sanding my rotors? - 986 Forum - The Community for Porsche Boxster & Cayman Owners

jhandy · 05-23-2011, 04:03 PM

I would like everyone's thought about sanding my rotors.

I have OEM pads on the car, and the brake light turned on today. It looks like the drivers side front is the culprit.
I wanted to replace the pads with pagid orange and I remember reading somewhere that if you change pad compounds you should turn or sand the rotors.

I cant turn them, they are drilled. Also I DO NOT want to sand them. I would love it if I could drop in the new pads and get to driving in 30 mins without taking everything off.

So what is the consensus? Sand or change and go?

Thanks,
James

san rensho · 05-23-2011, 04:21 PM

If the rotors are glazed, hit it with 60 grit on a rotary sander. Ive done this on rotors and flywheels to clean them up. If they are not glazed, just put new pads on, they will wear into any imperfections on the rotors.

Steve Tinker · 05-23-2011, 04:27 PM

I've changed pads on a dozen different cars and never "sanded" them!!

If the rotors are within spec for thickness and are not heavily grooved, glazed or rusted (especially at the back of the rotor) I would just blow out the cross drill holes - they tend to hold brake dust - and fit the new pads and wires.

I found when I fitted new pads (Texstar) to my Boxster S last year, it pays to follow the break in procedure as per manufacturers instructions. This makes a big difference to overall braking efficiency and lifespan for the new pads.

Jager · 05-23-2011, 04:36 PM

I replace the rotors when I replace the pads... It's a Porsche!!

Jager

jhandy · 05-23-2011, 04:54 PM

The rotors have been replaced. They are new. They do not need to be replaced, Porsche or not.

The questions is not to remove imperfections, rather do I bother removing the thin invisible film that all pads place on the rotors.

the theory is that the film from the OEM pads will bleed into the new compound and do something bad.

Jager · 05-23-2011, 05:00 PM

????????????????????????

You have new rotors and the brake warning light came on? Are you saying the rotors were replaced but not the brake pads?

WhipE350 · 05-23-2011, 05:27 PM

Heck, too much science going on here...my rear rotors are 11 years old, threw on new pads did the normal high speed break in and they work great!
On the front I needed new rotors and pads, I put on Mintex pads drove for a 1000 miles, hated the dust and put on Akebono, did the break in again and they work fantastic and no dust at all.
Think I have heard this concern before and maybe I don't know much, but I think you would be fine to put new pads on, heat'em up good and you'll be real happy.
Good luck!

blue2000s · 05-23-2011, 05:53 PM

The pads are constantly wearing down the rotors, so the thin layer from the old pads will soon wear off. Bedding helps to get the naked rotors coated with the pad material but after that, the rotors are constantly getting "bedded" as they wear thinner. If you just put on your new pads and run through the manufacturer's bedding process, you should be good to go.

Lil bastard · 05-23-2011, 08:25 PM

Get some #40 sandpaper and a piece of 2X4 as a block and sand them (both sides). This is not rocket science or hard to do at all - Hold the block on the rotor and turn the wheel. With the wheel off to swap the pads anyway, it will only add 10 min. to the job.

Pads bed-in partly by depositing a layer of material on the rotor and the interaction of this layer with the pad creates the most efficient braking.

Different material from different pads are not usually compatible or consistent with the most efficient braking. This is why you want to sand the rotors - to remove the old material, so a good layer of the new material can be laid down.

Cheers!

ekam · 05-24-2011, 03:49 AM

My Toyota mechanic would do it if he puts in new pads on used discs.

NOT required (as most mechanics simply don't do this) but would definitely help the bedding process.

jhandy · 05-24-2011, 05:22 AM

thanks for all the info. I ordered new pads and new steel brake lines.

I will sand the rotors, it sounds like it may help, and surely wont hurt.

I got the pressure bleeder from pelican parts.....Any pearls of wisdom on flushing the system?

paulv · 05-24-2011, 06:14 AM

Quote:

Originally Posted by jhandy

thanks for all the info. I ordered new pads and new steel brake lines.

I will sand the rotors, it sounds like it may help, and surely wont hurt.

I got the pressure bleeder from pelican parts.....Any pearls of wisdom on flushing the system?

Pelican parts has many tech articles including brake bleeding -- check it out:

http://www.pelicanparts.com//boxster/boxster_tech.htm

Regards,
paul...

WhipE350 · 05-24-2011, 06:50 PM

If you got the Motive Euro Power bleeder you are going to love it...comes in real handy. I even used it to bleed clutch.

Idaho Red Rocket 3 · 05-24-2011, 09:01 PM

You need a lot of brake fluid. I used a full liter and half of a second one till I was satisfied. The old fluid came out green. What is that all about ?

blue2000s · 05-24-2011, 09:09 PM

Quote:

Originally Posted by Idaho Red Rocket 3

You need a lot of brake fluid. I used a full liter and half of a second one till I was satisfied. The old fluid came out green. What is that all about ?

If you swap between ate super blue and ate gold fluid alternating changes you know exactly when the new fluid is all the way through. Takes much less than a liter including clutch.

Lil bastard · 05-24-2011, 09:40 PM

Quote:

Originally Posted by jhandy

I got the pressure bleeder from pelican parts.....Any pearls of wisdom on flushing the system?

Yes... the brake and the clutch master share the same fluid reservoir. because of this, you need to flush/bleed the clutch at the same time, or the old, dirty, moisture ridden fluid in the clutch line, master and slave will contaminate your new brake fluid.

As mentioned, plan on forcing 1-2 qts through the system, or you will have air trapped in it, and have to do it over. Be sure car is level and bleed the calipers in the proper order and sequence (inside/outside)

Also, as mentioned, switch between ATE super blue and gold - they are the same fluid, different colors.

Cheers!

jhandy · 05-25-2011, 07:11 AM

Mr. Bastard,
I have to bleed the clutch as well? Ok, there is a valve on the top of the tranny, I am guessing that it is the one. It does not look easy to get to....is there any easy way do do this?

thanks

blue2000s · 05-25-2011, 07:22 AM

Quote:

Originally Posted by jhandy

Mr. Bastard,
I have to bleed the clutch as well? Ok, there is a valve on the top of the tranny, I am guessing that it is the one. It does not look easy to get to....is there any easy way do do this?

thanks

Take the wheel off, use a relatively long tube attached to the nipple to get to a catch can on the ground and a very short wrench due to the limited space.