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Post by daffey1 on Feb 26, 2013 7:11:23 GMT -5
Looks very clean and tidy. Nice job
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Post by III on Feb 26, 2013 10:45:58 GMT -5
I'm mechanically challenged...how much adjustment do you have - for drag vs. slip? I would think there is NO adjusting for those effects Ian. It either pushes the plates apart or closes them. The stroke of the pusher would be limited in the amount of travel the piston has only right? BUT... with a setup like that you could probably us a much heavier spring load to prevent slippage.
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Post by Walms on Feb 26, 2013 11:31:58 GMT -5
Probably the easiest way to look at it is the volume of oil moved... If you know the diameter and stroke of the master cylinder, you can figure out the stroke of the slave based on its diameter.
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Post by lc on Feb 26, 2013 11:41:52 GMT -5
I'm mechanically challenged...how much adjustment do you have - for drag vs. slip? Provided the slave cylinder's piston does not bottom or push itself out of its bore so it leaks, hydraulic systems are always self adjusting. As Walms states, the stroke of the slave is directly determined by the fluid output of the master. Bigger master bore= more fluid displacement/longer slave stroke and more effort on lever. Smaller Master bore = less slave stroke/less lever effort... VERY nice looking piece you have there Dave! J
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Post by lc on Feb 26, 2013 11:57:59 GMT -5
BTW, Its a good idea to use mineral based fluid in this hydraulic system. All hydraulic slaves will develop a leak sometime in their life due to wear. With mineral based fluid it will be a non issue if the clutch rod seal gets wet with leaked hydraulic fluid. However, if your hydraulic system uses DOT 3/4 the aforementioned rod seal may get attacked.. DOT5 might be OK though... J
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Post by Ned on Feb 26, 2013 12:07:15 GMT -5
Thanks J. I used the DOT5 as per Jim's recommendation.
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Post by Ned on Feb 26, 2013 12:08:54 GMT -5
I am waiting for the Zed Master to come over and give it the official squeeze.
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Post by lc on Feb 26, 2013 12:19:31 GMT -5
The lever "feel" tested with 5 heavy Barnett springs installed in the clutch would be best, should you decide to market the unit in the future.. J
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Post by Walms on Feb 26, 2013 12:35:01 GMT -5
Maybe a fish scale is in order...
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Post by Ned on Feb 26, 2013 12:41:02 GMT -5
Probably the easiest way to look at it is the volume of oil moved... If you know the diameter and stroke of the master cylinder, you can figure out the stroke of the slave based on its diameter. Maybe Jim can help out here with the stroke of the master. I used the same one as him. 9.5mm bore Magura and the slave is 0.875" in dia.
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Post by Walms on Feb 26, 2013 12:48:08 GMT -5
You could just take the slave cylinder out and measure the travel directly...
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Post by lc on Feb 26, 2013 12:57:07 GMT -5
I can see where this may end up being sort of like "balancing a ball bearing on a razor blade".
Too light a lever feel /small displacement of slave = draggy clutch. Good displacement of slave to release clutch fully= hard lever pull... The mechanical Sytec seems to favour the limits of light pull...
A "Bandaid" to expand the "envelope" of a given master/slave ratio is the addition of the pressure multiplier (or installed in reverse, a pressure reducer) such as TTnut used...
J
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Post by Jim on Feb 26, 2013 13:01:46 GMT -5
You could just take the slave cylinder out and measure the travel directly... That would be the best way, since I have no idea what the master cylinder's stroke is. I picked the 9.5mm master cylinder based on my previous experience with lever force when using a modified stock H2 brake master cylinder. It turned out to be just what I was looking for, with plenty of slave cylinder travel, and silky smooth easy lever pull, noticeably easier than stock. LC, the Magura master cylinders require mineral oil or DOT5. Their sales guy recommended their "Blood" mineral oil, but said he knew for a fact that some customers successfully used DOT5. Since I had been using that with my converted stock master cylinder, I stayed with it. I've been using DOT5 for about 35 years now without any seal problem, and have used it in the Magura master cylinder for about 2 years now. The pressure amplifier does nothing for the balancing act, it only compensates for an improper master to slave diameter ratio. The balancing act is much easier to pull off than with a stock or Sytec actuator, because there is essentially no friction with the hydraulic clutch. This means the lever pull is easier than mechanical actuators with the same travel. You can end up with stock travel and a noticeably lighter lever pull. Unless you go nuts reducing lever pull with the hydraulic clutch, I don't think lack of travel will be a problem.
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Post by Walms on Feb 26, 2013 14:30:48 GMT -5
Agreed, the only other place to change force would be to change the ratio of the perch, itself. Also agreed that the hydraulic should have less frictional losses compared to a mechanical cable... I think I mentioned earlier though that it would be a good idea to talk to a seal company regarding the seals with the lowest stick/ slip I use Sealtech, Able O-Ring and Halllite For seals in Mississauga... The guy at Hallite is the best for tech assistance. They also specialize in metric seals.
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Post by Jim on Feb 26, 2013 16:33:07 GMT -5
I used a standard 7/8" brake piston cup. It just sits against the piston, and the pressure keeps it there. It's rubber, and quite low friction, because there's nothing much pushing it against the cylinder except fluid pressure. They were very common a couple decades ago, but are getting harder to find.
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