Hayes HFX9 caliper pistons not retracting properly

[Techno Destructo]

This isn't a case of not having a disc between the pads before squeezing the lever, but a different variation.

I've had to put a bike in storage for a year. Unfortunately, it accumulated some corrosion over the last 12+ months. Tuning the bike back up, most of the bike has bounced back nicely, except for the brakes, which are Hayes HFX-9's. Firstly, around the bleeding area on the reservoir cap on top of both the levers have shown a lot of white corrosion... which sort of looks like aluminum corrosion, but is a lot more condensed and concentrated... is this from leaking DOT fluid? There was never a problem when regularly riding the bike, and nothing was done to the brakes before putting it in storage. This corrosion came off with a quick wipe of mineral spirits though, so that's not a huge concern.

The real problem is that the pistons in the calipers (while the disc is in, all bolts tightened, while riding the bike, yadda yadda yadda....) won't retract after applying the brakes... the pads stay pressed up against the disc causing HUGE drag... a similar pressure to lightly squeezing the brakes.
The oil pressure seems decent, very little sponginess to the levers, the pull doesn't go all the way into the lever... everything seems half decent...
I've taken the pads out of the caliper, squeezed the brake so the pistons came a healthy distance out of the caliper, and put teflon lubricant around the outside of the pistons before pushing them back into place in the caliper. The hope was that it would make the pistons easier to slide back and forth in the caliper. No dice, however... still have the same problem.

Does anybody know what's causing this problem, and/or how to fix it? I need those pads to back off from the disc after applying the brakes...

 

[AngoXC]

A complete overhaul (new seals in both the caliper and master cylinder) should rectify the problem but I am still curious. I take it your maually resetting the pistons/pads with a screw driver or the likes? Do they go all the way back in (ie, is there anything to suggest there is too much fluid in the system?)
Are they returning very slowly or is it dead after you have applied the brake?

It could be possible this corrosion you speak of has entered the system (but that would show with the quality of the oil right?...might just be in the caliper itself...blocking the pistons retraction)...it might be a case of just flusing the whole thing out and starting over...

Other then that, im stumped...

Just my $0.02...good luck!

 

[Techno Destructo]

A complete overhaul (new seals in both the caliper and master cylinder) should rectify the problem but I am still curious.

Yeah, I was wondering if the solution was a complete overhaul. That'd be a pain, but surely the cost would be less than buying a new brake? I've got lots of documentation as to how to do a complete overhaul, but does anyone have any experience with doing it to an HFX-9?

I take it your maually resetting the pistons/pads with a screw driver or the likes?

Only when inserting the wheel in when I've taken it out...

Do they go all the way back in (ie, is there anything to suggest there is too much fluid in the system?)

Yup.

Are they returning very slowly or is it dead after you have applied the brake?

They seem to be dead. The only retraction it's doing (it's only the front brake, btw...) is when it's forced back by the rotating disc itself... and that ain't much...

It could be possible this corrosion you speak of has entered the system (but that would show with the quality of the oil right?...might just be in the caliper itself...blocking the pistons retraction)...it might be a case of just flusing the whole thing out and starting over...

Other then that, im stumped...

Just my $0.02...good luck!

Thanks AngloXC! Anybody else got any thoughts? I'm of two minds whether to go through with this overhaul idea, or if it'd just be better to buy a new brake, since HFX-9's aren't exactly prized or high price, and heck... I don't even think they're a great brake... I'd rather buy a Shimano Deore/525....

 

[AngoXC]

Id rather Deores as well frankly...
Though, that said, you can pick up HFX-9 with BFL lever sets for just on 200 or so new on eBay...I daresay overhauling them completely wont be cheap considering youll need parts and oil. And its not even guarenteed to work in the end...

Hummm...

 

[spyderman_au]

A couple of years ago when getting back into riding I bought a few set of hayes that people said were rooted.

Firstly the corosion on the outside is just the brake fluid.

The first thing I did was to take the pistons out of the calipers. I then carefully removed the seals and scrapes out all the built up bits of corosion around the inside of the caliper and the outside of the pistons. I then put them back together and never had trouble with them again.

Easy and cheap solution. I was very surprised when I did it that the seals didn't leak. But, I did 2 full sets and no problem...

Hope this helps.

 

[Jon]

Spyderman has it. The pistons may be fouled by corrosion or the seals are plain old stuffed and gone rock solid with no use. Pull the caliper to bits, clean it out and put new seals in it. Should be good to go.....maybe

 

[Techno Destructo]

Sounds good guys... however, when checking the replacement costs of seals and such to do a rebuild of the HFX-9's, I was told $35. This is $35 for a fix that might not work, on a brake that I wasn't crazy about in the first place. I think it might be a new brake on the way... we'll have to see. Anybody want to buy a Hayes HFX-9 for spare parts? Going cheap....

 

[Rik]

Juicy 3, $150 per end. Best fix for HFX-9's

 

[Techno Destructo]

Juicy 3, $150 per end. Best fix for HFX-9's

Probably a great replacement, but I'm looking for a very cheap alternative since this is for the commuter, and not a really good bike. Heck, maybe I should be looking at a mechnical disc brake?

 

[leitch]

Probably a great replacement, but I'm looking for a very cheap alternative since this is for the commuter, and not a really good bike. Heck, maybe I should be looking at a mechnical disc brake?

If you're just doing it on the cheap, I've got a HFX-9 front brake here that you can have for $25 + $5 for post. Works fine. PM if interested.

 

[spyderman_au]

Sounds good guys... however, when checking the replacement costs of seals and such to do a rebuild of the HFX-9's, I was told $35. This is $35 for a fix that might not work, on a brake that I wasn't crazy about in the first place. I think it might be a new brake on the way... we'll have to see. Anybody want to buy a Hayes HFX-9 for spare parts? Going cheap....

It will cost you nothing to try the clean out and reassemble. 90% chance of working. As I said I did it to 2 full sets.....

 

[rajan]

the page below has the links to download the instructions for caliper repair. spyderman is right... if you have 2 hours some saturday just pop your caliper apart and clean it good with a dry cloth. make sure you're not working over your priceless antique rug though because that dot 4 is gonna come out in a hurry. I wouldn't use any solvents or water for cleaning, and i wouldn't use teflon either. teflon can break into pieces and then float through your system, possibly plugging something up.

http://www.hayesdiscbrake.com/support_downloads.shtml

the most likely problem is that your square seals are degraded. they are made to withstand the dot 4 fluid, but they might have broken down due to temperature or other conditions. their purpose is to deform when the brakes are engaged and then to return to their original position after brakes are released, thus pulling the piston back into the bore.

the process that you have in front of you is:
1. buying dot4 fluid, a length of 1/8 inch internal diameter vinyl tubing, and a G2 caliper rebuild kit. cost me about 30 bucks, US.
2. take apart your caliper and drain the whole system (remember, the DOT fluid is corrosive to paint and will completely ruin your pads).
3. switch the parts out that come with the repair kit.
4. bleed your system.

this is a PITA until you get it all fixed up and then you're really happy that you fixed your own bike and saved yourself $100.