No rear brake again

[Claudiu]

The ABS modulator has a pump and valves. Everything, including hill hold and brake lights, is controlled by ECU. There are no switches. When the bike needs, it will break with whichever brake it needs.
Regarding the leaks, fluid grade, etc. it worth to see my post with the study attached.

 

[stingray]

You think those little copper windings designed to hold the ABS Modulator slide valves open (but no longer than 60 seconds or it can burn up the ABS Modulator) is somehow a hydraulic pump motor pressurizing the entire rear braking system? Man that is some wild creative thinking there. Hahaha, you're bike is a special one.

 

[TURBO200R4]

You think those little copper windings designed to hold the ABS Modulator slide valves open (but no longer than 60 seconds or it can burn up the ABS Modulator) is somehow a hydraulic pump motor pressurizing the entire rear braking system? Man that is some wild creative thinking there. Hahaha, you're bike is a special one.

I work with solenoids all the time and the only ones i seen burned out was some gm's that had a spot on the plastic that kinked the copper rap and caused it to brake.
now most of them last a long time applied for all day use so i don't see them only working for 60 seconds. but might be a weak link from abs or wiring/fuse
they do get hot and short out the coils causing a short to ground code/low voltage. if it breaks the wire the code will be high voltage because the ecu just reads the 12-14 volts with no drop in voltage when ecu applies the circuit.
on most circuits the ecu monitors the positive voltage so it can set a code when something happens.

 

[stingray]

I work with solenoids all the time and the only ones i seen burned out was some gm's that had a spot on the plastic that kinked the copper rap and caused it to brake.
now most of them last a long time applied for all day use so i don't see them only working for 60 seconds. but might be a weak link from abs or wiring/fuse
they do get hot and short out the coils causing a short to ground code/low voltage. if it breaks the wire the code will be high voltage because the ecu just reads the 12-14 volts with no drop in voltage when ecu applies the circuit.
on most circuits the ecu monitors the positive voltage so it can set a code when something happens.

same here. I've worked on hydraulic systems for over 40 years. Our Rocket 3 is a modulator controlled ABS. No pump is involved as there are also no abs valving at each wheel. It is all done through trapping and relieving pressure in the modulator. You are the hydraulic pump. The modulator either allows you through or not. I just hate to see this erroneous information being spread around.

 

[Martynbradley]

All of this still doesn't explain my original post,as why air is getting into rear brake line on some bike even after rear masters cylinder recall.
I'm thinking next time I remove the tank on my bike I will swap out Bango washers for some copper ones.

 

[stingray]

That's been the question for years. The last memo from Triumph I read was they claim it is just normal degassing from the brake fluid and humidity from the air that is absorbed by the brake fluid. Some think it comes in through the piston seals in the calipers. Pretty unlikely in my experience if they aren't also leaking brake fluid as you pressure up the calipers. The problem is where they mounted the ABS modulator. It is under the tank on top of the engine, higher than the calipers or the rear master cylinder. The hottest spot on the bike besides the exhaust. Hot isn't a good enough description. All the air/gas collects there and has no where to go on the rear. I've seen several different ways to bleed it out and none are effective for the problem bikes. Count your blessings if your bike does not have the issue.

 

[TURBO200R4]

All of this still doesn't explain my original post,as why air is getting into rear brake line on some bike even after rear masters cylinder recall.
I'm thinking next time I remove the tank on my bike I will swap out Bango washers for some copper ones.

there are lots of opinions and this is my opinion
i think that air is getting into the rear wheel cylinder might be from the seals or might be leaking from the air bleed screw. any way seem as though bleeding the rear wheel cylinder takes care of it for a while.
being that Triumph is not overly concerned to find out if i had a bike like that i would run some tests like hang a weight on the foot pedal over winter to see if fluid would come out or if it still worked correct in spring. i think that when you release the brake that it creates a vacuum (it is not suppose to) and that is how it gets air into the cylinder i would pull the bleed screw and silicone the top threads (not the bottom where you might push silicone into the cylinder.
in my world the dealers put out a vehicle with a transmission problem and wait for the mechanics to figure it out letting the shop owners take the loss till they figure it out
my customers do not want to hear that there is still a problem when i hand them the key.
like i say there are a lot of opinions and this is just one. if Triumph has study this for years and can not fix it then who am i to say this will work. lol

 

[stingray]

• DOT 3: Dry boiling point 205°C (401°F) - Wet boiling point 140°C (284°F)
• DOT 4: Dry boiling point 230°C (446°F) - Wet boiling point 155°C (311°F)
• DOT 5.1: Dry boiling point 260°C (500°F) - Wet boiling point 180°C (356°F)

Now how hot is it under the tank?

Design flaw they're not going to admit.

 

[TURBO200R4]

i have never seen brake fluid boil that does not mean that it won't boil on the late rockets.
i do know that any air in that brake cylinder will get hot and expand a lot pushing the brake fluid back into the abs unit so even if you have rear brakes when you first start after you heat up the rotors you are going to expand the air and probably loose the rear brakes and hill hold
jmo

 

[RUN666]

Turbo200R4,
If you've never seen brake fluid boil, you probably live in a flat area... I once lost the rear brake on my Harley going down a mountain pass because, with worn front pads, I only used the pedal! It's not normal, but it can happen. And I'm not even talking about braking in competition... Anyway, I think Stingray's explanation is the most plausible, considering the locations of the various components involved. This would also explain Triumph's inability to solve, or lack of willingness to solve, this problem!

Perhaps we could try installing a fan like the ones used on enduro motorcycles to cool the ABS unit? Or an air intake to naturally ventilate the area? I'll look into it as soon as my workshop is cleared of the motorcycles that are currently lying around . For now, after bleeding the brakes and changing the fluid to 5.1, my braking system is working perfectly, better than when I first bought the motorcycle... and I can clearly feel the action on the rear disc when I only use the front brake. Will it last? Only time will tell!