I’m inclined to agree. The gas is able to compress before a useful working pressure is built up, irrespective of whether the fluid is moving anywhere.
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R1250GS calliper bolt length
- Thread starter Daggerit
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I’m inclined to agree. The gas is able to compress before a useful working pressure is built up, irrespective of whether the fluid is moving anywhere.
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Pressure is pressure (unless your system is a gas system, where dynamics play a part, dependent on the volume of the system).
You apply a set force to the lever - you get a set force applied from the caliper. makes no difference if it is gas or liquid in the pipes.
In the case of a hydraulic system (pistons at each end) - there is negligible dynamic effect (to the extent you can ignore it).
Bleeding air - is done as the thermal expansion is greater than the hyd fluid, and it expands to push out the oil in the reservoir + it will mean that your brake lever must travel to exert the pressure. There is even the danger that it pulls back to the bar! But - that is not FADE.
That is true, however....
Before a pressure sufficient to approach a high braking level is achieved, any gas (air or steam) will have started to compress and will result in longer master cylinder piston travel. In extremis, the master cylinder piston runs out of travel before maximum braking effect if achieved. That's baaaad....
I covered that - with the sentence you cut out - I think.
it will mean that your brake lever must travel to exert the pressure. There is even the danger that it pulls back to the bar! But - that is not FADE.
fred_jb
Registered user
I covered that - with the sentence you cut out - I think.
it will mean that your brake lever must travel to exert the pressure. There is even the danger that it pulls back to the bar! But - that is not FADE.
Most people would understand fade to be a reduction in braking efficiency following repeated use. If the heat generated by repeated heavy use leads to gas in the system and this in turn allows the lever to pull back to the bar before maximum braking effect is achieved, then to me that is brake fade. What would you call it?
I follow you Blackal from what I can remember from physics.
Don't ride with your fingers covering the brake. 2 reasons.
1. You can drag the pads on the disc.
2. For road riding your first instinct will be to pull the brake when you can steer around the emergency.
Oh, and it is not a 2 stroke
Don't ride with your fingers covering the brake. 2 reasons.
1. You can drag the pads on the disc.
2. For road riding your first instinct will be to pull the brake when you can steer around the emergency.
Oh, and it is not a 2 stroke
I covered that - with the sentence you cut out - I think.
it will mean that your brake lever must travel to exert the pressure. There is even the danger that it pulls back to the bar! But - that is not FADE.
You did.
I follow you Blackal from what I can remember from physics.
Don't ride with your fingers covering the brake. 2 reasons.
1. You can drag the pads on the disc.
2. For road riding your first instinct will be to pull the brake when you can steer around the emergency.
Oh, and it is not a 2 stroke
See - I've always ridden with two fingers over the top of my lever, and do recognise that there may be an instinctive reaction when not warranted, but - if my fingers are already on the lever, I think I am more likely to apply a gentle pressure (initially) - rather than the 'grab'.
The other reason is better throttle control. I think I started that when I had a 954 Blade which if you sneezed with a normal grip on the throttle........ you'd be off into the pedestrians!
(the lever doesn't move from 'released' when I am riding like that)
fred_jb
Registered user
If the "sponginess" appears after heavy repeated use of the brakes and results in you being unable to obtain the same retardation you would normally expect, due to excessive lever travel, then how else can you describe it other than brake fade? If not, what else is brake fade - is it some mysterious reduction in friction between pads and disks once they are thoroughly heated, because I don't see why this would be the case, and suspect that these components would actually work better when hot so long as they are being operated with the same force as when cold.
fred_jb
Registered user
Excellent - that was the explanation I was after. So contrary to what I thought it is actually a materials issue with the pads at temperatures above what they are designed for.
Good reading! They do mention that air in the line could be the cause of fade/sponginess, so I guess that helps to answer that a bit?
What I'm taking from it is that my initial responses to renew the fluid and change to more suitable pads was the correct initial reaction and now using a larger disc is the next step, as the braking experts have advised.
'If you experience brake fade on the road or on the track, consider installing an EBC oversize brake kit with larger diameter rotors and curved internal vanes to help with heat dissipation and eliminate unwanted brake fade.'
So I'll make sure I update once I finally get them sorted out. Thanks for the help and the cracking debate lads.
What I'm taking from it is that my initial responses to renew the fluid and change to more suitable pads was the correct initial reaction and now using a larger disc is the next step, as the braking experts have advised.
'If you experience brake fade on the road or on the track, consider installing an EBC oversize brake kit with larger diameter rotors and curved internal vanes to help with heat dissipation and eliminate unwanted brake fade.'
So I'll make sure I update once I finally get them sorted out. Thanks for the help and the cracking debate lads.
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So much info learned from a simple bolt question, well worth 12 quid a year................
Curved internal vanes - let us know how you get on.
The very reason that carbo-ceramic discs (and appropriate pads) are used - they limit fade. They generate huge amounts of heat, but what that does to the exotic brake fluid - doesn't reduce their fade-resistance
After all the good debate and info - now you're just being silly... I'd like to think you were intelligent enough to understand what I was getting at with the quote in that the larger diameter discs should dissipate more heat.
So much info learned from a simple bolt question, well worth 12 quid a year................
Definitely!
You could chill and just go a bit slower
I put a new set of braided lines. On the wee paraffin pony the other week , WHAT a difference that makes .
That was on my list until I saw it’s fitted with Goodridge braided lines from factory! Pleasant surprise. Haha.
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