Shmurzik

Hello,

I am planning to do a brake job on my 928 in the near future, so I have a several questions for the experts among us:

Any 928-specific tools that have to be purchased?
How do I know that rotors need to be changed?
Are there any particular tricks to changing the silencers (‘cause right now the brakes do squeal intermittently)?
What kind “while-you-are-here” maintenance should I do (wheel bearings and the like)?
Any general words of wisdom of caution?

And last but not least: would any of the Bay Are 928 gurus be interested in verifying the results once I am done? Besides my heartfelt thanks I am promising a large amount of calories in either solid or liquid form (or both).

Thank you, everybody!


p.s. I am shopping around to have a mechanic do the job, but would prefer to do it myself – “knowledge is good” ©

Gretch

How many miles are on the rotors? You can get some nice Zimmerman upgrades to cast-hole from the folks at 928 international. They will give you some advice on the brake pads choice too. The job is quite easy. Do a search here for "brake job" and other associated strings and you will get all the info you need to do the job well.

I did brake pads, rotors, sensors and backing pads last winter. All new stuff for about $600 in parts. It was a fun job and easy. You will need a set of metric allen wrenches, If memory serves, that is all the special tools required.

Steve J.

You might also want to flush the system. I use a Power Bleeder and alternate between blue and gold brake fluid. Also a good time to inspect brake hoses.

Lizard928

for the rotors if you have big groves, or any blueish marks on them, take them to a shop and see if they can machine them, if they are under a certain width they will say they are unmachinable, and it that time you then replace the rotors

as per the anti squel plates, you can actually get a goop you apply to the back of the pad, use this along with a think aluminum/steel sheet should come with pads, and this will help or eliminate all brake noise,

I would recommend replacing the brake pad wear sensors, I think they are around $15 from porsche but not 100% sure on that, just replace them they get brittle with age, and the heat they see, if you get really motivated, you can definatly repack all the wheel bearings if you would like to do so while in there, wouldn't hurt,

to push the calipers in you can either use the a pair of channel lock pliers or a C clamp to push the caliper pistons in, you should be able to do it with a pair of channel lock pliers if you can't it might be a good idea to rebuild them, but they should be fine.

also it is a good idea to flush/bleed the ENTIRE brake system and replace all the brake fluid, I suggest a Dot 4 or 5 fluid, and replace every 6 months to 1 year, most ppl dont realize that brake fuild does have a shelf/use life to it and should be replaced.

Lizard928

the other thing to mention, the cross driller rotors are NOT worth the money, they eat through brake pads WAY faster, and have a greater tendency to break/crack, where you will almost never be able to crack a solid rotor, slotted rotors are ok but are not going to do alot for city driving, your best option is to get with a set of cyrogenically frozen rotors, this does increase the life of the rotors.

Chucker

Just like Gretch said. Replace the sensors (15.00 bucks a pop). Mine were fine until we removed them from the pad.

Lizard928

the metric socket is a 10mm IIRC also

Gretch

Respectfully, I have to disagree with Lizard931. I have Cast-hole rotors on both cars. The braking is nothing short of astounding (most Porsche brakes are anyway), and I really like the way they look. Design wise, the holes are cast-in rather than cross-drilled, and chamfored to reduce the potential to crack even more. I have near 100k of driving experience in my '89 GT and I believe the brakes are the best they have ever been in all that time. (***-o-meter results only, sorry, no "brake runs")

So it is more a matter of choice than what is "better". Neither choice is a bad one. As proof I offer thet cast hole rotors are Porsche OEM on my '00 C4 and every 996 that I have seen at least since 2000.

Lizard928

in responce to Gretch, it is unlikely that they will crack I do agree, and having the holes cast in do help to prevent it from happening, more personal preferance really as well as the holes do also reduce the actual surface area, and the more surface are you have the better the stopping power you can get, oh and I would recommend going with a ceramic comp pad to decrease fade at high speeds/temps

now IIRC also in regards to the 00'C4, and the 996 models, they do not have steel rotors, they have a ceramic type rotor, can someone confirm this plz,

Jim bailey - 928 International

the 86 1/2 - 95 brake calipers are "racing" Brembo 4 piston calipers designed for quick change at the track . With the wheel removed simply by squeezing the retaining spring and pivoting it out of the way the pads will slide out and after you push back the pistons slide right back in . It takes no time at all to change pads . If you want to run the noise suppression discs you will need to remove the caliper from the spindle ( two big allen head bolts in front , two 19 mm bolts rear caliper ) or you can use the "goop in a tube " to glue the pads to the old suppression disc or pistons . Unless the rotors are very badly worn or grooved there is little need to try to machine them ..the new pads will break in quickly to the somewhat irregular surface . Rarely will worn rotors clean up before going undersized at which point machine shops are not allowed to cut them thinner . Typically you go through two sets of pads before the rotor needs to be replaced but this will vary greatly depending on the pad composition and driving style . Flushing the brake fluid should be done at least every two years , more often for track cars note that your calipers have TWO bleed screws per caliper . Greasing the wheel bearings probably will not hurt anything might even help .

Robert_H

Shmurzik,

When I did my brakes (less than a year ago), I replaced everything from the rotors to the sensors and all of the lines as well. Since I was having problems with loss of brake pressure (turned out to be leaking seals in the front calipers), I even replaced my master cylinder.

I bought a Motive Power Bleeder and a set of Speed Bleeders to help with the bleeding process. Even though I could have easily gotten some local 928 help, I wanted the tools to be able to tackle this as a one man operation. The 2-different kinds (colors) of brake fluid also helped in this regard. The only real problem that I encountered was with the removal of the front calipers. On my S4, they are held on by hex bolts. I broke 3 hex/sockets trying to get them off. I finally had to have a shop take them off for me. The rears are held on by regular (but huge) bolts. I was able to deal with them very easily with some Liquid Wrench and a large torque wrench.

It was the first really big project I had done on my car. I took my time, printed out anything I could find on the procedure and posted a lot of items on Rennlist. It took me a little over 1 month (cleaned everything and didn't work on it every day), but it turned out great.

Just take your time and ask a lot of questions.

Rob

Shmurzik

Okay, to re-cap:

I don't know the history of the car all that well, so to be on the safe side I will change the rotors (or, at least, the front rotors). So, the parts (let's see if I understood everybody correctly) linked from 928int site, since they have a web store, :

Front brake disk - need two - $190

Front pads - $55

Rear pads - $45

Front brake pad sensor - $15

Rear brake pade sensor - $15 (do I need this one? )

Front brake hose - need two $156 - is this the line that goes to the caliper? If yes - where are the rear ones?

Front wheel bearing seal - let's say four $20 and - is it also advisable to change the bearings themselves just in case?

Damping plate - here I am once again confused: is this what I called a "silencer" or "anti-squeal springs" and Jim "noise suppression discs"? If yes - will I need 16 of these? If no - where are they?!

Also, what am I missing?

And many thanks to everybody, who answered!

Lizard928

always replace the wear sensors, they are plastic and are in a high heat zone, they get brittle,

as for the front brake lines, I would say go with a braided steel line

2V4V

Shmurzik,

Bearings: Check adjustment, if really interested (which you should be) remove hub, clean thorougly, repack with full synthetic bearing grease. Replacing bearings will require a press, or at least, the judicious use of MAPP gas and a freezer - which your significant other may object to.

One (ok, a few) more interesting point(s) on the drilled/cast-in hole/slotted debate - If you look at most any race car, they quit using drilled/cast-in-holed rotors quite a long time ago. They changed to slotted rotors - more swept surface area, more thermal mass, less chance of failure/warping - negligible impact on unsprung weight. In the early days, the holes were as much about "lightening" the unsprung weight, as they were about shedding the gas boundary layer that forms between the pad and rotor under braking. There are now plenty of ways to reduce unsprung weight on a racecar...

3 or 4 gas slots cut into the surface of a rotor will bleed off any gas layer that forms. Some folks like to run more, varies by manufacturer and application.

Also, the accelerated wearing of pads on "holey" rotors seems to be, at least partially, related to the accuracy of the chamfer of the hole and whether or not it was a "cast-in" or "drilled-later" hole.

But, dammit, holes still look way cooler than slots.

PCCB (Porsche Ceramic Composite Brakes) were still a (relatively) expensive option on the new cars. Somebody I spoke with last year at PRI was working on a way cheaper, and more mass producible, and more functional for the street composite brake rotor, just can't remember for sure who it was. You'll see them in the aftermarket soon though folks. Start saving now...

BTW- Personally, I run slotted. Cut the groove down to the wear limit, and when the groove goes away, so do the rotors. I prefer the look of holes, but practicality sometimes wins.

Greg

PorKen

As I understand it, you can ditch the splash protector plates with cross drilled/cast hole rotors, as they eliminate water through the holes.

Another unsprung weight benefit.