brake problem.....out of ideas.....

[mbellaver]

I've been trying to get my front brakes working for quite a while now. I've bled them the normal pump, hold, and release the bleeder valve method. I've tried to back bleed them using a syringe to suck the fluid through while someone filled the reservoir. I've tried the opposite of that by filling the syringe and pushing the fluid through. I've take the master cylinder apart and cleaned it. Still they feel spongy. The work somewhat but they don't offer any real stopping power. So I'm begging here for some more ideas. Thoughts anyone.....

After all that can air still be trapped?

Is the master cylinder worn out?

[rideracelivemx7]

how are your pads? get a rebuild kit for the master cylinder. just a couple o rings i believe. easy stuff.

[mbellaver]

The pads are plenty thick. I've been thinking about a rebuild kit. Does the master cylindar visually leak when they fail or do you just have weak pressure (like ive got)?

[blaaze416]

I've had the same problem for a month or so now. Bled them every which way but loose, still spongy. It just so happens that I was in the market for some new brake and clutch levers. I've been waiting on them for a couple weeks. they came in yesterday so i hooked them up, and guess what? NO MORE mushy feel. And where I used to be able to pull the brake lever almost all the way to the hand grip, now it stops with at couple inches to spare and its rock hard. I bet I can endo now! ;) Not sure if this helps, but it's just what I've experienced.

[mbellaver]

so you replaced the entire brake master cylindar/lever ....and end of problem. Did you go with new oem stuff?

[blaaze416]

Originally posted by mbellaver
so you replaced the entire brake master cylindar/lever ....and end of problem. Did you go with new oem stuff?

Sorry. No i replaced just the brake lever and clutch lever assembly. Took about 3 minutes total to switch out. Got some ASV levers from ASV inventions for a little over a franklin. Actually it was from ATV Galaxy off ebay, but screw them, they suck at shipping. Just search ASV inventions. Did not replace the master cylinder or anything else.
I love the way the new levers feel....so much more crisp on the pull with a lot more response from both the clutch and brakes. But yeah, end of problem!

[mbellaver]

So in your situation, do you think the original lever was just worn and wouldn't push the cylinder in all the way? That's the kind of fix I'd like, but it seems too simple!

[blaaze416]

Well it sure does seem that way...Now i only tested the levers out going up and down my drive way, but it seemed to do the trick. It suprised me though, too. I know my clutch lever was crap. It's been broken, rigged, broken and rigged again. But I didn't think a brake lever could just wear out. I figured the resevoir diaphram or master would go, but the lever?? Whatever works, ya know?! Bottom line...I LOVE the new levers!!!:D

[hornetgod13]

My bet is that you need to replace or repack your master cylinder. It sounds like it's bypassing fluid. Replacing the lever assembly isn't going to cure your problem.

[mbellaver]

Well, I guess it would be a good time to buy some nice new levers anyway! You did get me thinking though. I sometimes notice fluid leaks out from the resavour cap. So would a leaking resevour cause weak pressure?

[Gibson]

my brakes r really spongy too, mine also leaks from around the cap, iput a 450r brake lever on it a month or so ago, but it never helped anything so i think its our master cylinders

[hornetgod13]

The reservoir isn't pressurized. It only provides a supply of brake fluid. The plunger on the bottom of the master cylinder is what is most likely needs repacked. A new lever won't help this.

[mbellaver]

that sounds most logical. I had it apart to look at it already. I guess I'll go ahead and buy the rebuild kit. I believe moose makes them for about $25.00. Thanks.

[madmax400ex]

I have had the same problem for about 2 months.
I replaced my front brake pads and did a caliper rebuild on both sides, and when i bleed the brakes i just couldn't get it back to were it was, they were just really spongy. So i went and bought a MityVac brake bleeder, but that also didn't work still spongy.

But i didn't know they sold kits for the master cylinder:D, so now that is my next step.
Great Advice Guys

[hornetgod13]

I struggled to bleed my brakes after installing braided steel lines. I eventually bought a vacuum bleeder at AutoZone and it's just what I needed.

[blaaze416]

Originally posted by hornetgod13
My bet is that you need to replace or repack your master cylinder. It sounds like it's bypassing fluid. Replacing the lever assembly isn't going to cure your problem.

Yeah, I'm with ya. What do you mean by repacked? ...I guess if that is the case, the rebuild kit will come with some detailed instrutions (hopefully). Although I've got to say, I went out after work today to test the brake lever out again, and it still feels nice and firm. I mean it's like night and day. So for now I'll bide my time.
Now I must say i have flipped my quad a few times, so maybe my oem brake lever was damaged somehow. I KNOW my clutch lever was. Hopefully in my case the new lever(s) solved my problem. We'll see here a little later....

[hornetgod13]

I'm an aircraft mechanic. I primarily specialize on hydraulic sytems. When I say "repack" I mean replace the packings (o-rings).

If the master cylinder needs rebuilt. The kit costs between $25.00 and $35.00 and the maintenance steps are covered in the manual.

[project400ex19]

I had the exact same problem, it turned out one of my calipers was leaking somewhere, we never did find it. I ended up just buying new front calipers, I rebuilt the master cylinder twice b/c I had two mechanics tell me that's what It was. This happened when I put on the Streamline Stainless Steel dual brake lines. So I would check the calipers.

[project400ex19]

I forgot to mention, i rebuilt the calipers completely the first time, and that did not help...so then i ended up buying new ones. If I was to do it over, i would've put on 450R front spindles/hubs/rotars/calipers. then I would have some more stopping power.

[gibbygsxr]

Just fixed the same poblem on mine. Thought I was going to have to rebuild the master cylinder after I tried the normal bleeding and all it did was piss me off! I did a search and someone else had a post on here and now I cant find it to link to it. He called it reverse bleeding. Hope this helps.

This is what I did and it worked great!

1. Loosen reservoir caps

2. Pull brake handle in and zip tie it in the closed position
for the back I zip tied it to the frame.

3. Let it sit for a couple of hours

4. Undo zip ties and pump brakes 5 - 10 times and repeat steps 2 and 3 (I did this 4 times)

5. Once you get the air out it will be like new!

Let me know how you make out!

[blaaze416]

Well, I don't know if anyone cares, but I took the ex out last night for a night ride and had absolutely no sign of mushy front brakes. The lever is tight and the front stops hard. I don't know for sure, but it really seems in my case, the new levers have done the trick!! Though I'm sure the 42 times I bled my brakes helped out a bit too. I found no leaks in the lines or calipers, either. :confused:

[mbellaver]

well....I got my new master cylinder rebuild kit in and put it in last night.....guess what....same problem. It does feel a little bit better, but it is still soft. I think I'm done...of to the shop! I did try the pump up and zip tie method and let it sit overnight, but it didn't seem to help. If I spend anymore time in the garage working on this "simple" problem i'm going to wind up divorced.

[mbellaver]

blaaze416 - I wonder if the design of the new levers allow you to pull in further than the stockers... Can you put the originals back on and verify that is the case....just kidding.......

[blaaze416]

Originally posted by mbellaver
blaaze416 - I wonder if the design of the new levers allow you to pull in further than the stockers... Can you put the originals back on and verify that is the case....just kidding.......

Just for the heck of it....i prolly will. I'd like to see the reversed difference, too. But as for more pull distance with the new levers, yes.....they do allow for more pull. They stick out from the bars just a bit further. I must stretch a bit more to reach them than the stockers, but I assume thats because I have small hands, and most people wouldn't even notice.

[gcart2]

do you hve stock brake lines? if so theirs a possibility they are stretched.

[mbellaver]

the brake lines have been replaced. However, the ones I replaced them with were used ones in excellent condition. So, they aren't new. One thing that sticks out in my mind is that when I bought the ex, the left caliper was disconnected and the line was plugged with a bolt and nut. Could there be something wrong with the caliper that would make the brakes feel spongy. I would have thought that if the caliper was bad, I would see fluid leaking....By the way I threw in the towel last night, but I was back at it again today trying to figure it out. Chalk up one more bottle of brake fluid........

[project400ex19]

mine showed no signs uf leaking, but it was allowing air in somewhere in one of the calipers.

[mbellaver]

Before I shell out the 75.00/ hour shop fee, I think I'll see if I can determine if it's one of the calipers or not. I was thinking I'd try to block of one of the lines with a bolt and nut through the end of the brake line on one of the sides and see if I can get pressure. If it looks like one of the calipers is bad I think I'll order a rebuild kit. Anone done a rebuild on a caliper? The master cylinder was super easy. I would have thought that if the caliper was getting air in, I'd see a leak....maybe not!