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post #1 of 6 (permalink) Old 12-08-2008, 01:43 PM Thread Starter
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At Reverse Bleeding front brakes vuncan 750

All,

We are still trying to finish up the last issue on the Vulcan 750 we bought
last year that had set out in the rain for 4 years and had some problems that we fixed however, we still need to bleed the front brakes. They are dual brakes and I tried the methods in the Clymers book with thumb pressure and such but there is no way to get pressure in those lines. The next thing we are going to try is a reverse bleeding with a home made rig described on the internet with a few plastic bottles (You hang them up) and barb's and tubes that flow into the bleeder nipple (One rig on each side) which is basically letting gravity push the air up the lines and out the Master Cylinder. It seems like it might work but what seems to be causing problems is the Banjo bolts don't really seemed to be aligned to let fluid flow, and it seems like the Cylinders in the Calipers are well... Stuck.... Anyway, I'm interested in how to get this done. We live around Lorton, VA and if anyone out there want's to offers suggestions or has expertise in brakes and can help us get this done (Even if we haul it to you) I'd appriciate it. This is the last issue before we can get it inspected and on the road. Help would be appriciated and comments on reverse bleeding rig workability also.
Tnx
David and Andrew
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post #2 of 6 (permalink) Old 12-08-2008, 03:49 PM
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The best way to bleed them if you drained everything is with a power or vacuum bleeder. I picked mine up at Harbor Freight for like $20 or so. Doing it manually is a PITA and takes forever. If it turns out that the calipers and/or master cylinder are toast, KMIM. I have the calipers and MC from my 96 in good condition for sale.

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post #3 of 6 (permalink) Old 12-08-2008, 04:28 PM
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Congratulations on getting the bike restored this far guys. I haven`t any experience bleeding bike brakes but have worked on my own cars and trucks for about 35 years, so I may be able to offer a few suggestions. You don`t mention any previous experience of your own so I will assume that you are new to wrenching on your bike or autos.

I just checked my Clymer manual to see what you tried. The only mention of "thumb pressure" is with regard to the first step of bleeding the master cylinder, before starting on the brake lines. Were you able to get pressure in the master cylinder before reattaching the brake line? If you can`t get any pressure in the master cyl. itself, you won`t be able to get any in the lines either , even if they are full of brake fluid and do not have any air bubbles to be bled out. So IMO the first thing you need to do is be sure the mc will pressure up as per the Clymer manual. Once you can feel resistance applying the brake lever with a thumb over the hole, reinstall the hose and rebleed mc as per instuctions. Keep mc full of fresh brake fluid

Moving down to the slave or wheel cylinders, right side first (farthest from master), remove the cap on the bleed valve and loosen it slowly until brake fluid starts to leak out and watch for bubbles. If there is no cap and you have to screw it all the way out, the valve is plugged with dirt and needs to be cleaned out with a small drill bit twirlled between your finger tips. I have gravity bled many cars with good results and believe it may work here too. If after making sure the bleed valves are clear, the fluid will not flow, try once again the manuals directions to alternately loosen and tighten the valve while applying and releasing the brake lever, until you don`t see any more bubbles or you feel resistance at the lever. Keep an eye on fluid level in mc.

If after doing first the right caliper then the left, it still feels spongy, try a few more pulls on each side. I have never tried a reverse bleed , so cannot offer any insight there. Also do you have any pics of the banjo bolts that you could post so we can see this apparent misalignment you say you have. I cannot visualize what this might be. Have you tried loosening or removing the banjo bolts to see if there is fluid in there or if they are cross threaded, plugged or damaged in some other way. Good Luck and I hope this may be of some help to you.

PS. I see AJ posted since I started this, and has offered another (bike experienced) option that may very well be the most efficient, if it is available to you.

Gordon

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Last edited by OlHossCanada; 12-08-2008 at 04:39 PM. Reason: PS
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post #4 of 6 (permalink) Old 01-12-2009, 12:43 AM Thread Starter
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We have to try again......No luck this time

All,

I can't find the web site right now but we went and got (2) plastic bottles,
drilled holes in the caps, put in the plumbing barb's, hung them up with 3/4 plastic tube, filled them half with fluid and attached the clear plastic hose to the bleeders.. This is a very smooth and cool trick and once you open the bleeder valves you can pumb the master cylinder and watch those air bubbles flow out of the caliper and on up the line. You can also squeeze the bottle and basically watch fluid flow the other way.. You get the point.. No Air in the lines.. Now here is the problem we are having still....

With no air in the lines.. (Trust me.. There was no air in there).. What I decided to do to was take off the calipers and put a wrench between the new Brake pads on both sides... That's because the pistons will "Push out" to grip the pads..and basically adjust to where the caliper is loaded with fluid.
So basically now the rubber hoses, banjo bolts are alighed.. and you can watch the pistons.. push out.. IN fact, without the wrenches between, you can almost pop out the pistons by pumping the brakes.. All looking good there but .... But....

We did feel once.. The Master Cylinder "Go Hard" and when Andrew went to close the bleeder.. (He did know know how to pump bleed and close) he let air back in.. We bleed it out again.. But could not for the dang life
of us after hours get the master cylinder to go hard like that again.. We know it's capable but can't get them all airless, closed and hard brake..

I went back and reviewed the the Clymers.. and on the step being talked about.. "Benchmark Bleed with thumb" is where I think we are having problems. You see.. You can stick your thumb over the hold just out of the
master cylinder and pull back a bit, pump and it will go hard as it squirts fluid out etc... But if you take your thumb off to replace the banjo bolt... it's like good luck trying to get it to go hard again with the banjo and line back on... Just can't seem to get them all in sync... This reverse bleeding with the bottles is very easy and cool... Makes for air tight lines and calipers very fast and easy.. but this master cylinder getting hard like my brakes on the Intruder.. It's not happening... Can't figure it out..???

We are going to likely spend another 6 hours this next Monday/tue and try, try again.. Andrew got his Class M this Saturday after about a year of Permit only.. So.. Getting these brakes nailed is last step to road worthy...

I surley will be reading all these comments again and belive you me.. They are getting us there and very helpful indeed.. More suggestions are welcome!

Thanks much..
David
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post #5 of 6 (permalink) Old 01-19-2009, 07:17 PM
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Buy a set of speed bleeders, they are fantastic. You install them, open them 1/4 turn pump the brake handle and the air goes out. The speed bleeders DO NOT let air back in so there is no need to constantly open and close the bleeders. I absolutely love mine! As for the Master Cylinder, bleeding it is also easy. Fill it with fluid then take out the the bolt holding the hose to the MC, put your finger tightly over the hole and pump the brake handle. Then very slightly release some pressure with your finger, you'll feel the air escape. Press your finger again hard on the hole and repeat the process until you think you have it all out, about 4 or 5 times should do it. Then quickly remove your finger and put the bolt back on tight. Fill the MC with fulid DOT 4 only!, then start bleeding the calipers with the right one first then the left one. I've done mine by myself several times and it works great. You really should get the speed bleeders, they are the invention of the century as far as I'm concerned.

If you haven't rebuilt the MC, I'd recommend doing that. Parts are about 28-30 Bucks and well worth it. There is a very very small pin hole in the MC that needs to be clear for the MC to work properly. See my earlier posts on this subject, it gave me fits until I got it figured out and now my brakes are prestine!

PM me is you have any questions, I've been through this a few times and may be able to help you.

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post #6 of 6 (permalink) Old 01-31-2009, 07:46 PM
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Speed bleeders are the SHIZNET!


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