Replacing brake fluid?

[steelhorseuk 1,690]

Hi Guys,

 

Yesterday I mentioned to my mate that I was going to bleed out and replace the brake fluid in the NC and he laughed at me.

 

In fact, he was laughing so much I thought he was going to split his side open ...

 

"No-one changes the brake fluid, why do you want to do it?" he says.

 

It's in the service manual to change it every 2 years. Its been 4 years now so I thought I better get it done.

 

"No, don't bother, no-one does!" he continues... 

 

What do you guys think? Am I being stupid ?

 

-Mark-

[Guest machinman]

Get it changed, it does absorb water over time. You will notice a different feel when you have done it.

You'll be surprised how dirty it is when it comes out.

[Guest Hati]

Nope, he is. Brake fluid is hygroscopic, meaning it will attract moisture from the air. Over time that can be significant, hence the regular two-yearly fluid changes. Cars need it done too, just a little less frequently.

[Andy m 23,533]

Two years is probably towards the dealer profit end of the safety scale, but not by much. Change it.

Your mate is right though. No one bothers. You won't find any web wars over which brand of DOT4 or guys who insist it should be changed daily either.

Andy

[Rocker66 34,443]

Depends how well you want your brakes to work.Over time you don't notice the gradual loss of feel of your brakes but once you change the fluid you will notice the improvement

[bazza 3,629]

Funny isnt it -alot of guys buy stainless brake lines - because they don't expand so much as the rubber ones ( which i think are inside anyway) and give you better braking.yet the fluid that does the job some people ignore.Yes its a pain to change but surely more important?

[DaveM59 1,605]

Many bikes go for possibly all their life without changing the fluid without any obvious problems, but as has been said the fluid in theory absorbs moisture and deteriorates, but in reality is hermetically sealed apart from when you take the lid off, so doesn't get the chance to do much of this. What it does do is get burned, or at least heated and this creates dirt particles that can collect in the reservoirs and behind the calliper pistons which can damage the seals. 

If you decide to change the fluid, use a vacuum bleeder (mityvac or similar) and draw it through from the calliper but take the top off the reservoir and with a soft brush stir it up and get all the settled gunge re-suspended in the fluid then suck it through, keeping the reservoir topped up until what comes out is clean clear fluid. Never let the level drop low as if you get any air in the system with ABS it's a sod to get out again. Do the longest run first so rear, then front and maybe go round both twice. Never let the reservoir get low then loosly fit the covers and pump the lever a few times and you should have a nice firm feel. Top up to the correct level and refit the rubber seal and lid and nip the screws. Don't pump the lever with the top off as when you release the lever it squirts a jet of fluid up into the air (and all over your paintwork!).

I wouldn't recommend stirring the gunge up then pumping it through conventionally with the levers as you are then passing the crap through the piston seals but it's OK with a suction bleeder. Then again after only 4 years there may not be any gunge. Don't use DOT 5 in a system designed for DOT 4 though.

Edited May 5, 2016 by DaveM59

[embee 7,288]

(Edit - see Dave's post above, I was typing this as he posted)

 

Yes, change it.

 

Treat yourself to a vacuum bleeding kit, my choice is the Mityvac but others are available. The Mityvac kit is available in different specs, but the basic kit can be had for around £35, like here

https://www.amazon.co.uk/Mityvac-MV8020-Automotive-Bleeding-Silverline/dp/B005O2LQLQ?ie=UTF8&*Version*=1&*entries*=0

 

Once you've used one you'll wonder why you ever tried any other way. Have you read all the tales of woe on bike forums of people struggling to get firm brakes? Also once you find how simple and easy it makes it, you'll do it more often.

 

The only issue I find is the vac bottle tends to fall over, so I made a heavy stand for it to sit in. Other than that, a piece of cake.

 

You can use it to empty the reservoir first so no need to draw old fluid through the system.

 

There is no problem doing ABS systems, just bleed it through from the caliper nipple. Make sure you keep the reservoir topped up so no air gets in. Doing the combined systems is no issue, just do each line in turn. I guess there may be some debate about whether to do the front or rear section of the combined brakes first, I'm not sure I can argue which is best, I tend to do the front line first but I doubt it matters much, they separate early on.

 

As Andy/Dave suggest, just use a branded DOT4 fluid.

Edited May 5, 2016 by embee

[steelhorseuk 1,690]

Great to hear your comments as always guys and great advice thrown in for good measure.

 

I will crack on with it with the feeling I am not so stupid after all!

 

-Mark-

[ontwowheels 19]

Just a thought (from someone who doesn't own an NC).  On previous ABS equipped bikes I've owned, there has been a separate procedure for changing the fluid in the ABS unit itself, and the pipework that joins the ABS unit onto the main master cylinder-to-calliper lines.  The reason for this, as I understand it, was that the ABS unit was off a "Tee" junction from the master cylinder-to-calliper brake line, meaning when you changed the fluid from M/C to calliper, it effectively bypassed the ABS unit and associated pipework.  In other words, I understood that by using the normal fluid changing/bleeding procedure at the calliper, the fluid did not route through the ABS unit.

 

Does this make sense? Or is the NC arrangement different in that the all fluid flows through the ABS unit such that a normal bleed procedure completes a thorough job?

[DaveM59 1,605]

The ABS modulator is in direct line from the master cylinders so it shouldn't be an issue. The manual gives both the vacuum and manual pump methods that are the usual ones. It does say do the front first probably because of the combi link.

[ontwowheels 19]

Thanks - very helpful clarification.  Another tick for the NC design then.

[Guest sykospain]

Errrmmm, are you asslutely sure, Dave ?

 

During a Berlin assembly plant visit ( a fascinating experience,  to be recommended to anybody interested in motorbikes )

I watched a tecnico charging big boxers with DOT 4 as they rolled along the assembly line. This was year 2012.

The technique was to force the fluid in under high pressure backwards up from the callipers with both lids off the two reservoirs, front and back.

With an eagle eye on the levels, he then lidded the reservoirs and separately primed the ABS modulator located under the driver's seat.

Certainly in all their bike owner advice literature, BMW says no DIY-er should ever try to re-DOT4 an ABS bike.  Their stealers have a gubbins called a MoDiTec that flashes the ABS unit separately.

 

Are we sure that Honda's bike ABS isn't the same ?

[Rocker66 34,443]

We wnt to plant in Berlin when much of the assembly work was done by hand including the pin striping on the tank

[embee 7,288]

You can certainly successfully bleed the NC ABS systems using a vac bleeder, I've done it a few times, also on ABS Deauvilles with combined brakes. I always vac empty the old fluid from the reservoir first and then refill, alow to stand for a while to make sure all air bubbles are out then vac bleed at the caliper nipples.

 

I've never tried to refill the systems from empty. I avoid getting air in.

 

BMW have used some rather quirky brake systems on some of their models.

[Andy m 23,533]

BMW are an odd experience from a design project point of view and not one I care to repeat. Think trying to explain the internet to elderly relatives!

Andy

[Derek_Mac 1,404]

Smudger, once you do it you'll be amazed at the difference it makes.

[kayz1 2,928]

Tis only the BM's that use that ABS unit.

[Guest sykospain]

Good news - so the MitiVac rules !

[michael 324]

I'm a "change the fluid," proponent as well.

 

While this thread started on the debate on whether to change or not, I'll offer this: Merely look at the window in the front reservoir. Has the brake fluid changed colour from the light tan is was when you got the bike? 

Reason enough to replace it…just like any other consumable. Like engine oil. Like coolant. Like fork oil.

 

Now as far as replacing the fluid yourself? Your garage confidence should by the guide as to whether you spend some quality garage time or have the dealer or shop do it for you.

 

Me? It's a matter of time-I don't have much of it for things like these, as therapeutic i find garage time - so likely the dealer will handle for me.

[steelhorseuk 1,690]

I decided to make life easy on myself gents.

 

I looked at the cost of the bleeder kit as suggested by Embee (thanks mate for the link and info) and I decided to offset that against Daz at Grafton's hour labour charge.

 

The manual makes it more complicated than it is for a C-ABS system and I decided life's too short. (It certainly would be if I screw the job up!)

 

So, its going in next Monday ...

 

-Mark-

[embee 7,288]

There are much cheaper options than the Mityvac, like this for example https://www.amazon.co.uk/gp/product/B00HHXRBWI/ref=pe_1982711_132397761_em_1p_4_ti , but I have no experience of them so can't comment on quality. We used to use Mityvac equipment in an industrial R&D department and I'm familiar with the quality and durability.

[larryblag 14,236]

Many bikes go for possibly all their life without changing the fluid without any obvious problems, but as has been said the fluid in theory absorbs moisture and deteriorates, but in reality is hermetically sealed apart from when you take the lid off, so doesn't get the chance to do much of this. What it does do is get burned, or at least heated and this creates dirt particles that can collect in the reservoirs and behind the calliper pistons which can damage the seals.

If you decide to change the fluid, use a vacuum bleeder (mityvac or similar) and draw it through from the calliper but take the top off the reservoir and with a soft brush stir it up and get all the settled gunge re-suspended in the fluid then suck it through, keeping the reservoir topped up until what comes out is clean clear fluid. Never let the level drop low as if you get any air in the system with ABS it's a sod to get out again. Do the longest run first so rear, then front and maybe go round both twice. Never let the reservoir get low then loosly fit the covers and pump the lever a few times and you should have a nice firm feel. Top up to the correct level and refit the rubber seal and lid and nip the screws. Don't pump the lever with the top off as when you release the lever it squirts a jet of fluid up into the air (and all over your paintwork!).

I wouldn't recommend stirring the gunge up then pumping it through conventionally with the levers as you are then passing the crap through the piston seals but it's OK with a suction bleeder. Then again after only 4 years there may not be any gunge. Don't use DOT 5 in a system designed for DOT 4 though.

Well said, excellent description of the job too. The vacuum bleeder also avoids ruining the master cylinder piston seal by it repeatedly running over a part of the bore that hasn't "seen" the piston since the bike was new.

Definitely worth changing though. I "cured" the failing clutch on my old 1150RT simply by changing the clutch fluid.

Edited July 15, 2016 by larryblag

[Tex 36,817]

Definitely worth changing though. I "cured" the failing clutch on my old 1150RT simply by changing the clutch fluid.

I did the same on my R850R! Plainly we're cut from the same cloth..

[larryblag 14,236]

I did the same on my R850R! Plainly we're cut from the same cloth..

 

Yes Simon, Bird's eye Maple I believe?