brake issues

[hondaripper]

hi i just recently bought a 2002 400ex with many mods but the only thing that seems to be giving me any problems is the brakes. when i bout the thing the front brakes didnt have a leaver so i replaced it and bledd them they now work but still feel spongy. but my main problem is that the rear brakes have a parking brake elimanator and when i bought the quad the rear brakes worked fine but after a day of riding they blew out completly and when i went to try and bleed the fluid started to seep out of the parking brake block off plate i tryed useing gasket maker to seel it up but with the brakes being under so much pressure it still leeeks threw i dunno if anyone else has had this problem but any ideas on how to seel it so it dosent leek or any ideas on why the front bakes could be spongy would be appriciated i cant take full advantage of the 426 big bore kit in the thing with out being able to stop.

[JOEX]

Originally posted by hondaripper
hi i just recently bought a 2002 400ex with many mods but the only thing that seems to be giving me any problems is the brakes. when i bout the thing the front brakes didnt have a leaver so i replaced it and bledd them they now work but still feel spongy. but my main problem is that the rear brakes have a parking brake elimanator and when i bought the quad the rear brakes worked fine but after a day of riding they blew out completly and when i went to try and bleed the fluid started to seep out of the parking brake block off plate i tryed useing gasket maker to seel it up but with the brakes being under so much pressure it still leeeks threw i dunno if anyone else has had this problem but any ideas on how to seel it so it dosent leek or any ideas on why the front bakes could be spongy would be appriciated i cant take full advantage of the 426 big bore kit in the thing with out being able to stop.
Trying to seal the block off plate is pointless, there shouldn't be any fluid in there anyway. There is an o-ring on the piston shaft that needs to be replaced, might as well replace the other two seals while you're in there.

For the fronts it could be either the calipers and/or the master cylinder...

[hondaripper]

i acctually just ordered the new o ring this morning have to wait for it to come in to see if it helps looks like im riding on mushy front brakes untill then

[hondaripper]

stupid dealership ordered me the wrong o ring anyone happen to know what size i need so i can go to the auto parts store and try to find one the same size, i really dont wanna have to wait another week for a new one

[JOEX]

Found my old one...

I don't remember how they are measured. These are approximate..

Inside diameter 8mm
Outside diameter 11mm

[hondaripper]

thanks its probibly going to be a nice headach trying to find one the correct size

[JOEX]

The one I ended up using wasn't an 'exact' match but close enough. The difference may have been from comparing new to used... hasn't leaked yet...

[svahle]

Do you have rubber or steel braided front brake lines? If they are rubber that could be the cause of the spongy feel. Also, these brake systems are notorious for air getting trapped even with proper bleeding. Also, make sure the slide pins on the front caliper are smooth and greased up (both the caliper slide pins and those for the pads). If these bind up it can equal a spongy lever. Also, check to make sure the pistons are freely moving. I've torn down several calipers and you would be amazed at how much crap gets into the caliper and gums everything up. Hope this helps.

[hondaripper]

i have rubber front lines ive bleed them several times and no matter what i do they still feel mushy i cant evan get them to lock up in snow from what i can see i dont have any leeks so im not sure whats happening

[svahle]

Originally posted by hondaripper
i have rubber front lines ive bleed them several times and no matter what i do they still feel mushy i cant evan get them to lock up in snow from what i can see i dont have any leeks so im not sure whats happening

The rubber brake lines could definitely be the problem. Over time they start to expand. When the brake lines expand it in essence lowers the pressure applied to the brake pads. I would invest in some steel braided brake lines. Watch ebay - I have picked up three sets for less than $5.00 each. New they will run you around $50. They are worth every penny. Great feel at the lever, more stopping power, and more predictable. If everything else is fine on the braking system I suspect the lines are the culprit.

I suppose another culprit could be the master cylinder. Over time the seals wear and it will create less pressure even when completely bled. There are rebuild kits out there. But, I recommend just buying a front brake lever, reservoir, and master cylinder from a YFZ. It will work on the 400ex. It also had an adjustable brake lever which is very nice. This allows you to adjust the distance between the lever and the bars. You can pick them up cheap on ebay.

So, if the caliper is fine and the brakes are completely bled, there is a pressure problem and the above suggestions should probably take care of the issue.

[hondaripper]

i got the o ring for my back brakes and was woundering how you get it to seat properly. i would assume you dont just slide it over the little rod but there dosnt seem to b a groove or anything for it to sit in

[svahle]

Originally posted by hondaripper
i got the o ring for my back brakes and was woundering how you get it to seat properly. i would assume you dont just slide it over the little rod but there dosnt seem to b a groove or anything for it to sit in

You must remove the caliper piston from the caliper. The oring seats in the caliper (in the hole the piston's shaft comes through) rather than the shaft. There are also seals for the piston itself which you should change while you're in there. If you are mechanically inclined you can just start tearing into it and figure it out. That's how I did it. If not, get a manual. One little hint is when you are putting in the new o-ring and other seals make sure the grooves they go in are free from debris and clean, otherwise the o-rings don't seat well. Be patient or you will tear the o-ring or seals. Have some brake cleaner handy to clean things up. Go ahead and sand any rough spots of the sliders (both for the caliper and the pads) and grease them up. Since you will be disassembling the caliper just do it right and clean it all up and make sure everything functions smoothly. A little extra time now will same time later.

[hondaripper]

sounds like fun

[svahle]

I just read something on another forum about bleeding brakes. After you have bled them as good as you can try this. Loosen the cap on the reservoir. Pump the brake lever until it gets as firm as it will and hold the lever in. Keep the lever held in and zip tie or bungie the lever in this position. Leave it overnight. The next day, tighten up the cap, release the lever, and off you go. I understand that the coninued pressure overnight can allow any additional air to be pushed back up the line and with the reservoir cap loose it has somewhere to go.

I don't know if the this works but it seems so simple it is worth a try.

[hondaripper]

new o ring is in the rear caliper actually alot easyer then it sounded im gonna go reinstall the caliper now ill let ya know how it worked out

[hondaripper]

back braked are workin nicely now

[svahle]

Originally posted by hondaripper
back braked are workin nicely now

That's good to hear. Did you try the trick I posted above on the front brakes to see if it helped? Mine are all good and tight right now, but I am curious to know if it really works. If you try it let me know the results.

Ironically, I rode my Dale today and kicked up a stick into my rear brake line. It broke the banjo fitting at the master cylinder. I had to use an old rubber line I had laying around. I'll be getting a new SS line ASAP.

Shannon.