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Posted by: ahdoman Mar 17 2008, 10:13 PM

Hey all,
Just a couple of brake bleeding questions and a little background as to why I am doing this; Just finished installing the 5 lug conversion in the front (carrera brakes). So I had to unhook the brake lines (lost a little on the garage floor) and the newly rebuilt calipers need to be bled.
1) This is a long shot but; my brake fluid is blue in color. Any guesses as to what kind it is? I'd like to use the same DOT formula and not have to bleed the entire system.
2) If I do have to bleed the entire system how much fluid does the 914 hold and any recommendations for brake fluid?
3) I still have my proprtioning valve in place. What are the chances that the rear brake lines were effected? I am hoping to just bleed the front for now and bleed the rear brakes when I do the 5 lug conversion on the rear later this week.

Thanks for your help.

Posted by: byndbad914 Mar 17 2008, 10:20 PM

if it is blue in color and in a German car I would have to guess ATE blue. I run that in my race car, so to answer #2... ATE is a good brand. If you track it and heat 'em up then get the high temp ATE blue again. As to #3, may not be affected at all, but I would do a bleed anyway.

In fact, given you don't know the fluid implies it has been there awhile, so use this as an opportunity to fully bleed the system as brake fluid collects moisture and lowers the boiling point anyway. With newly rebuilt calipers would be nice to do anyway. You can also get the ATE hi-temp in gold color to make flushing obvious (you stop seeing blue fluid and start seeing nice clear gold when it is done). Rumor is (or maybe fact, dunno) that ATE has gold and blue for that reason - ease of flushing and determining what's new and fresh.

Posted by: sww914 Mar 18 2008, 02:10 AM

I use the ATE blue and the gold, I switch back and forth to make it easy to tell when I have all clean new fluid coming out. The blue is called Super Blue Racing, the gold is called Typ 200. The specs are identical, the only difference is that the blue looks really cool. It's only going to take another 10 minutes to bleed the rears too, You might as well do it all, but you can get away with just doing the fronts for now. 1 quart should do it, even if you bleed them twice, but it's only about $12.00 a quart, If you have to order it you might as well order 2 just in case and you'll have enough for next time.

Posted by: Spoke Mar 18 2008, 02:21 PM

I did the same thing. Converted the front end to 911 and left 4-lug rear end for a couple of weeks. I had to bleed the rear brakes after converting the front end. Of course I changed the master cylinder also. If you didn't change the master cylinder, there's a good chance you won't have to bleed the back brakes. After you bleed the fronts, it should be obvious if you need to bleed the backs.

Posted by: Eric_Shea Mar 18 2008, 03:34 PM

Do a full bleed once per year... like it or hate it.

I've seen hundreds of calipers from the inside. It makes a H-U-G-E difference if they have been taken care of properly. This is not something to save 30 bucks on.

914's are notoriously hard to bleed. The good thing about not cracking into the rear system is; you have probably not let air into the p-valve. This is where most people run into issues.

Posted by: Krieger914 Mar 18 2008, 06:16 PM

I am curious to know what to do if you do get air in the prop valve. How do you bleed them then?

Posted by: Eric_Shea Mar 18 2008, 06:30 PM

I personally think "you don't". I've heard of people cracking the lines and getting a good portion of the air out but you can get a "good portion" of the air out by simply bleeding the brakes.

With the p-valve the air simply has to be forced out during the normal bleeding process. If you don't put a "serious" stomp on the pedal while bleeding you won't get it to open up effectively and you won't be able to get all of the air out.

I recommend the "buddy system" bleed technique and then driving the car once you get a decent pedal. Take it out for a couple of days of RR tracks and back roads. Do some empty parking lot panic stops and then re-bleed for a final time.

Posted by: Krieger914 Mar 19 2008, 10:46 AM

Thanks Eric,
Andy

Posted by: angerosa Mar 19 2008, 02:45 PM

I got the solo bleeder valves (I think maybe $25 for 4) so I don't have to ask my wife to come out and sit in a car that's jacked up while I crawl under it. I also saw a thread where someone suggested putting vinyl tubing on the nipple of your bleeder valve and running it over to a drip pan right next to you so you could see what was coming out while you were pumping the pedal. With this method if you know all the fluid in your lines is clean, you could also run the vinyl tubing right back into your reservoir and go to town on the pedal to get air out of p-valve.

Posted by: byndbad914 Mar 19 2008, 02:56 PM

This is the point I meant to make and forgot, but fully agree.

And because I do this on my race car once per year, I bought a pressure bleeder (you can make one but I got a good deal at the end of an auto show one time so I bought it 'bout as cheap to make it) for about $50 IIRC and it will be the best thing you ever do if you truly maintain your brake system. I can flush a dual reservoir system pretty quickly with that setup.