Help! Very Noisey Front Floating Rotors

spsfiend · 12-12-2008, 05:41 AM

I have a 1987 911 with Porsche 1979 930 calipers and rotors. I have heard that the floating rotors can be a little bit noisy but mine are ridiculous. What can I do to fix this? I inspected the rotors and I can move them with my hands and it is the cause of the noise I am hearing (when no pedal is applied). When the brakes are applied the noise goes away.

Everything looks nice and tight. Are there little tensioners that perhaps I need to replace? If so where can I buy them? I heard that there are little washer/ tesioners behind each little bolt that holds the rotor.

Greatly appreciate the help. This is driving me nuts!!!

equality72521 · 12-12-2008, 06:36 AM

Pics are worth a thousand words. It would be much easier if we could actually see them, maybe someone could identify the problem then.

FPB111 · 12-12-2008, 08:12 AM

Pics would help
What type of carriers are you using? Are they the original two piece 917 aluminum type? On my installation I found that the locating tabs would wear enough in 6 or 8 track days to allow much "clunking" at speeds below ~30mph. You could have someone heli-arc the tabs and machine them to a tighter fit. You can also machine some off of the tops of the tabs to reduce the clearance bwetween the two pieces where the rotor rides. They will wear just as fast the 2nd time.
Are they a variation of the "T" shaped mounts bolted to an aluminum backing plate similar to the type that VCI sells? If so you can loosen the bolts and twist the "T"s to decrease clearance. They are noisy to begin with and will also wear. What do you use the car for? Is it a dedicated track car or street DE car or…?? You might be happier with solid mounted rotors. There are a number of suppliers that have “turbo” rotors that will mount on narrow fender cars.
A couple of suppliers are:

Steve Weiner
Rennsport Systems
Portland, Oregon
503.244.0990
E-mail: porsche@rennsportsystems.com
Visit Rennsport Systems on the Internet at:
http://www.rennsportsystems.com

Vehicle Craft
Mine Hill, NJ
Call Toll Free: 800-845-5948...... Local: 973-366-6577
http://www.vehiclecraft.com/Brakes/vciweb4.htm

kojo911 · 12-12-2008, 08:16 AM

the anti-rattle clips, spacers, wear out over time. You can buy replacements from Brembo. I'm not certain that they will work but that is where I would start.

http://www.racetechnologies.com/pages3-13/WhereToBuy should be able to point you in the right direction.

spsfiend · 12-12-2008, 08:17 AM

Thanks guys. Will take some pictures and post later today. The car was primarily used as a DE car but now it's my daily driver. It's a clunking noise that I hear.

Steve@Rennsport · 12-12-2008, 10:24 AM

Thats normal for floating rotors.

Now you know one of the main reasons why Porsche stopped using those,....noise complaints.

I get very worried when those DON'T make that clunking noise,...

equality72521 · 12-12-2008, 12:20 PM

Quote:

Originally Posted by Steve@Rennsport

I get very worried when those DON'T make that clunking noise,...

Uh oh, mine doesn't make any clunking noises!

NY65912 · 12-12-2008, 02:25 PM

I have not heard any cklunking noise from mine.

I torque to specs.

But I may not be able to hear anything due to the fact that a 3.8 is making such beautiful music that I am distracted!

Seriuosly, I'll re-check all fasteners to make sure they are torqued correctly.

TRE Cup · TRE Cup's Garage

930 rotors as fitted from the factory are NOT floating rotors. The fasteners get tightened up (between the flat plate and the discs) and no movement is present./ hence no click and clack

Floating rotors have fasteners with clips that are designed to let the rotor move axially under braking. Because of this design, you can hear the click and clack at low speeds= normal
Do NOT overtighten these to stop the slop, as they are designed to work this way

NY65912 · 12-12-2008, 03:42 PM

Floating rotors

Dennis Kalma · Dennis Kalma's Garage

Quote:

Originally Posted by TRE Cup

930 rotors as fitted from the factory are NOT floating rotors. The fasteners get tightened up (between the flat plate and the discs) and no movement is present./ hence no click and clack

Floating rotors have fasteners with clips that are designed to let the rotor move axially under braking. Because of this design, you can hear the click and clack at low speeds= normal
Do NOT overtighten these to stop the slop, as they are designed to work this way

I guess this comes as a surprise to me, I installed the early Turbo brakes (the flat plate etc) and near as I can tell the sole reason for it was that it would allow the rotor to expand axially when hot. In my case I machined up steel plates and they do in fact make a decent amount of noise.....which I have duly complained about and was told that they all do that it is the price one pays for floating rotors.

Why on earth would they do it that way, complete with the slots in the rotor if it was not for float?

Dennis

equality72521 · 12-12-2008, 07:07 PM

Quote:

Originally Posted by TRE Cup

930 rotors as fitted from the factory are NOT floating rotors. The fasteners get tightened up (between the flat plate and the discs) and no movement is present./ hence no click and clack

Floating rotors have fasteners with clips that are designed to let the rotor move axially under braking. Because of this design, you can hear the click and clack at low speeds= normal
Do NOT overtighten these to stop the slop, as they are designed to work this way

My understanding is that the 1978-79 turbos have floating rotors.

Steve@Rennsport · 12-12-2008, 10:29 PM

Quote:

Originally Posted by equality72521

My understanding is that the 1978-79 turbos have floating rotors.

Indeed, they do,...

One easy giveaway to floating rotors is the shape of the mounting holes. Bolted rotors have holes (10-12) around their annulus and floating rotors have cutouts or slots.

These are designed to float on several types of fasteners such as drive dogs, special shouldered bolts, etc. Some new designs have spring-loaded fasteners (Brembo) to reduce noise at low speed and some do not.

equality72521 · 12-13-2008, 03:40 AM

Quote:

Originally Posted by Steve@Rennsport

Indeed, they do,...

One easy giveaway to floating rotors is the shape of the mounting holes. Bolted rotors have holes (10-12) around their annulus and floating rotors have cutouts or slots.

These are designed to float on several types of fasteners such as drive dogs, special shouldered bolts, etc. Some new designs have spring-loaded fasteners (Brembo) to reduce noise at low speed and some do not.

So, should I be concerned that mine don't make any noise? You stated above that you get worried when they don't.