Rear brake line leak

Speedbump

Speedbump

Joined
Mar 3, 2019
Messages
8
Age
57
Location
85083
Hello!
First post.
I purchased a 1991 ST last week and already love how smooth and comfortable it is. (My other bike is a 1989 Transalp.)
I bought the bike knowing that it had a brake line leak, so now I need to fix it. The leak is on the right side of the bike, downstream from the master cylinder. My hope is that I can have a local store fabricate this section of line, but if not there are plenty available on ebay.
I have ordered a factory repair manual, but would like to get started before it arrives.
Here is my question:
It looks like if I remove the fuel tank, I should have good access to the rear brake line...is this true? If not, what is the best way to gain access to that line.
Thanks!
236629
 
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Welcome to the forum and congrats on your Pan purchase.
There should be some ST1100 gurus along shortly to help you.
 
That image is extremely helpful!
I don't think the '91' has linked brakes as there is only one line to the rear caliper.
My assumption is that the line from the master cylinder is a flexible line, as opposed to a pipe.
Thanks again!
 
See that clamp near the middle of the frame lateral tube ? Make sure it's not compressing the brake line. The clamp for the front brake hose on the underside of the triple tree is known to be a problem. And that clamp in the photo above looks identical to the front. I enlarged the ID of the front clamp by using a socket placed inside the clamp and then I "squished" the socket in the clamp using a vise. The clamp holes didn't line-up after I did that and I had to enlarge one hole a little to get the bolt through it. The next time I have access to the rear clamp, I plan on doing the same to it, to be on the safe side.
 
Friendly suggestion : First see how tight the hose is in the clamp. Maybe it's not a problem like it is on the front brake hose. Check out the front clamp too, to see what I'm talking about. IMHO, the hose should be able to be moved through the clamp with just a little force, after the clamp is tightened.
 
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Yes, it’s a single flex hose.
Yes, remove the fuel tank after disconnecting the fuel and electrical connections (incl the red 2P down on the left side!)
You could also remove the rear wheel for better access to the hose clamps on the swing arm.
Hopefully the leak will be evident and it will only be a ‘tighten a banjo bolt’ job. If not, there is a Honda MC rebuild kit (don’t have the part number handy just now). And the aftermarket will be glad to make you a replacement SS hose. Years ago I replaced my 1991SSMST’s clutch and brake hoses with Galfer SS ST1100 specific hose and fittings sets through a STOC group buy that Warchild organized. I did have to shim the thinner SS hoses with scrap rubber tubing where they passed through the routing clamps. It was a nice upgrade, very happy with it.
FWIW YMMV

John
 
Speedbump : If you want a little less expensive alternative, send your old hose to Brake Material and Parts in Ft. Wayne and they can duplicate it for a decent price. Give Scott a call. He duplicated my front and rear hoses.

Are you located in the States ?
 
Yes, I do live in the in the states, Arizona. I do have a local source that did the lines for my Transalp when I rebuilt that.
Thanks for the resource though!
 
Just an update: I removed the brake line, and it looked suspiciously clean. Took it to the local hose shop where they tested it at 3000psi for a minute...no leak.
I took all the fairings off, got under the bike and slowly tracked a line of fluid to...the clutch slave cylinder. The leak is from the clutch hose. So I guess I better move this to the "clutch" thread.
I ordered a slave cylinder rebuild kit, and the hose shop will make a new clutch line for me, so I think I've got it figured out.
 
Speedbump said:
Just an update: I removed the brake line, and it looked suspiciously clean. Took it to the local hose shop where they tested it at 3000psi for a minute...no leak.
I took all the fairings off, got under the bike and slowly tracked a line of fluid to...the clutch slave cylinder. The leak is from the clutch hose. So I guess I better move this to the "clutch" thread.
I ordered a slave cylinder rebuild kit, and the hose shop will make a new clutch line for me, so I think I've got it figured out.
Click to expand...
And yet another clutch slave cylinder.
Best of luck with your rebuild.
There have been a number of posts on this subject lately which should prove helpful.
Keep us posted.
 
Got everything taken care of, and none of it was what I thought it was!
The rear brake system was completely out of fluid. When I tried to fill it, even with my vacuum pump, I could not pull fluid through. After some appropriate language, I removed the rear master cylinder (and you know how fun that is!) and it was jammed. I was planning on rebuilding it at some point anyway, so I had the kit on hand, and was easily able to clean the cylinder and install the new piston, gaskets, and spring. Working great now.
The leak at the clutch was not from the seep hole after all, but from a punctured clutch line, which a local shop was able to duplicate for a little over $30USD. Installed that, bled the system, and that is working perfectly now as well.
The next project, when I feel up to it, is the timing belt and all of the other "while you are in there stuff."
 
Speedbump said:
Got everything taken care of, and none of it was what I thought it was!
The rear brake system was completely out of fluid. When I tried to fill it, even with my vacuum pump, I could not pull fluid through. After some appropriate language, I removed the rear master cylinder (and you know how fun that is!) and it was jammed. I was planning on rebuilding it at some point anyway, so I had the kit on hand, and was easily able to clean the cylinder and install the new piston, gaskets, and spring. Working great now.
The leak at the clutch was not from the seep hole after all, but from a punctured clutch line, which a local shop was able to duplicate for a little over $30USD. Installed that, bled the system, and that is working perfectly now as well.
The next project, when I feel up to it, is the timing belt and all of the other "while you are in there stuff."
Click to expand...
That's a good way to start the weekend.
 
I did document the Galfer hoses install with sequential captioned photos on Webshots but the site died and I never reconstructed. Pretty straightforward though.

Pull the fuel tank and maybe the rear wheel too. Check the orientation of the banjo fittings for which end connects where. You can adjust the ends for optimum angle by inserting a smooth rod (e.g. drill bit shank {Jeff Bertrand tip}) that just fits, into the “eye” and twisting while holding the sheath. BTDT

My Galfer [edit: non-ABS ST1100] rear brake was a single hose, master cylinder all the way to the rear caliper. The front brake set was two separate hoses, one to each front caliper from the master cylinder, with a double hose banjo bolt at the master cylinder. Post a picture of yours please.

IIRC, the Galfer sets’ copper sealing washers are a different size (smaller) than Honda OEMs. You can reuse copper ones by heating to cherry red. No need to quench, you’re not tempering steel.

I used a big 600cc equine(?) syringe from Farm and Fleet to push brake fluid from the caliper up to the master cylinder. Fill the caliper first and hold it so the hose slopes upward all the way to the master cylinder. I didn’t have to bleed the system when I was done. YMMV

I’m sure I’ll think of more after posting. Good luck. [Sorry, I never did catch your first name]

John
 
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Just occurred to me that you have an ABS II. Haven’t worked on those brakes but guess there’s a second brake line on the rear caliper. Maybe someone with that experience will chime in with specific advice/tips.
 
ST-ABSU said:
Seems like there MUST be an easier way.
Click to expand...
Nope. You own a fully faired motorcycle, by choice. To work on the bike, parts must be removed. By a shop or preferably by the owner. Accept this and get on with it.

The rear wheel is optional but the tank must come out; however, that’s quite easy on this bike. Splash cover and drain hoses, top and side electrical connectors, fuel line, and 4 bolts. Grab the tank tower with one hand and the rear with the other. Lift the rear up a bit and then hoist the whole tank up and out toward the rear. BTDT x 10(?) You’ll probably bump the air cleaner housing, don’t sweat that. Helps lot if the tank isn’t full.

You can pump out any excess fuel to lighten the load by connecting a drain hose from the pump output pipe to a catch container, then jumper from the battery to the male spade on top that takes the OEM white 1P connector (nearest to left side).

I don’t know of a Honda published step-by-step for rear brake hydraulic line R&R, but it would say:
Remove:
Seat
Side Covers
Saddle Bags
Top Shelter
Fuel Tank
(above all covered in Chapter 2 of the Honda ST1100 Service Manual)
Hydraulic fluid hose (Rear Brake Master Cylinder and Caliper, Chapter 15)

Chapter 17 in the Honda Motorcycle Common Service Manual covers brake systems, operation, bleeding and caliper/master cylinder rebuild very well. It’s been a wonderful resource to me over the years.

HTH

John
 
John OoSTerhuis said:
Yes, it’s a single flex hose.
Yes, remove the fuel tank after disconnecting the fuel and electrical connections (incl the red 2P down on the left side!)
You could also remove the rear wheel for better access to the hose clamps on the swing arm.
Hopefully the leak will be evident and it will only be a ‘tighten a banjo bolt’ job. If not, there is a Honda MC rebuild kit (don’t have the part number handy just now). And the aftermarket will be glad to make you a replacement SS hose. Years ago I replaced my 1991SSMST’s clutch and brake hoses with Galfer SS ST1100 specific hose and fittings sets through a STOC group buy that Warchild organized. I did have to shim the thinner SS hoses with scrap rubber tubing where they passed through the routing clamps. It was a nice upgrade, very happy with it.
FWIW YMMV

John
Click to expand...
what size rubber tubing did you use?
 
tmills said:
what size rubber tubing did you use?
Click to expand...
To shim the Galfer SS lines in the OEM routing clamps? I honestly dont know. Whatever I had in my scrap box that worked. Vacuum, coolant or maybe even fuel hose. Snipped to length and slit to slip over the hydraulic line. I suppose a strip of inner tube wound around the line until thick enough to hold in the clamp would work fine also. Clear PVC hose too. If you’d worry about the shim moving you could zip-tie it to the line.

John
 
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