DOT investigation into rear brake issues

[d3vi@nt]

I just learned on another Ducati forum that DOT is looking into rear brake issues on MY 2012-2020 Ducati's.

In general terms they are looking into, "Inconsistent braking, extended stopping distance and unexpected soft rear brake pedal when applying the brakes."

Specifics are in the DOT document here: https://static.nhtsa.gov/odi/inv/2021/INOA-PE21003-8330.PDF

I emailed the investigator, who replied with the following details for anyone who has had these issues and is interested in contributing to the investigation:

The absolute best way to help is to have your constituents file a complaint through File a Vehicle Safety Complaint | Safercar.gov | NHTSA This gives me the ability to call these consumers back while having the capacity to confirm their issue by the identifying VIN supplied (this is important for the investigative process).

The link to file a complaint is here: https://www-odi.nhtsa.dot.gov/VehicleComplaint/

Please help if you can. I'm sure it will be appreciated.

[Charlie98]

I don't know about all that... it's just a really poor design, at least on the ABS model.  I wasn't aware the actual brake line had issues...

[koko64]

I've lost count of the number of cooked rear calipers and discs I've seen on Ducatis. Many were due to poor adjustment (lack of freeplay). Seen many an old bike with shiny new rear caliper, disc and master cylinder with original front calipers with faded paint but still working well.  Often I check the pedal adjustment/freeplay and it's still going to fry the new components in time!

Brake line routing, brake line junction design (for ABS) and the line's proximity to exhaust pipes appears to be an issue for some models for sure.

[d3vi@nt]

It's been a long-standing issue with at least the 10-14 MTS models. Ducati issued an updated bleeding procedure, as well as an update MC along the way, which still don't sufficiently address the issue.

The issue isn't related to cooking due to limited freeplay (I did that to myself on my ST2), rather the pedal constantly going soft.

I agree (at least on the MTS) that it's a poor design: the caliper is mounted lower than the MC and the bleed nipple is on the bottom of the caliper. Not to mention the MC and line sit very close to the cat.

The updated maintenance guidance had techs remove the caliper and cable ties, invert it so the bleed nipple is facing up, then tie it up as high as possible before bleeding. This still seems to provide mixed results.

Based on the NHTSA report, Ducati acknowledged the issue by allowing brake lines to be replaced if a customer had issues. From forum discussions, it seems not many shops are/were actually aware of this option.

[Howie]

It is not Ducati specialty thing that the rear caliper on a motorcycle is mounted with the bleeder screw on the bottom.  To bleed properly you remove the caliper, find something about the width of the rotor to place between the brake pads and with the bleeder pointing up bleed as you stated.  Not necessary when changing the brake fluid.

Yep, too close to the cat is a problem.  I've seen quite a few with black brake fluid.  The rear brake will recover from that when the fluid cools down.  The brake line issue explaines the rear brake going soft over time.  Bleed, wash, rinse repeat. 

[greenmonster]

Different brake fluid.

[d3vi@nt]

Different brake fluid.

That stuff is about $75/liter. Sounds like it addresses the fluid blackening issue, but certainly won't fix a sub-par brake line assembly.

I typically flush mine annually with everyday DOT5 , as opposed to the 3-year recommended interval, so the fluid never gets super dark. Though it does get darker than the clutch and front brake.

It's a pretty mixed bag. Some folks have reported success after removing the cat, others had the issues persist. Another member fabbed up an MC heat shield and reported good results, others had no success. Makes one wonder how much is mechanical issue versus poor bleeding methods.

Regardless, the gist of it is, if you've experienced the issue, file a report and hopefully we'll get a resolution. 

[Howie]

For several years some owners have complained about Ducati rear brakes going soft and needing periodic bleeding including Monsters.  Seems the Multi is plagued with two problems.

Also, that Castrol SRF is silicone brake fluid.

[stopintime]

.....

Also, that Castrol SRF is silicone brake fluid.

Sure? 

[Howie]

Actually, sort of.  Silicone ester is a component it is not silicone based.  It is supposedly compatible with poly glycol fluids and brake components, but I remember back when they claimed silicone brake fluid was too.  Took them a few years to discover they were wrong.  

https://www.ogracing.com/products/castrol-react-srf-brake-fluid#:~:text=The%20key%20to%20Castrol%20SRF%20brake%20fluid%27s%20superior,industry%20unheard%20of%20518%C2%B0F%20%28270%C2%B0C%29%20wet%20boiling%20point%21

This is a link to the MSDS, if there is a chemist among us maybe we could learn more.

https://msdspds.castrol.com/ussds/amersdsf.nsf/Files/036CB2746F71193B8025865C0059D405/$File/2696658.pdf

Weird that the label it DOT 4 when it well exceeds DOT5.1 temperatures.  This fluid does not show up on the US Castrol website.

[stopintime]

It has been on the market for quite a while. 'Never' a warning. Very distinct advantages, but expensive. The liter bottle will last forever - for me and my mates. "Change every 18 months".



https://www.castrol.com/en_gb/united-kingdom/home/car-engine-oil-and-fluids/brake-fluids.html#tab_react-srf-racing

https://msdspds.castrol.com/bpglis/FusionPDS.nsf/Files/86313FD0787A0073802583900050AB33/$File/BPXE-8DHDD7%5F0.pdf

[koko64]

DOT 5 fluid certainly proved incompatible with systems that had DOT 4 through them. I know of a total brake failure with a change to DOT 5. The two fluids reacted and the brake lines were filled with gel. The whole system was toast.

5.1 appears new in the bike shops and different again.
https://www.penriteoil.com.au/products/dot-51-brake-fluid

Of note is that it appears compatible with DOT4 systems and designed for the micro valves in ABS systems.

[d3vi@nt]

The liter bottle will last forever - for me and my mates. "Change every 18 months".

I've always read that you shouldn't keep an opened bottle of brake fluid for more than 3 months, 12 months at the absolute longest. Being that it attracts moisture, the enemy of the braking system.

Probably a whole other can o'worms there.

[stopintime]

I've always read that you shouldn't keep an opened bottle of brake fluid for more than 3 months, 12 months at the absolute longest. Being that it attracts moisture, the enemy of the braking system.

Probably a whole other can o'worms there.

Race teams will probably want the 'dry' boiling point. Only way to acheive that is to replace every weekend/day.

I guess (not knowing) that the wetness reaches a point where it doesn't get worse. If so, after 'a while' it's wet and won't become worse. My own experience supports this theory.

[Charlie98]

It is not Ducati specialty thing that the rear caliper on a motorcycle is mounted with the bleeder screw on the bottom.  To bleed properly you remove the caliper, find something about the width of the rotor to place between the brake pads and with the bleeder pointing up bleed as you stated.  Not necessary when changing the brake fluid.

My '13 Monster ABS has an even worse issue... besides the 'upside down' bleed screw.  The ABS valve body is mounted high up on the frame, under the tank.  So, the line travels from the pedal, UP to the distribution block, then DOWN... past the exhaust... to the caliper.  Trying to pedal bleed this system is impossible because any air in the system goes UP to the distribution block... and stays there.  You can get a better pedal temporarily... but it's gone in less than 6 months.