Spongy front brake lever

The Speed Triple crowd went through the same problems. The ziptied handle would only work for a day or two and so would bleeding. They found that the seal on the piston was sticking causing the piston not to fully return after being applied. This created some lagg between the pistons and the pads. Pushing the pistons out and lubing the seals solved the problem.
 
Re: piston seal

Brake cylinders are not supposed to return out all the way--when you replace old pads with new, they need to be pushed out to fit over the rotor (be careful not to overflow master cylinder!). So, I assume you're referring to the master cylinder piston not returning all the way. I would think I'd feel that in the brake lever, but maybe not... Might give it a try.

vonbonds, as far as I know, the only approved 'lubricant' for any rubber brake parts is the same brake fluid you're filling the reservoir with. The material in brake seals/parts is not made to withstand standard lubricants, which can cause them to break down and leak.
 
OK I found some posts on it... There are about 4000 on Trat.net regarding the issue.

Motorcycle News in the UK has today published this response to a reader's question about excessive front brake lever movement. MCN's expert Chris Dabbs replies " The problem is the brake pistons. The earlier bikes have a shiny metallic surface and theymay have been assembled dry by the brake manufacturer. This makes the seals drag the pistons too far back off the pads giving excessive travel.
The brake pistons noe fitted in the speed triple have a special black coating that's less susceptible,but themajor fix is to remove the calipers and pads and carefully lubricate the caliper pistons with brake grease. As long as the rest of the system is up to scratch it should totally transform the performance".


When you pull your brake lever, fluid pressure forces the pads against the rotor causing the friction needed to stop. When you release the lever, the pressure stops but you would imagine the pads could stay in contact with the rotor and this could cause unwanted friction, noise and heat.

To stop this from happening, the piston seals are designed to retract the pads a bit on release, creating a gap to allow free rotation.

The next time you pull the lever, the initial travel you feel is closing the gap to bring the pads in contact with the rotor. Once the gap is closed, the lever feels solid and braking should be as usual. If it's not, then you most likey have air in the system. This is a mushy brake.

The amount of retraction depends on the design of the seals. When everything is brand new, the gap is small. As the pads wear, they should get advanced closer to the rotor, but are limited by the retraction properties of the seal. The seals can also stick and make the gap bigger.

Clearly, Nissins seal design retracts the pads further than other designs and what most people are used to. Not having the brakes function as expected can be a problem. However, it doesn't seem to affect the absolute stopping power of the bike.

By manually pressing the pads back, you break this sticking effect and bring the pad closer to the rotor. This degrades as the pads wear and don't advance close enough to the rotor, and you have to repeat. This is why guys with 200 miles on the S3's don't have an issue, they have no pad wear yet.

The point of all this is to understand that the seal retraction/sticking seems to be the issue with the Nissin brakes. Not to be confused with Mushy/spongey brakes that have air.

Now, should Nissin be pressured to change the seal design and swap them. I believe so.

One other potential weakness is the Y-split in the brake lines.

yes the y-split probably is the problem. air pockets may be stuck in there. A reliable source says in some cars they do the same thing. He said it's all about getting the air out which is a pain in the rear! try a power suction bleeder. I just bled the heck out of them went through 2 resvoirs of fluid and now they are nice and tight. will see how long this will last but I might try the piston push that was spoken of on another tread. ( went to the dealer to check the display bike and they were mushy) I think it's all in the bleeding.
 
So if I'm understanding this properly, the piston lubricant should solve the issue of excessive lever travel, but if brakes feel mushy then most likely there is still air in the lines. When I tried bleeding, I went through 3 or 4 reservoirs of fluid without success. Evidently the suction bleeder is the key... I'm still wondering why the dealer(s) can't seem to take care of the problem.
 
Roadsters and Brake Bleeds

New owner of a 2011 Roadster here. But have many years of experience bleeding /changing fluid on many bikes, and a few cars, and the suggested 'backwards -bleeding' of the brake fluid has served me well many times. Esp. helpfull in eliminating spongey feeling brakes-getting rid of air bubbles in the system! Esp. when I have no helper to assist! Use new/fresh Dot4 out of a new tin/bottle. Don't use Dot 5 fluid. Question - when I serviced my Corvette C4 with ABS, it required different procedures than with a non-ABS brake system. Does anyone know if the ABS on 2010/2011 Roadsters with ABS require special steps when changeing or bleeding thier brakes? :)
 
I've had bad Front brakes since I owned my classic. I have bleed with little help and if it worked only for a while. I would install new pads and everything was OK for 2-3k I finally tried somethng out of desperation. I lost all front brakes and bleed with no results. THis time I stuck my finger in the master over the fluid hole on the return on the lever after 3 times I had GREAT brakes. the best i ever had. Can it be the check valve in the master is bad on all the bikes? Just a thought
 
Another fix....

I have had the same issue with front brakes. The fix that I use was found on another site, but works for me. I do this adjustment about every 4000-5000 miles (2007 R3). Here is what to do:

1) get a good quality needle nose pliers (long).
2) looking down on the brake caliper put the pliers between the U and the M on the Triumph. and the outside of the caliper.
3) now "gently " squeeze to take the slack out of the pads(pushing the pad back into the caliper.
4) Do the other side.
5) Pump the front breaks a few times, and let it sit for a couple of minutes. Then check to see.

This has always worked for me and I use only one finger to stop the bike. Hope this works for you too. I got 18,000 miles off my first set.
 
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