Advice for Shimano brakes with J kit

[JXV]

Hi

 

Bought an XT brakeset that comes with the easy joint kit in which the lever and caliper are separate but pre-charged with fluid. I've not worked with a J kit brake before.

 

When the cover is removed from the end of the hose there is a tiny white membrane on the barb to keep fluid in and air out.

 

The instructions do not say if this membrane should be removed or not before fitting the hose into the lever. Can anyone advise?

 

Presumably if not removed the pressure will burst it when the brakes are first applied...or is there a spike in the hose socket that will puncture it?

 

Question 3: If I have to shorten the hose can I use a normal spare Shimano barb on the new end?

 

 

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[BaGearA]

Pictures please

[JXV]

Eish....let me get the macro lens and lights out....these things are tiny....and the documentation not entirely clear..

 

With the J kits the olive and compression nut are pre-fitted into the brake lever. To fit you remove a plug then just push the hose into the lever through the compression nut and tighten up.

 

See pic of hose end attached.

 

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[JXV]

hmmm...ok just measured the new brake lines against the bike. I will have to cut both as they're too long....so that means a bleed anyway and I'll need some new hose barbs.

 

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[Spoke101]

hmmm...ok just measured the new brake lines against the bike. I will have to cut both as they're too long....so that means a bleed anyway and I'll need some new hose barbs.

 

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First off if you are careful you wont have to bleed the whole system just top up the reservoir.

 

Second, If those inserts haven't been crimped yet then you could try to carefully remove them and re-use them once you have cut the hoses.

 

Thirdly If you get new inserts make sure you get the right ones as Shimano make two slightly different types. One for the old brakes and one for the new ones (8000/9000).

If memory serves you will need the shorter silver insert NOT the brass one.

[JXV]

First off if you are careful you wont have to bleed the whole system just top up the reservoir.

 

Second, If those inserts haven't been crimped yet then you could try to carefully remove them and re-use them once you have cut the hoses.

 

Thirdly If you get new inserts make sure you get the right ones as Shimano make two slightly different types. One for the old brakes and one for the new ones (8000/9000).

If memory serves you will need the shorter silver insert NOT the brass one.

Thanks...agreed

 

I will recover and re-use the barbs already in the hoses. They have not been crimped before.

 

Any air that gets in during cutting and barb insertion will be near the lever end so a simple bleed upwards from the caliper end using a syringe should suffice. I have a Shimano bleed kit and oil.

 

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[Spoke101]

Thanks...agreed

 

I will recover and re-use the barbs already in the hoses. They have not been crimped before.

 

Any air that gets in during cutting and barb insertion will be near the lever end so a simple bleed upwards from the caliper end using a syringe should suffice. I have a Shimano bleed kit and oil.

 

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I would never ever bleed a shimano brake from the caliper upwards. The risk of folding the lip on the main piston seal the wrong way it not worth it. (Yes Shimano Int. say some wear that this can/should be done) Speak to anyone who does It for a living (including Coolheat) and they will tell you to only ever gravity bleed shimano brakes because once that lip folds the wrong way the chances of it doing again in normal use are increased. So you will end up with a brake where the leaver blows through and cannot hold pressure, then you might as well bin it because you officially cannot service shimano brakes.

 

I would suggest: (Done this countless times with swapping brakes left to right and back on demo bikes).

Cut the hoses and install in the leavers.

Then attach the lever horizontally to the bar and attach the caliper to its mount with the pads installed and a disk between the pads.

Then remove the reservoir cap and fill up the reservoir till you can see the mineral oil coming up the treads.

Then repeatedly pull/flick the lever waiting a second or two between pulls and watch the oil level reduce and any air rise out the fill port. Keep topping up the reservoir as needed. You might need to keep the lever depressed for a second or two but the release must always be instantaneous so the lever flicks back to its normal position.

Flicking the brake hose will also help any bubbles stuck to the inside of the hose to rise up and out. Should take 5-10 min's.

[JXV]

The normal Shimano procedure says fit the funnel to lever and a syringe to caliper. gently pressure the syringe to expel bubbles upwards through reservoir while flicking/tapping hoses and caliper. Then remove syringe and gravity bleed down. Close up and done.

 

I've done it a few times no problems. Always gently on the syringe. But yes I've heard about the seal flipping thing so will try it your way in future.

 

I normally remove pads and fit a brake block to bleed. This way the pistons are retracted to the correct position and you don't overfill/underfill the reservoir which can come back to bite you later when you lose braking before the pads wear out or when you can't retract pistons enough to fit new pads.

 

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[Spoke101]

The normal Shimano procedure says fit the funnel to lever and a syringe to caliper. gently pressure the syringe to expel bubbles upwards through reservoir while flicking/tapping hoses and caliper. Then remove syringe and gravity bleed down. Close up and done.

 

I've done it a few times no problems. Always gently on the syringe. But yes I've heard about the seal flipping thing so will try it your way in future.

 

I normally remove pads and fit a brake block to bleed. This way the pistons are retracted to the correct position and you don't overfill/underfill the reservoir which can come back to bite you later when you lose braking before the pads wear out or when you can't retract pistons enough to fit new pads.

 

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Yes the manual does say that but who on earth knows why.

Yes if done gently it can work, but have never had issues with bleeding top down only.

Yes if pads are worn then use a bleed block but if new then no issue, I also like minimal lever travel and run them close to the bar..

[Wolf Lyle]

Eish....let me get the macro lens and lights out....these things are tiny....and the documentation not entirely clear..

With the J kits the olive and compression nut are pre-fitted into the brake lever. To fit you remove a plug then just push the hose into the lever through the compression nut and tighten up.

See pic of hose end attached.

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I recently assembled a set like this . When you insert the hose into the lever it punctures the white seal straight away . Just insert and tighten up . Easy done