Brake hose failure

Exmoor beast

Exmoor beast

Hero member
Location
Minehead,Somerset, ENGLAND OF COURSE
Ok it’s on the Guzz but fundamentally the same braking setup as Lavs - Brembo original equipment.
I was out riding when I came across a road closure so I stopped quickly to do a u turn only to find the back brake has sticking on, it freed off but obviously not right. On the bench it turned out the rear master cylinder was graunchy & sticking momentarily- orderd a PS15 seal/ piston kit. Fitting the kit today I noticed the bleed nipple not flowing correctly- cut a long story short the short hydraulic hose between the master Cylinder &the proportioning valve / rear calliper was full of lumps of rubber that have delaminated from inside the hose.
I have never seen this in the flesh and externally the hoses are not perished, hard or remotely degraded. I have changed the fluid every two years & never used Silicone/ DOT 5 . Obviously a stern letter to Piaggio is in order- the bikes only 32 years old ffs😂
How old are your hoses? Never seen this on a Japanese bike or a BMW for that matter.
 
Exmoor beast said:
Ok it’s on the Guzz but fundamentally the same braking setup as Lavs - Brembo original equipment.
I was out riding when I came across a road closure so I stopped quickly to do a u turn only to find the back brake has sticking on, it freed off but obviously not right. On the bench it turned out the rear master cylinder was graunchy & sticking momentarily- orderd a PS15 seal/ piston kit. Fitting the kit today I noticed the bleed nipple not flowing correctly- cut a long story short the short hydraulic hose between the master Cylinder &the proportioning valve / rear calliper was full of lumps of rubber that have delaminated from inside the hose.
I have never seen this in the flesh and externally the hoses are not perished, hard or remotely degraded. I have changed the fluid every two years & never used Silicone/ DOT 5 . Obviously a stern letter to Piaggio is in order- the bikes only 32 years old ffs😂
How old are your hoses? Never seen this on a Japanese bike or a BMW for that matter.
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Nothing unusual, I've found the same on all sorts of vehicles. Regular brake fluid change/flush can help, as well as using the specified fluid, but rubber hoses generally have a limited life span. If not deteriorated from within, they'll degrade on the outside. Had to replace the hoses on a Triumph T140 with Brembo equipment out of the Harris production a couple of years ago, they would expand to the point the brake refused to bite properly, with a completely mushy lever that could be pulled to the grip. New PTFE lines restored brake performance to a level the owner had never before experienced. The hoses on my 2001 Skoda needed renewing after 19 years. I threw away the OE hoses on my own bikes decades ago. Japanese rubber seems to be vastly superior to most others.

I still have a limited NOS of OE Laverda/Brembo hoses if any rivet counters are interested.

piet
 
I had totally blocked hoses on the front of my Chevy, I was changing discs, bearings and fitting exchange calipers, the hoses looked realy good (externally) but on refilling with fluid, I could not make them work at all, I disconected the hoses (calliper end) just to be sure I wasnt going mad and found the blockage, new hoses and all was good, a week later, I cut into the hose, and they were blocked solid, then I made a cut every inch or so of the rubber part,, and the total length was completely blocked, nothing at all in the metal ends, which on the Chev are quite long, the wierd thing is the brakes worked OK before I started the job, and the calliper change was beacuse, they were very cheap to buy and I wanted the preventative bit, for security, why I did not plan to change the hoses still leaves me baffled five years late, what causes this blockage and how is that possible?
CLEM
 
I had the same problem on a 750 GT Ducati I briefly owned back in 92. Brake hose blocked on 1 side.
And some water in the fork.
That was sold to help finance my SFC in 93.
Paul
 
The Monty has Goodridge hoses, just re-sealed all callipers with new pistons and the the brakes work!
I panicked and decided to change the OEM hoses on the 2007 Fireblade for HEL braided ones, only to find the Honda ones were perfect inside?!!!!
 
Exmoor beast said:
Ok it’s on the Guzz .....the short hydraulic hose between the master Cylinder &the proportioning valve / rear calliper
Click to expand...
The proportioning valve? Isn't it just a joiner, the proportioning being achieved simply by the smaller rear disc? That's what I was told when I worked in a place that does Guzzi.
 
Tippie said:
The proportioning valve? Isn't it just a joiner, the proportioning being achieved simply by the smaller rear disc? That's what I was told when I worked in a place that does Guzzi.
Click to expand...
I think the very early Mk1 Lemans had a joiner but my 1000s has a sprung loaded valve ( not dissimilar to a master cylinder piston but sprung closed in relaxed state) so the rear brake is applied for gentle braking ( pretty much all of my riding) then the front left disc is applied as well under heavier braking. I really like it- if you do really hit the brakes the whole bike seems to hunker down and grip the road. Must admit , I didn’t give it a lot of thought until I’ve had it apart and also thought it was just a two way splitter. People do remove them but this may be because they are unavailable as a spare part or repair kit as opposed to being disliked as a system. I think the system gives a degree of anti lock by bypassing excess pressure from rear to the front - similar to a mechanical anti lock system that Lucas pioneered back in the 60’s.
 
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