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 Post subject: Shimano M785 Brake tuning tips
PostPosted: Thu Mar 05, 2015 9:43 pm 
Posts: 345
I've just installed my new brakes, all went well, didn't have to trim hose length or anything.
I had to adjust the angle of the rear banjo connector, but I don't think that let any air into the system.

The lever pull is very easy with one finger, I have not had to adjust the reach position.

I do note that the levers come quite close to the grips at the point where they really firm up, but I'm guessing there is some modulation available before this point (haven't ridden the bike yet).

Does this sound normal? I know there is the extra adjuster on the 785's to tune out any 'free stroke', I've not really messed with this.

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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Fri Mar 06, 2015 6:34 am 
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Could be free stroke adjustment, or it could be needing a bleed from the banjo adjustment you did?
I had to bleed my XT's for that reason when i fitted them to the Yeti. (still not named)
takes 2 minutes to bleed, happy to do it for you if needed.

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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Fri Mar 06, 2015 8:29 am 
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They will need bleeding. The free stroke adjustment doesn't do much. As VW has said, takes 5 minutes to bleed these brakes, much easier than the old shimano ones.


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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Fri Mar 06, 2015 8:44 am 
Posts: 345
OK thanks. I have the epic bleed kit and have done it before on a previous bike.
I think the brakes are working fine? My question was more of a 'should there be lots of travel in the lever before it binds fully'?
If not, then yes, I can bleed.
The front lever exhibits the same thing, and that bolted straight on, so I didn't mess with anything.

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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Fri Mar 06, 2015 8:46 am 
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They should be no more than a few mm movement before the lever starts to get harder.

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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Fri Mar 06, 2015 8:48 am 
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With the reach adjustment at about half way the lever should stop about half way through its travel. The levers should not be able to touch the bars, that would signify lack of brake fluid, air in the system or a leak somewhere.


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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Fri Mar 06, 2015 9:48 am 
Posts: 345
OK, in that case, they need a bleed.
But first, I need a 7mm spanner.

When you bleed your brakes, do you bleed with the bleed blocks in, or with the pads fitted?

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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Fri Mar 06, 2015 9:52 am 
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Blocks in, just in case.

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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Sat Mar 07, 2015 4:46 pm 
Posts: 345
Well, just spent ages bleed the brakes.
With the bleed blocks in, they firmed up really well.
Removed the blocks, but the pads back in, wheel back on etc, the lever nearly goes to the bars again !?!?!?!
Went out for a quick spin around the car park, brakes perform very poorly, very little stopping power.

What do I do?

Discs are what I have been using all along, pads are new.

Do they need to bed in? Should I put the old pads into the new callipers?

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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Sat Mar 07, 2015 4:47 pm 
Posts: 345
I'm very pissed off that I hit that tree !!!!

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 Post subject:
PostPosted: Sat Mar 07, 2015 5:04 pm 
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Sounds like there not bled right? Or the caliper isn't light up right?

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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Sat Mar 07, 2015 5:16 pm 
Posts: 345
I am sure they are bled correctly, when the bleed blocks are in, the levers are very firm. It's only when I put the wheel back on that loads of slack comes into the lever. The calliper is correctly aligned, the wheels spin free with no rubbing and stop with a nice jolt whilst on the stand, but with me riding the bike, not a great deal of stopping power.

Im taking it to Thetford tomorrow, so a little bit annoyed that they are not right. I just called Bike Art, I have booked their demo fatty for a few hours and they are going to look at bleeding my brakes.

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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Sat Mar 07, 2015 6:49 pm 
Posts: 345
I'm wondering if the disc is contaminated?
I might rub it down with some IPA and see if that makes a difference,

With the blocks in, the lever only moves about 1cm and is then completely firm. With the pads in and the wheel on, the lever moves about 3cm and feels spongy.

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 Post subject:
PostPosted: Sat Mar 07, 2015 7:11 pm 
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When you pull the leaver do the pads move, how far they sitting away from the disc?

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 Post subject: Re: Shimano M785 Brake tuning tips
PostPosted: Sat Mar 07, 2015 7:31 pm 
Posts: 345
I've just cleaned the pads and discs with rubbing alcohol, they were dirty, but it has had no effect on the braking power.

The pads are very close to the disc, almost touching there is not a great deal of observable movement when I pull the lever.

The rear lever has firmed up more than the front, but still, when the bleed block is in, the lever is firm, the rear more so than the front, but a softer lever with the wheels on and no stopping power, the rear wheel will not lock up with me sat on the seat and there is just no braking power.

I have also ,are sure the pads are on the correct side.

Very frustrating.

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