ADVrider

Go Back   ADVrider > Bikes > Old's Cool
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 09-29-2012, 03:42 PM   #1
svejkovat OP
Studly Adventurer
 
svejkovat's Avatar
 
Joined: Jun 2009
Oddometer: 856
Advice on brake bleeding?

1982 R65 has been in storage. Single disc in front w/Brembo caliper. Rode it a couple of times last year. Couple of times this year. That's about it.

I know, don't yell.. I've neglected to replace the brake fluid in many years. When I brought it up out of the basement this year the level was fine but the lever was spongy. Got worse. Decided to flush with new fluid and bleed.

Took off cap of reservoir, drained what was in, put in fresh, and started the bleed routine. Lever just got spongier. The harder I tried the less pressure I sensed and finally just offered no resistance whatsoever. I'm doing the bleed procedure correctly according to my experience in the past and a refresher look here..
http://www.bmwmotorcycletech.info/brakes.htm

Question then. Shouldn't the lever actuated piston/plunger develop pressure regardless of what may be amiss downstream? There is no fluid leakage evident downstream whatsoever. The tiny feeder hole at the base of the reservoir is visually unclogged and I can see the piston moving back and forth beneath it.

Is this evidently (certainly?) a completely blown seal on that plunger? Or could it be something else? Reason I ask is that the plunger only has about five years on it since new replacement and has only seen about 12,000 miles of use (mostly highway at that). I'm hesitant to inspect it since that commonly abrades the seal lip yanking it out of an old corroded barrel. I'd rather not replace it unnecessarily.

Thanks for any advice.
svejkovat is offline   Reply With Quote
Old 09-29-2012, 04:16 PM   #2
baloneyskin daddy
bikaholic
 
Joined: Oct 2009
Location: southcentral PA.
Oddometer: 2,001
Take the banjo bolt out of the mastercylinder and plug the opening with your finger and with barely a pump of the lever you should feel enough pressure to easily push your finger away. If you can find a matching thread ,block the hole off and then pull the lever while cracking the bolt to bleed out any air and it should get stiff as a rock. If not the fluid is bypassing the plunger.Sort of like bench bleeding the master cyl.
baloneyskin daddy is offline   Reply With Quote
Old 09-29-2012, 04:35 PM   #3
svejkovat OP
Studly Adventurer
 
svejkovat's Avatar
 
Joined: Jun 2009
Oddometer: 856
Quote:
Take the banjo bolt out of the mastercylinder and plug the opening with your finger and with barely a pump of the lever you should feel enough pressure to easily push your finger away. If you can find a matching thread ,block the hole off and then pull the lever while cracking the bolt to bleed out any air and it should get stiff as a rock. If not the fluid is bypassing the plunger.Sort of like bench bleeding the master cyl.
By banjo bolt are you referring to the bleed fitting? I've already loosened and tightened that while pumping the lever.... to no avail. Are you suggesting by removing it an plugging the hole that the bolt itself may be faulty? I don't see how that is possible.

I will try your suggestion, but with no evident fluid leaks anywhere at the disc or caliper or hose, I'm already fully "blocked" at that banjo bolt when it's seated...no? If the seat of the bolt were faulty the fluid would have leaked out of it long ago.

Quote:
pull the lever while cracking the bolt to bleed out any air
That's what I've been doing with the bleed screw/bolt per instructions. No fluid emerges and no pressure builds at the lever.

Or are you referring to the the line-in? Mine is hard plumbed instead of swiveling banjo bolt. Don't know if that's common OEM but that's what I've got.





svejkovat screwed with this post 09-29-2012 at 05:01 PM
svejkovat is offline   Reply With Quote
Old 09-29-2012, 05:04 PM   #4
mark1305
Old Enough To Know Better
 
mark1305's Avatar
 
Joined: Feb 2005
Location: Merritt Island, FL
Oddometer: 5,981
Not necessarilly. Air can hide in many parts of the system downstream from the M/C. The advice to plug the M/C outlet with either finger or bolt is sound, because if the piston seal has failed already you will have isolated the problem to the M/C.

If the M/C passes the pressure test, and conventional bleeding just doesn't work, try to position the bike so that the entire brake line from the caliper up to the M/C is all uphill. pull the brake lever in halfway and tie it off that way. Leave it overnight, and with luck any air bubbles will float up and out through the reservoir. Yes it works, as long as the line can be made all uphill with no reverse downhill turns.
__________________
Mark J
Merritt Island, FL

When a person asks you for advice, they don't want advice. They want corroboration.
mark1305 is offline   Reply With Quote
Old 09-29-2012, 06:47 PM   #5
baloneyskin daddy
bikaholic
 
Joined: Oct 2009
Location: southcentral PA.
Oddometer: 2,001
I said the master cyl ,you're down at the caliper. By disconnecting the line and plugging the outlet you can test the master cyl to see if it is bad. The banjo bolt is the bolt that is drilled to allow the fluid to pass through it to the caliper.
baloneyskin daddy is offline   Reply With Quote
Old 09-29-2012, 07:38 PM   #6
mike in idaho
Gnarly Adventurer
 
mike in idaho's Avatar
 
Joined: Aug 2011
Oddometer: 112
Quote:
Originally Posted by svejkovat View Post
. The tiny feeder hole at the base of the reservoir is visually unclogged and I can see the piston moving back and forth beneath it.
.
There should be two holes there, the second one will be very small.
__________________
'68 TR6R
'69 T100R
'69 T120R
'72 Commando 750
My company car is a Kenworth
mike in idaho is offline   Reply With Quote
Old 09-29-2012, 10:35 PM   #7
anonny
What could go wrong?
 
anonny's Avatar
 
Joined: Mar 2007
Location: Beautiful Revelstoke BC
Oddometer: 5,513
Get a BIG syringe with a hose that fits it and the bleeder screw, fill with brake fluid. Loosen bleed screw and push new fluid up from the bottom, tighten bleed screw..... done.
__________________
Kawasaki H1 build thread

71- 450 Honda CL re & re

Just another pathetic sheep following the herd

anonny is offline   Reply With Quote
Old 09-30-2012, 03:43 AM   #8
Claytonroy
Gnarly Adventurer
 
Joined: Jan 2006
Location: Oregon
Oddometer: 287
All good advice, but since it's a 30 year old motorcycle, the Brembo caliper is ready for a rebuild. Probably the M/C as well...and upgrade to a SS brake line if you haven't already.

Why not? Two finger modulation is better than a four finger lever-to-the-grip fade

I believe there is a step by step article on refreshing the Brembo single puck commonly used on BMW's. Search the web and you'll find it.
Claytonroy is offline   Reply With Quote
Old 09-30-2012, 08:16 AM   #9
svejkovat OP
Studly Adventurer
 
svejkovat's Avatar
 
Joined: Jun 2009
Oddometer: 856
Quote:
There should be two holes there, the second one will be very small.
Any confirmation on this? There are two holes, but..... looking at my master cyl from this perspective,

... with the cup/reservoir removed, there is an approx 5/8 round hole where the cup and oring press into it.
Looks (very roughly) like this.....


At the bottom of the large hole are two approx 2 to 3 mm OD identically sized holes (going by memory). The left one leads to the master cylinder plunger, the one to its right is dead ended. Tried inspecting it with a dental pic. It is dead ended. Did I not inspect hard enough? (I'll run out the garage right now and look again)

Quote:
Get a BIG syringe with a hose that fits it and the bleeder screw, fill with brake fluid. Loosen bleed screw and push new fluid up from the bottom, tighten bleed screw..... done.
Found this on the net...

Quote:
I got a 60cc syringe from a medical supply store and then bought a piece of 3/8 vinyl tubing from home depot(about 1-2 inches long). The tubing slips on the end of the syringe and then I put the other end on the nipple of the brake with a zip ty. I just back bled the brakes yesterday and it worked really well. I didn't put a screwdriver in between the rotor and brake pad but it seemed to work well. My front brake is much better but still a bit spongy. Don't even try this with a turkey baster for pushing the fluid up as you need a strong push from the plunger of the syringe.

1. fill your syringe with brake fluid.
2. take off the master cylinder top and pull out the old fluid with another syringe or turkey baster.
3. place wrench on the nipple
4. push brake fluid all the way up in the syringe and tubing end so there is no air.
5. insert the tubing on the nipple ( some fluid will leak but you should have no air in the tubing).
6. loosen the bleed screw
7. push your new fluid in and you will see the master cylinder fill up with fluid.
8. I filled and emptied the master cylinder about 3 times and then filled it all the way up and tightened the bleed screw.
9. remove syringe
10. placed top of master cylinder back on.

All done in about 5-10 minutes per brake! I did not push any levers or brake peddles and it turned out really good. If i can I will post pics of my contraptions.
Sound about right?

svejkovat screwed with this post 09-30-2012 at 08:38 AM
svejkovat is offline   Reply With Quote
Old 09-30-2012, 12:55 PM   #10
svejkovat OP
Studly Adventurer
 
svejkovat's Avatar
 
Joined: Jun 2009
Oddometer: 856
What a damn drag. Went to Walgreens and the biggest syringe they had was 3cc. Sunday today so the orthopedic supply at the hospital is closed. Went to Meijer's (local equiv of Walmart) and got a "seasoning and marinade" injector for $4.50.

Looked well built. Got it home and put a foot of poly tubing on the end of the steel needle and over the flare of my bleeder bolt. Opened the MC reservoir and siphoned off the contents.

Dipped the bleeder bolt in the DOT4 and withdrew two full ounces of fluid. Inverted it and bled off the air while tapping the syringe.... ER style. So far so promising.

As I walked over to the bike to start screwing the bolt into the caliper body the fu@ing syringe started melting before my eyes. The inside of the clear plastic first started turning frosty and then the seals on the needle and top just disintegrated spooging brake fluid all over my hands and floor. All in about 30 seconds! I couldn't even unscrew the top over a rag in the waste can as the black plastic top just started to crumble!!!! Wow.

This shit is nastier than I thought. I was really hoping that I could switch over to silicone dot 5 while I was at this just for the sake of peace of mind since a little of this fluid inevitably ends up on the master cylinder body, caliper body, and even a little slung onto my powder coated snowflakes over time... no matter how diligent or careful I am since a bit of it eventually finds its way past seals, fittings, and hoses. But all the reading here and at other forums discouraged me from switching over.

AAAAAARRRRRGGGGHHHH!!!!! Just wrapped it all in the rag and shoved it in the waste can.
Don't bother with this type of syringe....

"Grand Gourmet" or "Mr. Barbeque" brand. But they're probably all similarly made.
Shame too since the plastic looks pretty robust, there are soft plastic seals/seats on the needle and top, double orings on the plunger, and the needle is a fairly heavy gauge chrome plated brass (i polished the face where it met the seal for a perfect fit and it was brass underneath).

Too irritating to do more tonight. I'll have to check the hospital supply tomorrow.

Sometimes I just miss wire spokes and drum brakes for god's sake.

svejkovat screwed with this post 09-30-2012 at 01:18 PM
svejkovat is offline   Reply With Quote
Old 09-30-2012, 01:19 PM   #11
squish
Out of the office.
 
Joined: Dec 2003
Location: Where the Ghetto meets the sea.
Oddometer: 6,062
Quote:
Originally Posted by svejkovat View Post
I was really hoping that I could switch over to silicone dot 5 while I was at this just for the sake of peace of mind since a little of this fluid inevitably ends up on the master cylinder body......
Nope, not unless you want to put new seals in the whole system and a Dot five compatible master cylinder and lines.

I suspect that your brake lines are going away from the inside out.

I'd suggest rebuilding the master cylinder and caliper and replacing the brake lines, You might be able to find a new caliper which I found was going to be cheaper then rebuilding my calipers that needed new pistons
Between the cost of parts and the labor (I figure my labor into working on my personal bikes, since it's what I do)
It was cheaper to pay 108 bucks for a new caliper then 120 bucks for the seals, pins, pistons and new bleed fittings that my old caliper needed. Turned out that these were like the last few new ones floating around. I don't know if that's still the case but look around, you might find one cheaper.

Also you can upgrade the caliper using some of the kits sold, or roll your own. If your master cylinder is shot, this might be a perfect time to modernize your brakes, it's amazing what modern caliper and master cylinders do to the feelings of brakes on these bikes.
__________________
On vacation for a spell
squish is offline   Reply With Quote
Old 09-30-2012, 08:55 PM   #12
svejkovat OP
Studly Adventurer
 
svejkovat's Avatar
 
Joined: Jun 2009
Oddometer: 856
108 dollars for a new replacement caliper for this? Sound great.

I'll have to look around. For the time being I'm going to give it one more try tomorrow with a different syringe and try to get a few more years out of what's here.

Thanks for all the help here.
svejkovat is offline   Reply With Quote
Old 09-30-2012, 09:17 PM   #13
victor441
Studly Adventurer
 
victor441's Avatar
 
Joined: Jul 2009
Location: Sonoma, Calif.
Oddometer: 865
sometimes a vacuum bleeder does the trick if you are having a hard time getting all the air out...this one is easy to find and not too expensive

victor441 is offline   Reply With Quote
Old 09-30-2012, 10:07 PM   #14
H96669
A proud pragmatist.
 
H96669's Avatar
 
Joined: Nov 2009
Location: Hiding off Hwy 6, B.C.
Oddometer: 4,462
Big Syringues at Wal-Mart, just around the fuel cans & accessories. Called a Mixmizer (?), used to mix small quantities of premix gas. About $5.00.
__________________
Have tools, will travel!
H96669 is offline   Reply With Quote
Old 10-01-2012, 06:33 PM   #15
svejkovat OP
Studly Adventurer
 
svejkovat's Avatar
 
Joined: Jun 2009
Oddometer: 856
I'll check out those walmart syringes. I like the idea of pressure feeding bottom up.

Since some have weighed in here let me ask a question that I've not seen addressed in any of the comparisons or tutorials.

I realize the bleeder screw is situated in the caliper body at the very top of the cavity, but there is also a couple of feet of hose leading upward to the master cylinder body. Everyone obsesses over getting all the bubbles out. Of the half dozen or so optional methods why wouldn't pressure feeding from the bottom (caliper bleeder screw) be by far the best one? Seems like the only one that pretty much guaranteed to purge bubbles as you fill/bleed.
svejkovat is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 01:47 AM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014