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Help replacing hydro hose please
OK I finally have my replacement hose for the Juicy 7 that I nearly cut through at Canberra. Have a bleed kit and both manuals but do you think I can find instructions on how to change the hose anywhere? Nuh only how to shorten a hose that is already full of fluid. Mostly common sense but I have a couple of questions for anyone that may have had to replace their hose before.
The bleed kit comes with 2 syringes. Should I be sucking all the fluid out of the system before I start? If I do can I reuse this fluid that is less than about 100km old, the manual says not to reuse fluid gained from bleeding brakes but that is presumably from ones that have done alot more k's.
If I do suck out all the fluid should I fill the system from the bottom, caliper end, till it comes out the lever and then bleed the system as per the instructions?
If I don't suck out the fluid and only the new hose is empty, should I try to fill it somehow before fitting it and then bleed the system as per the instructions?
Or am I totally off the track?
Thanks
Stuart
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Stuart,
I have no actual practical knowledge to offer because I decided to totally rely on my LBS to maintain my brakes after it took my ages and many cuss words just change my Juicy 7 brake pads. I think I ended up with bits left over.
If it was me I would;
1) Re-use the fluid 100k's is nothing.
2) Fill the hose from the bottom, thus forcing the air bubbles to the top - this is how you do it with cars.
3) Fit the new hose before filling it (anything else is a recipe for brake fluid everywhere.)
If you need a hand I'm happy to help - give me a call.
Paul
Just didn't want to stuff up this close to heading to Coffs.
Should be right, but thanks for the offer.
Stuart
I was hoping someone would be along who's actually done this, but... here's how I figure it should go:
- Remove calliper from bike and remove pads from them, put something between to stop pots falling out.
- Connect pipe to calliper bleed nipple, put pipe into some kind of container to catch old fluid.
- Open bleed nipple on calliper.
- Open 'valve' on brake lever. Erm... dunno what these levers have, this step might just involve removing the hose (be very careful not to let fluid go everywhere).
At this point I figure all the fluid will drain from the existing hose. Hold lever high in the air to help it?
- Connect new host between calliper and lever.
- 'bleed' brakes in usual manner (ie, inject fluid into the calliper bleed nipple until it's seen coming out of bleed hose attached to lever).
Job done.
FWIW, I wouldn't re-use the old fluid, but it's up to you. If it's clean and free of bubbles when inside your captured container then you might be OK. You'll need extra anyhow so might as well just use all new.
Park Tool site is useful as ever: Avid Hydraulic Calliper Brake Installation & Hose Length Changes.
I had been to Park tools as my second port of call after searching through both manuals. There isn't even stuff on the Avidbike.com website, surely I'm not the first schmuck to squash a hose, then again maybe I am. I guess my real concern was if I put the new hose on empty then when I bled the hose from the caliper end, as per the manuals and Pauls suggestion, I might force some of the air back into the caliper and then I'd be bleeding the system a second time.
TBH I don't think I'm going to have time before I leave now anyway so I think I'm best to wait to see if the guy I got the hose from responds to my RFI and tackle it when I get back. I think I should be alright, besides the guys at the LBS are use to me coming in with jobs half done or botched.
BTW the nice thing about the proprietory Avid bleed kit is it come with a pair of syringes that have hoses fitted with bleed screws so you pull the screw out of the caliper then screw in the hose. Everything gets captured in the syringe top and bottom. The mini hoses also have clamps that allow you to seal the system with syringes intact. Well worth the invesment for anyone inclined to have a stab.
Stuart
Stu let me know and I can either talk you through it or come over and help.
I am a little scared at some of the advice, but thats me and I guess you will work out whats best by the end.
Craig
IF you are careful you can cut the hose without draining the fluid.
It is best to use new fluid when you bleed the system. Dot fluids absorb water from the air and the more water they get in them the less effective they become. Of course if you are only sucking the fluid into the syringe that may not be a problem.
When you do cut the hose you will need to recover and reuse the fitting on the end of the hose.