rotorheadcase

Hey Mark,

I'm running DBA 4000 series 6X6 slotted rotors. They're for road/track use but DBA also do a "street series" rotor in either plain, slotted or a slotted/drilled combo. Mine were fitted by my local indy but I'm pretty sure are a straigtforward DIY (there are a number of threads where other members have shared their experience). Can be ordered from Big Brakes in SA. Can't remember exact cost but the street series were comparable to the Zimmermans at the time.

Drop me a PM or email if you want any more info.

Neil

pete000

I thaught I had Zimmerman drilled rotors, but mine are directional. I cant remember where I got them. Might be a shop that drills blank Zimmermans.

ian89C4

Here are the pics from my battle with the rotors. Yes, the screws holding the rotors on are very soft, took a while to convince them to come off, but they finally did. Everything went on rather well all things considered, however, I do have a question. I started using the power bleeder initially and all was going well, then I noticed bubbles come from the brake/clutch holding tank back into the power bleeder, so I decided to remove it and do it the onld fashioned way. That may have been a mistake, but my wife helped me bleed them that way and then came the moment of truth. Here is my problem, the car stops and I know it takes a while to get the new pads and rotors broken in, but I have to pump the peddle at least 2 times before I get a good feeling peddle, is there a problem some where or is that normal for new pads and rotors and brake lines all together??

ian89C4

well, in doing some research, I am pretty sure that there is still air in the system....perhaps I will have to bleed them again....

rotorheadcase

My understanding is that you cannot bleed the C4's "the old fashioned way" Ian. What pressure did you have the power bleeder set at? I would try again with a lower pressure and see how it goes. I don't remember anyone reporting problems when using the power bleed system.

Neil

ian89C4

I had it set at 20 PSI, and pumped it back up when when it went down to around 15 PSI. I am going to talk to my mechanic tomorrow and see if he can show me what I did wrong. I also have never heard of bad thing about the power bleeders, so it must have been user error. Thanks for all the help!

dfinnegan

I recently came across a thread in the race forum where it was suggested that 10 psi is the best way to bleed. I've been doing it at 20, as you have, and have had some trouble. Mostly my own fault, but still not getting great results even when I'm careful.

I'm going to do a full flush and bleed again soon using the 10psi method and will report my results.

ilko

I've never had issues with 20 even 25 psi, but then again, mine's a C2 so I don't know if that matters. Also, whatever you do, don't use the brake pedal to bleed the brakes it can damage the seals in the master cylinder.

mpeters951

Can't do it the old fashioned way is incorrect. You can w/o problems. My use of vacuum bleeders has not gone according to plan and has been a ****-up w/ a good deal of wasted Super Blue.

I've checked in with my highly trusted wrench, with 30 years 911 mechanical experience and racing history, and he'd said that some cautionary notes 'round not using the old fashioned way was internet bull****. So readying my sled for this season's DE events, using said method has resulted in no problems with braking whatsoever. Rock hard pedal and a minimum of fuss and wasted fluid.

Whats the issue with the pedal method ? I see none. Are we bunched up about killing a diaphram in the booster/master or what ?

rotorheadcase

I think you'll find that the old fashioned way cannot be used on the C4, which is the model we are discussing, because it has a hydraulic boost system. Perhaps your trusted wrench is referring to the vacuum boosted systems only as found on the C2 model.

Neil

Bill Verburg

964 and 993 both were available w/ 2 very different brake systems.

The vacuum system can be bled the old fashined way but does require a "Hammer" to bleed the abs/abd sections.

the other system, is electro-hydraulic and is far more complicated consisting of 3 separte procedures
1) master cylinder incs brake, lock control & clutch
2) lateral locks(C4 only) & pressure lines
3) booster circuit


It would be well worth your time to consult w/ the shop manual, Chassis, vol 4, section 47-1 thru 47-12, you will want a system tester 9288

BlueHeeler

Before you pumped pressure in the reservoir, did you clamp off the overflow as seen here?



garrett376’s thread and pics:
https://rennlist.com/forums/964-1989...i-thought.html

elbeee964

[almost don't have the heart to mention at this point about painting the disk hats before rust arrives.]

Hammer-impact screw drivers work well on those disk flush head Phillips. Breaking loose, & torquing on.

pete000

I also heard the C4 is not all that easy to do and takes some special procedures as Bill V mentions...

ian89C4

Well, I bled the system again and the peddle was getting better, but not too the level that it had been before. So....I took it to my mechanic and we took a look see. We ended up using 10 PSI and bleed all four corners again, out of both nipples, nothing much different then when I did it. We then bled the brake master cylinder at both release vavles by having him open them slightly and me pushing ever so slowly on the peddle, about 4 reps on each valve. there were many burps of air from the system so we figured that there was a bubble caught up in the upper most portion of the cylinder. We then bleed the "ABS accumulator ball?" if thats what its called and also had a burp of air there. Just to be sure, we bled every corner again and to what should we find, a nice firm brake peddle that is worlds better than I just had. I still have a lot to learn!!

What kinds of paint can you use on the rotor hats that is heat resistant??
Thank you all for all of the help!!

I guess we can chalk this one up in the victory column!