help with elixir lever travel

danlightbulb
danlightbulb Posts: 701
edited November 2012 in MTB workshop & tech
Hi,

Today I adjusted the starting lever position on the rear brake (Elixir 3) as it has been too far away since I bought the bike. However this appears to have had the unwanted effect of also bringing in the bite point of the brake also. Now the bite point is far too close to the bars.

In contrast the front brake is fine, having both the correct starting lever position and the correct bite point. I've only adjusted the rear brake to be in the same position as the front one.

Help please! :)

regards
Dan

Comments

  • bennett_346
    bennett_346 Posts: 5,029
    It's just how elixirs are, either live with it or learn to bleed them with a thinner than normal bleed block to "overfill" them.
  • Sorry I dont quite understand. The front brake is fine. All I've tried to do is get the back brake lever to be in the same position as the front brake lever.

    Do I need to add some fluid so it doesn't compress as far when the lever is pulled?
  • bennett_346
    bennett_346 Posts: 5,029
    get the back brake lever to be in the same position

    Far too vague sorry, specify what you mean. Reach? Bite point?

    Do I need to add some fluid so it doesn't compress as far when the lever is pulled?

    Again i think you do not know how brakes work. As i said above learn to "overfill" them or try advancing the pistons.
  • I'll try to explain the best I can.

    The front brake lever is just the right distance from the grips, just on the joint of my index finger for single finger braking. When I pull it, the 'bite' is just in the right place, a nice distance from the grip (I'd say it moves about halfway towards the grip before it stops moving).

    However the rear brake lever was initially further away from the grip. I had to overstretch my fingers to reach it. So I adjusted the reach hex screw on the pivot to bring the lever closer to the grip (to match the front brake lever). The problem is that when I pull the lever now, it pulls nearly all the way to the grip before stopping. This is far too close for me.

    I need the rear brake lever to be the same distance from the grip as the front brake lever, and to stop its travel in the same place too.
  • bennett_346
    bennett_346 Posts: 5,029
    Ok bite point issue, common elixir issue. Again they need overfilled. Standard bleed procedure but shave 2mm off the bleed block and then use that.
  • Right. Do I need to do a full bleed, can't I just squeeze in a tiny bit of extra fluid to overfill it?

    Also, wont shaving 2mm off the bleed block make the pads go too close to the rotor and cause rubbing?

    Why would the front brake position be fine but the rear brake position not? (I've never messed with them since I got the bike so they would be the factory fluid levels).
  • If the brakes have never been bled from new, and the problem has existed from new, I would suggest doing a standard normal bleed with the standard normal bleed block, and see where that gets you.

    Avid's factory bleeds are quite inconsistent - it sounds like your rear brake might have been a bit "under-filled"
  • Yes its been this way from new but I've just lived with the fact the lever was a bit too far out for my liking.

    I have ordered a bleed kit off ebay. If it is underfilled slightly, can't I just use the syringe to squeeze in a bit of extra fluid without doing a full bleed procedure?
  • bennett_346
    bennett_346 Posts: 5,029
    Yes its been this way from new but I've just lived with the fact the lever was a bit too far out for my liking.

    I have ordered a bleed kit off ebay. If it is underfilled slightly, can't I just use the syringe to squeeze in a bit of extra fluid without doing a full bleed procedure?
    It's actually easier to do a full bleed since what you are suggesting can be done but requires a lot of thinking.
  • Ok. Never done a bleed before so will just follow instructions and online video guide.

    One more thing, what can I use instead of a bleed block as I dont have one of those.
  • bennett_346
    bennett_346 Posts: 5,029
    You need a bleed block or something of exact same dimensions. By doing a normal bleed ofcourse the lever will still have a lot of dead travel in it.
  • I like the way the front is, which was done at the factory too so as long as it gets towards this (it should do shouldn't it? Its the same brake), I'll be happy.

    I'm guessing the amount of fluid that makes the difference between too hard and too sloppy is tiny, as hydraulic fluid is incompressable.

    Could you tell me the width of the bleed block please?
  • bennett_346
    bennett_346 Posts: 5,029
    I like the way the front is, which was done at the factory too so as long as it gets towards this (it should do shouldn't it? Its the same brake), I'll be happy.

    I'm guessing the amount of fluid that makes the difference between too hard and too sloppy is tiny, as hydraulic fluid is incompressable.
    Correct and as for point one you made it should in theory but doesn't always in practice.. i've always found the rear brake is less tolerant. It's a fine art getting elixirs right and takes trial and error, and believe me i've had the practice. Sometimes the issue is solved but the pistons don't return enough to fit the pads and rotor in in which case you need to let fluid out again and accept a poor lever feel, sometimes you'll find you haven't added enough fluid to make any change.
  • And is it really not easier to just remove the lever bleed screw only and attempt to squeeze in a tiny bit more fluid?
  • bennett_346
    bennett_346 Posts: 5,029
    Try it if you like. I can't see how it would work but do report back.
  • I'm sure you're right when you say it won't, I've had no experience with hydraulic brakes at all.

    But logically speaking, if the fluid is currently underfilled, then squeezing a little more in through the bleed hole *should* add some fluid to the system so *should* fix the problem? It sounds so logical I can't see why it wouldn't work...
  • bennett_346
    bennett_346 Posts: 5,029
    Its not like filling a bucket with water, it has a reservoir and parts of the system are shut off from other parts depending on whether the lever is open or closed. Like i say it may or may not work and i don't know whether it would or not. Would you do it with the lever pulled to the bar or fully extended?
  • Lol i dont know...

    What is the reason for having the lever pulled in to the bars when doing a full bleed?

    Edit: Just looked at the SRAM bleeding video. The reason for pulling the lever back for the first bit is simply to isolate the caliper for the first part of the bleed. I assume this is because the lever plunger will be fully pressed in so no fluid can travel down from the reservoir. I guess this also creates positive pressure in the caliper so it doesn't suck any air in when the bleed screw is opened. Makes sense.

    So in my case I'd be adding a little extra fluid to the reservoir only, so I don't need to pull the lever. I'll attach the syringe to the lever end, pull a vacuum to remove any air, then push some fluid back in to fill it a bit more. If the wheel stops freely rotating when I do this I've put too much in. *Hopefully* this will firm up my lever travel.

    Question: as pads wear they have further to travel in the caliper. Wouldn't this alone result in longer lever travel over time? I can't see how the basic hydraulic system can compensate for pad wear as its just a fixed volume system.
  • angry_bird
    angry_bird Posts: 3,786
    Try this, taken from Avids set up guide. For Elixir 3s just ignore step 2.
    DEADBAND

    Deadband is the distance your brake lever travels before the brake pad makes contact with the rotor. “Long deadband” means your lever moves a lot before the pad contacts. “Short deadband” means the lever moves very little before the pad contacts. There isn’t necessarily a right or a wrong deadband. It has a lot to do with your hand, your preference and your comfort. The quickest way to adjust the amount of deadband your brakes have is to use Avid’s proprietary Pad Contact-Point Adjustment. If your particular brake model doesn’t have Pad Contact-Point Adjustment, try
    the Tech Tuning Tidbits below.
    ADVANCING THE PAD POSITION
    ! Note: If lever pulls to the bar a bleed is not necessarily required. 1. Remove wheel or red plastic pad spacer insert from disc brake caliper.
    2. If your brake has Pad Contact-Point Adjustment, rotate the adjuster to the full “out” position. Now it’s in the most open position (short deadband).
    3. Squeeze the brake lever slowly several times while watching the brake pads move toward each other. Stop when you see an approximate 1 mm gap between the pads.
    4. Insert the red plastic pad spacer between the pads. The pads will be a little hard to push apart, so use some force to properly spread them to the correct position. Now, remove the spacer again.
    5. Install wheels with rotors mounted to bicycle and give the lever a squeeze. The brake pads should now be properly advanced to the correct position, and the brake lever will have a proper firm feel. Repeat if necessary.

    If that doesn't work then bleed time, but it worked fine for me and my old Juicy 3s.
  • Thanks for this. Tried it but no good. Think it made a slight difference but not enough.
  • angry_bird
    angry_bird Posts: 3,786
    Thanks for this. Tried it but no good. Think it made a slight difference but not enough.

    Worth a try, especially as it's a 10 second job, bleed time then by the sounds of it...