Triumphrat

HiVel · 06-17-2006

Counterman at dealer (rides 05 Speedy)told me the new fix on front brakes is to bleed thoroughly then pull the lever back hard and put some pressure on the lever (they use heavy rubber bands) in the pushed back position for about 4 hours. This is an air bubble cure I surmise as my brakes have worked really great since they did this to them.
Maybe it will help some of you folks. It did the trick on mine so far...

FelixLeiter · 06-17-2006

I needed to change my brake fluid as it was going brown, so I just performed this "trick". Used most of a bottle of brake fluid flushing the system (no air bubbles though). I zip tied the brake lever back (will remove in a few hours, after the hockey game).

Here's a question:
The diaphragm in the front brake resevoir looked like a top hat turned upside down--the top hat portion was quite "tall" though. It was also creased (actually curved) across the top like a cowboy hat... it would not straighten out. When I filled the resevoir to the upper line I could not refit the diaphragm and lid without risk of overflowing the fluid, so I bled a bit more. Is this normal or do I have an NFG diaphragm?

kuhlka · 06-17-2006

That fix is nothing new. People on here and T595.net have been zip-tying their brake lever overnight for years. Its not a permanent fix.

Actually, I went around and felt a bunch of different people's brake levers at bike night wednesday and noticed all the other guys with standard master cylinders had about the same amount of mush as my own lever. I'd still like to know what I need to do to get that rock solid feel I had back when I first did the MC and EBC HH pad swap a year ago though.

Geof3 · 06-17-2006

I have a thought...

We have all come to the realization that Triumph put a standard MC on a bike with radial calipers. Some have done a radial MC upgrade and the problem is solved... I have yet to do my install...

Anyway, in a system that pushes things out via applied pressure, there has to be enough back pressure to pull things back... Could it be that the 14mm MC is not building sufficient back pressure to overcome the stiction of the pistions, thus not allowing the lever to come back to it's full firm postion? If the radial MC applies more pressure, there will be more back pressure to bring the pistions back into original position... Seems to make sense to me....

Legman · 06-18-2006

Hey Geof,

It is my understanding that when you release the brake lever, nothing pulls the pistons back, at least that is how it is supposed to be. It is a very small amount of runout in the disk (they are not absolutely perfect) that pushes the pistons back a very small amount and then the next time you apply the brakes very little lever travel is required to start braking action.....as I said that is how it is supposed to be.
I the case of the S3, the piston seals pull the pistons back, further than is needed and hence too much lever movement is needed to start braking again.

AlaskaS3 · 06-18-2006

There is actually springs that bring the lever back into position.
I'm not sure if this is even a motorcycle master cylinder, but the principle is the same.

Geof3 · 06-18-2006

Quote:

On 2006-06-18 04:44, Legman wrote:
Hey Geof,

It is my understanding that when you release the brake lever, nothing pulls the pistons back, at least that is how it is supposed to be. It is a very small amount of runout in the disk (they are not absolutely perfect) that pushes the pistons back a very small amount and then the next time you apply the brakes very little lever travel is required to start braking action.....as I said that is how it is supposed to be.
I the case of the S3, the piston seals pull the pistons back, further than is needed and hence too much lever movement is needed to start braking again.

I understand that, but there still is a pressure issue... Pulling the lever produces pressure, releasing lessens the pressure. Something has to pull the pistons back... Or, could it be that there is NOT ENOUGH pressure generated by the normal MC to keep the entire system pressurized properly? Thus allowing the seals to pull the pistons back too far?

rodneybrown · 06-18-2006

The rubber band trick is nothing new and was actually a common practice with dirt bikers. All you are doing is driving the air into solution, if there is air, but it will come out again.

Hairball · 06-18-2006

I talked to my mechanic about the brakes and about cinching the lever...

He said the same thing RodneyBrown said... forcing air back into solution.

He said that because the banjo is above the bleeder, along with the wishbone plumbing
it is very hard to get all of the air out...
He suggested using the Banjo as the bleeder, Sounds messy but worth a try.

Gotta buy a couple of cans of brake cleaner.

HiVel · 06-18-2006

Quote:

On 2006-06-17 20:34, Geof3 wrote:
I have a thought...

We have all come to the realization that Triumph put a standard MC on a bike with radial calipers. Some have done a radial MC upgrade and the problem is solved... I have yet to do my install...

Anyway, in a system that pushes things out via applied pressure, there has to be enough back pressure to pull things back... Could it be that the 14mm MC is not building sufficient back pressure to overcome the stiction of the pistions, thus not allowing the lever to come back to it's full firm postion? If the radial MC applies more pressure, there will be more back pressure to bring the pistions back into original position... Seems to make sense to me....

OK-my son told me to be sure and loosen the cap on the reservoir as he has been doing this trick on his Mountain Racing Bicycles for years!! It does work.

Question-where and what kind of radial MC do you get to upgrade??

Also , I have been measuring some temps with my laser thermometer and the calipers seem to get hotter than the discs or at least they trap more heat longer. I do not know exactly what this means other than to
prove some laws of physics. Interesting and good to know??