Warped DBA rotors!!

[The Dok]

About 9 months ago I fitted a pair of DBA rotors (& Bendix Ultimate pads) to the front of the wagon, initially, (apart from the harder pedal I was told to expect from these pads) I was reasonably impressed with the slight increase in braking performance (it is series 1 after all). Over the last few weeks however, I have noticed the rotors starting to warp (pulsating pedal etc), so I removed them, had them machined, & during this process I was chatting to my mate at his workshop & he informed me that it's not uncommon for this to occur, the biggest cause of warping is apparently using a "rattle gun" (of which I'm guilty) to tighten the wheelnuts. He tells me that the (floating) rotors are actually "quite soft" & don't like the extra torque from the gun. I took his advice & shall monitor them over the next year or so, but I must say I was a little surprised by this. Am I the only person who was unaware of this issue with soft rotors??? _

[feebs]

I have slotted rotors and they do not wobble yet, but I admit it has not been in for treatment from a rattle gun yet either.

Will watch this thread I think, as I HATE the wobble!

[S3SR]

thanks, i was gonna get a set soon and now i shall be careful.

when you say harder pedal do you mean the brakes is more responsive ie it only takes a little touch and youve just broken all your bones? or just an improvement over the standard one?

[ratter]

Rattle guns themselves do not cause the problem, but their use can lead to them warping, If the gun is calibrated to torque the wheel nuts to the correct tension or a tensioning device is used on the gun, the nuts will be done correctly.

It is possible to cause the problem just doing them up by hand if the recommended tension is exceded.

Driving habits also lead to warped rotors.

Id say driving habits will cause the most problem with rotor warping. Putting the car in neutral at the lights does a LOT to prevent the problem.

You'll find manual falcons don't have this problem as often as autos.

[Lukeyson]

i have had DBA slotted on the sedan, front and back since xmas, with the same pads and no warping thus far.
But i noticed a dramatic increase in braking ability, possibly because did the back too

[The Monty]

I have slightly warped mine and they have only been on a few months, and about 6 thousand K's. I think it was a combination of doing a big run through the mountains when they were brand new, and washing my car one day when the brakes were still really hot. And probably from the rattle gun you mentioned as JAX do my wheels up with the rattle gun.

[AUTickford]

Rattle guns dont warp rotors, rubbing brakes or someone riding the brakes all the time will do it. Rattle guns break studs and crossthread them and leave them too tight to get off without a breaker bar, yay broken studs!!!

[The Dok]

Some interesting observations I must say. Driving habits.........well, I replaced the original rotors predominately because they were 6 years old (1 machine left before being undersize) & had NEVER had warping issues (even with the same rattle gun/driving habits over 3 years since I rebuilt this AU) moreover, in the 5 years I've owned my EF, the fronts have only been machined ONCE, & this was when I needed to replace pads, not because of warping. My AU has done very little driving, is not driven hard & is exceptionally well maintained as is my EF both of which are driven solely by me, so I can only conclude that these DBA rotors are the issue, however I may switch to a softer pad as these could also be a contributing factor. In my earlier post I (wrongly) stated I was using Bendix "Ultimate" pads, they are in fact Bendix "Advance" pads, sorry if I misled anyone.

Originally Posted by FALCONSR

when you say harder pedal do you mean the brakes is more responsive ie it only takes a little touch and youve just broken all your bones? or just an improvement over the standard one?

Definately an improvement over the std rotors/pads, however in order to generate less dust, I opted for a harder pad, the downside is harder pedal, less wear, not as immediate with stopping power (those are my observations).

[auvct]

i also had a set of slotted dba's on my 99 fairlane with ultimate pads.
I went back to oem discs and the shudder and wobble was gone which i also fitted bosch pads.
1.I heard two stories:that heat builds up at the end of the slots causing hot spots.
2.ultimates need a lot of heat to work properly.

As mine is a daily driver the pads weren't getting hot where as i check my slotted discs they were worn by .010" on each side after 6 months.
So the new ones on now and i havent had a problem.

[Robe]

For more than 10 years my work car was always a Falcon wagon (mid 1990's to mid 2000's). Due to the distances I travelled the organisation probably turned them over at least every 12 months often earlier. (40,000km was the trigger distance for chage-over.) In that time I had plenty of experience with not very old discs warping and requiring machining.

And not due to riding the brake pedal or other bad driving habits

I came to think it was just a normal new Ford thing.

Funny but my ancient AU, bought two years ago, and now with around 250,000km on the clock does not show any indication of that problem.

.

[GK]

Doing up the nuts really tight with a rattle gun would only affect the drum part of the disc being pushed harder against the hub wouldn't it?

How would that warp the actual disc surface, unless it's torqued unbelievably tight!

My few ponderings! LOL!

Cheers,

GK

[ratter]

Yes it affects the drum part but apparantly this will cause run out in the rotor due to distortion from the drum part.

[brandbuster777]

Originally Posted by BlackLS

Id say driving habits will cause the most problem with rotor warping. Putting the car in neutral at the lights does a LOT to prevent the problem.

You'll find manual falcons don't have this problem as often as autos.

Why is this?

[Uncle_Ken]

Mate he was a guest back in 2006 and it comes up with a invalid user name.

[aussiblue]

See this thread and check out the links, if any, that still work (most don't after nearly 10 years) https://fordforums.com.au/showthread.php?t=11429164 "Warped Discs and Other Brake Myths"

Here's some links on the subject that still work:
https://www.centricparts.com/media/t...c-8-2018_1.pdf
https://www.motortrend.com/how-to/18...ed-rotor-myth/
https://www.crossdrilledrotors.ca/bl...the-right-way/
https://alconkits.com/blogs/brake-te...ed-brake-discs
https://www.hellcat.org/threads/the-...optech.218717/
https://alconkits.com/blogs/news/the...d-brake-rotors
https://ipgparts.com/blogs/blog/stop...ny-brake-myths

[8POT]

Originally Posted by brandbuster777

Why is this?

the idea is that if you are sitting at the lights with your brakes on the disk will not cool down evenly (where the pads are touching) and cause it to warp.

Manual cars don't need the brake on constantly to stop the car from moving.

[Metdevil]

Originally Posted by 8POT

the idea is that if you are sitting at the lights with your brakes on the disk will not cool down evenly (where the pads are touching) and cause it to warp.

Manual cars don't need the brake on constantly to stop the car from moving.

I can see where the theory comes from, but I don't think anywhere that you're waiting at lights, you're going to be getting your brakes hot enough to cause that kind of damage anyway.
If your brakes are getting hot enough to warp between street lights, there's got to be something else going on.

I decided to check my own brake rotors with a thermal camera after a 40-minute drive (highway followed by town driving) one day and they were no hotter than 70°c, and even then, that was from the internal vanes of the rotor. Turns out that ventilated brakes are actually really efficient at transferring heat away from the friction surface.

[NCII40]

Installing new discs on old rusty hubs will warp discs everytime
Cleaning them with a wire wheel prior can still cause high and lows
Repalce hubs and discs at the same time