does this look like a well machined rotor to you? [56k biggish pics]

Simmo · 05-09-2005, 07:54 PM

i took my car into ultratune today cos it was close to work and asked for a machining of my warped rotors. they tell me the rotors are totally rooted and even though they machined them twice it still shudders. now i used to be able to brake ok from under 100 and got shudder when braking over 100. now the whole car friggen shakes and i can hear rattling from the front right. get home from a damn scary trip hardly being able to stop and see these.

i can feel the massive grooves in the rotor now and its no where near smooth. now i am totally ****ed off and not able to drive my car to work tomorrow cos i fear if i have to brake hard i WILL cause an accident. anyone in brisbane know some NON-dodgy pricks who will do this right.

AUXRVIII · 05-09-2005, 08:00 PM

It appears the machine they used isn't suited to doing slotted rotors.

svo347 · 05-09-2005, 08:01 PM

Looks like he went to quick when they were skimmed.
Did he put the rubber band around the disc?

Simmo · 05-09-2005, 08:02 PM

no idea what they did. i had to goto work. it looks like they used a rock to do it though.

RegSpec · 05-09-2005, 08:27 PM

Looking at the pattern on those rotors, I reckon SVO's hit the nail on the head. If you dont use a vibration damper while machining rotors you will end up with a surface on them, exactly the same as those in the photos!!
Take it back and spew, hell ,they'll only have to drive it to feel how bad it is.
AND if by having to remachine the rotors to correct crappy workmanship takes them under spec. the bastards owe you a new set of discs

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**Peuty** · 05-09-2005, 09:55 PM

And on an unrealated note (sort of), how much for the slotted rotors?

xdclevo · 05-09-2005, 10:02 PM

It nearly looks like it was "ground" instead of cut on a lathe.

svo347 · 05-09-2005, 10:05 PM

you can get em for around $150 per corner

Simmo · 05-09-2005, 10:14 PM

yeh i got my 'once good' slotted's for about $149. and they arent laying another greasy finger on my car. its going to my regular guy. every time i try and save time by going elsewhere i get majorly burned. let this be a lesson kids, if you find a good mech, stick with him and be patient.

MustangNicko · 05-09-2005, 10:19 PM

Definately looks like the harmonic band was not used. Also seems like the cutting tips were blunt, which can stuff the harmonics (vibrations). There is also different speed settings on the lathes. Obviously doesnt look like a fine cut :/

Mike Gayner · 06-09-2005, 05:28 AM

A harmonic band is a waste of time when machining rotors, they are designed for drums where there is only one cutting edge on the drum. If you do it right you don't need a rubber band on disks.

jmc-007 · 06-09-2005, 09:25 AM

Far out it doesnt look like it has been machined at all. the face should be like when they were new but with cross hatches in the face.

They just look like someone has given them a hard time with the left foot. you can see from one of the pics where the Brake pad has scalded the rotor.

Take it back and complain. Because its totally unsafe.

:eclipsee_

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MustangNicko · 06-09-2005, 10:59 AM

Quote:

Originally Posted by Mike Gayner

A harmonic band is a waste of time when machining rotors, they are designed for drums where there is only one cutting edge on the drum. If you do it right you don't need a rubber band on disks.

Lol yeah whatever mate ;)

Try machining one with a band and then without.... mmm can ya hear that whistle... can ya feel that vibration...

Mike Gayner · 06-09-2005, 04:33 PM

Quote:

Originally Posted by MustangNicko

Lol yeah whatever mate ;)

Try machining one with a band and then without.... mmm can ya hear that whistle... can ya feel that vibration...

:rolleyes:

I've machined dozens of rotors and I can tell you from experience you can get a perfect finish without a rubber band. The rubber is designed for when you are machining drums and there is only one cutting blade in contact with the surface, which sets up a harmonic resonance through the drum. When there are two blades equally in contact with the rotor the harmonics cancel each other out and it works fine, if your machine is in good condition. I have never machined slotted rotors, so I wouldn't know if this still applies but I can't imagine why it wouldn't.

RegSpec · 07-09-2005, 09:06 AM

Quote:

Originally Posted by Mike Gayner

:rolleyes:

I've machined dozens of rotors and I can tell you from experience you can get a perfect finish without a rubber band. The rubber is designed for when you are machining drums and there is only one cutting blade in contact with the surface, which sets up a harmonic resonance through the drum. When there are two blades equally in contact with the rotor the harmonics cancel each other out and it works fine, if your machine is in good condition. I have never machined slotted rotors, so I wouldn't know if this still applies but I can't imagine why it wouldn't.

Agreed Mike, the rubber band is used for drums but for machining discs our Ammco drum and disc lathe has 2 spring loaded pads that contact each side of the disc and when combined with a sharp cutter and the correct speed setting it gives a top surface every time , regardless of drilled ,slotted or whatever pattern is on them.

svo347 · 06-09-2005, 11:17 AM

Quote:

Originally Posted by Mike Gayner

A harmonic band is a waste of time when machining rotors, they are designed for drums where there is only one cutting edge on the drum. If you do it right you don't need a rubber band on disks.

W@NK cough cough

:

The MaDDeSTMaN · 06-09-2005, 10:55 AM

Yeah, I'd DEFINITELY complain, that's just not good enough! I wouldn't let them get away with such crappy workmanship.

Simmo · 06-09-2005, 12:14 PM

well ive called my regular guy and hes dropped/suffled some around to fit me in this arvo. champion i say. i dunno if im allowed to say but it was the valley ultratune in brisbane, so dont go there. i cannot speak for the other franchises.

TheSneakiness · 06-09-2005, 12:18 PM

If they are warped Simmo, wouldn't it be better to go for new discs? Or is that out of the question? Does machining fixed warped discs?

Simmo · 06-09-2005, 12:33 PM

yeh im getting new rotors anyway now. if they are warped you can machine em flat again. mine 'apparently' were full of hotspots and fatigue cos i kept driving on em for so long.

MustangNicko · 06-09-2005, 12:43 PM

No doubt they would be close to minimum thickness then. Id invest in a new set of discs if they were originally "machined" twice and now going to get another machining.

XPcoupe · 06-09-2005, 01:57 PM

My brake guys have always told me, you can not machine slotted or drilled discs. People do it but it never works. Apperently the cutting blade skips when it hit the notches, it might be in micron's but enough to cause the pedal to feel crap. So I always throughout the disc's.

stiddy · 06-09-2005, 01:49 PM

from what i was told you cant machine slotted rotors????
well your not supposed to..

thats just what i was told when i was getting new tyres..

MustangNicko · 06-09-2005, 01:50 PM

LOL who told you that crap?

MustangNicko · 06-09-2005, 01:57 PM

I never had a problem when i machined mine

and they are circular slots like T-Series/HSV

stiddy · 06-09-2005, 01:58 PM

aparently with slotted rotors and when they warp a bit if you try and machine them they chip and stuff cause of the slots hitting the blade or something.. what xp coupe said
i cant remember the reason 100% but this was a bloke in sydney out west..
he said with slotts when they are a one use throw out type of thing..

MustangNicko · 06-09-2005, 02:00 PM

Thats only when they havent been cut fine enough and the blade arm moves to fast back

stiddy · 06-09-2005, 02:04 PM

if it was up to me i would just fork out and get some new rotors and pads :P not a fan of having it all machined and stuff.. they never seem to get them good again..

MustangNicko · 06-09-2005, 02:05 PM

Try getting your rotors machined on-car. Perfect everytime.

06-09-2005, 03:57 PM

Why would you machine slotted rotors? They're not really designed for that anyhow. Just buy newbies. I just got DBA Cross Drilled and Slotted Premium Gold rotors for $108 a corner. Where's the $150 come from? Slotted were $106 (if you can get them).