Brake fluid - all the same or should I be more selective?

[sburns]

Just wondering where you all buy your brake fluid (Dot 4 is what I need). I just need to change the brake pads. I may have to top up or not. But just in case would like have a bottle on hand. Was planning to just go to Canadian Tire but thought I would check with you all first.

 

[DJM]

Valvoline and Prestone DOT 4 synthetic is what I remember always using.

 

[GreyGhost]

Just wondering where you all buy your brake fluid (Dot 4 is what I need). I just need to change the brake pads. I may have to top up or not. But just in case would like have a bottle on hand. Was planning to just go to Canadian Tire but thought I would check with you all first.

When was the last time you flushed the brake fluid? Now's a good time as once you open a bottle, I use whatever I need and toss the rest. I don't trust brake fluid that has been sitting in an open bottle. Might as well pump it through the lines and start with new fluid (assuming you feel comfortable with this task).

 

[sburns]

When was the last time you flushed the brake fluid? Now's a good time as once you open a bottle, I use whatever I need and toss the rest. I don't trust brake fluid that has been sitting in an open bottle. Might as well pump it through the lines and start with new fluid (assuming you feel comfortable with this task).

I haven't done it yet. I just found out it should be done every 2 years. But it's a bit tricky because of the ABS module. I have to research it a bit more. For now I just want to deal with the brake pads.

 

[PrivatePilot]

The ABS module will only be an issue if you allow air into the system, at which point you may require dealer level tools to command a prime/purge of the module while introducing new fluid.

The key to flushing fluid is to never let the master cylinder get to the point where it sucks air. Open the bleeder valve, give it a pump or two while watching the fluid level at the master cylinder (being prepared to pour more in immediately if it goes down lower/faster than you expect), close bleeder valve, refill master cylinder, and then repeat until you're getting fresh fluid at the bottom end. Use a piece of latex or neoprene or latex hose on the nipple of the bleeder valve and keep it submerged in a small jar of brake fluid - this serves two purposes - it will let you visually see when the old fluid is completely flushed out, and it will also prevent any air from being sucked back into the master cylinder accidentally. I prefer the neoprene/latex hose to the cheap plastic stuff because it seals better on the bleeder nipple and it's also way more flexible (so less likely to flip out of the jar of fluid when you open and close the bleeder valve, but YMMV.

It's a pretty simple process and can be completed quickly, at least on the front brake - the rear may be a little more work depending on the location of the calliper(s).

Lastly, take note that brake fluid will ruin paint, so be sure to cover everything. The master cylinder will "burp" fluid back up when you release the brake handle with the bleeder closed, and with the cover off it will sometimes geyser if you release the brake too fast while under pressure...so be prepared.

 

[taximan62]

Doubtful you will need any with a pad change. When you remove the old pads and push the caliper pistons back in the fluid level will go up. What you need to watch is as you push the pistons back in is that the fluid does not overflow. If you or someone previously added fluid as the pads wore down when you push the piston back in there may be too much fluid now.

 

[Trials]

Regular brake system, personally I never add brake fluid, only change it. There is normally sufficient fluid in the reservoir to push the brakes to their maximum wear limit, when your fluid level hits low, theory is your brake pad material also is low. Once you push the pads back take a look at the fluid level and it should be back up to near full.

ABS brakes :/ that's a different animal for working on, you have a whole lot of plumbing to flush, drain, bleed and refill plus if your fluid reservoirs are connected then the reservoir level might not be a true indication of brake pad wear and I should think under those circumstances you should always change all the pads at the same time. Refer to your bikes service manual for the correct procedure on that bike.

 

[Trials]

On what brake fluid to use; needs to be the correct DOT spec, needs to be clean, needs to have never been exposed to water moisture. Brake fluid is hygroscopic meaning it absorbs water from the atmosphere, it is the water content that ruins the fluids properties as brake fluid and makes it necessary to change. We live in a very moist climate.

 

[DJM]

Normally, when you bring your bike into the HD dealership for a brake fluid change they use their scantool to activate the ABS module valving This ensures all the fluid in the module itself is replaced and no moisture remains in there to cause issues down the road.

I know of one chap that sells his own activation module. I have the 4-pin unit for my bike but I think yours takes the 6-pin CAN unit, otherwise I'd let you borrow it. For me, it's good insurance against any ABS issues that may crop up, those modules aren't cheap.

ITM HD2 ABS Flush Utility (CAN bus equipped/6 pin bikes) – Information Technology Mercenaries LLC

 

[GreyGhost]

Normally, when you bring your bike into the HD dealership for a brake fluid change they use their scantool to activate the ABS module valving This ensures all the fluid in the module itself is replaced and no moisture remains in there to cause issues down the road.

I know of one chap that sells his own activation module. I have the 4-pin unit for my bike but I think yours takes the 6-pin CAN unit, otherwise I'd let you borrow it. For me, it's good insurance against any ABS issues that may crop up, those modules aren't cheap.

ITM HD2 ABS Flush Utility (CAN bus equipped/6 pin bikes) – Information Technology Mercenaries LLC

Wth? $200 for a tool that just activates the abs pump? Doesnt someone sell a proper multi-purpose HD scan tool? I'd think there would be a market for it and obviously the price point is there (obd11 is ~$100, vcds is ~500, both do almost everything you would want to the brainboxes).

 

[DJM]

Daytona makes an all-purpose but it's over $450 iirc. Besides, I can always sell this and recoup some money if I sell the bike, it's not like it's locked to the VIN.

 

[J_F]

you're telling me a company that still uses air cooled push rod engines
uses CANBUS in the brakes? madness, just madness

 

[blackcamaro]

If you end up flushing out the old brake fluid I suggest buying a mity vac as it makes the job much easier doing it by yourself.

With the abs module, flush brakes with new fluid (like mentioned do not let the master cylinder go dry or your bike is going to the dealer) go for a quick ride, do a couple panic stops to activate the abs, go back home flush the system again. If you don’t activate the abs by either the diagnostic tool or riding you will still have old fluid contaminated fluid in the module.


Whenever I do it I use up the whole bottle because it shouldn’t be used again after opening.

 

[DJM]

you're telling me a company that still uses air cooled push rod engines
uses CANBUS in the brakes? madness, just madness

Best be sitting down mate. They also started using fuel injection in 2001...

 

[nakkers]

Have a decent torx wrench set and make sure it’s got a T27 for other jobs outside the brakes.

Pretty sure the pads are fairly standard issue. I’ve swapped them out without a fluid change no problem.

There is some caution with not mixing the dot fluid such as putting in dot 4 when it calls for dot5 etc. Don’t remember the reasoning but, pretty sure it’s easy enough to find out the dot spec for you bike and get the proper stuff.

I also do a clutch cable adjustment at the same time as the brake service.

Youtube is your friend with that job.







Sent from my iPhone using Tapatalk

 

[sburns]

Have a decent torx wrench set and make sure it’s got a T27 for other jobs outside the brakes.

Pretty sure the pads are fairly standard issue. I’ve swapped them out without a fluid change no problem.

There is some caution with not mixing the dot fluid such as putting in dot 4 when it calls for dot5 etc. Don’t remember the reasoning but, pretty sure it’s easy enough to find out the dot spec for you bike and get the proper stuff.

I also do a clutch cable adjustment at the same time as the brake service.

Youtube is your friend with that job.

Sent from my iPhone using Tapatalk

Yup got a whole bunch of sockets and torx's. HD sure likes to mix and match all the different screw heads types. I heard this is another thing HD is known for.

 

[Trials]

There is some caution with not mixing the dot fluid such as putting in dot 4 when it calls for dot5 etc. Don’t remember the reasoning but, pretty sure it’s easy enough to find out the dot spec for you bike and get the proper stuff.

Mixing dot 3or4 with dot5 would be like mixing ethyl glycol with silicone.

... difference between 3 and 4 is the boiling point and if you get water in it that lowers its boiling point even more which is normally higher then water. Water boils at 100C and poof your hot brakes make the words smallest steam engine inside your brake system :| brakes drag and get all mushy like.

 

[DJM]

Gets even more confusing with DOT 5 and 5.1. I distinctly remember someone on HDForums mixing the two up, it was a clusterfluk. I ran Motul 5.1 in my BMW bike, boiling point is over 250 C.

 

[sburns]

</sigh> nothing is ever easy.

Ok so I got the rear caliper off, removed the old pads. I was able to push 3 of the pistons back in, and the third one popped out a bit more. It somehow got itself angled a bit. I was able to tap it straight again, and push it in like the others. Put in new pads. Check fluid level, good.
Pumped the pedal, got some pressure. But pressure on the rear is not staying.

The pedal goes way down much more then before. If I pump it a bit, the pressure stays, but then looses it.
I think one of the pistons isn't working right, sticking? Can I grease it somehow.

As far as I can tell no air got into the system the fluid wasn't very low, and it did go back up to normal.
Ideas? Thx

 

[GreyGhost]

It has a four piston rear caliper? You pushed he pistons in one at a time? Next time, use the old pads as a surface the pry against to reseat the pistons.