Front brake issue- not releasing on 91

jim 91 st

Jim 91 ST1100
Joined
May 10, 2008
Messages
46
Location
Holland, Michigan
Bike
91 ST1100
I am having a perplexing brake issue on my 91 ST (non-ABS) with about 96k miles. I bought the bike with 62k on it and have never done anything to the brakes but pads.

When I took it out of (dry) storage a couple of months ago, I detected slight brake drag but attributed it to a soft tire. I started riding it and all was fine, no brake issues.

A few weeks ago, when backing the bike up first thing in the morning, I found the front brake to be almost locked up? very hard to roll, so I did not ride it of course. I bled the front brakes and all seemed fine again. Brake fluid looked OK and master cylinder was not spongy? very firm. From what I recall, I rode it a bit (to work) and had similar problems a couple of weeks ago, so I parked it assuming there was more to this problem. I then purchased a RF caliper off eBay and installed it yesterday. Bike rolled fine and brakes worked fine before I took RF caliper off. However, I still replaced it and noticed the old caliper pistons retracted just fine. I bled right side (only) very well and thought I was all set.

Result? Unable to turn front wheel by hand. So, I took left pads out and pistons retracted nicely I noticed. STILL unable to turn front wheel by hand (on my lift I should add). Wheel bearings were replaced about 20k miles ago, in case it is relevant.

So? what the heck is going on? Something in my bleeding? Something with master cylinder or collapsed brake line? I bet when I get home tonight wheel will turn again, as sitting ?seems? to affect it. I am suspecting brake line issue, but more of a guess for now.

I am at a loss as to what to replace next, hoping the collective wisdom on here (which I have not had a lot of need for, as the bike is so reliable!) will steer me in the right direction.

Note: I read a little about a plugged weep hole on this forum? Where is that? could that be it? I've been riding my KLR for a month and want the ST back soon! :)

Thx!

Jim
 
Joined
Mar 13, 2012
Messages
5,046
Location
soCal
Bike
'97 ST1100
STOC #
687
I haven't had the problem, but I think I remember reading what you're referring to as the weep hole. I think there is an orifice in the master cylinder somewhere that gets plugged up and interferes with the pistons retracting properly. Take a look at the parts fiche and see if that gives you any info on where it is, and hopefully someone who has had the same problem will come along with more details. It sounds like that might be your problem, I think you're on the right track.
 

ST1100Y

Site Supporter
Joined
Dec 4, 2012
Messages
4,981
Age
59
Location
Vienna, AuSTria
Bike
ST1100Y, ST1100R
STOC #
637
...have never done anything to the brakes but pads.
Methinks you already have a silent suspicion there... ;-) ... what a brave motorcycle...

Always start with the "longer" line when bleeding them brakes, thus first the LHS calliper, then the RHS...

Clogged orifice in the master is likely an issue, but I'd go and rebuild all, master and slave cylinders... its a '91... :cool:
 

Bigmak96

R.I.P. - 2021/08/07
Rest In Peace
Joined
Jul 2, 2008
Messages
3,868
Location
Rural Mn
Bike
04 GL1800 Past tense
STOC #
7910
Also, if when replacing pads, you did not clean the caliper piston prior to pushing them back, they could be too tight to retract.
 

John OoSTerhuis

Life Is Good!
Joined
May 10, 2005
Messages
5,218
Location
Bettendorf, Iowa
Bike
1991 SSMST1100
STOC #
1058
Time to rebuild the the calipers. Those piston dust and fluid seals are overdue for replacement. N.B. - clean their grooves in the caliper body completely! If it was mine, I'd buy the master cylinder rebuild kit too. Rear brakes too.

Edit: check the brake line where it passes under the steering stem/bottom triple tree, especially if you have a fork brace installed. A crushed line there, pinched by the hose holder, will allow fluid to be pumped past it but not allow return/release. Yes, it's happened before.

John
 
Last edited:
Joined
Mar 13, 2012
Messages
5,046
Location
soCal
Bike
'97 ST1100
STOC #
687
Time to rebuild the the calipers. Those piston dust and fluid seals are overdue for replacement.
No denying the PM aspect of this thread, but if he says the pistons seem to be retracting normally, wouldn't that also point towards a blocked orifice in the master cylinder? Or would the blocked orifice make them harder to retract to where you'd be able to feel it when trying to retract the pistons?

to OP: are you retracting the pistons using your hands, or some kind of mechanical advantage? Are you sure they're retracting "normally"?
 
Last edited:

John OoSTerhuis

Life Is Good!
Joined
May 10, 2005
Messages
5,218
Location
Bettendorf, Iowa
Bike
1991 SSMST1100
STOC #
1058
Hmmmm... if the pistons can be pushed in by hand, fluid is flowing in both directions then. I'll have to think about this... why the fluid seals aren't enough to withdraw the pistons when the lever is released.
 
OP
OP
jim 91 st

jim 91 st

Jim 91 ST1100
Joined
May 10, 2008
Messages
46
Location
Holland, Michigan
Bike
91 ST1100
>>to OP: are you retracting the pistons using your hands, or some kind of mechanical advantage? Are you sure they're retracting "normally"?

Well, the RH caliper I used a pump pliers on and both old and "new" replacement caliper took only small amount of effort to retract... both of them off the bike at the time. So I assume those are OK.

The LH caliper I retracted with it still attached, but pads out and a slight pry with a large screwdriver. I was amazed they retracted so easily, and I had forgotten to take the top off the master cylinder (so brake fluid oozed out). I still think it sounds like the weephole thing, if I can find that. I swear they retract overnight, an indication of only partial blockage. And that makes it hard to diagnose. And to John OoSTerhuis- yes I will verify lines are clear of pinch points too, but I think this is something in m/cyl. The only other thing I can think of is some sort of brake line collapse. Do they ever do that?

Then again, on a bike of that age, a lot of things can be suspect, I realize. Frankly I am amazed how reliable it has been considering all the outdoor storage and stop-n-go traffic riding when commuting all over Michigan and Illinois the past 7 years. I wish my 08 KLR was as reliable!
 

wjbertrand

Ventura Highway
Joined
Feb 8, 2005
Messages
4,407
Location
Ventura, CA
Any chance you have an aftermarket fork brace installed? If so make sure the little hose routing clamp under the lower triple clamp is not squished.
 
OP
OP
jim 91 st

jim 91 st

Jim 91 ST1100
Joined
May 10, 2008
Messages
46
Location
Holland, Michigan
Bike
91 ST1100
No aftermarket fork brace I am afraid. Bike was apart about 3 years ago for head bearings etc and I am fairly sure everything is routed correctly, or it would have happened many miles ago. I will check external brake lines however... never know where one may have gotten kinked somehow, but since I had the only key to my storage unit over the winter (and it was fine last year) I find the chance of that rather remote.

It could be corrosion on pistons, but as I said both sides retracted easily. No, I suspect this is the "weep hole" issue, if I can find the darned thing. Corrosion is my second idea (I commute in all weather after all), but this problem is more on/off, if you guys get my drift. Either it works fine, or suddenly it is not releasing. There is probably something I am doing that is prompting this, perhaps in the bleeding process, and that is what leads me to think something in master cylinder.

My assumption is this means draining mastery cylinder and poking around for this? Seriously... there IS a weep hole right? :)

Jim
 

ST1100Y

Site Supporter
Joined
Dec 4, 2012
Messages
4,981
Age
59
Location
Vienna, AuSTria
Bike
ST1100Y, ST1100R
STOC #
637
My assumption is this means draining mastery cylinder and poking around for this?...
Yep, place a blanket or old bed-sheet over the false tank and plastics underneath the work area, remove the reservoir cover, drain the fluid, check below the steel clip at the bottom (probably some goo there), remove brake lever, the small push-rod, that rubber boot (probably rotten away, but there should be one... ;-)), remove the Seeger ring, pull the piston with the seals, etc... out and clean the whole thing thoroughly ...
You'll probably need a master cyl rep kit (piston, seals, assembly paste, etc...)
While at it check the pivot bore/bearing in the brake lever for wear, same for that brass cylinder the push-rod rests in... both are wear-parts and require frequent replacement...

And about that "mysterious" rubber boot: P/N 45504410003, boot comp.
http://www.cmsnl.com/products/boot-comp_45504410003/#.VWdjh0a4Jgs (link for reference only...)

Order two while at it, cause the same thing is supposed to protect the guts of the clutch master... ;-)
 
OP
OP
jim 91 st

jim 91 st

Jim 91 ST1100
Joined
May 10, 2008
Messages
46
Location
Holland, Michigan
Bike
91 ST1100
Thanks. This is what I was trying to avoid, of course, but at 80mph in traffic I am sure I will be glad I did eventually. :)
 
Joined
May 30, 2007
Messages
1,387
Age
72
Location
Grand Junction, Colo.
Bike
92 ST1100
Time to rebuild the the calipers. Those piston dust and fluid seals are overdue for replacement. N.B. - clean their grooves in the caliper body completely! If it was mine, I'd buy the master cylinder rebuild kit too. Rear brakes too.

Edit: check the brake line where it passes under the steering stem/bottom triple tree, especially if you have a fork brace installed. A crushed line there, pinched by the hose holder, will allow fluid to be pumped past it but not allow return/release. Yes, it's happened before.

John
lol......exactly what happened to my bike seveal yrs. back. After removing calipers and lines, wife was holding line and asked why the hose was pinched closed by that 'clampy looking thing'.:rolleyes:. Had already blown the pistons out of calipers....lesson learned(better half pays attention better than we think at times:D).
 
Joined
Feb 5, 2005
Messages
8,538
Age
77
Location
Kingman, Arizona
Bike
2000 ST1100 ABS TCS
STOC #
004
Came to suggest the pinched hose, Jeff and Brant beat me to it. :D

Have to say, tho, this is probably a hopeless case, irreparable. As a gesture of good will, I'll take the ol' hulk off your hands if you'll pay the shipping to Arizona. :D
 
OP
OP
jim 91 st

jim 91 st

Jim 91 ST1100
Joined
May 10, 2008
Messages
46
Location
Holland, Michigan
Bike
91 ST1100
Came to suggest the pinched hose, Jeff and Brant beat me to it. :D

Have to say, tho, this is probably a hopeless case, irreparable. As a gesture of good will, I'll take the ol' hulk off your hands if you'll pay the shipping to Arizona. :D
Gee thanks George... you people on this list as SO thoughtful. As soon as I wear it out, I will send it to you COD for shipping. :)

I bought the master cylinder rebuild kit, but somehow managed to get the wrong one. Back needs it anyway, so I'll just buy another one. Drained the (front) master cylinder and took everything out and cleaned it out with a paper towel and Q-tip so far. Some gunk in it, enough to make me thing yes, it was overdue! But how do I get the little "protector" thing out of the bottom of the master cyl? Does it just pop out? I think therein lies my problem, that the weep hole is clogged, leading to this issue. So far the schematics make it appear to have little clips on the bottom, so I just pop it up? I plan to do that next, just wondered if anyone could shed some light on it.

I need the old girl back on the road... started it up in my shed the other day and warmed it up, and 2 little mice drop out of it. Guess it got too warm in there. so then it ran some more and I smell smoke. As in "burning mouse nest"? Guess I'd better drop the Tupperware and see how much of a mess they made.
 

John OoSTerhuis

Life Is Good!
Joined
May 10, 2005
Messages
5,218
Location
Bettendorf, Iowa
Bike
1991 SSMST1100
STOC #
1058
Quick answer: yes, the little plate over the hole just pops out, it is a friction fit.

Front brake MC kit: 45530-MA4-671
edit: this rebuild kit is used on many Honda models. Odds are a dealer may actually stock this. I have one I could overnight if necessary.

John
via iPhone 6
 
Last edited:
OP
OP
jim 91 st

jim 91 st

Jim 91 ST1100
Joined
May 10, 2008
Messages
46
Location
Holland, Michigan
Bike
91 ST1100
Thanks for the p/n and offer of assistance John! I can get them locally off eBay (Riders Warehouse I think it's called) actually, so quick delivery, and my KLR is in service in the interim. My main question you answered, and that helps. I did not want to risk goofing my m/c and have to buy another if there was a trick to getting the protection plate (as the fiche calls it) out. I think I'll pop that out and see what might fit in there to clear it out, and I could be back on the road. I do need to overhaul rear m/c too, all of which I thought about over the winter, but did I act on it? Noooo... something about that 10F weather I guess.

Jim
 

John OoSTerhuis

Life Is Good!
Joined
May 10, 2005
Messages
5,218
Location
Bettendorf, Iowa
Bike
1991 SSMST1100
STOC #
1058
Just trying to help a fellow SSMST owner, Jim. :)

BTW, what's the Honda part number of the rear brake rebuild kit? TIA

edit: you might want to pick up a few of the banjo bolt sealing washers.

John
via iPhone 6
 
Last edited:
Top Bottom