Brake Discs - 2 part question

[Zilli]

Hey guys,

I recently bought some DBA slotted discs for up front (by recent i mean 6 months ago). They've probably had about 3000kms on them in that time, but as soon as i got them i went to Wakey... been experiencing some shudderring, and i cannot understand why. Let me explain, my understanding of under brake shuddering is the discs are warped... need machining. I did cooldown laps etc, so i cannot identify why they are doing this again already.

BUT thats not the issue (if anyone has any thoughts i dont mind hearing them though)

What i want to know is

1) Can i machine the discs and leave the old pads in? any potential issues come from this? The Ferodo ds2500's are as old as the discs
2) Does anyone know of any DIY's out there that describe this process?

Cheers lads

Kalen

[ChargeR]

Read THIS.

This fellow at Stoptech claims that there is no such thing as a warped rotor just a rotor with uneven pad deposit buildup and possibly resultant hot spots. I am not suggesting that his is the only explanation just that the guy seems to make some good points. He goes on to say that uneven deposits often result from inappropriate pad selection for purpose, as well as improper bed in procedures. Did you bed in the pads according to the manufacturers specifications?

I have had discs machined to rectify pulsation through the pedal and reused old pads on them. I couldn't really comment on whether the vibration would have returned as I ran out of pad and munched the rotors at the next track day I went to. If you do elect to do this be sure to follow the bed in procedure for the pads after you reinstalled the rotors.

Since I have switched to RDA and DBA rotors with Project Mu LM500 and LM700 pads for street and track I haven't had a problem with shuddering with any of the combinations. I always bed in my pads correctly.

You will need to find a workshop that has the correct equipment to resurface slotted rotors as it is more difficult than blank rotors.

[Zilli]

i great read, thanks for the link...

My understanding is that the ferodo's are not an abrasive pad but an adherant friction pad... where the break in is all the more important

I have th say i didnt do the install... my mechanic did, and i didnt experience this vibratory issue for the month or two before i went to Wakey...

I suppose moving forward, i either get the discuss off and rub them down with an abrasive? or do i get them machined, then follow the breaking procedure to a tea, and that way i know ive done them?

Im on the north side of Sydney, can anyone recommend somewhere that can do the slotted rotors?

[DrTran]

i used to work at a parts store in america you are able to machine those rotors just make sure that they they slow cut them the whole way and take off a little at a time. the deal with rotors that I've seen is either they come warped from the factory itself or when it is sitting on the shelf and half the box is on the shelf and the other half is hanging. so with gravity taking its course it warps.

[l3vnd1]

so with gravity taking its course it warps.

A DBA4000 rotor warping not from extreme brake temperatures, but from gravity by being half on a shelf.

A bit unrealistic dont you think?

[DrTran]

working at the auto parts store I've actually seen it. no pictures for proof but I am sure of it. kind of sounds like im full of it but i've seen it so you can take my word or just don't believe what I say. Also it might have have caused that rotor to warp from being halfway on the shelf was that it was made in china so the metal might be sub standard.

[l3vnd1]

Yeah true. There is a possibility.

[Zilli]

not possible, as i didnt have the shudderring when they first went in... was after the track day...

[tinkerbell]

I have th say i didnt do the install... my mechanic did, and i didnt experience this vibratory issue for the month or two before i went to Wakey...

when you "broke the pads in" how much smoke was there and for how long?

[Zilli]

dunno dave... my mechanic did the break in...

[DrTran]

Theres a few other people that have had the same problem.

http://www.fordforums.com.au/showthread.php?t=69055

http://forum.pulsar.org.au/archive/index.php/t-222.html

[tinkerbell]

dunno dave... my mechanic did the break in...

oh well, there's your problem.

if both disc and pad are not properly broken in, material transfer between the two materials can take place in a random fashion - resulting is uneven deposits and vibration under braking.

[Zilli]

so what you're saying is the weak link is most probably the breakin the mechanic did?

What i dont get is why then did everyhting work fine at the beginning? hmmmm well maybe they werent broken in at all? or because they werent broken in properly the issue happenned over the month, or due to lack of driving it all happenned on the track...

hmmmmm

[T-BaGGeR]

A far fetch, but did you over torque your wheel nuts? I have heard that can cause wheel hub and rotors to deform.

[Zilli]

some interesting views on the above links :-)

the ford one is just plain funny... the pulsar one makes some itneresting mass observations on DBA's quality...

i think perhaps at this stage im happy to go with Daves theory... i may remove the discs and get them machined, and have a late night bedding session...

i have however lost the paperwork that came with the pads... can anyone help?