Slotting rotors that aren't slotted?

**TERRA Operative** · 11-03-2011, 11:00 PM

I've got a set of 4 pot Wilwood calipers and machined Celica rotors from Bazda on my Levin, and I want to slot them.

Is this something that can be done without affecting the structural integrity of the rotor? I assume a machine shop with a mill that has an indexing head or similar will be able to do it. I'll also be looking at using a rounded bit to prevent fracture points.

Any advice or ideas? I'll be using slotted rotors on the rear to replace the worn stock ones, and I want the front to match (as well as the performance benefit).

The setup so far.

**banana_socks** · 12-03-2011, 12:34 AM

I reckon it would be fine. A quick check on the DBA website shows no difference in thickness between the standard and slotted rotors, so I reckon you can follow their example.

Just make sure you get them done in the right direction. I've seen it done.

**TERRA Operative** · 12-03-2011, 01:08 AM

Yea, I'll be sure to get the directions correct for each side of the car. I assume the manufacturers would do the same at the factory as what I want to do, just want to make sure I won't end up with bit's of rotor liberating themselves from my hub...

**ToyTA22** · 12-03-2011, 08:55 AM

If someone has a similar new set already slotted measure depth of cut to tell machine shop the minimum metal between rotor face and vent passages. You don't want to cut to deep to weaken metal between rotor face and vent ribs or they could self destruct when under heavy braking, which no one wants to happen

**TERRA Operative** · 12-03-2011, 11:46 AM

True.
These are OEM Toyota rotors though, so slotted were never available from stock (for me to measure from).
I'll find out what the minimum thickness is as you mention and will make that my minimum depth.

**Braedos** · 12-03-2011, 04:44 PM

Hey mate, I could call up DBA at work and find out for you if you like. I'm sure they would be able to tell us something, but try and get a price on how much they'll be to get slotted, and I'll compare it to a brand spanker set of slotted ones- I don't think there'd be that massive of a difference? Just PM the year, engine number, etc. of the celica they came off.

Only catch is, I can't do it till Monday..

**TERRA Operative** · 12-03-2011, 04:58 PM

These are brand new rotors, so I don't want to buy replacements yet...
I work next door to (and supply welding gear to) two engineering shops, so getting it done cheap isn't too much of a problem.

Thanks for the offer though.

**Billzilla** · 13-03-2011, 02:28 PM

Originally Posted by banana_socks

Just make sure you get them done in the right direction. I've seen it done.

FWIW the direction doesn't matter, either way is fine.
If you want to make it easy on the miller, you can just run two parallel slots across the disc with the middle of each slot just touching the inner section of the disc.

**TERRA Operative** · 13-03-2011, 03:45 PM

But then it's not as pretty!

I'll talk to the engineer shop on Monday and see what they can do.

**Draven** · 13-03-2011, 04:47 PM

also a good idea to leave ~5mm at the outer edge unslotted - that tends to be where fractures on the disc start (speaking from experience of fracturing them)

**TERRA Operative** · 13-03-2011, 06:15 PM

Yea, I've seen many rotors that come slotted from the factory with that 5mm clearance. I thought it would be due to something like that.

**andrew_mx83** · 14-03-2011, 12:38 AM

my brake dude does it for like $30 a rotor. he slots them down to minimum thickness so no strength issues.

**rick q** · 14-03-2011, 02:51 PM

Same as when you buy them new from DBA or RDA.

If you want them slotted, ask them when you order them. They then take the standard disk and slot it for around $40-$50 per disk.