BA Falcon Disc Rotor Thickness Variation - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

russellw · 11-01-2003, 15:55

Read this as you will ...

Some BA Falcon vehicles may experience front brake shudder / vibration.

The cause is excessive lateral run-out of the brake disc which can cause high spots which wear down during non-braking disc rotation, this creates Disc Thickness Variation. DTV generates shudder / vibration when the brakes are applied.

For BA Falcon only � Brake discs must be machined on car with a lathe capable of machining the disc to less than 40 microns of Lateral Runout (LRO). Off car machining of brake discs is no longer acceptable. Brake pads do not need to be replaced.

For front brake discs that have three machining claims or more for Brake shudder and are undersize, then disc replacement will be covered up to the end of the vehicle's factory warranty.

Till next time ...

XR6VCT · 11-01-2003, 19:35

Interesting stuff there Kno-all. Our XR6 goes in for its 30,000km service this week and once again the brakes are vibrating badly.

For the record, we have had the discs machined at 7,500km. Then again at the first service (15,000km) and now they are gone again (30,000km).

I hope this time they will be fixed for good.

Mike Gayner · 11-01-2003, 20:10

This has nothing to do with BA Falcons, this can happen to any car with disc brakes. It will happen alot more if you are hard on the brakes.

XR6VCT · 11-01-2003, 20:27

Quote:

Originally Posted by MrAssface

This has nothing to do with BA Falcons, this can happen to any car with disc brakes. It will happen alot more if you are hard on the brakes.

This has everything to do with BA Falcons! Sure it can happen to any car with disc brakes, but it is a FACT that many BA falcons have experienced brake vibration problems.

To put it more simply, brake vibration is a common fault with BA falcons and is something that Ford needs to fix.

Rollin · 11-02-2003, 02:54

pretty much all commodores since VT series one have been doing this hardcore...i wish i had a dollar for every disc i have machined on the buggers!!

XR6VCT next time you are due for a set of pads get an aftermarket set, like metal king plus or something, part of the reason they tend to shudder is due to the pad material not being suited to the disc.

also when you are sitting at lights and stuff, try and have the brakes on as lightly as possible, and make sure you warm them up and cool them down before and after 'spirited' driving.

XR6VCT · 11-02-2003, 05:12

Thanks for the tips Rollin.

As you can imagine it's a very frustrating issue. I wonder how long they will last this time. :hrm:

Kieron · 11-03-2003, 00:47

Mines done 11,500k's now, i've had them machined twice and the steering wheel now vibrates in my hands, it appears to be worse on warmer days too.

Will take it back, but i'm not putting up with a third machining as clearly my rotors have problems.

Rollin · 11-03-2003, 05:07

its not really the rotors as such, its due to the design of the disc/hub assembly (along with a bazillion other factors, pad/disc material/driving style/uneven wheel nut tension etc)

in VS onwards and AU onwards they used a different front brake setup; there is a hub that contains the studs for the wheel nuts, and a sealed bearing. the disc is just a 'hat' shaped bit of metal that sits over the hub, and when you bolt the wheel on the tension on the wheel nuts holds the disc in place.

if there is any foreign particles in between the two or if surface rust starts to form (impossible to stop unless you make disc and hub out of stainless steel, or a galvanized coating maybe??)

the holden fix for brake shudder is to pull the discs off, clean the back of the disc and the hub with sandpaper to a 'bright metal' finish, machine the discs, then 'dial them in' to the hub - ie rotate it around the different wheel studs (which gives 5 different positions) to find the point of least runout - specs are .04mm front and .08mm rear - kind of like matching the runout on the rotor and hub to equal the smallest amount.

then when you put the wheels back on the wheel nuts are supposed to get tensioned to 110Nm each, in the traditional sequence.

thats the way they reccomend, most techs just wind them up with a rattlegun after machining a set of discs...some people are just lazy...

JR · 11-03-2003, 15:22

The brakes are definately an issue on the BA, but the many other factors involved like driving style, vehicle weight etc.. just make it worse.

The pads Ford use are also a bone of contention - basically they're shit.

I put DBA slotted rotors on the car at 13000km when the rotors were ready to be machined for the second time (first at 8000km). Replacing the front pads when we switched rotors, they were 3/4 gone already.

Now at 27000km they're ready to be replaced (fronts only) again. The backs still have about 1/2 their wear left.

Only good thing is that the first time we had to get genuine Ford replacement pads for $192 (remember that's front's only), while this time I can use Bendix pads for only around $100.

Cheers
Jason

russellw · 11-03-2003, 16:23

The comments from Rollin are quite correct.
Ford, likewise, wants the discs phase matched to the hub - which basically means you ensure that the date stamp on the disc is adjacent to the painted stud and the wheels tightened to no more than 135 Nm in the correct sequence.

Cheers
Russ