Spongy front brake lever

[ratpick]

DOT 5.1 Brake Fluid

Dealer sold me DOT 5.1(??) brake fluid, which is supposed to be compatible with DOT 3 and 4, just not 5 (which is silicone). Why they called it 5.1 in that case...? Whatever--I believe it's what they put in the bike; guess I'm assuming the dealer adds brake fluid and bleeds the brakes on new bikes. Made by "Motul", which also manufactured the engine oil they use.

Another interesting point--according to techs at dealer, the brake lines are the type lined with braided steel. Again, given the small volume of fluid moved by the master cylinder, evidently the expansion of brake lines could conceivably cause a spongy feel, but that shouldn't be the case here.

Gonna give it a try tonight or tomorrow AM, and will post results. I am familiar with the process; didn't mean to give the impression of being a total amateur. The bleed valves are very near the top of the caliper--though the line does go in above, any air that has been pushed into the brake cylinder should be expelled.

 

[ratpick]

Results...

well, maybe a little better now, but not much--appeared that some small air bubbles came out. Along with a very noticeable amount of metal filings. I'm sure that's not causing my problem, but can't be good for the master and brake cylinder seals.

One of the parts guys at the dealer is looking for aftermarket master cylinder and/or brake calipers. Maybe I'm nit picking--yes, they stop the bike (though I haven't had to panic stop yet), but I do not have a good feel of the front brakes, and as a consequence I'm tending to lock up the rear much more readily than I should. Any other suggestions?

 

[wilbur-t]

My front brakes aren't spongy, but the lever does move farther than on other bikes I've had. With dual front calipers, the master cylinder piston has to displace enough fluid to move four caliper pistons, instead of two. Maybe this has something to do with it also? I can tell you that when I have to get on em' hard, that thing will stop!

 

[Dobieman]

Spongy brakes were pretty common with speed triples and daytonas also (which share the same brakes). Bleeding them seemed to help.

Triumph finally put out a TSB on these and replaced the pistons and seals. Coated pistons were the answer. Bleeding was temp fix at best. My S3 was not affected and had a perfect solid feel with minimal lever travel. While the lever travel is a bit further on my Rock its very firm.

I would confront the dealer with the Speed Triple TSB and fix....took Triumph too long to admit to the problem but finally did.

 

[vonbonds]

Ratpick, have you figured out a solution to your spongy brake issue? Mine are spongy now (after 35K miles) and replacing my old fluid with new and a bleeding didn't resolve the issue. They still work as others have stated but they feel nothing like the brakes on my Thunderbird Sport.

 

[Baggage1]

I had mine go to the grip and I gripped to the dealer. They took the top off the resevoir and found the brake fluid quite dark. They got that out and filled with new and never had a another problem. Vonbonds I know you have replaced your pads before now did that help any? I suspect some trash can get stuck in the there and cause blow by. Ratpick I think I would let Triumph America know about your dealers blow off.

 

[Pig9r]

When replacing the pads do you completely push the pistons all the way out?

 

[vonbonds]

I had mine go to the grip and I gripped to the dealer. They took the top off the resevoir and found the brake fluid quite dark. They got that out and filled with new and never had a another problem. Vonbonds I know you have replaced your pads before now did that help any? I suspect some trash can get stuck in the there and cause blow by. Ratpick I think I would let Triumph America know about your dealers blow off.

Baggage1, my front pads are probably 2K old..no difference from when new till now.

 

[Baggage1]

I did notice quite a difference when the new pads went on with the lever stroke reduced by about half. However there was the sponginess factor that seems to be the beasts trait.

 

[dutchie]

There are only two reasons for having spongy brakes. There is air in your system, or there is expansion in the lines. With the brake lines being the stainless steel braided kind, I would not expect the latter to be the problem (there may be some, depending on the volume of the system). If you have air in your lines (which isn't necessarily easy to bleed out) Then in most cases there is a (small) leak somewhere. A (premature) discoloration of the fluid would also indicate this. Finding crud in your fluid is not good at all.
On older bikes I’ve had good results by running a lot of new fluid through the system and then leaving the bike with the handle depressed (ziptied) over night.