13,000 miles warped disks - yes another one....

[ArthurPE]

adsgren: are you sure the discs are forged?

By forged I mean the holes are part of the orignal casting and not drilled after the disc has formed.

Even then I don't like them - dimples much better.

thanks...
pretty sure the Audi and BMW are cast in place holes, not drilled...
although the Audi do seem pretty small...

honestly, I'm have mixed opinions
holes vs slots vs dimples/crescents
and JHM will do plain on special order
which tells me theirs are drilled/milled, since they are slots?

for strett duty, imo, doesn't really matter
in fact plain may be better

seems to come down to preference...

[ArthurPE]

thanks, I'll have to check that out...

2.25 mm is a lot...
after 1mm of wear they would be getting pretty thin
with less internal structural support (ie, larger voids or air gaps) that would make me 'nervous'
especially with the heat cycling going on making it brittle

do you know the oem wear limits
new vs replace, front & rear
???

aren't they internally vented/vaned?
air is directed at the center, and thrown out via centrifugal action...
the M3's were actually directional, different parts for each side...

If you have a look at them the next time you change your discs you will notice they are not airfoil vaned, they are pinned. Airfoil vaned discs using centrifugal action draw air into the space at a greater flow rate then air forced into them and expel it quicker too.

The JHM discs do have thinner wear surfaces to accommodate the larger vaned air gap between the discs whilst retaining the OEM overall thickness as you will see from the dimensions given, you lose 5.5mm of overall thickness of OEM or 2.25mm per plate.

[P_G]

IIRC approx. 2.5-3mm but then you have 34mm original overall thickness. You are losing 26.2% overall OEM plate thickness in JHM discs with the increased air gap (OEM plate 10.5mm each, 13mm gap = 34mm, JHM 7.75mm each, 18.5mm gap = 34mm). Even if it were a mximum 3 mm that 1.5 mm each you would still have 6.25mm on each plate and airfoil vane are structurally stronger than straight fin IIRC.

[pad125]

I'm sitting here reading all this and feeling smug......but as you know Graeme its the only thing I can feel smug about at the moment

[ArthurPE]

I'm sitting here reading all this and feeling smug......but as you know Graeme its the only thing I can feel smug about at the moment

you have an email...

[P_G]

I'm sitting here reading all this and feeling smug......but as you know Graeme its the only thing I can feel smug about at the moment

Don't be, you might wake up and find your ceramics have been replaced by steel discs and EBC yellowstuff pads...... I know where your car resides.....

[RS4VR]

I've heard nice things about JHM front rotors.. If they hold up, they seem priced right as well.

[bye bye]

Well audi have come back and offered a 50% contribution =£600. A nice gesture from them but if I have the same issue in 12 month/13k miles then they have set a precedent in my opinion.

I feel a bit caught between a rock and a hard place as I'd like to continue to try and "fix" my existing disks but I do not want to decline the 50% offer as my pads will need replacing in the next 6 months or so (3 months ago a local garage who fixed my aircon radiator said they were 60% worn)

I think yellow stuff are on the shopping list once the year 4 warranty is over.

Thanks for all your input.


Mark

[adsgreen]

I'd go for the offer to. Whilst you fix the discs it takes time and money.
Least with new ones (guessing new pads too) you can bed them in yourself and know it's been done right .

Just remember not to be too easy on them

[ArthurPE]

go for the offer, tell them you want the old parts
get the old 'skimmed' if possible

[bye bye]

Thanks for confirming my thoughts. Taking the deal and keeping the old parts......

.....anyone interested in a pair of "slightly" warped RS4 front disks....offers?

How and how long do I bed them in?

Mark

[adsgreen]

First couple hundred miles just use them normally - not too light just firm. Think engine braking in 1st gear kind of deceleration as a limit if you can help it. (course if a muppet pulls out in front screw the bedding in and save the car!

this will get rid of all the protective and other compounds that are present in all brakes during manufacture and the main rough edges are worn down. Then just do the process above of a few hard stops then some big stops with no abs to get some proper heat in them. Job done.

Failing that, the best brakes I ever bed in were factory fresh before a track day. Not ure if that was a one off or not as not repeated it since!

[ChrisCSL]

As for pads, has anybody tried Carbon Lorraine pads? they've kinda created a positive storm on other forums for my other marques and are light years ahead of Pagid's (and I like those). RC5+ are stunning for the road and RC6 for track

I run Carbon Lorraine RC5+ pads on my supercharged Lotus Elise and swear by them. They are better than Pagid in my opinion. They have a more progressive pedal feel, don't squeal and make less dust. Most importantantly stop slightly better, work when cold and can operate at a much higher temp than Pagid. Important for track work. The RC6 has proved very strong in the Lotus Cup series also. Sorry I can't comment on RS4 usage as I still run OEM pads in mine. I just use my RS4 as a daily driver and my Lotus for serious driving and track

[ArthurPE]

just mic'ed the front...33+ mm at 37k miles (1/2 way thru my second set of pads)
if original is 34 mm, what is the wear limit spec?

spec is 32 mm
so I'm only 50% worn, nice

[bye bye]

Disks and pads on.....just popping out for a blast to bed them in