d510addict Posted February 26, 2013 Report Share Posted February 26, 2013 I did the disc brake conversion by Mklotz and was finishing up today but I cannot get my brakes proper. I used a new 3/4" M/C from a late model 620 with a disc drum setup as well as everything recommended by him for the conversion minus the bias adjuster. I bleed my brakes starting with the longest line in the front, and after bleeding all lines at the wheels and at the M/C I have no brakes still. They pump up but after a few seconds of not holding the brakes the brakes fade to nothing or very close to it. I see no leaks anywhere and I cant hear anything leaking. Is there a method to bleeding the lines? Is this most likely caused by air in the lines still? Help would be much appreciated as I don't feel like taking 4:30 am bike rides all week long. Quote Link to comment
I'm BLUE Posted February 26, 2013 Report Share Posted February 26, 2013 I assume brake master was slowly bench bled before install. Quote Link to comment
DeviousPsycho620 Posted February 26, 2013 Report Share Posted February 26, 2013 You started bleeding from the front? You should be bleeding the passenger rear, then driver rear, the passenger front, then driver front. You could have a huge air bubble by now. How you get it figured out. Quote Link to comment
d510addict Posted February 26, 2013 Author Report Share Posted February 26, 2013 not entierly sure what.bench bleeding is, i bled the master before i bled the front. How should i start over to get that air out? Quote Link to comment
d510addict Posted February 26, 2013 Author Report Share Posted February 26, 2013 ok so according to google i did not bench bleed the ml/c. what would be the appropriate next step for me? Quote Link to comment
izzo Posted February 26, 2013 Report Share Posted February 26, 2013 pull the master back out. put some fluid in it, and pump the rod with your hand (lol) get it to squrt out the MC Quote Link to comment
d510addict Posted February 26, 2013 Author Report Share Posted February 26, 2013 ok then bleed as posted above? Quote Link to comment
izzo Posted February 26, 2013 Report Share Posted February 26, 2013 yeah, once you get some fluid pumping thru the master it should be fine, or has been for me in the past. Then re-install. bleed like stated above. careful not to get any brake fluid on the paint under the hood :D Quote Link to comment
Laecaon Posted February 26, 2013 Report Share Posted February 26, 2013 Bench bleeding, something I have escaped doing... Quote Link to comment
d510addict Posted February 26, 2013 Author Report Share Posted February 26, 2013 yeah, once you get some fluid pumping thru the master it should be fine, or has been for me in the past. Then re-install. bleed like stated above. careful not to get any brake fluid on the paint under the hood :D Wait there is supposed to be paint under the hood? I thought patina was the norm.... Quote Link to comment
mklotz70 Posted February 26, 2013 Report Share Posted February 26, 2013 It doesn't sound like you bled the rear brakes. Since you broke open the line to install the m/c, you have to bleed the rears too. I'm pretty sure on the 521 the line to the rear runs down the pass side......so the longest line would be to the driver's side rear.....so that's where you'd want to start. D-rear, P-rear, P-front, then D-front. Bench bleeding the m/c is to get all the air out. This can not be done by pressing the brake pedal since it does not bottom out the piston. You can do it in the truck. Use a rod or long screwdriver to push the piston all the way in. Obviously, move the pushrod out of the way. Do the m/c first. This should fix your prob if your rears were working well and adjusted correctly before. Quote Link to comment
Laecaon Posted February 26, 2013 Report Share Posted February 26, 2013 Why does the pedal not bench bleed? I did it attached to my car, but I made sure the pedal had no interference. Without the MC, I can get the pedal to hit the floor. With the MC I feel the pedal stop hard as if I am bottoming out, but Im still like an inch off the floor. Quote Link to comment
banzai510(hainz) Posted February 26, 2013 Report Share Posted February 26, 2013 I have never bench bleed a Master since I have owned Datsuns myself.25years I just bleed from the rear pass then work fwd to the driver side front. adjust the manual brakes also for slop. Quote Link to comment
mklotz70 Posted February 26, 2013 Report Share Posted February 26, 2013 Why does the pedal not bench bleed? I did it attached to my car, but I made sure the pedal had no interference. Without the MC, I can get the pedal to hit the floor. With the MC I feel the pedal stop hard as if I am bottoming out, but Im still like an inch off the floor. You're right....if the m/c is bottoming out before the pedal hits the floor, it should work. You weren't as clear about that in your post and the vast majority of vehicles out there will not bottom the m/c before hitting the floor. I just wanted to be clear. If his push rod is not adjusted quite right, it may not work. Before I learned the real reason behind bench bleeding(thanks Bleach!!) I did a lot of cars without doing it. It can be that last little bit of difference between good brakes and really good brakes. I have never bench bleed a Master since I have owned Datsuns myself.25yearsI just bleed from the rear pass then work fwd to the driver side front. adjust the manual brakes also for slop. It's the longest brake line.....which is the driver's rear on the 521 and 620. The 320 ran down the driver's side so the pass side rear is the longest. Will it work.....sure......there's all kinds of stuff that works, but when you're trying to dot the i's and cross the t's, it's not the most correct. A bungee cord works as a battery hold down.....right? :) Quote Link to comment
d510addict Posted February 26, 2013 Author Report Share Posted February 26, 2013 So ? in what position should the bleeder be on the calipers top or bottom? My father seems to think we have them in on the wrong sides but idk. Quote Link to comment
izzo Posted February 26, 2013 Report Share Posted February 26, 2013 They need to be on top to bleed them correctly. Air rises up. Some people on 510s with the bleeders on bottom removed the calipers so the bleeder is above, bleed them, then reinstall them. (I think, datto510 did that?? Been a minute since I've read his stuff can't remember) Quote Link to comment
d510addict Posted February 26, 2013 Author Report Share Posted February 26, 2013 THat would make sense but I installed the calipers based off of what I saw on Mikes page on the installation which shows them on the bottom. Guess ill change them over. Quote Link to comment
izzo Posted February 26, 2013 Report Share Posted February 26, 2013 ^^ I'm not saying they were installed wrong, this is just what I've always been told, have always seen and have bleed on all my cars. Quote Link to comment
d510addict Posted February 26, 2013 Author Report Share Posted February 26, 2013 okies Quote Link to comment
d510addict Posted February 27, 2013 Author Report Share Posted February 27, 2013 Got em, the bleeder being on the bottem was messing me up. Thank you all once again. Quote Link to comment
mklotz70 Posted February 27, 2013 Report Share Posted February 27, 2013 Sorry about that! I didn't notice the calipers were on upside down. The install pics came from someone else. I guess I'd better put a note up on the site about that!! Thanks! Quote Link to comment
banzai510(hainz) Posted February 27, 2013 Report Share Posted February 27, 2013 (I think, datto510 did that?? Yes Eric did that as he had the same proplem Quote Link to comment
d510addict Posted February 27, 2013 Author Report Share Posted February 27, 2013 Ahh well at least I wasnt the only one to make the mistake lol. Well if you are mechanically inclined (which I am not, learning this stuff has been pretty tough) it wouldn't be a problem but I threw common sense out the window when I saw pictures and didn't think twice about following those. Quote Link to comment
d510addict Posted February 27, 2013 Author Report Share Posted February 27, 2013 That was a fast edit on your page there Mike! Quote Link to comment
mklotz70 Posted February 28, 2013 Report Share Posted February 28, 2013 :) It's a Weebly site.....super easy to edit! Quote Link to comment
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