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PostPosted: Sun Mar 29, 2020 5:09 am 
Dirt Disciple

Joined: Thu Jan 30, 2020 5:01 am
Posts: 36
Location: Sunny Southsea
I have a set of these that I am trying to fit onto a tandem frame (to provide at least some retardation!)
Anyone got foolproof bleeding technique for the long rear set up?


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PostPosted: Sun Mar 29, 2020 9:35 am 
Gold Trader
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Joined: Sat Oct 23, 2010 10:33 pm
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Location: Bournemouth in 2008
TBH, all the maguras I've had have responded perfectly to the following, but I've never done a tandem...

Get a LARGE syringe - 50ml should do it for a tandem (I normally use a 20ml). You'll need tubing and adapters for it to screw into the rear caliper.

Remove bleed screws at the lever and caliper. Fill the syringe with LHM (No air bubbles at all)and screw it into the caliper.

Have a helper hold the lever in a towel or rag, bleed port up, and blast most of the 50ml through the system - push it through HARD.

When almost done, and still pushing LHM through, flick the lever a few times.

With the last few ml being pushed in, refit the lever screw. Then remove syringe and fit caliper screw.

All the waste fluid is in the towel/rag. It's a messy way of doing it, but has worked 100% for me
:)


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PostPosted: Sun Mar 29, 2020 9:59 am 
Gold Trader / PoTM Winner / RB Rider
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Joined: Fri Jul 23, 2010 4:13 pm
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Location: Royal Forest of Dean (Still looking for the Bear !)
What he said ^^^

Forget buying Magura’s Royal Blood (might be a funky colour but that’s about it) LMH does exactly the same

Bubbles are your enemy so you’ll need to flush them out and that does/can make a mess but done properly I doubt you’ll need to do it again for many years to come. There are kits on eBay with the kit to aid refilling the system

I’ve done 11,22’s and 33’s and they are all the same process, as has been pointed out the only additional challenge you have is the extra length of hose between the lever and the pistons

If you have the oil / syringe/ tubes all you’ll need are these https://www.ebay.co.uk/itm/Magura-Bleed ... Sw1r5bXPmB


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PostPosted: Sun Mar 29, 2020 10:15 am 
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Retro Spud wrote:

If you have the oil / syringe/ tubes all you’ll need are these https://www.ebay.co.uk/itm/Magura-Bleed ... Sw1r5bXPmB



^^^ That's all I've ever used.


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PostPosted: Sun Mar 29, 2020 10:19 am 
BoTM | rBoTM | rider
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Whilst RS & MTS are feeling responsive, can I ask if you’ve got any recommendations with regards to cleaning/flushing out the lines?

Or would it be simpler/cheaper to buy new tubes?


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PostPosted: Sun Mar 29, 2020 11:44 am 
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I've never bought magura hose, only ever used old stuff (The new stuff available now is different - softer).

Big syringe and plenty of LHM. I reckon there's lass than 5 ml in a set of maguras. you'll see it running clear very quickly.


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PostPosted: Sun Mar 29, 2020 12:17 pm 
Old School Hero

Joined: Sun Feb 28, 2010 11:46 pm
Posts: 166
Location: Northants
If you want less mess fit a syringe to the lever as well, you can then push/pull the fluid through the system which helps chase out any errant bubbles.


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PostPosted: Sun Mar 29, 2020 1:03 pm 
Gold Trader / PoTM Winner / RB Rider
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Location: Royal Forest of Dean (Still looking for the Bear !)
This is me probably over thinking things but I always have the lever (filling end) lower than the oil exit end to have gravity aid bubble travel
Usually means having the bars off unless doing just the back in which case lift the back wheel higher than the bars, How much difference it makes is anyone’s guess - it’s more a case of patience and only stopping when there are no bubbles coming out since there is no load on the fluid at this point I find it hard to tell if there’s any sponginess (due to trapped air being compressed) at the lever so don’t skimp on the fluid going through.

Just a case of common sense, bit of time and a mini physics experiment with hydraulics - something even the Greeks and Romans played with.


Oh and wear old clothes - the old oil is always dirty and generally stinks plus it soaks into everything.


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PostPosted: Sun Mar 29, 2020 1:20 pm 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 10055
Location: New Forest, UK
I've done it on a tandem. Frankly the easiest way is to take it off the bike, tape the top to the top of a door. I fit an extra hose at the top from the lever port running into an old ketchup bottle.

Pump it in from the bottom, collecting in the bottle at the top. Then do the straddle pipe.

Alternatively, raise the front of the bike by a metre or so. The critical thing is to get gravity working with you along that long top tube line.


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 Post subject: Re:
PostPosted: Sun Mar 29, 2020 1:43 pm 
Old School Hero

Joined: Sun Feb 28, 2010 11:46 pm
Posts: 166
Location: Northants
Retro Spud, fill from the caliper for the 'bubbles rise' reason you mention above, if you replace the bleed screw in the lever before removing the caliper syringe then capillary action stops it all leaking back out of the caliper, if once filled it's still spongey, connect a syringe to the lever with a bit of fluid in it, pulling the lever should push any remaining bubbles into the syringe. I've bled a lot of Maguras over the years, it's more or less mess free save a couple of drips, never had to remove one from a bike to bleed it.


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