Does anyone know the actual hydralic pressure reached during maximum braking in the hydralic circuit? I'm thinking of making some modifications to make bleeding (the brakes, not me) easier on an MTS1200. To avoid adding myself to the Darwin list I'll make the modifications during the bleeding only at the present.
The pressures reached in an average performance motorcycles hydraulic braking system is approx 25-40lbs/psi with 40psi being a overly generous maximum !
It depends on how hard you squeeze the lever . How long the lever is and what the lever ratio is I.E. 5/1 , 4/1 , 3/1 etc x The size of the bore of the master cylinder . But its quite a lot . 1 bar is about 14.5 psi and there is going to be about 90 to 100 bar sooo its going to be well above 1000 psi . Heres a peddle bike brake pressure scale for different types of systems fitted to bicycles but it will give you an idea .How we test hydraulic disc brakes - BikeRadar Only thing is it measured in N/m so theres another calc to get it to Bar or psi .
I think I better measure it once I've done my modifications. My gut feel is that I doubt if most people could exert more than 50Kg of total grip with their right hand, thats not Kg/cm that's total grip. I had mine measured regularly duriing my recovering from having my arm rebuilt. Given what I do for a job I had a good grip that measured more than 55Kg on the left hand, while my poorly right only did 8Kg. SHMBO did about 30Kg, but then she's a pianist. My physioterrorist could only manage the same as her, but then he was light in the loafers. No matter what happens with hydralic advantage you are still squeezing both sets of pads together with your fingers (no assist from a servo), so I going to go with a low overall psi. Also they do have to move a quite a bit to get a good grip of that disk. I'll stick my neck out and say it will be under 100psi MAX, but once measured I will report (right or wrong).
Oh yes it will be a lot less as you haven't got a servo adding 10-20times the pressure of your foot alone. I had a V12 XJS engine cut out at high speed and that isn't fun trying to stop. I think I bent the steering wheel.
Make up a T- piece and plumb a gauge in the line. A servo doesn't add extra pressure in the system, just aids the pressure applied to the pedal/master cyl.
Somewhere around 800psi is normal, max will be around 2000psi. Most brake lines and fittings are rated to around 4000psi max use and in excess of 10,000psi failure. If you're making modifications, these last two figures are the ones I'd use. Not too sure what you're doing but operating temperature is also a key factor.
Half way down this page tells you the pressure of motorcycle lines . 800 to 1000 psi . Standard Brake Lites | Motorcycle Brake Lites | Sportbikelites
Right we can work it out, hope some of you are thirsty.:tongue: I'll round a few figure up or down lo simplify the maths. Grip strength 50kg = 110lbs Typical sports bike master cylinder piston area 0.45 sq inch Typical leverage ratio, we'll base it on a mean assuming you use 4 fingers to brake. 5:1 load on piston 110lb x5 = 550lb line pressure 550lb/0.45 = 1222.2 psi or 83bar Your unlikely to squeeze the lever with all your strength even in a panic situation, but I would say 30-40bar would be a typical for max braking effort.
Its written in the said posted web site "Our Hoses have been batch tested to 18,000 psi without failure.[normal motorcycle braking pressure is 800-1,000 psi ]" Or are they wrong as well . Our Hoses have been batch tested to 18,000 psi without failure. (normal motorcycle braking pressure is 800 - 1,000 psi) So most companies only test assemblies up to to 5,000 psi. We choose to use line material that out performs industry standards
Motorcycle Braided Hoses, Hydraulic Brake Lines and Teflon Clutch Cables | Venhill FAQs Q: Do you factory test every brake and clutch line that you make? A: Yes, every hose we make is pressure tested to 1500psi and every 30 days we also test lines at random to 10,000psi. Most motorcycle and car brakes systems operate at around 25-30psi, even under hard braking. Perhaps Venhill are wrong? I've searched the internets, like everyone else interested in the correct answer, & strangely this is all I can come up with from a respected source. Maybe it's a typo ! If you're prepared to risk drinking my fine vintage Dot 4, then I'm prepared to e.mail the technical dept's of any respected brake component manufacturers we can think of.
That's a typo, should read 25-30 bar. I'll happily take up your kind offer if I'm wrong. Interesting read http://www.fasterandfaster.net/2012/04/brembo-motogp-vs-f1-and-future-of.html
Units? Mass/Mass/Area? Thats just 1/Area. Please can we have base SI units. kg, N, Pa, m etc otherwise this thread loses its scientific validity.
Why would they test to 10,000 psi every 30 days and 1500 psi on every hose when , as you wrongly think , theres less pressure when I you for a piss. Your wrong just admit it.
I will measure this with a lazy needle on a gauge soon. Just for the record I intend silver brazing a standard heat pump service port into my brake hydraulic circuit. This will allow me to vacuum out all the air and water vapour, before drawing in my new rbf600 brake fluid. Further I can use pressurised nitrogen to blown out the old fluid. Together with removing the callipers to ensure gravity is helping I should be 100% sure of pure fluid. Note my equipment will only allow me to test to 850psi. As I don't want any issue with reliability the modification will be removed once the brakes are bled. I believe all the rear brake issues are down to trapped air in the abs modulator.
Why not just buy a proper brake bleeding kit that fastens onto the brake resovoirs ,fill the container with your fancy brake fluid and bleed the new fluid through as normal . Do the multistradas still have the bleed nipple on the rear caliper at the bottom even though air naturally goes to the top ........ or am i thinking of aprillias here ........the design engineers though that one through didnt they ! ..........
