A little winter hydraulic project - Wrist Twisters
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post #1 of 18 Old 06-06-2018, 12:16 PM Thread Starter
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A little winter hydraulic project

A pleasant hour or so in the garage. Parts from wrecker and ebay.

Took my chances on leverage ratios etc. and don't seem to have any easier pull at the lever, but I might be able to change that.

Haven't ridden it yet, since it's cold and dark and the roads are wet. Will let you know.
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post #2 of 18 Old 06-06-2018, 07:25 PM
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Great..... another thing I'll have to do!
Looks good. Let us know how it feels.

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post #3 of 18 Old 06-06-2018, 10:03 PM
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I spent hours in the garage today (96 outside, garage doors face the sun...) bleeding the brakes on my race bike. Teammate complained of notchy brakes in the last race (I was out of town.) Advised 'give the caliper a good douching.' He proceeds to order rebuild kits as well as fresh pads. He reworks the caliper (I just did that 3 races ago) and starts on the master cylinder, only to discover it's the wrong rebuild kit. He put it back together, with the 1 seal he touched on backwards without realizing it. He called me just as I broke the banjo loose to swap the new master in. I just couldn't understand why I could build pressure, but then it would suddenly go away. It seemed like it depended on how I pulled the lever if I would get pressure or not. I pulled out all the tricks I know, short of pushing fluid up from the caliper, and was still convinced that somehow there was air in the line.

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post #4 of 18 Old 06-07-2018, 12:23 AM Thread Starter
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Great..... another thing I'll have to do!
Looks good. Let us know how it feels.
Yeah, so, having taken a complete punt on the cylinder sizes, sadly I've ended up with a bit more pressure at the lever, not less. Ah well.

Operation is very smooth and predictable, with the clutch take up point shifted to a fair way out from the bar - a good sign, I think, as it means the clutch should be clearing nicely with the lever all the way in.

Other than that, all is well. Cool little slave cylinder, fits in nicely, has the right amount of throw - I'm just not driving it with the right master cylinder ATM.

https://www.ebay.com/itm/Hydraulic-C...72.m2749.l2649

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post #5 of 18 Old 06-07-2018, 12:24 AM Thread Starter
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Also, I went for an 1100mm hydraulic line, might have got away with 1000mm. I thought getting the clutch cable out and the hydraulic line in was going to be a pain, but one led the other through just fine, after I coated both of them with 808 silicone to be sure of the slide. Got the gas tank up off its mounts too, which helped.

https://www.ebay.com/itm/M10-Black-5...72.m2749.l2649
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post #6 of 18 Old 06-07-2018, 12:31 AM Thread Starter
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Quote:
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I spent hours in the garage today bleeding the brakes....
Did the same when I was trying to get pressure in totally dry Brembo calipers after my fork swap over the summer. Couldn't get a consistent result - lost my rag, slept on it, then eventually used the bleed nipple on the master cylinder to feed fluid into the top of the system, and somehow that fixed my issue.

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post #7 of 18 Old 06-07-2018, 02:00 AM
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Well Kiwi sux that the clutch isn't any easier to operate. But it wont get any harder like a poorly maintained cable will. Also yours has a cool unique factor. It's different.
I was thinking of adding a banjo bolt with a bleed nipple at the master when I do my brake lines. Would that be waste of time?

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post #8 of 18 Old 06-07-2018, 03:53 AM Thread Starter
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It might not be altogether a waste, but not something you'd expect to use often, either...go ahead, if it's not too spendy.

Are you doing separate lines from the top?

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post #9 of 18 Old 06-07-2018, 06:47 AM
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A single line from the top. A similar setup to stock, 1 into 2.

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post #10 of 18 Old 06-07-2018, 01:00 PM Thread Starter
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Quote:
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sux that the clutch isn't any easier to operate
I see from a bit of web research that the Suzuki m/c is 14mm, so I'm thinking for more ease of pull at the lever, I would need a bigger diameter cylinder at the top end. There are some Maguras listed on ebay at 16mm and 18mm, but that's the $$$ end of the pool...I'll keep an eye out.

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post #11 of 18 Old 06-11-2018, 12:43 PM Thread Starter
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Maths CAN be fun!

So, I found an old-school looking Magura clutch master cylinder on an Asian marketplace website for cheap, and was wondering if it would be worth the swap, from a 14mm to a 16mm m/c. I thought the extra size in the cylinder would be helpful, but 2mm didn’t seem like much.

Until…I worked out the relative volumes of the cylinders. The 14mm works out [pi r squared times height] to 1231 cubic mm, if I allow for 8mm of piston travel. The 16mm one comes to 1608, because of the extra 1mm of radius.

1608 is 130% of 1231 - if I could get a 30% change in lever effort from the swap, I would be well pleased.

I’m hoping the website hasn’t taken my money and spent it on bitcoins or blockchains or unlocking Nigerian treasure troves…will let you know.

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post #12 of 18 Old 06-19-2018, 09:46 AM
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Whoa there! If you want a lighter pull at the lever the master cylinder bore will have to be smaller, not larger.

Stock, the mechanical leverage ratio is about 1.2 : 1. For a similar hydraulic ratio it will have to be the same or higher. Since a 14mm master feels heavier, go with a 13mm one for a 15% reduction in pull effort. The stroke necessary for full engagement will increase, but by very little.

What is the bore size of the slave cylinder? It would be easier to calculate the optimum size of the master cylinder with that information.

Rob
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If it has already been done, it is safe to assume it is possible to do it.
On the other hand, if it has not been done never assume it is impossible to do it.
------- Rob --------
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post #13 of 18 Old 06-19-2018, 09:40 PM Thread Starter
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Hey Rob!

Bugger, I wondered if I had my thinking right about the ratios, and clearly I didn't.
An external measurement on the slave cylinder says around 16mm, so I guess 14mm internally.

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post #14 of 18 Old 06-20-2018, 03:51 AM Thread Starter
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...or more like 12mm - just remembered my slave cylinder came with a spare seal which I have measured.

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post #15 of 18 Old 06-22-2018, 08:14 PM Thread Starter
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Ok, so now that I've got my thinking round the right way, thanks to Rob, I'm going to try a bigger slave cylinder - one of these chubby little fellows is on its way.

https://www.ebay.com/itm/253686476607?ul_noapp=true
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post #16 of 18 Old 07-02-2018, 02:07 AM Thread Starter
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v2.0 not far away
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post #17 of 18 Old 07-02-2018, 02:33 AM
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Quote:
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v2.0 not far away
Tease!

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post #18 of 18 Old 07-02-2018, 10:38 PM Thread Starter
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So, it's in place. Not as much adjustability in placement etc as the first iteration, but it's in and working. Smooth and consistent, lever effort reduced, so that's a plus reduced down from 70's Norton Commando to something else. No longer have the muscle memory to know how heavy the cable pull was, but I'll go with this version for the long term.
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