BRAKE SHUDDER ISSUE

[Dagabond]

[replicant]

Part of the brake shudder issue relates to pad knock off... this is an expansion of an earlier post elsewhere...

Pad 'knock off' (as opposed to knock off pads which are the bamboo fibre things you buy at less than reputable outlets that are truly horrible and cheap'n'nasty) occurs because as the rotor wears, the pads have further to travel to have effect.

When the driver take your foot off the brake, the normal spinning (radial) motion and the longitudinal twist (as the caliper is usually only attached on one side to the hub/carrier you get a twisting action - which also manifests itself in the hub and bearings too) are reduced and the caliper moves back to its normal position relative to the rotor.

Think of the twisting force if you tried to stop a grab a bicycle tyre by closing your hand on it and it will give you an idea of what I mean.

But because of the twisting movement, pads don't normally wear evenly and wear at an angle. That means the rotor will push the pad back on the piston (or pot) further into the brake caliper.

This means that you end up pushing further to get the rotor to brake each time (progressively worsens) and then you use more fluid and hence the brake pedal travels further.

This tends to be worse with larger rotors and calipers because the brake forces are heightened and all of this unsprung weight tends to pitch/yaw when you drive on real roads with bumps in them (and there's even more load with big wheels on the hub and its bearings).

A byproduct of this is all that squealing (and eventually vibration) due to the uneven wear - the pad wears at one edge more than the other... and the rotors tend to wear unevenly (think of a warped record) as when you actuate the brake it tends to hit one smaller spot (a bit like flat spotting a tire) which gets progressively worse.

Think of it on a bicycle brake when the pad starts to look like a wedge rather than the rectangular block it started out as...

There are products that allow for some disc float - often these come from motorsport applications (eg AP do strap drive discs) or disc bobbins... From memory, that's part of the reason why most race cars don't have power assisted brakes so the driver is aware of the additional travel and also the forces involved in the braking system are much more progressive...

The BF is different from the BA and predecessors for the XR6T and the V8's as the caliper and the rotors are different sized but the top hat is fairly similar... in any case the same twisting motion occurs... hard braking exacerbates the problem so it tends to manifest itself in the performance versions rather than a cab as the braking forces are much more powerful due to additional speed and the need to scrub it off faster by braking.

[2003XR6Turbo]

On the brake shudder issue. I've been continually going back to Ford. Suffice to say they have tried all sorts of things, that I am not at liberty to say, but the DBA rotors DO NOT fix rthe problem! I know. The dealers have no hope of fixing the issue and the Ford engineers seem to be going down the road of making statements that the problem is one of "perception" and that the owners are to sensitive to the issue. Look out, as if Ford was serious about a fix they would have initiated a recall or something similar but on the "quiet". I've driven a Jan 2003 build XT auto, only the slightest shuuder/shimmy.(2578km on the clock) I've also driven a April 2003 build Failmont,(2800km) and it is just as bad as my Turbo. They are still building cars which are faulty. Does anyone actually believe that Ford will recify this problem, after 7 months of production. My car is a manual, so it appears that every car is affected to some degree.

I for one have had enough as my car has almost spent more time at the dealer than in my garage. Anyone interested in getting together to force a change, be that through and with the co-operation of Ford or through legal / civil means, leave me a message. If the response is big enough, I'm prepared to do the leg work, for my sake and every other owner.

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[genebaby]

Update on my car. My XR8 has standard brakes, which I upgraded to DBA slotted rotors and Ferodo Formula pads all round days after I got the car. That was two and a half years ago now and I am almost at 68000kms, still on the same set of rotors and pads and with NO sign of shudder. I have done the odd quick stop where you really test out your brakes, the rest of my driving is on the street like normal. There seems to be some life left in my brakes, no mention that anything needs replacing at the last service.

The Ferodo Formulas have squealed a bit from day one, but they have gone the distance, and certainly work better than standard.

[Iconic Bionic]

HAd my BF in for some shudder the other day. Ford says unheard of and claimed that the rotors were warped. All the BA's at work suffered brake shudder pretty bad as they required flogging on a regular basis so I know what shudder feels like.

[tab]

Didn't you mention elsewhere that you had them glowing at one stage? If so then the warping sounds very feasible and would feel similar to shudder.

[Iconic Bionic]

Didn't you mention elsewhere that you had them glowing at one stage?  If so then the warping sounds very feasible and would feel similar to shudder.

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Yeah I did. Now got a good reason to get DBA rotors.

[ritzy]

My car has just hit 21000. BA mk2 xr6t auto ute..

I get it bad when I use brakes lightly. It also pulls to right a bit too.

Going to take it in to Ford, so they can do the normal, it your fault and this is the bill.

Anyone have any ideas of what it could be?

Edited 07/05/07 03:39 PM by ritzy

[Soul Reaver]

I got to 40k before mine decided to shudder, mind you I think a little NSW cruise up to Bathurst did not help the situation

[SDWAYZ]

Got the word off a guy about a place in Sunshine VIC that cryogenically treats components to increase hardness and resistance to wear. Does it on the trucks I sell to him and swears by it. Turns out these does the brakes for alot of Auscar/Late model camira cup etc cars and runs his own 9 sec subaru as well as doing the treatment to engines/drivetrains for alot of pro-stock teams, so guess he has the runs on the board.

It involves cooling to -200 degrees C then bringing them back again, and where required a final treatment to relieve the component. Neil recommended DBA or RDA slotted rotors, and Formula Ferodo or Bendix Ultimate pads. Not cross drilled as these tend to "Tram Track" the pads. He then treats the rotors AND pads whole process takes a week. You can machine the discs/engine components and it wont affect it because it treats the material right the way through. Long disc and pad life and no brake shudder. I will let you all know how it goes!!!

I am looking at getting all my new engine components done too, including engine block, pistons, head, valves the whole lot for $1200.00

www.cryogen.com.au