Definitive clutch-fluid change procedure?

[Larry Fine]

I'm ready to do a clutch-fluid change, and have a few questions:

1. I know I want DOT-4 fluid. Is there one best brand or type, or one to avoid? I should get enough for the brakes, too. Same best for both? How much?

2. With the bleeder at the top of the slave cylinder, how do you maximize draining the old gunk? Cracking the banjo bolt with the clutch lever pulled in?

3. Is there a definitive best fluid change procedure posted in the forum? Links, please! Also, how do you dispose the old fluid? Does it go to recyclers?

 

[Al st1100]

dot 4 is oil right? stay away from any fluid not marked DOT 4

 

[Erdoc48]

I’ll tell you what I did...I used Speed Bleeders on both front brakes, rear brake and clutch slave cylinder (simply unscrew the existing bleeder and insert the new one, tighten carefully, then when ready to use, crack it open 1/8 turn and then bleed making sure to not go below the level of the master cylinder- add fluid as needed). I used a syringe (without any squeeze on brakes or clutch), took out the old clutch and brake fluid and poured in new fluid before I started, then bled carefully using the speed bleeders and the collection bag they sell. DOT 4 is fine, whatever brand is available. DOT 5 is silicone based so no good for the STs. As for recycling, I think Advance Auto took the old fluid

 

[ReSTored]

...I used Speed Bleeders on both front brakes, rear brake and clutch slave cylinder................

I've been using Speed Bleeders for about 12 years + have their collection bag as well. Makes changing out fluid a very easy task.

If you have no issues now with your clutch in terms of engagement, disengagement etc.... then doing what Erdoc48 says is dead simple and quick. If you have issues you're trying to/hoping to address with the fluid change then you might need to check the bushing in the lever, bleed air from the master cylinder banjo bolt as well etc............. based on what the problem is.

 

[SMSW]

No best brand, but I feel a false sense of comfort buying recognized brands. I'm not kidding here, since brand names are bought and sold by different companies we have no real idea if the present brand owner is faithful to the originators high standards. I usually go for a middle of the pack price wise, of a known brand (to me). Last time I went with NAPA brand, iirc.

Yes buy enough for the brakes, but remember that an opened can of brake fluid is only good for 6 months. I usually plan on emptying the master cylinder, refilling it w/ new juice, pumping that thru and repeating with a second fill. When the second fill is down, I fill up the reservoir and close the cap. A quart usually does me with a fair amount left over (this is for my 1300).

I don't worry about getting every last drop of old juice out. I think my vacuum bleeder and two reservoir fills should either do it or dilute the old juice enough to make no difference. I do not crack the banjo bolt - only use my vacuum bleeder on the bleed nipples.

My auto mechanic told me he can mix as much as a pint per gallon of old brake fluid in his used oil that goes to refiners for recycling. Another mechanic said he is allowed up to a quart, but since they never put that much brake fluid in with oil, I could drop a few gallons in his big tank for all he cared. Our city takes used motor oil and I drop off the brake juice in a labeled plastic jug separately from the oil. YMMV.

 

[rwthomas1]

With the clutch, let the clutch springs push the fluid out. Suck all the old fluid out of the reservoir, wipe it out and add fresh. Attach hose to bleeder and run to collection bottle. Pull clutch lever in, and then crack the bleeder. The clutch springs will now force the fluid out. KEEP THE CLUTCH LEVER PULLED TIGHT UNTIL YOU TIGHTEN THE BLEEDER! Once the bleeder is tight, then release the lever and start all over again. Watch the reservoir closely and don't let it run out.

RT

 

[TerryS]

With the clutch, let the clutch springs push the fluid out. Suck all the old fluid out of the reservoir, wipe it out and add fresh. Attach hose to bleeder and run to collection bottle. Pull clutch lever in, and then crack the bleeder. The clutch springs will now force the fluid out. KEEP THE CLUTCH LEVER PULLED TIGHT UNTIL YOU TIGHTEN THE BLEEDER! Once the bleeder is tight, then release the lever and start all over again. Watch the reservoir closely and don't let it run out.

RT

I do it the same way. Actually I think you can do a much better job of flushing fluid and gunk from the clutch slave than you can from the brakes because of the piston movement. I use a syringe to empty the master as much as possible, then swab out any remaining gloop with a tissue, then refill with fresh fluid, before I start the slave flushing.

 

[mello dude]

I'm ready to do a clutch-fluid change, and have a few questions:

1. I know I want DOT-4 fluid. Is there one best brand or type, or one to avoid? I should get enough for the brakes, too. Same best for both? How much?

2. With the bleeder at the top of the slave cylinder, how do you maximize draining the old gunk? Cracking the banjo bolt with the clutch lever pulled in?

3. Is there a definitive best fluid change procedure posted in the forum? Links, please! Also, how do you dispose the old fluid? Does it go to recyclers?

A tip on the gunk question.... grab a turkey baster or syringe or simular and suck out all the fluid in the master cylinder. The clean it spotless, with paper towels and in the corners, finish cleaning the gunk with Q tips. (if there is any)

Fav brake fluid is Valvoline Synthetic Dot 4.

For the clutch, I do like speed bleeders, the thing is to go slow....

 

[CYYJ]

A tip on the gunk question.... grab a turkey baster or syringe or similar and suck out all the fluid in the master cylinder. The clean it spotless, with paper towels and in the corners, finish cleaning the gunk with Q tips.

If you empty out the clutch master cylinder as @mello dude has suggested, you will likely encounter a problem with an air bubble being trapped at the banjo fitting where the clutch fluid hose connects to the master cylinder. I'm not discouraging you from doing what Mello Dude suggests, just advising you that you might need to add an extra step to the refill procedure if you empty out the clutch master cylinder.

To solve this problem, what you need to do is fill the clutch master cylinder up with fresh fluid, then crack the banjo fitting bolt up at the master cylinder (put a bunch of absorbent towels underneath it first), and bleed a little bit of fluid out of leak you have created where the master cylinder fitting connects to the clutch fluid hose.

I learned this the hard way when I replaced the clutch slave cylinder on my ST 1100 a few years ago. See this post: A different clutch question - hopefully not dumb, and also this post: Clutch master or slave? That is the question for more details. I'm eternally grateful to @paulcb for telling me about the need to crack that master cylinder banjo bolt and bleed the bubble out.

Michael

 

[mello dude]

If you empty out the clutch master cylinder as @mello dude has suggested, you will likely encounter a problem with an air bubble being trapped at the banjo fitting where the clutch fluid hose connects to the master cylinder. I'm not discouraging you from doing what Mello Dude suggests, just advising you that you might need to add an extra step to the refill procedure if you empty out the clutch master cylinder.

To solve this problem, what you need to do is fill the clutch master cylinder up with fresh fluid, then crack the banjo fitting bolt up at the master cylinder (put a bunch of absorbent towels underneath it first), and bleed a little bit of fluid out of leak you have created where the master cylinder fitting connects to the clutch fluid hose.

I learned this the hard way when I replaced the clutch slave cylinder on my ST 1100 a few years ago. See this post: A different clutch question - hopefully not dumb, and also this post: Clutch master or slave? That is the question for more details. I'm eternally grateful to @paulcb for telling me about the need to crack that master cylinder banjo bolt and bleed the bubble out.

Michael

Sometimes adding a banjo with a bleed valve on it is a good thing.....

https://www.amazon.com/M10x1-25mm-Motorcycle-Cylinder-Caliper-Aluminum/dp/B07MW29HY3/ref=sr_1_3?dchild=1&keywords=Banjo+fitting+with+Bleed+valve&qid=1600119251&s=automotive&sr=1-3

It seems to be Brake Fluid Day.... BFD??

 

[Bush]

Not mentioned yet, but all brake fluids are a synthetic product, so don't buy one just because it says that on the label. That usually just jacks up the price. Another vote for Speedbleeders.

If you don't have a piece of proper size hose to connect to the bleed nipple, go to any pet store and buy a pack of clear airline tubing for aquarium use. It will fit the bleed nipple and being clear helps to easily see when the old, coloured fluid has been cleared from the slave.

I get an old bottle with a metal lid - spaghetti sauce - punch a hole in the lid, just big enough to slip the tubing through securely and you won't have to worry about your hose slipping, or falling out of the collection bottle as you pump the lever.

 

[Bush]

Another thing to watch for - the little shiny piece of shaped metal in the bottom of the MC is there to prevent splashing of the brake fluid upwards, as you pump the lever. Make sure it is in there as you bleed, otherwise you may have brake fluid geysering out of the open MC.

 

[CYYJ]

Another thing to watch for - the little shiny piece of shaped metal in the bottom of the MC is there to prevent splashing of the brake fluid upwards, as you pump the lever. Make sure it is in there as you bleed, otherwise you may have brake fluid geysering out of the open MC.

Below is a photo of the part that @Bush is referring to.

Michael

 

[Igofar]

No best brand, but I feel a false sense of comfort buying recognized brands. I'm not kidding here, since brand names are bought and sold by different companies we have no real idea if the present brand owner is faithful to the originators high standards. I usually go for a middle of the pack price wise, of a known brand (to me). Last time I went with NAPA brand, iirc.

Yes buy enough for the brakes, but remember that an opened can of brake fluid is only good for 6 months. I usually plan on emptying the master cylinder, refilling it w/ new juice, pumping that thru and repeating with a second fill. When the second fill is down, I fill up the reservoir and close the cap. A quart usually does me with a fair amount left over (this is for my 1300).

I don't worry about getting every last drop of old juice out. I think my vacuum bleeder and two reservoir fills should either do it or dilute the old juice enough to make no difference. I do not crack the banjo bolt - only use my vacuum bleeder on the bleed nipples.

My auto mechanic told me he can mix as much as a pint per gallon of old brake fluid in his used oil that goes to refiners for recycling. Another mechanic said he is allowed up to a quart, but since they never put that much brake fluid in with oil, I could drop a few gallons in his big tank for all he cared. Our city takes used motor oil and I drop off the brake juice in a labeled plastic jug separately from the oil. YMMV.

Most of the companies that make brake fluid state that brake fluid only has a 2 week shelf life once the bottle is opened, not 6 months.
The same companies also indicate that unopened brake fluid has a shelf life of 1 year.
Any brake fluid left over after a job goes into the cleaning fluid only shelf.

 

[rwthomas1]

Most of the companies that make brake fluid state that brake fluid only has a 2 week shelf life once the bottle is opened, not 6 months.
The same companies also indicate that unopened brake fluid has a shelf life of 1 year.
Any brake fluid left over after a job goes into the cleaning fluid only shelf.

I have used brake fluid from opened containers that is older than that for decades and never had a problem. Not one. In any of the machines I have maintained, and there have been many. If the brake fluid is "water clear" I use it. Any color at all and its no good. Stored in a well sealed bottle on the shelf, I've not had any issues. A one year shelf life? Does anyone believe the parts stores purge slow moving inventory.... When I'm standing looking at a reservoir full of "mud", and all I have is a open container of nice clear fluid, the newer stuff is going in. Its certainly not going to make it worse.

This is not always intentional. Often I find myself in need of supplies at 8pm on a Sunday, or a holiday weekend, etc. where buying a nice new bottle is not an option, and neither is not fixing the problem. Sure its nice to have fresh fluids, and when I can plan for things, I do. I realize this is a highly personal choice, and what I do, others may not.

Planned or mandated obsolescence used to sell a product is absurd. Child car seats expire in 5 years, as do motorcycle helmets. I'm told the materials degrade. Really? And the seatbelts and airbags in my car are good for the lifetime of the vehicle? Hmm, something here doesn't make sense. Viewed from a liability/litigation standpoint, it all starts to make sense. But that is a topic for another thread....

RT

 

[sirbike]

The way I see it, the definitive change requires disassembly of the master and especially the slave cylinder.
Anything short of that is just diluting what is there.
Where on the spectrum of how important total disassembly is depends on the condition of the fluid.
In the case of just bleeding, at the worst brake fluid has turned into a white gel etc. Fresh fluid will just go around the gel rather than effectively dilute dilute it.
At the best, fluid has been changed regularly from the start. New fluid coming into relatively clean fluid should mix and dilute better.
Running fresh fluid into the system, pumping the slave cylinder several times to stir thing up, then bleeding several master cylinders full of fluid through the slave cylinder banjo and nipple is the most thorough way I can think of without disassembly.

 

[mcarver351]

I'm ready to do a clutch-fluid change, and have a few questions:

1. I know I want DOT-4 fluid. Is there one best brand or type, or one to avoid? I should get enough for the brakes, too. Same best for both? How much?

2. With the bleeder at the top of the slave cylinder, how do you maximize draining the old gunk? Cracking the banjo bolt with the clutch lever pulled in?

3. Is there a definitive best fluid change procedure posted in the forum? Links, please! Also, how do you dispose the old fluid? Does it go to recyclers?

I use a one way/one person brake bleeding valve that you can purchase for about $9 on amazon. You install it on the bleeder nipple, crack the valve and either start pumping the clutch lever or use a pump to withdraw fluid until it runs clean, and then close the valve. Make sure to watch the window on the reservoir so you don't go dry and put the cap back on every time you fill it or you will have a mini fountain of brake fluid the first time you depress the clutch lever. https://www.amazon.com/Tools-Brake-Bleeder-Single-Person/dp/B00REU0QH6

 

[SMSW]

Most of the companies that make brake fluid state that brake fluid only has a 2 week shelf life once the bottle is opened, not 6 months.
The same companies also indicate that unopened brake fluid has a shelf life of 1 year.
Any brake fluid left over after a job goes into the cleaning fluid only shelf.

With all due respect, Larry, I don't believe this. I've never seen an intelligible date code or warning on brake fluid cans/bottles ("Discard two weeks after opening"), and elsewhere I've seen it written that brake fluid is good for years if not opened. I question the latter because if those plastic bottles show shrinkage after a couple of years for other fluids it means they are permeable - and not being a chemist, I don't know what may pass in or out of those brake fluid containers. Regarding the shelf life of an opened bottle - our brake systems are open systems. My master cylinder reservoir is vented, so that means the juice in the system should be changed twice a month? Even you don't bleed your brakes monthly.

Do you honestly believe there is a dealership or service station that doesn't use brake fluid from an opened bottle that is a month old?

I am the first to say that 6 months is what I have read in more than one article somewhere, and I cannot cite the authority who said that (in fact, it might be repeated misinformation). However, I would not have stated it here if I had read that in only one location or my sources were dubious.

Last time I bought brake fluid I bought an expensive brand (c. $13 a quart) solely because it was in a metal can. I thought I could torque the top down tightly and keep it for more than the 6 mo. Alas, I used it all w/in a month.

 

[mcarver351]

With all due respect, Larry, I don't believe this. I've never seen an intelligible date code or warning on brake fluid cans/bottles ("Discard two weeks after opening"), and elsewhere I've seen it written that brake fluid is good for years if not opened. I question the latter because if those plastic bottles show shrinkage after a couple of years for other fluids it means they are permeable - and not being a chemist, I don't know what may pass in or out of those brake fluid containers. Regarding the shelf life of an opened bottle - our brake systems are open systems. My master cylinder reservoir is vented, so that means the juice in the system should be changed twice a month? Even you don't bleed your brakes monthly.

Do you honestly believe there is a dealership or service station that doesn't use brake fluid from an opened bottle that is a month old?

I am the first to say that 6 months is what I have read in more than one article somewhere, and I cannot cite the authority who said that (in fact, it might be repeated misinformation). However, I would not have stated it here if I had read that in only one location or my sources were dubious.

Last time I bought brake fluid I bought an expensive brand (c. $13 a quart) solely because it was in a metal can. I thought I could torque the top down tightly and keep it for more than the 6 mo. Alas, I used it all w/in a month.

I usually do the brakes and clutch fluid changes at the same time, which requires approximately 2 bottles of Honda DOT 4 brake fluid to do it thoroughly. I use the Honda fluid because its only $4 a bottle on Reveille and its what was in the bike originally, not that it is better or worse than any other brand.

 

[Igofar]

Before I moved from California to Arizona, I had three 5 gallon water bottles full of Dot 4 brake fluid in the garage (yes, I was bleeding a lot of brakes)
What I noticed was that after a few weeks of sitting in the hot garage, I was getting floating Lilly Pads of what looked like mold in the fluid. When I placed some Dot 4 fluid in a clean mason jar, screwed the lid on, and left it sit for several weeks, I found more Lilly pads etc.
If you search the internet a bit, and check several of the brake fluid companies, you'll find most of them indicate a 1 year shelf life, and a few of them even indicate a few weeks to months after open etc.
As far as Honda Brand brake fluid....you don't really think Honda makes this stuff?
I've thrown away several bottles that folks brought me to bleed their brakes with because when they were opened, they were already very dark brown (probably from sitting on the shelf at the Honda shop for years).
If the fluid is clear, clean, and has been re-sealed and stored in a cool and dry place, your probably ok to use it.
Me, I follow the instructions on the master cylinder cover....Only use Dot 4 from an unopened sealed bottle etc.
Folks think I'm addicted to brake fluid....but I can stop anytime I want