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Bleeding rear brakes?

26K views 57 replies 19 participants last post by  Old Kentucky Guy  
#1 ·
I'm having an issue that perhaps the collective knows the answer to. I took my bike in for the 10K service, and they replaced the fluid in the rear brake as outlined in the service data. After that, they were not able to get the brake pedal to feel right again... like it was when I brought it in. It now has way too much travel... more than double what was there before. I've never seen a Scout rear brake pedal like this, and the tech was baffled. They bled it over and over to no avail.

Anyway, the master cylinder has now been replaced and I believe they even rebuilt the rear caliper, and it actually seems even worse. The pedal now drops all the way to the floorboard. It isn't hard, not much resistance... feels way too limp.

So my question is: is there some trick to properly bleeding the rear brake on a Scout? I'm wondering if their vacuum bleeder isn't working properly? It acts like air in the line, but repeatedly pumping the brake pedal doesn't make it any better, which is what you usually get when there is air in the line?

If anybody has a suggestion, I'd appreciate it. I want my brake back the way it was...
 
#2 ·
Look for loose connections that are introducing air, everything indicates air in the system...
Maybe an orifice in the brake cylinder has debris, or a high spot in the line that is holding air. Maybe bleeder valve is leaking. Manual says that it takes more than 2 cups of fluid to properly bleed system.
You might try manual recommended method of reverse pressure bleeding the system (Vacuum). Best of all, maybe taking it to a different dealer along with a repair manual.

You didn't mention if it was an ABS bike......... very complicated bleeding sequence.. .
 
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#3 ·
I had the exact same problem after I replaced the brake hose with a longer one that came with forward locator kit. I must have pump bled it and vacuum bled it fifty times with no luck. A buddy came over with a homemade device to push fluid from the bleeder forward. Nothing worked. A few months later, I took it to the dealer where I bought it and the mechanic got it right. I asked him what he did to fix it. As near as I can tell, it was by pushing the rear caliper piston the whole way in and bleeding it in that position. I had a lousy pedal until he worked on it. Now it’s the same as it was new. I had felt pretty inadequate about it (and still do). I worked on automotive hydraulic brake systems most of my life, and this one stumped me. I’m 71 and I still learned something new.
 
#8 ·
That does not sound right, or we are not getting all the info here. Something is missing, you went in the dealership with good brakes, right? After they did whatever procedure, you have no brakes right? Now you need a part that you did not need before. This is a common sounding theme in the automotive world where someone somewhere is either not communicating or, someone somewhere does not know what they are doing. Hard to tell from here, but something does not jive (for you young guys jive means same as Kosher) somewhere. I'm believing you are thinking the same thing.


I mean really, flushing a brake system is usually a simple procedure if you don't have to replace any components.
 
#7 ·
Just an FYI. And just my opinion ( but it works every time) If you ever need to bleed the brakes or want to replace new fluid AFTER you replace the brake pads-do not pull the front brake lever or touch the brake pedal. Purchase a Mighty-vac (auto parts store- $35 ) or equivalent from Harbor Freight $18-20. Place the one end of the clear hose on the brake bleeder, to the small collector bottle that came with the Vac unit. Loosen the bleeder on the rear caliperafter you hook up the hose. Then just vacuum/ suck the brake fluid through the system. Real easy. Be sure to keep the Master cylinders full while doing this.Then do the Front caliper .-THEN-, when done, pump the pedal (2-4) times, check and top off the fluid level, then do the front same way. If just replacing the fluid, do the same way, but don’t need to pump the brake pedal/ lever. Use fresh unopened container of brake fluid. Simple way to bleed brakes by yourself. Besides- you need more tools anyway.
 
#14 ·
When doing work on motorcycles, one thing that is not easy to get done is get the air out of the master cylinder. If you don't get that right, you will not get good fluid flow at all because you always wind up with enough air inside the plunger and the return hole that will compress the air instead of pushing fluid. In automotive terms, you have to bench bleed the master cylinder. Getting air out of the system can be difficult if any part of the brake system and tubing is higher than the master cylinder. This is where the vac bleeder works. I've used them but was not impressed with the results. I prefer pressure bleeders that push fluid from the master cylinder all the way through the brake system. There is a tool to push fluid through the brake system from the bleeder on the brake calipers. I have not used one but a lot of techs that have them love them. I have used a syringe on motorcycles from the caliper bleeder to push fluid towards the master cylinder. This method seems to be better than the vac bleeder, at least for me and other techs I have known.

When flushing a brake system, the best method I've used is the old method of using a clear tube into a clear jar with fluid in it. This works but this method can also be used to bleed air from the system and you can see the air coming through and out into the fluid in the jar.

I may be telling you something you already know, but I have no way of knowing the level of your knowledge or technical ability. Some reading this may benefit from this exchange of posts.
 
#15 ·
When doing work on motorcycles, one thing that is not easy to get done is get the air out of the master cylinder. If you don't get that right, you will not get good fluid flow at all because you always wind up with enough air inside the plunger and the return hole that will compress the air instead of pushing fluid. In automotive terms, you have to bench bleed the master cylinder. Getting air out of the system can be difficult if any part of the brake system and tubing is higher than the master cylinder. This is where the vac bleeder works. I've used them but was not impressed with the results. I prefer pressure bleeders that push fluid from the master cylinder all the way through the brake system. There is a tool to push fluid through the brake system from the bleeder on the brake calipers. I have not used one but a lot of techs that have them love them. I have used a syringe on motorcycles from the caliper bleeder to push fluid towards the master cylinder. This method seems to be better than the vac bleeder, at least for me and other techs I have known.

When flushing a brake system, the best method I've used is the old method of using a clear tube into a clear jar with fluid in it. This works but this method can also be used to bleed air from the system and you can see the air coming through and out into the fluid in the jar.

I may be telling you something you already know, but I have no way of knowing the level of your knowledge or technical ability. Some reading this may benefit from this exchange of posts.
It's all good. Never hurts to hear someone's thoughts, even if you know some of it. Usually something new in there to learn.

I have a lot of experience with automotive brake systems... and yes we always bench bled them first. I have no experience with the Scout brake system because it's still under warranty. I do suspect that there is air in the system, and for whatever reason, the tech has not been able to get it out. Strange since he changed the brake line on another Scout the same week, without any issues...
 
#16 ·
I see a lot of young guys in the dealerships now. The Indian service manuals leave a lot to be desired. They need some new technical writers. Either that or Indian is depending on service training to fill that gap. The % of warranty claims is something that is closely monitored. Since most dealers (heavy truck, automotive, heavy equipment) have to contend with approval before doing repairs I think that sometimes problems are inherent in this system. I know it is in some places I have wrenched over the years.

Remember, Doctors bury their mistakes, mechanics have to live with theirs.
 
#19 ·
I too use a big syringe with a rubber tite fitting vacuum line attached.Quick and easy.
I've done this before on "stubborn" brakes that just don't want to firm up.

-Remove M/C cap, use syringe to suck out most of the fluid.
-Fill syringe with fresh fluid, attach to bleeder, crack it loose.
-Gently push the syringe. Keep an eye on the M/C reservoir so it doesn't overflow. Close the bleeder as soon as you stop applying pressure to the syringe. Suck out the reservior, rinse and repeat a few times. pump the brake pedal several times after each time, note if any bubbles appear while pumping the pedal. If so, keep repeating until no bubbles/firm pedal.

Otherwise, just observe the entire brake system- caliper, line, to M/C and note the elevation. Any "hills" that would trap air? Often helps for rear brakes to park the bike on a slight incline upward and do it on the sidestand (rather than a vertical chock or lift), to help the rear M/C be the highest point of the system.

A bad m/c will never firm up, and I suppose it's possible an o ring in the m/c went bad, although pretty unlikely if the brake was fine when it went in the shop.
 
#20 ·
A bad m/c will never firm up, and I suppose it's possible an o ring in the m/c went bad, although pretty unlikely if the brake was fine when it went in the shop.
To be honest, I never liked the rear on my bike from the day I first bought it, but it worked. I always thought I was just being picky, until I rode some other Scouts. Mine was never firm like other Scouts... had a weak feel to it. At the 5000 mile mark, I asked about that. The tech said he bled it a bit and it seemed a little better, but even he said it didn't seem quite right. Then at the 10K, they replaced all the fluid (as recommended), and everything went to hell in a hand basket... which is where I am now... :)
 
#21 ·
I passed 10k miles on my Scout, so I decided to bleed the brakes. The front went o.k. using the tried and true method of pumping fresh fluid through the system by squeezing the lever every time I cracked the bleeder open while connected to a catch bottle. I began doing the rear in a similar fashion, but carelessness got me, because I pumped the rear lever once or twice too many times before topping off the reservoir. Damn! Air in the line. O.k., I will just keep up the procedure until everything firms up. Well, as the entries in this thread can verify, that never will happen with this bike. Despite all my efforts, I was left with a very mushy rear brake. Finally I pulled the rear caliper and compressed the piston all the way into its bore hoping this would push the air out of the line at the master cylinder. No, One thing I did discover though was that the rear caliper was pretty dirty. It sits where you cannot see it, and is mounted upside down. Definitely worth dropping it and cleaning it well with the pads removed. My pads are down to 2 mm thickness at 10k as well. Wear limit is 1mm, so I'll be picking up a new set soon. I put the caliper back on and pumped the brake until it began to grab the disk. Still mushy! Time to head off to Harbor Fright and get a vacuum bleeding kit. Several applications of this procedure gave me a brake that is maybe at 75% of normal firmness. At this point I figured I had had enough and will just ride it as is and maybe bleed it again after the last air bubbles have made their way to the bleeder valve. After just a short ride of less than 20 miles, POP!, everything is back to normal. I'll be damned! I believe that at issue here is that the plumbing somewhere up near the master cylinder traps some air in the system in a way that makes it very hard to purge. Apparently the vibration and pressure of use while under way got the job done. Moral of the story: If you are pumping fresh fluid through the system, never let the level in the reservoir drop too low as I did or you will be kicking yourself all the way into next Thursday.
 
#23 ·
It's the curved section at the master cylinder. Solution seems to be to remove the master cylinder and turn it at an angle so the air doesn't get trapped in that kink. The local tech just came to the same conclusion last week after struggling with another bike like mine.

When you change the pads, make sure you hit the rotor with some emery cloth first. If you don't, the pads will glaze and squeal like hell. They didn't do that when I asked them to change the pads after this ordeal. It goes in Tuesday, I can't stand that loud noise anymore. People are staring at me...
 
#26 ·
you might think this is hillbilly but i have a jar with two tubes soldered into the lid ,one long one short.the long one has a long rubber hose that goes to the bleeder,the other one has a long hose that i attach to the intake manifold on my 74 chevy pu.fire up the truck and open the bleeder,you can go through a bottle fluid quick,so best keep an eye on the level,yep sounds hillbilly but works great.
 
#32 · (Edited)
This just sucks. I have NEVER seen such a problem before!!! I still have spongy rear brakes with brake pedal travel that almost bottoms out. My fault... I allowed master cylinder to suck air when trying to flush new fluid at the 2-year mark. But this is too high a price to pay.

Is is possible they used a large bore brake line that allows fluid to slip by air pocket. I have done "normal" traditional bleed, vacuum bleed, reverse syringe bleed. I even did a banjo bolt bleed right at the M/C using both regular pedal bleed and reverse pushback bleed from the rear. This is insane! Where is this air and how do I expunge it? I have been doing brakes all my life and have never, ever seen this.

I would like to know if anyone from Indian (or anyone who has actually had success doing it themselves) can give us a definitive procedure to bleeding the dang rear brakes on this thing. Its not supposed to be rocket science folks!!!

BTW: my rear brakes were fine before I sucked air, so its not a bad master cylinder. And its a NON-ABS system
 
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#43 ·
This just sucks. I have NEVER seen such a problem before!!! I still have spongy rear brakes with brake pedal travel that almost bottoms out. My fault... I allowed master cylinder to suck air when trying to flush new fluid at the 2-year mark. But this is too high a price to pay.

Is is possible they used a large bore brake line that allows fluid to slip by air pocket. I have done "normal" traditional bleed, vacuum bleed, reverse syringe bleed. I even did a banjo bolt bleed right at the M/C using both regular pedal bleed and reverse pushback bleed from the rear. This is insane! Where is this air and how do I expunge it? I have been doing brakes all my life and have never, ever seen this.

I would like to know if anyone from Indian (or anyone who has actually had success doing it themselves) can give us a definitive procedure to bleeding the dang rear brakes on this thing. Its not supposed to be rocket science folks!!!

BTW: my rear brakes were fine before I sucked air, so its not a bad master cylinder. And its a NON-ABS system[/QUOTE

See above post
I work in Indian dealer and do these regularly
This is a common issue with the scouts when air gets in the system or the system needs to be stripped for part replacement
Above method is the only method that has worked 100% of the time

Good luck and let us know how you get on
 
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#37 ·
OK. So here’s the deal. 2017 Scout69 with NON_ABS brakes. I was flushing the fluid after two years and sucked air on the rear; major disaster

As I described, I tried many methods to bleed the rear brakes (normal, reverse syringe, manual and pneumatic vacuum, bleeding at master cylinder banjo bolt, etc.), all to varying, yet unsatisfactory results; no matter what I did, I still had squishy brakes with excessive travel.

I was about to give up and figured I would try the tie-it-down method I have seen on videos... I did not have high hopes because it was such a foolish looking thing to try, so I decided to try foolishness because nothing sane seemed to be working. Guess what? It worked!!!

The tie-it-down (TID) method is where you use a rope or something to depress and tie down the rear brake leaver and hold under pressure it overnight.

Here is what I figure: I had air trapped either inside or nearby the master which eluded normal bleeding procedure because the brake line is vertical coming out of the master and trapped air wants to rise up that vertical path. When you pump/bleed the master, each time you push a small bit of air goes down only somewhat because the travel and consequent brake fluid volume is so small on each pump. Using the normal bleeding method only pushes the air to the bottom of the uphill and when you release the pedal, it just rises right back up. You are never able to purge it because the bubble just moves down and back up with each pump.

The TID method basically starts with a normal pump, driving that nasty bubble down somewhat... but this time by holding the pedal down overnight, that bubble rises slowly back up the the master. When you finally release the rope the next morning, low and behold... the bubble gets sucked into the master and out the fill holes. I got a rock hard pedal with minimal action the first day.

But it slowly seemed to get worse again (but not as bad as before). So I did it again and this time I was careful to release it slowly and not pump it for a bit to allow the air to fully escape. Some folks say that at this point (before pumping), if you spread the pads in the caliper with a screwdriver it will drive the air out even more because this is like doing a reverse bleed . Don’t ask me why the reverse (syringe) bleed did not work for me... probably not enough brake fluid volume to drive the trapped bubbles out... I don’t know.

Its not the sustained overnight pressure... its the pushing of the air down that vertical section and allowing it to bubble back up overnight up to the master before releasing the leaver and sucking it through to bubble out the feeder holes on the reservoir.

Anyway... the TID method does work and I think I understand why now (after reading many posts and viewing many videos). You have to have things fairly well along for it to work because it only gets those last few bubbles out. I don’t think it would work on a dry system.

I’m sharing this little tidbit follow-up because so many people (myself included) are having trouble with the rear brakes. I hope this solves it for you too.
 
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#58 ·
Well, my rear brake has been soft since the dealer flushed the system. I tried this and damned if it doesn't work! My rear brake is the best it has been in a long time.
 
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#38 ·
So, I’m having the same issue, I had to change out the master cylinder because of a small accident and while trying to fill the reservoir and run fresh fluid through the system I got zero firmness.

While after hearing about the 2 cup rule for swapping out rear brake fluid, I realize it is entirely possible that I need to give it another go, this time persevering to the end of 2 cups. However I am first trying the “TID” (tie-it-down) method coined by MattyBoy. I also found a YouTube video of a guy suggesting the “trick” with a quick how to, giving me piece of mind that this isn’t just some kind of Hail Mary pass. (Although He did the front brake, difference only being pedal vs lever)

Didn’t work the first night, but I did notice a reduction in the amount of fluid in the reservoir meaning that some air must have displaced some fluid overnight... so I parked it on my driveway (slight incline) and removed the brake line hanger just prior to the rear tire (because that is where the line curves up and then back down again a possible location for stored air bubbles hanging out at the highest point of the routed line). I’m going to leave it for 24 hours this time as the video suggested, and check it in the morning.

Here’s the link to the video

By the way, standard weight plates fit perfect on the brake pedal for holding it down overnight
 

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#57 ·
So, I’m having the same issue, I had to change out the master cylinder because of a small accident and while trying to fill the reservoir and run fresh fluid through the system I got zero firmness.

While after hearing about the 2 cup rule for swapping out rear brake fluid, I realize it is entirely possible that I need to give it another go, this time persevering to the end of 2 cups. However I am first trying the “TID” (tie-it-down) method coined by MattyBoy. I also found a YouTube video of a guy suggesting the “trick” with a quick how to, giving me piece of mind that this isn’t just some kind of Hail Mary pass. (Although He did the front brake, difference only being pedal vs lever)

Didn’t work the first night, but I did notice a reduction in the amount of fluid in the reservoir meaning that some air must have displaced some fluid overnight... so I parked it on my driveway (slight incline) and removed the brake line hanger just prior to the rear tire (because that is where the line curves up and then back down again a possible location for stored air bubbles hanging out at the highest point of the routed line). I’m going to leave it for 24 hours this time as the video suggested, and check it in the morning.

Here’s the link to the video

By the way, standard weight plates fit perfect on the brake pedal for holding it down overnight
I've had a not too bad, but not nearly as it should be, peddle since the dealer did a flush for me a year ago. I noticed last week that my rear brake light was not coming one. I did the tie down and got a full pedal back and my brake light. I surmise that with air in the line insufficient pressure is generated to actuate the hydraulic brake light switch.
 
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#39 ·
How did this work for you? I'm having the same issue. I replaced the brake line with a longer one that came with the extended control kit and now I'm having trouble getting the brake to bleed. It's pushing fluid through the line fine it seems but no brake pressure. Baffling really. This is non-ABS. I've bled ABS systems before in cars, so I'm baffled this bike isn't bleeding, and it's not ABS, just regular.
 
#41 ·
Try a Mightyvac.
You could probably even use the biggest syringe you could find,around 60ml, Fit a tite fitting piece of tubing on it and the bleeder and it will suck out enough fluid to remove any air.
Keep an eye on the master,you dont want to run it dry. You might need to smear some grease around the bleeder base if it leaks air. Easy to do and effective.
 
#42 ·
You need to unbolt the master cylinder / footpeg assembly front the frame
With just enough brake fluid in the master cylinder to cover the plunger feed rotate the whole assemble slowly in your hand while gently pressing the pedal and watch the air bubbles come up
It seems to get trapped and no matter what you try using pressure blender, vacuum blender, doing manually by hand you never get a good brake till this is done
Straight after you get the air out using the above method the brake can be bled any method and it shall be perfect
When your trying to get the air our master cylinder as described above it's kind if like that game with ball bearing and the hole trying to get it to fit ( best way to describe the method and movement you need to do)
Good luck guys
 
#44 ·
You need to unbolt the master cylinder / footpeg assembly front the frame
With just enough brake fluid in the master cylinder to cover the plunger feed rotate the whole assemble slowly in your hand while gently pressing the pedal and watch the air bubbles come up
It seems to get trapped and no matter what you try using pressure blender, vacuum blender, doing manually by hand you never get a good brake till this is done
Straight after you get the air out using the above method the brake can be bled any method and it shall be perfect
When your trying to get the air our master cylinder as described above it's kind if like that game with ball bearing and the hole trying to get it to fit ( best way to describe the method and movement you need to do)
Good luck guys
That method sound promising as well. The problem is the bit of air trapped in the downpipe out of the master cylinder.

You need to bleed by regular methods to about 80%... to where where you're not getting air out of the rear, but the pedal is still not tight because of the trapped air in the downtube. Detaching the master cylinder might work, but makes it hard to pump because the plunger is not connected anymore. The TID (tie it down) method worked for me (and its simpler), but you have to get most of the air out first, as mentioned. I'm not sure if it really need to sit overnight... maybe just half a day or even a few hours might do it.

Also: take a box wrench and tap the break line a bit up front to jar loose any air bubbles that are sticking to the inside wall of the break line. The fancy vacuum methods did not do it for me.

Have you tried the TID method yet? I though it was a bunch of BS, but then it worked. so I'm a believer now.
 
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#48 ·
You only unbolt the footpeg hanger from frame so you can still pump pedal as plunger still attached
Problem with the scouts is the air seems to get trapped in a little pocket and it's always the same
Tie down method may work but only method I've had 100% success rate with is method I described above and we work on scouts on a daily basis in the dealership
Sounds like good advice... and it avoids the waiting period, so kudos! I'll be sure to try it that way next time (hopefully never!)

Must be fun working on Scouts in Scottland all day... and getting paid for it to boot! I guess I could say the same thing about working on Indians in India! Any others?
 
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#49 ·
Love my job and working on Indian motorcycles are awsome
Has the opportunity to attend Gold Level Technician this year which was amazing and to be 1 of the 1st 5 Gold level techs in the UK is pretty cool
Visiting Florida this year and plan on doing a few visits to some shops see how it's done in USA
 
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#50 ·
OK I have some good pedal pressure. What a hassle, but this is what I did. I'm not sure what worked and what didn't but here it goes. I first bled the brakes traditionally without using any gadgets. Just the old school 'open the screw and press the pedal-close the screw. I put about half a bottle of fluid doing that, but didn't have pressure in the pedal so that didn't work. Then I did the TID method described above. It helped. I then removed the foot peg and did the method described above, moving the master cylinder around by hand to try to get the air bubbles out. I didn't see any air bubbles, but that doesn't mean there wasn't any. I did another traditional brake bleed, but didn't put a ton of fluid through it this time. I then removed the entire assembly and hung it off of my toolbox for a day. I figured that air bubbles would travel best when strait up, so I was hoping any air bubbles would be at the master cylinder after a day of hanging there. I then reinstalled the brake caliper and placed the foot peg and master cylinder on an elevated table and put a weight on the pedal so it was all the way down and left it there overnight. There was still some pressure so I opened up the bleeder just enough to let the pedal down. I was hoping any air near the master cylinder would escape with it elevated into the reservoir. After reinstallation, I found I had pedal pressure. This is a lot and most of it was probably not necessary, but it worked in the end.
 
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