[jolyon]

Hi Everybody,

I am a total novice to mountain biking, so your patience with me on my questions would be appreciated.

On advice from a friend I bought a Kona Hoss last year. The brakes are hydraulic, Hayes, although which model I am not sure, looking at pictures on Hayes' site makes me believe they are HFX Mag.

Various pressures (new baby) meant that it pretty much spent the last year unridden. I took it out a couple of weeks ago and immediately encountered two problems:

1. Squeezing the back brake lever caused all the hydraulic fluid to spurt out onto the floor. The master-cylinder seemed to be missing a black plastic plug which was present on the front brake.
2. The front brake was working fine, but the cable seemed to be damaged (amazing what my kids can destroy with plastic garden tools!)

I took the bike to the local shop, who frankly charged me lots of cash and I still have an unridable bike. I have lost faith in them and so would like to fix the problems myself instead of being beholden to them. The back brake seems to be fixed fine. The front brake is in a sorry state. The shop had it twice for longer than two weeks but failed to fix it, their original remit was simply to replace the front hose. The hose has been replaced, but I believe it is leaking near the master cylinder. There is hardly any braking power. I took the front wheel off, and under closer examination it looks like the post which goes into the cylinder/piston on the caliper has been broken off. I'm not sure if I have done this putting the wheel back on in the dark or the shop is responsible. Either way I want to rectify the problems myself. The current problem list is:

1. Front brake wont stop the bike although it will push the pads in a bit, which grip the disc slightly.
2. One of the posts in the caliper is broken off, I have the post.
3. There seems to be a leak near the "plug" on the master cylinder. Perhaps this explains the poor braking power?

I have downloaded all the PDF's from Hayes website to help me. I have no bike specific tools, so I am guessing I am going to need to invest in some kit. My questions are:

1. What tool sets should I buy to allow me to remove the hose, bleed etc.
2. Do I need a replacement piston on the front caliper or is it OK to use without the post (I guess this just helps keep the pad seated properly?)
3. I am in the UK, which is the best online place to source the kit I will need?
4. What other equipment, spares (olives?) should I have on-hand so that I can complete the job?

Thanks for your help,

Jo

 

[ioscope]

Mag levers are more expensive than HFX nine levers.
Mags are smooth and thick looking.
Nines have lots of ridges etc. on them. They are thin and wimpy.
You probably have Mags


G2 calipers (the part that grabs the disc) thread the hose straight in.
G1 calipers use an olive, and the hose mounts at a 90 angle to the body of the caliper. You probably have a G2.

All you need is some metric wrenches, a squeeze bottle, DOT3 or DOT4 fluid (don't mix them) some tubing that will slide over the bleed screw (protrudes from outside of caliper, has rubber cap on it.), and finally some small zip-ties or wire ties. You will aslo need a bleed fitting.

NOW (instrucitons for mag lever and G2 caliper)
Phase1
1. Unscrew pinch screw that holds lever on bar, rotate vertical. Retighten
2. Prepare a bleed bottle and hang it off of the handlebar grip with a coathanger.
3. Put the bleed fitting (plastic cone) on a paice of hose, put hose's open end in bottle.
4. unscrew bleed screw on lever. Make sure to keep track of the small screw, don't let any fluid onto the lever.
5. Jam bleed fitting into hole. Just jam it on in there. Make sure the hose connects to the bleed bottle hanging on your handlebar grip.

Phase2
1. Prepare a peice of hose connected to the tip of your squeeze bottle (or large syringe if you please)(Full of DOT fluid).
2. Fill the hose with fluid.
3. Jam the end of the hose onto the bleed fitting on the caliper (covered by a rubber nipple, silver with wrench flats at base.
4. Fix securely with zip-ties or wire ties.
5.Take the appropriate metric wrench and loosen the bleed fitting by 1/4 turn.

Phase 3
1.This is where many variation in technique take place.
Basically you want to purge your fluid up through the brake and into the bottle above.
2. Squeeze the squeeze bottle repeatedly, making sure no air gets into the brake.
3. Continue squeezing.
4. You really want it to be full of fluid.
5. While squeezing, tighten that bleed fitting.
6. Dissasemble apparati carefully, not getting DOT fluid on brake of hands (not good for paint or people.)

FINALLY
1. Reinsert bleed screw into lever
2. Reposition the lever.
3. Make sure disc is inside caliper between 2 pads. (now is a good time to replace pads that are oily or worn.)
4. Pump the lever.
5. Ride it around, doing lots of hard stops.

Note: For best results, some attempts may have to be made to fill the brake with fluid. (Phase 3)

DO NOT GET DOT FLUID ON HANDS OR BIKE.
WIPE OFF IMMEDIATELY
USE RUBBING ALCOHOL TO CLEAN

 

[ioscope]

I can sell you a hayes bleed set with detailed picture instructions for $15 USD + Shipping

 

[jolyon]

ioscope,

Thankyou for your reply. I have been trawling the web and it seems that the spec on my bike for the brakes is "Hayes Hydraulic HFX-9 XC". They don't have ridges on them though. Despite this I'm sure your instructions apply, so thanks for that. Do you think I need to get a replacement piston for the caliper for where the post has been broken off?

I found this UK site which has bleed kits http://www.chainreactioncycles.com/Models.aspx?ModelID=1476 and replacement cylinders for the caliper.

Thanks for your help,

Jo

 

[Dirtbike]

I would be able to fix them, replace lines, bleed them, etc., but you probably dont live near me. Sounds like you should try a different shop.

 

[jolyon]

Thanks, I think I'm a few thousand miles away!

I took the caliper apart, one of the pistons is completely screwed. I think I'll buy a replacement brake i.e. lever, cable, caliper and disk. Do these normally come as a single sealed unit with oil or should I get a bleed kit as well?

Cheers

 

[WarEagle2K]

I had the same sort of problem. I returned them to SUPERGO where I bought them on sale and got a new set. I think Hayes will take them back and give you a replacement. Go to their website and check out the return policy.

 

[SpasticJack]

Another tip for getting a really good bleed on any DOT 4 compatible brake is to get a bottle of blue brake fluid. You can usually find it online at automobile racing sites. You bleed as usual and when the fluid coming out the top changes color, run it a bit longer and presto, total fluid change. For the next service, swap out normal fluid and wait for the color change again. It takes a lot of the guess work out of brake bleeding.

http://www.amazon.com/exec/obidos/tg/detail/-/B0007SN6F6/104-7636766-6821509?v=glance

I've also had great success using a big syringe instead of the bleeder bottle to push the fliud through.

 

[Connundrum1]

what is the difference between DOT 3 and DOT 4 brake fluid? my car uses DOT 3 so is that the same fluid or different? is one better then the other?

 

[Jayridesacove]

Taken from common Harley Davidson questions:

DOT 3, DOT 4 and DOT 5.1 brake fluids are glycol based compounds that are compatible with one another. DOT 5 brake fluid is silicone based and should never be mixed with DOT 3, DOT 4 or DOT5.1. DOT 3, DOT 4 and DOT 5.1 fluids may damage painted surfaces and DOT 3 and DOT 4 have lower boiling temperatures than DOT 5 (DOT 5.1 has the same boiling point as DOT 5). Furthermore, DOT 3, DOT 4 and DOT 5.1 fluids are "hygroscopic", which means they absorb moisture from the air. This causes the fluid to turn dark, indicating that it is time for the brake fluid to be replaced. DOT 5 fluid will not damage paint, has a boiling temperature in excess of 500ƒ F, and is not hygroscopic.