[chargedvx6]

Caster rod bushes are a common fail in commodores causing this issue too. Any mechanic should be able to make a clear diagnosis on the cause of suspension issues on commies. They're very common to fault and easy to diagnose compared to alot of other makes.

If they say machine rotors then I'd be tipping the cause is rotors

 

[Tree cutter]

Its easy to work out which rotor is warped. All you have to do is jack up your car and spin the wheel around by hand. You will feel a tight spot and hear the pad scrape against the rotor if the rotor is warped.

 

[TumTum]

Its easy to work out which rotor is warped. All you have to do is jack up your car and spin the wheel around by hand. You will feel a tight spot and hear the pad scrape against the rotor if the rotor is warped.

Now there's a cool DIY freebie! I'll give that a go. Also agree with Pollushon that it's probably the front given the steering wheel wobble. I reckon starting on the fronts, I might be able to figure out which ones to get done first (can always get the rears done if it's still a bit off).

This reminds me of something a mate at work was telling us about with his rotors a few weeks back after a track day. He and a mate jacked up his track car and put it on jackstands to swap out the rotors. Anyway, they dropped the front rotors off no worries and then moved to the rears. For the life of him, my mate couldn't get the rear rotors off. He ended up trying a hard rubber mallet etc to dislodge them, but no go. He said to his mate, did you take off the handbrake and he said of course he did. So the wrestling went on for another while with no joy. Eventually my mate gets up off the floor and looks over the door sill and there it is... handbrake ON. He swears at his mate and tells him he's an idiot and releases the handbrake. The rear rotors BOTH fall straight off (duh, of course) and one lands right on his idiot mate's foot. Gold I say, GOLD.