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devilswild66
10th June 2007, 05:30
Rear Master Cylinder Woes could there be a service bullentins:


I just put on a new rear tire and did not mess with the rear cailper (MoCo manual says you do not have to remove the rear caliper). After getting it all together and set up my rear brake quit working. :confused: So I tried to bleed the hydraulic system to no avil it did not work. I just disassembled the master cylinder and found the "PISTON SPRING" through the "PRIMARY CUP". Great...now I have to wait for the dealer to get parts in (I have to order) :censor :censor :censor (Just-in-time inventory is just great :doh ).

chrishajer
10th June 2007, 06:41
No bulletin or recall for the rear master cylinder that I know of. Most of the problems I see with the rear brakes, after a pad or tire change, are due to not getting the pins and pads installed properly on assembly.

http://www.xlforum.net/vbportal/forums/showthread.php?t=65379#postcount770026

That doesn't explain what you found in the master cylinder, but changing the rear tire didn't cause the problem in your master cylinder I don't think. If you didn't pull the caliper or the pins, I don't see what could be wrong back there either.

--Chris

Hot Rod Sporty
10th June 2007, 06:45
I took my 05 in for a spongy rear brake, and they first said that I needed new brake pads (at 7500 miles). When they put it up on the lift, the rear brake master cylinder was bad and they replaced it (under warranty). They never told me exactly what was wrong with it.

chrishajer
10th June 2007, 07:03
That would make three that needed repair then, all of the sudden (that I have heard of anyway). CBAS5 just had one replaced (http://www.xlforum.net/vbportal/forums/showthread.php?t=52733) too. Not sure what's going on there ...

--Chris

devilswild66
11th June 2007, 01:41
Here is a picture of the torn cup...

http://xlforum.net/photopost/data/655/medium/Torn_primary_cup_002.jpg

:geek

chrishajer
11th June 2007, 04:04
That's pretty crazy. Good picture :)

Any idea how it happened? Were there any pieces missing from it that would have caused something like this?

--Chris

devilswild66
11th June 2007, 05:34
All the major pieces are in the picture. Above the primary cup you will see the center section which is a nipple that goes into the piston spring. The last piece is just above the nipple (center section of the primary cup) which is 0.100" x 0.050" x 0.050" in size.

--Chris
I want to "believe" that I felt something different with the brake pedal about one to two months ago, but the brake had been function just fine by stopping the bike. When I pulled the piston spring out of the master cylinder the cup was through the first couple of loops on the spring.

chrishajer
11th June 2007, 07:30
That's definitely weird. Maybe you did feel something, but we all try to piece together things to make the explanation work. I've never had one of those master cylinders apart which is why I didn't know if all the piece were there.

It almost seems like a piece between the cup and spring is missing, or that something is missing off the end of the spring?

--Chris

CBAS5
11th June 2007, 08:14
I had problems with my rear brake for awhile before I took it in. However, mine was more obvious. I would lose brake pressure and then regain it as I rode the bike. Did you see any pieces of something in your brake fluid? I had orange globs in mine.

devilswild66
11th June 2007, 08:32
--Chris
I got a new picture that might give better details (3 pics in 1). :boxing

http://xlforum.net/photopost/data/655/medium/Torn_primary_cup_006.jpg

CBAS5
I will flush out the system once I rebuild the master cylinder and there is no since in cleaning out the system untill the new kit arrives. I could have globes of stuff in my lines which will get flushed in do time...and my guess is this rebuild kit will not get here till Thursday. :(

CBAS5
11th June 2007, 20:13
I could have globes of stuff in my lines which will get flushed in do time...and my guess is this rebuild kit will not get here till Thursday.

My globs were very noticeable. You saw them when you removed the cover from the reservoir.

xlr8
13th June 2007, 23:05
Master cylander went south on my 05 as well. Didn't think much of it at the time. Now I wish I had thought to have the stealership do it under warranty. The bike only has 31,000 miles on it. You would think you should get at least 100,000 from a master.

CBAS5
13th June 2007, 23:09
Did yours fail in the same way as ours?

xlr8
13th June 2007, 23:16
Had very simular symptoms as you did no brake when I first took her out in the morning. Took to local indy who replaced the master as he could not even get it to bleed.

CBAS5
13th June 2007, 23:23
Since this isn't an isolated incident (as I thought previously), I wonder if the new master cylinder will hold up or do the same thing with time. I wonder if their will ever be a recall on this. I doubt it.

klinesamuel
14th June 2007, 02:41
I'm having problems with my rear m/c also. I thought I could just flush the brake line but nothing would come out when I tried to bleed it. I'm also waiting on a rebuild kit from the moco.
By the way this started happening with only 12,000 miles on the bike. NOT HAPPY!

Sam

chrishajer
14th June 2007, 05:46
No recall that I know of. If you had yours repaired under warranty, then H-D has the info on the failure. If they get enough failures, they will look into it.

--Chris

streetfightster
16th June 2007, 00:30
i had problems with mine too. it took me a few hours to bleed after i flushed the system. the mc wouldnt draw fluid from the reservoir so i had to bleed it by filling the caliper.

XLFREAK
16th June 2007, 05:19
I had problems with my rear brake for awhile before I took it in. However, mine was more obvious. I would lose brake pressure and then regain it as I rode the bike.

I had the same thing happen on my 04 last summer. I tried to bleed the rear for days using every gadget I could find. I finally brought it in and the dealer said it (the master cylinder) was no good.

DIESEL
19th June 2007, 20:18
I had mine replaced at 9500 miles, first a rebuild, then replacement. I have 22000 now and it is bad again. Rebuild is 18 bucks, but third one--Piss poor design to begin with.

F--it I have been downshifting and using the fronts.

CBAS5
19th June 2007, 20:35
I had mine replaced at 9500 miles, first a rebuild, then replacement. I have 22000 now and it is bad again. Rebuild is 18 bucks, but third one--Piss poor design to begin with.

That's not what I wanted to hear and that was actually my fear; that in another 10,000 miles the rear brake would be bad again. These are japanese brakes, I thought they were suppose to make reliable stuff. ????

Deicer18
19th June 2007, 20:50
My M/C was replaced at approx 17k miles. I now have 27k and the rear seems real spongy. I just ordered floating rotors and will be checking the M/C when I do the install.

DIESEL
19th June 2007, 20:52
OK-so I called the dealer and they "improved the design of the rebuild kit"

Now it is 31 dollars.

They said if was a safety issue, Harley would issue a recall. I said isn't not being able to stop a "safety issue?" He said "I guess"

CBAS5
19th June 2007, 21:40
When I was looking up the part number for the rebuild kit I noticed there is an A and B version. That means there were two revisions of the rebuild kit. That's not very comforting.

devilswild66
20th June 2007, 10:23
I had checked my posting in a while (a week ago)...sorry...I guess I might have brought something up??? :doh I did notice when I finished rebuilding the master cylinder on Saturday that the new H-D brake fluid was purple and the previous fluid color was yellow. :confused: :confused: :confused: I used some of the grease that was left over to grease the rear caliper because it was not floating (sliding back and forth on the pins). Brakes are all better now!!!

I did by the bike used and I wondered if the previous owner or maintenance shop might have put in DOT 3 brake fluid???

(IMHO) The way the design of the primary cup and piston spring are made is a weak link. The reason for my belief is the pressure that is exerted on surface of the primary cup is not flat and there is the hole for the primary cup nipple.

I did notice the A and B version when I was calling to see if any dealer on the East side of Phoenix might :doh have one in stock. I forgot :smackh just-in-time inventory…I still can’t believe H-D is operating with a just-in-time inventory.

Does anyone know if or where I could send in these broken parts to H-D to have them analyzed or make an official complaint???

chrishajer
20th June 2007, 17:51
DOT5 purple fluid turns yellow after a while. It's possible someone mixed fluids at some point, but the fact that the DOT5 is no longer purple does not mean they did. They smell, feel and taste totally differetnt.

If you call H-D and make a complaint, they will give you a reference number. Make a note of that and ask if they want the parts back. If they do, they will give you an address. It's good that you are willing to do that because other than looking at the quantity of kits sold for rebuilding the master cylinders, with non-warranty repairs they have no way of knowing the extent of the problem.

Harley-Davidson Customer Service
3700 W. Juneau Avenue
Milwaukee, WI 53208
(414) 343-4056

--Chris

devilswild66
21st June 2007, 04:15
DOT5 purple fluid turns yellow after a while. It's possible someone mixed fluids at some point, but the fact that the DOT5 is no longer purple does not mean they did. They smell, feel and taste totally differetnt.
:roflblack :roflblack :roflblack
I guess I will have take your word on it that it taste totally different. :drinkup

devilswild66
21st June 2007, 04:33
chrishajer

I will make a call to H-D on Friday (06/22/07) to make a complaint on the part and also see if they want the bad parts back for analysis. Thanks for the info on what to do.

I did make a complaint to them regarding a front fender but I don't know if they (H-D) took care of the issue or the dealer. It is a very long story and it took someone three times to get it right (or till the customer was satisfied-that would be me :D ).

CBAS5
21st June 2007, 04:39
DOT5 purple fluid turns yellow after a while. It's possible someone mixed fluids at some point, but the fact that the DOT5 is no longer purple does not mean they did. They smell, feel and taste totally differetnt.

The stock brake fluid that came in my bike was clear (although it's suppose to be DOT 5). The replacement brake fluid is purple. I don't know why the stock stuff is clear (turns yellow of time) and the replacement purple.

sportysrock
27th June 2007, 03:46
I finally broke down and greased the rear caliper pins for my 10k service. It seems like the rear brake has been dragging a little because the rotor is sometimes warmer than I would expect.

I couldn't hardly do this by hand like the front calipers last night, so using a c-clamp, brake pads and a cushioning spacer I pushed the caliper piston back in its bore. I did it while looking into the fluid reservoir, and noticed bits of orangey globs were visible in the returning fluid. The pins were greased-up, pads reinstalled, and everything is back together. Now the rear brakes will not pump up.

I have an extended warranty, but am thinking of fixing it myself anyway since that has a $50.00 deductible. At least it will get done right

The rebuild kit is at revision B according to the dealer I called in California. They must be some QUALITY parts! :rolleyes: :rolleyes: :rolleyes: It appears these brake systems are the pits. They did a recall on the front master cylinder and may as well issue one for the rear brake too.

I'm disgusted right now. The weather is great and I have no rear brake. My wife said I may as well buy a Ninja. She may be right! HA HA HA!!!


Edit:
Getting a rear master cylinder rebuild kit is going to be a waiting game, so I am thinking of disassembling, cleaning, and reassembling it with new fluid. If you think that's a bad idea, then I welcome your feedback. Thanks!!!

Another Edit - 6/29/07, 2 days later:
3 dealers said a week for the rebuild kit arrival. I found one in stock an hour the other way and snatched it right up. The master cyl. is getting rebuilt this weekend.

klinesamuel
30th June 2007, 02:10
Another Edit - 6/29/07, 2 days later:
3 dealers said a week for the rebuild kit arrival. I found one in stock an hour the other way and snatched it right up. The master cyl. is getting rebuilt this weekend.[/QUOTE]

I'm still waiting for my rebuild kit and it's been over a week now. My dealer said he never heard of any problems with the brakes. I ran into the parts guy over the weekend at the autozone and he told me the they sell a lot of those kits and that they are waiting on there next shipment of rebuild kits.

Sam

streetfightster
30th June 2007, 08:03
i had that problem on mine, the brake wouldnt pump up. the reason it wont pump up is because it wont pull fluid in from the reservoir. i had to remove the caliper from mine, fill it with the piston almost maxed out of its bore, and then bleed it. like bleeding it backwards. it worked, my rear brake works ok now. im still mad at it though.

Deicer18
1st July 2007, 20:50
This coming week my Indy will be doing a lot to my bike........installing floating rotors, bleeding brakes, and checking the M/C, along with other MX stuff. As I said earlier my M/C was rebuilt 10K miles ago and the indication I'm getting is spongy/bumpy feeling when applying the rear brake. So I'm gonna try to remedy the situation by changing rotors and probably having the M/C rebuilt with the "B" revision. I'm not gonna let the dealer tell me its my imagination. Just gonna fix it and be done.

sportysrock
4th July 2007, 15:25
The rear brake feels a lot better than before. If you do it yourself, have some good snapring pliers with a taper on them. I bought some new ones that didn't work that great until I ground a bit more taper on them to retain the large snapring. For those that may not know, the tips should be a bit fatter than the rest of the pin on the snapring plier tips which helps keep the snapring on the pins.

tcspannerwrench
4th July 2007, 17:21
10,000 miles on my 05 and in the morning the first time i get on the rear brake it goes all the way down with very little brake action at the rear wheel i guess i should go ahead and order the kit before it goes all the way out

DG_Sportster
11th July 2007, 08:55
I noticed the mention of "orange globs" in a number of posts. Quite a coincidence, as earlier today i noticed some strange looking orange goo dripping from the honeycombed rear bracket that the rear master bolts to.

I had gotten a drip from this area before which turned out to be gas from the tank vent. I initially thought This orange goo was grease from the swing arm area, but on further inspection it appeared to be coming from the tank vent as well. I dismissed it as residue caused by gas sitting in a rubber line for a few days. I honestly don't know what it is.....

...BUT, could this stuff somehow be finding it's way into the near-by master cylinder or the reservoir, causing your problems?

My brakes have been fine so far ( knock on wood ).

tyke
17th July 2007, 20:30
I had the same symptoms as you guys, (no pedal feel, and wouldn't bleed).
I ordered my rebuild kit and waited for my parts to arrive. I didn't notice any visible damage to my original parts when I opened it up. But after putting everything back together it works fine. All it cost me was 31 dollars and two weeks of prime riding time.

tyke
17th July 2007, 20:45
I had the same symptoms as you guys, (no pedal feel, and wouldn't bleed).
I ordered my rebuild kit and waited for my parts to arrive. I didn't notice any visible damage to my original parts when I opened it up. But after putting everything back together it works fine. All it cost me was 31 dollars and two weeks of prime riding time.

DIESEL
17th July 2007, 23:11
I recently rebuilt mine. Took a while to bleed. THe M/C was NOT adjusteded properly to begin with. I think when the Moco tech put it back together he/she did not follow the directions. I removed everything and cleaned out lines, replaced caliper rubber, etc... and it works ok. will lock it up if need be.

Replace M/C guts
Cleaned all brake lines
replaced caliper rubber
replaced brake pads
replaced hydraulic switch to turn on light

works ok--kind of a pain in the rear all together. Especially since this was supposed to have been done 10000 miles ago by H-D.

This is either my 3rd or 4th M/C or rebuild.

sportysrock
18th July 2007, 05:29
Nice work Diesel, I hope this one's a keeper for ya.

DIESEL
18th July 2007, 16:57
Thanks Man--Was glad I did it myself.

Now, if I can stop spinning that back tire? hummmmmm.

Paul
21st August 2007, 05:52
I noticed a problem when I changed rear pads at 22,000 Miles. The pedal wouldn't pump up. Luckily I found a rebuild kit at my local dealer. All the old parts looked fine so I still don't know what the problem was but they work great now. The purple DOT5 fluid turns yellow with use when it gets hot.

alsipd
9th September 2007, 20:02
I went through all of the replies and did not see the part number for the Rev B of the MC rebuild kit. Does anyone have this so I can order one and be ready to rebuild the MC this winter? I have an 06 and it has 5k on it now. I think I will be proactive on this issue since it is only $31.

Thanks

klinesamuel
11th September 2007, 00:43
42810-04B is what the label says on my kit.

DIESEL
11th September 2007, 17:24
I forgot to post this. The u shaped fastener that attaches to the actual rod whcich attaches to your brake was out of spec.:censor :censor :censor

I mean so far out that the plunger wouldn't even go 1/3 of the way down. In hindsight, I think that if this was adjusted correctly I would not have had to rebuild it.:doh

whispanic
16th September 2007, 08:40
My rear pedal has been strange for some time. Sometimes its just right and then it has more travel before responding.

Today I went to apply the brake and the damn pedal was like a rock!

Like 1/2" of travel and it was stopping.

Parked and caught a ride...

Returned 4 hours later to show a friend and the damn pedal had normal travel 'cept the master cylinder makes a noise. I cant replicate the sound in words other than to say its a "plunger" type sound...

whispanic
16th September 2007, 23:31
bump..............

rolnlow
17th September 2007, 13:52
I didnt read the whole thread but just a heads up... I found if your over tighten the slide bolt on the caliper. the caliper will not come back open, it will seize shut causing the master to feel as though it bottoms out or stops and wont create pressure again. check your torque and use blue lock tight to hold the bolt with a firm torque. I'll post the exact torque later.

xena
26th June 2008, 16:23
Bringing this thread back up since I am having the discussed
problems and have a rear mast cyl rebuild kit on the way.

I did check the plunger adjustment and it's fine so I ordered the kit.
Curious as to how the bikes that needed this fix are doing?

klinesamuel
28th June 2008, 00:47
Bringing this thread back up since I am having the discussed
problems and have a rear mast cyl rebuild kit on the way.

I did check the plunger adjustment and it's fine so I ordered the kit.
Curious as to how the bikes that needed this fix are doing?

I installed this kit on my bike over the winter months. So far it is doing really well with no signs of trouble.
This is an extremely easy job as long as you have a good set of retaining ring pliers. Oh, and if you loose the retaining ring that holds the master cylinder plunger to the bell crank it is a 1/4" (I think). :D

Sam

DIESEL
28th June 2008, 01:09
Take your time on the rebuild and you will be fine. You will need some needle nose O-Ring pliers.

Mine is working fine since I did it myself.

xena
2nd July 2008, 16:07
Thanks so much for the info Sam. The kit is due to
arrive tomorrow. Will have to buy a set of the ring pliers
and not at Ace hardware. Last pair I bought from them broke.

klinesamuel
3rd July 2008, 01:24
Thanks so much for the info Sam. The kit is due to
arrive tomorrow. Will have to buy a set of the ring pliers
and not at Ace hardware. Last pair I bought from them broke.

I bought the Craftsman Professional snap ring pliers. I really like the fact that with a simple slide of a button they change from either inside or outside use. After I used them I noticed that Lowe's sells them at about ten dollars cheaper with the Channelock brand (same tool)on them.
See, now you get to add a new tool to your collection, isn't life great!

Sam

xena
6th July 2008, 00:35
Reporting back with a positive outcome.
I rebuilt the rr master cylinder and now
have brakes again. Interestingly enough,
I could find nothing wrong with the components
that I removed. Oh well. $35 and some change
from zanotti's and the brakes are good again.
14,600 for mileage on the bike just for reference.
Thanks for the help you guys. :)

rolnlow
6th July 2008, 02:18
watch when you tighten up the caliper. if you over tighten the bolt that the caliper slides on , the caliper ceases. and the rear brake locks up .

klinesamuel
6th July 2008, 03:16
Reporting back with a positive outcome.
I rebuilt the rr master cylinder and now
have brakes again. Interestingly enough,
I could find nothing wrong with the components
that I removed. Oh well. $35 and some change
from zanotti's and the brakes are good again.
14,600 for mileage on the bike just for reference.
Thanks for the help you guys. :)

Yes, same here. I also could not find anything wrong with the components last time I rebuilt the M.C.

Sam

xena
6th July 2008, 06:00
watch when you tighten up the caliper. if you over tighten the bolt that the caliper slides on , the caliper ceases. and the rear brake locks up.

Thanks for the tip but when you rebuild the rear master cyl
there's no need to touch anything on the caliper - other than
the bleeder screw.

rolnlow
7th July 2008, 12:52
Thanks for the tip but when you rebuild the rear master cyl
there's no need to touch anything on the caliper - other than
the bleeder screw.

O h I know. I was talking about when you remove the caliper. sorry I should have been more clear.

rolnlow
7th July 2008, 12:53
Thanks for the tip but when you rebuild the rear master cyl
there's no need to touch anything on the caliper - other than
the bleeder screw.

O h I know. I was talking about when you remove the caliper. sorry I should have been more clear. it will cause the same symptoms you decribed at first.

Mr M
17th July 2008, 22:24
Just to add to the conversation, my rear 05 mc has stopped pumping, likes many others here it wont draw from the reservoir, although the pistons are good as it creates pressure and suction if you put your finger over the banjo bolt hole. Fitted a rebuild kit - the original parts looked fine - but no joy. I will chat to the dealer and see what I can get out of them.

French_Phil
29th July 2008, 13:42
Thanks for this thread guys! I have a 2005 1200 roadster and for some time now the back brake felt spongy like there was some air in it. I tried bleeding it which made things worse: I ended up with no pressure at all. After reading this thread, I got up the courage to remove the rear master brake cylinder and take it apart. Everything looked fine inside except for one thing: there was grease behind the piston! I took ages to make sure that I got rid of all traces of the grease, then rebuilt the cylinder, stuck it back on the frame, and bled the brakes in less than 30 minutes. They're better now than they've been for a long time.

God knows why there was grease in the master cylinder. The service manual specifically states that you should only use DOT 5 brake fluid and nothing else. In any case, that was the problem: the grease was gradually making it more and more difficult for the spring to return the piston to its starting postion after the brake had been activated.

OK I s'pose I should order the rebuild kit because some of the components you're not supposed to reuse...

plevine1
6th October 2008, 01:26
I had the same symptoms as you guys, (no pedal feel, and wouldn't bleed).
I ordered my rebuild kit and waited for my parts to arrive. I didn't notice any visible damage to my original parts when I opened it up. But after putting everything back together it works fine. All it cost me was 31 dollars and two weeks of prime riding time.

I just did the rebuild and my rear brake still stinks. I have slightly more brake pressure then before but not enough to stop the bike. The pads are fine. I really dont want to buy a new MC in the guess that that fixes the problem. Anyone have other suggestions.

pvlittrell
7th September 2009, 17:24
Changed my rear pads and found I had no brakes at all. Had orange globs in the fluid reservior. Drained all fluid and replaced with DOT 5 as per Service Manual. Then couldn't get pressure enough to raise fluid aver a half inch in the drain tube. Got the rebuild and did it in about 1/2 hour. Spring had punched through the primary cup. Didn't even need to put the MC in a vise as per instructions. Put it together and installed. Filled with fluid and pumped it. Got pressure but had to play with the bleeder to get all the air out. Be sure you pump, open the valve, then close the valve before relieving pressure on the pedal, repeat this until all air is out. Now my brake is great. As per a previous post, chamfer the leading edge of the pads a bit to reduce squeal. I also removed the caliper form the mount and cleaned the boots and put a little brake grease in them to assure they slide well. Also replaced the caliper pin as it was slightly worn and didn't cost much. It's good to have a safe bike. No point having a fast one if you can't stop it.

WhiteKnuckle
12th September 2009, 08:39
Changed my rear pads and found I had no brakes at all. Had orange globs in the fluid reservior. Drained all fluid and replaced with DOT 5 as per Service Manual. Then couldn't get pressure enough to raise fluid aver a half inch in the drain tube. Got the rebuild and did it in about 1/2 hour. Spring had punched through the primary cup. Didn't even need to put the MC in a vise as per instructions. Put it together and installed. Filled with fluid and pumped it. Got pressure but had to play with the bleeder to get all the air out. Be sure you pump, open the valve, then close the valve before relieving pressure on the pedal, repeat this until all air is out. Now my brake is great. As per a previous post, chamfer the leading edge of the pads a bit to reduce squeal. I also removed the caliper form the mount and cleaned the boots and put a little brake grease in them to assure they slide well. Also replaced the caliper pin as it was slightly worn and didn't cost much. It's good to have a safe bike. No point having a fast one if you can't stop it.

Chamfer the pads? Are you talking about grinding them? If so, I don't suggest that, they do have asbestos in them. Better to deal with a little noise on the rotor than get cancer. Just MHO.

FoxsterUK
12th September 2009, 10:01
Chamfer the pads? Are you talking about grinding them? If so, I don't suggest that, they do have asbestos in them. Better to deal with a little noise on the rotor than get cancer. Just MHO.Brake pads haven't had asbestos in them for some years, its been illegal to use in the UK since 1999 and though I don't know for sure in the US I doubt its still a permitted material.

pvlittrell
13th September 2009, 01:36
My pads were metallic composite. Used a small file. No flying dust. You just want to round the leading edge a bit, so it isn't square. Once the pads are conditioned to the rotor and worn a bit they will square off again, but you don't get the squeal while they get conditioned to the rotors. You don't need to but I did. I know brake dust is not healthy but I didn't say "grind". And I don't think there is asbestos in them anymore, but I could be wrong. If I get mesothelioma it won't be from brake pads anyway. Used to make silver jewelry back in High School. We were given asbestos pads, not the hard ones but the semi hard fibrous ones, to solder on. Way before the asbestos scare. Exposed to it for a couple of years. So far, 49 and no cancer. I was referring to a post by "Cantolina" http://xlforum.net/vbportal/forums/showpost.php?p=2091146&postcount=9: It's an option.

Mop Bucket
20th September 2009, 08:27
I am a new rider and a newbie mechanic. I bought a 2005 sportster and decided to do all my own work. Bought a service manual. Sure enough, my rear brake light stopped working after a couple of weeks. Bought a part and replaced it. Had to bleed out the breaks after I was done. Had tons of trouble, but finally got it air free. Then I noticed no breaks. I bled it out for hours and no joy.

My co-worker told me about this forum and I did some searching for an answer to my problem. I found this post and decided I had to check the master cylinder. You guys helped me make the right decision. The spring had ripped through the plunger and was stuck. So happy it wasn't me that broke my bike.

So, thanks to everyone for posting. As soon as the part is in town I will be back to riding in the wind.

plevine1
21st September 2009, 02:28
I am a new rider and a newbie mechanic. I bought a 2005 sportster and decided to do all my own work. Bought a service manual. Sure enough, my rear brake light stopped working after a couple of weeks. Bought a part and replaced it. Had to bleed out the breaks after I was done. Had tons of trouble, but finally got it air free. Then I noticed no breaks. I bled it out for hours and no joy.

My co-worker told me about this forum and I did some searching for an answer to my problem. I found this post and decided I had to check the master cylinder. You guys helped me make the right decision. The spring had ripped through the plunger and was stuck. So happy it wasn't me that broke my bike.

So, thanks to everyone for posting. As soon as the part is in town I will be back to riding in the wind.

Your "Brake Light" stopped working. Are you talking about the actual light or the rear brake. One wont effect the other. Is the problem that you can't get pressure on the brake? Bleeding can sometimes be a pain. I bought a set of speed bleeder valves. They are great and make bleeding a cake walk.
If you can't build pressure then you might have a bad master cylinder. There is a rebuild kit which is cheap and somewhat easy to install.

Mop Bucket
21st September 2009, 22:35
The rear break light switch is what broke on my Sportster. In replacing the switch I needed to bleed the brakes. While bleeding the brakes manually I noticed that the rear brakes not longer worked. I am a newbie and had a problem with air being sucked in from the nipple on the caliper I got that fixed bleed the breaks until no air was coming out of the connection. After bleeding I still didn't have any breaking power and pretty much no resistance when pushing the brakes.

That is when I started searching the forums. I read this one about the bad master cylinder and decided to take my apart to make sure it was or wasn't bad. Turned out the master cylinder had a ripped plunger. The spring was through the plunger and jammed in place. I have ordered a replacement already. I just wish it would arrive faster then 7-10 days.

883+
2nd May 2010, 17:06
every rubbermount I see with this problem was because of a tire change or removing the shocks letting the belt slam down on the linkage right where it turns to go into the master cyl.

hooptygoo
2nd May 2010, 20:51
The belt isn't that heavy. What would it be knocking out of adjustment?

papadad
30th August 2010, 03:56
on the 04-up, is it a kit (spring and cap) or do you need to buy a hole cartridge like on the evo rear brake system

pvlittrell
30th August 2010, 08:50
It's a kit. All the guts that go in the tube.

matridge
10th April 2011, 21:39
i had the problem described with the m/c , but i hadnt messed with tire or caliper or brakes at all for about 7 months maybe. just went out while on a ride. no resistence when pushing brake. im about to disassemble now.

wedge
31st May 2011, 00:49
every rubbermount I see with this problem was because of a tire change or removing the shocks letting the belt slam down on the linkage right where it turns to go into the master cyl.
It shows up while changing a tire, but there is no connection. I recently spoke to someone who is an engineer for that MC. What seems to happen is that the primary cup gets torn in the center and it manages to still work as long as the MC is not disturbed much because it is backed up with that flat metal plunger which helps it seal even tho broken. Then they are a bit of a bitch to bleed, but with a broken cup they won't bleed anyway.

Those of you who have done the job will note that the new cup has a tit on it that goes into the center hole of the washer that is welded to the end of that spring. Well when the parts are new the problem doesn't seem evident, but if you take the broken cup and the spring/washer thing and hold them together on the bench you will see that the washer can slide sideways quite a bit within the center of the primary cup. I think that the tapered spring tries to cock some every time the pedal is pressed causing it to work against that tit until it breaks the tit off and leaves a split across the cup. I think the better cure would be to put a larger washer on the end of the spring so that it will not keep fighting the tit for centering. I sent a detailed explanation of this to the person I spoke too, but did not get a reply yet.

Bleeding is the other problem, and the big loop in the brake line is a possible cause for this (trap for air), and also some have said that the return hole in the MC is too small (I agree), but enlarging it is risky unless you can make sure that there is no burr left to hurt the new cup.

MaNickles
3rd July 2014, 19:16
i have the same spongey brakes what is the part number i need to get the rebuild kit and do i need kit A or B i have a 05 1200C