Turbo Calipers and Floating Discs

[ncseahawk]

I have just returned from Afghanistan. While I was gone I had a shop completely replace the suspension and braking system in my 85 Carrera.

To my chagrin, I now find that although I replaced my calipers with Turbo calipers, OEM Porsche brake lines, floating discs, and Sanders hollow torsion bars, I have to listen to a noticeable collection of noises ranging from a warbling noise and a squealing noise as the car moves while not braking. Both are absent while brakes are applied. Further, despite installing the larger and more appropriate 23 mm MC, the brake travel has a more spongy / giving feel than previously. This after three brake fluid purges.

The mechanic explained that the noises were all related to the floating discs and that the brake pedal travel was due to the larger MC.

Now...thousands of dollars later, I have shiny bits but am less confident in braking than previously.

Am I getting good input...or do I need to address some probable issues?

thanks

[DW SD]

the 23mm master should minimize pedal travel. I had 23mm master with 930 calipers and pedal is firm as could be. Did they remove the proportioning valve?

Some additional noise seems common on the 930 setup, my brakes squeeked, but not much extra noise while in motion.

Are they all new brake parts?

Also....some of the noise could come from suspension bushings, if not OEM or Rebel Racing or Elephant or WEVO.

What other suspension parts were installed?

Doug

[ncseahawk]

I used Rebel Racing Parts on the front a-arms and the rear trailing arms. I don't have the idea that squeaking is emanating from suspension. Seems very closely associated with rolling momentum.

But I could be wrong...I chose the Rebel Parts because of all the enthusiastic support on this forum.

[DW SD]

A simple test: try jacking up one front wheel and spin. Does the noise exist?
Rebel racing seems to have nice bushing products.

Doug

[ncseahawk]

Right. I intend to test each wheel as you mentioned this weekend.

Where do I look for the proportioning valve...on the MC itself?

[don911]

The noise is the front floating rotors. Think of it as the "sound of performance". that's what I do.

The pedal should be high and hard (that's what she said) I have the same brakes on my 87 and there's not much travel.

The propotioning valve should be removed when installing the 930 calipers on the carrera. The valve is near the MC in the trunk area.

Also, did you install 930 calipers all around? I've heard of soft pedal when rear calipers are not 930s.

[ncseahawk]

"The sound of performance"...excellent, I'll remember that as I prepare for my next track day.

930 calipers all around. thanks for the valve guidance.

Will check to ensure its absence.

[Tom '74 911]

Welcome back.

I have 930 brakes on my '74 with a 23mm MC and the pedal is rock hard when the system is properly bled; they work very well. My guess is that you have a proportioning valve issue or still have some air in the system. Mine are not boosted however and I also don't have floating rotors either. . . so I don't know if it's a good comparison to your setup.

For squeeking, what brake pads are you running? I have a set of Porterfield 4S's (I'm pretty sure that's what they are) that I run on the street and they are very quiet and nice. I also have a set of Pagid yellows that I run on the track - which are crazy obnoxious loud. I've tried to run them on the street, but just can't handle the noise. Brake pad choice threads are like black holes; everyone has an opinion and a favorite. I have found the Porterfields to be a good compromise.

On suspension, I doubt your new rebel bushings are making noise. That stuff looks superbly done and well thought out.

Wish I could offer more specific help. . . But it sounds like you are experiencing pretty normal "new system" break-in issues etc....

[RoninLB]

I have 930 x 4, w/floaters, soft pads, and ss lines, no dirt shields

pedal is firm

Makes a racket in town and ok on the hy. When a street racer is in the car and cracks a worried comment I give him the low down and my pos impresses him more. I actually like the noise as it lets me know the floaters are floating. One of our pelicanhead popes said to make sure they are always floating or you'll probably eventually have a problem. I sometimes check the slack when the wheel is off by using a screwdriver

after a week of sitting in the garage and then taking it out after midnight it squeals like a pig for a couple of stops 4 out of 5 rides. Maybe salt air?

930 brake setup is the greatest thing since sliced bread

[Bill Verburg]

It's normal for the 930 front floating rotors to make a mechanical noise around town, squeal is not normal and is caused by pad choice and/or dirt

2 possible reasons for a soft pedal
air in the system can be difficult to get out after a complete reconstruction like you have

using 4 sets of front calipers, this raises the slave volume and causes a longer softer pedal and poor bias

to check to see if front calipers are used in back check the distance between the 2 side pieces, 930 calipers are constructed of 4 main parts, 2x side pieces w/ the pistons and 2 x bridges connecting the sides. The front bridges are wider and separate the 2 sides to accommodate the wider 32mm front rotors, the rear bridges are narrower to accommodate the 28mm rear rotors, additionally the front pistons are 4x 38mm the rear 4x 30mm but that's harder to check.




the p/v is in the trunk on the line going to the rear brakes, it's a cylinder ~25mm in diameter. It needs to be removed w/ 930 brakes but has no affect on the pedal feel unless it has some trapped air.

[Chuck.H]

Just curious, why are you guys calling the 930 brake rotors 'floating'?

On my '89 Factory TurboLook, all 4 rotors are simple castings that are very much fixed to the hubs; In the front bolted to the hub with 5 small bolts, and in the rear sandwiched between the hub and spacer by the wheel lugs. Do I have my definition of 'floating' rotors wrong?

Chuck.H
'89 TurboLookTarga, 338k miles

[andrew15]

Originally Posted by Chuck.H

Just curious, why are you guys calling the 930 brake rotors 'floating'?

On my '89 Factory TurboLook, all 4 rotors are simple castings that are very much fixed to the hubs; In the front bolted to the hub with 5 small bolts, and in the rear sandwiched between the hub and spacer by the wheel lugs. Do I have my definition of 'floating' rotors wrong?

Chuck.H
'89 TurboLookTarga, 338k miles

Chuck:

78-79 930 models used a floating rotor / hat combination that allows people to fit them on standard 911 hubs and fit under narrow body fenders.

The 80's rotors were indeed one piece castings and fit a different front hub - that combo won't fit under the narrow body fenders.

Regards,
Andrew M

[Chuck.H]

Ahhh gotcha, thanks Andrew. And a belated 'welcome back' to the OP...

Chuck.H
'89 TurboLookTarga, 338k miles

[don911]

Also, if the calipers were rebuilt, the soft pedal may be just the pistons moving away from the rotor with the new seals causing more pedal travel until the pads hit the rotors. This happened on my carrera calipers after a rebuild but went away after some use.

Longshot - It doesn't sound like it but if your pedal feels like it's going to the floor, the o-ring on the MC may not be there. (o-ring at the booster/MC interface). I made this mistake when I did my 930 brakes and the brakes had pressure but the pedal went to the floor and had to pump up to keep pressure.

[Brian 162]

I did the same conversion this year on the fronts only with non floating rotors from VCI. I also replaced the master cylinder with a 23 mm unit.
Some of my observations. The first set of pads I used made so much noise I replaced them with a different make (forgot what I used).The noise setteled down after a few track days.
Pedal effort was harder but the brakes are flawless.

P.S. Welcome back

[SusnaWit]

Rebel racing seems to have nice bushing products.

[ncseahawk]

Is the the proportioning valve a different item than the brake regulator?

Based upon written description I found this. The PET diagram includes a regulator and a distributor...I would think the distributor would be plumbed in the rear and the regulator in the front (trunk area)






This is an 85 911 Carrera plumbed system that has been upgraded to a 23 mm MC and 930 Turbo calipers.

Do I need to simply take the regulator valve out of the system? If so, will any jointing solution do the trick? Anyone out there who has done the conversion please let me know.

thanks. It is my hope that the incredible stopping power of Turbo calipers is still in reach.

[equality72521]

I hate the sound of my floating rotors1!

[175K911]

Originally Posted by ncseahawk

Is the the proportioning valve a different item than the brake regulator?

Based upon written description I found this. The PET diagram includes a regulator and a distributor...I would think the distributor would be plumbed in the rear and the regulator in the front (trunk area)






This is an 85 911 Carrera plumbed system that has been upgraded to a 23 mm MC and 930 Turbo calipers.

Do I need to simply take the regulator valve out of the system? If so, will any jointing solution do the trick? Anyone out there who has done the conversion please let me know.

thanks. It is my hope that the incredible stopping power of Turbo calipers is still in reach.

That is indeed the proportioning valve that you've pointed to.
Two choices:
You can take the Prop Valve (the barrel part) out by disconnecting the brake fittings at each end. (Careful to catch the brake fluid that leaks out). Then open the barrel up and take out the guts and reassemble.
Or you can fabricate a short fitting to insert in place of the prop valve.

Personally I've always just gutted the piece and bolted it all back together again.

Good luck. Your brakes should be outstanding if all the calipers were the correct front and rear part numbers were used. The friends who have done this conversion on SCs and Carreras have never ever had an issue with their brakes.

And yes the floating rotors do make noise.

[Iciclehead]

I have floating rotors too, the noise drove me a little batty until I figured out a solution. I disassembled them, put a tiny dab of high temperature silicone on each of the rotor tangs and reassembled. They still make a little noise but it is way down. I figured I removed a bit of the lateral (axial?) play and still left the ability of them to move as they were designed to.

It has been about 5 years so far, including a track day and no issues at all....

Dennis