Brake bleeding process and frequency [Archive] - Bimmerforums

wintershade

08-16-2016, 07:38 PM

Hi all --

Super novice DIYer here. My 98 M3 serves mostly as an HPDE car. The Bentley manual make a big deal of having a certified BMW technician do the brake flushing / bleeding due to something about the ABS system. I'd like to do this myself to cut down on running costs. Is a simple Motive Brake Pressure Bleeder all I need to do this safely?

How often should I be bleeding brakes? Prior to every track day?

How often should I be doing a full brake fluid flush? I was thinking every 3-4 track days... Is there a simple way to measure brake fluid moisture content and use that as a more precise indicator or how often to flush? I'm currently running ATE Super Gold and haven't had any issues with fade, but was considering switching to Motul 600 or something more exotic.

Thanks for your help!

adamnur

08-16-2016, 08:41 PM

Recommended intervals are 2 years for a street-driven car. Fluid should be changed after each HPDE.

The bentley likely refers to the ABS system as using INPA, a tech can cycle the ABS pump to clear out the fluid locked inside. To do it fully and properly without this, you can flush, go out and activate ABS, flush again, but I believe most agree that the small amount of fluid left in the pump is not worth this process.

Pressure bleeder, 7mm box wrench for stock caliper bleed screws, bottles/tubes for bleeding into. These are good tools for a flush, but IMO 2 person method (one pumping pedal) is better for clearing air in the lines.

I recommend looking up Pelican's brake bleeding DIY for an overall look at the procedure.

ScotcH

08-16-2016, 09:41 PM

Fluid should be changed after each HPDE.

Depends on the fluid ... we run Castrol SRF (the best there is ... don't argue) and we change it at the start of the season, then bleed maybe one or twice. Pointless to change it more frequently. Now if you run some $3 fluid, yeah, change it, but also, don't run $3 fluid.

adamnur

08-17-2016, 02:52 AM

I was considering the standard stuff. Def defer to the track experts.

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ScotcH

08-17-2016, 10:53 AM

I was considering the standard stuff. Def defer to the track experts.

It comes down to many factors ... even brake pad choice since it will impact how much heat goes into the fluid. Basically, if you have to bleed after each track event, you've got the wrong parts ... fluid likely, pads maybe.

The Motul RBF 600 I found spongy, no matter how it was bled. Just didn't like it. The ATE Type 200 (yellow super blue) is great for daily and occasional track use, and will likely only needs flushing once or twice per year. The Castrol SRF is $70/L, but it is simply the best you can get. It will not give up and does not every get spongy with very aggressive pads and use. $70 per year is not much considering how good it works.

All your other points a valid. The 2 person method works everytime, and no need to flush the ABS, unless you really want to. Go cycle it on a gravel road a few times :)

NoLastName

08-17-2016, 01:06 PM

It comes down to many factors ... even brake pad choice since it will impact how much heat goes into the fluid. Basically, if you have to bleed after each track event, you've got the wrong parts ... fluid likely, pads maybe.

The Motul RBF 600 I found spongy, no matter how it was bled. Just didn't like it. The ATE Type 200 (yellow super blue) is great for daily and occasional track use, and will likely only needs flushing once or twice per year. The Castrol SRF is $70/L, but it is simply the best you can get. It will not give up and does not every get spongy with very aggressive pads and use. $70 per year is not much considering how good it works.

All your other points a valid. The 2 person method works everytime, and no need to flush the ABS, unless you really want to. Go cycle it on a gravel road a few times :)

This sums up my experience 100%. With appropriate brake pads ATE was good for 3-4 HPDEs before I wanted to bleed again. It was pretty easy and consistent. After using Motul RBF 600 for the past year or so my brakes have felt spongy no matter what. They never drop off, but the pedal feel and overall power doesn't seem as good as with ATE. Haven't tried Castrol SRF. Maybe it's time!

adamnur

08-18-2016, 04:13 PM

It comes down to many factors ... even brake pad choice since it will impact how much heat goes into the fluid. Basically, if you have to bleed after each track event, you've got the wrong parts ... fluid likely, pads maybe.

The Motul RBF 600 I found spongy, no matter how it was bled. Just didn't like it. The ATE Type 200 (yellow super blue) is great for daily and occasional track use, and will likely only needs flushing once or twice per year. The Castrol SRF is $70/L, but it is simply the best you can get. It will not give up and does not every get spongy with very aggressive pads and use. $70 per year is not much considering how good it works.

All your other points a valid. The 2 person method works everytime, and no need to flush the ABS, unless you really want to. Go cycle it on a gravel road a few times :)

Good advice--I boiled my ATE 200 after a few sessions here at Mission Raceway, which is very brake-heavy and all slow speed corners. Later in the day I started hard-braking earlier to keep the brakes cooler, but I think I also read too much into the cool carbon pads being good dual duty. They were great at first then felt like they turned to glass after a while.

wintershade

09-14-2016, 12:59 AM

So a few more questions.

After three HDPE track days (at hot hot Thunderhill running fresh ATE Gold), I've noticed the brake pedal must travel significantly further before the breaks bite. I think this is what people mean when they say the brakes feel "spongy." Is is it time to just bleed brakes? Or do I likely need to flush the whole system?

I also have questions about a few steps:
1) I've watched a few DIY videos. It looks like people remove the old fluid from the resovior with some kind of suction system? What system/tool do people recommend to suck it out? I assume it's necessary to get most of the old fluid out 1st. You then pour some fresh fluid in and then start the pressure bleeding process with the Motive?
2) Once you're bleeding the brakes, how can you tell when the old fluid is out and the new fluid is in? Alternating between ATE Blue/Gold doesn't seem possible anymore because I can't find the blue stuff. Is there some way to tell?

AJLM34A

09-14-2016, 07:43 AM

Go to NAPA, see if they still carry the eye drop style water filler for older style non-maintenance free batteries. It has a brown ball and black tube, and about 10" long.

582761

scooper

09-14-2016, 08:52 AM

DocWyte

09-14-2016, 09:44 AM

Depends on fluid, pads, driving style and how brake heavy the track is and how often you go to the track.

I usually get an entire season out of ATE Typ200 in my car. Although for me that's about 5-6 days, so YMMV...

wintershade

09-14-2016, 01:18 PM

get a turkey baster suction ball thing. I fill the reservoir almost to the top and connect it to the motiv bleeder. Then pump the bleeder up to 12 lbs. Open the nipples one by one starting with the one furthest from the reservoir (rear passenger). Let old fluid come out taking care not to replace too much fluid at one time so as to let air into the reservoir. Refill the reservoir to the top. You can do this by yourself. For full clutch bleeding for a dry system, having a helper pump the clutch pedal helps a lot while you are underneath fiddling with the slave.

Thanks Scooper. So just to be super clear on steps (I'm afraid to screw this up)...
1) Suck out old fluid with turkey baster
2) Fill reservoir most of the way up by pouring fluid out of can
3) Fill up Motiv. Attach Motiv. Pump Motiv.
4) Bleed brakes

Also, do I always need to suck out the old fluid and start fresh? Or if I'm bleeding before each track weekend, can I just top off fluid, use Motiv to bleed... just to get air out of lines, etc. I mean -- the fluid is only $20/L, so it's not a big cost to always have fresh fluid, but just wondering...

DocWyte

09-14-2016, 02:07 PM

No need to bleed before every track weekend. If you're going through the fluid that quickly I'd look into a brake ducting kit like what Hard Motorsports sells.

I suck out the old fluid, dump the fresh stuff into the Motiv, attach the Motiv to the master cylinder, pump it up, then start bleeding.

You shouldn't be getting air in the lines after you've done your initial bleed unless you're boiling the fluid. If you're boiling the fluid you need to get the Hard Motorsports kit and also think about how you're braking and if you need to adjust your technique...

wintershade

09-14-2016, 02:17 PM

You shouldn't be getting air in the lines after you've done your initial bleed unless you're boiling the fluid. If you're boiling the fluid you need to get the Hard Motorsports kit and also think about how you're braking and if you need to adjust your technique...

Thanks Doc! Will do your approach.

Is there an approximate amount of fluid to drain from each corner? How does one know when to stop bleeding / all the old fluid is out of the system. I assume the fluids will be same color so hard to tell....

My braking technique consists of mashing hard on the brake as late as my cajones will allow as I approach a corner, heel-toeing, and squeezing back on the gas. I'm probably scrubbing more speed than I need to and putting unnecessary heat in brakes given how slow my lap times are. I realize it's kind of off topic, but I'm open to braking advise here.

DocWyte

09-14-2016, 03:12 PM

Hard to know how much fluid. You'll get way more out of the rear brakes as the lines are so much longer.

The old fluid will be dark, so you'll see a color change as you bleed with the new fluid. Not as dramatic as what we used to be able to do swapping between Super Blue and Typ200 unfortunately.

Generally as you gain more experience you're easier on the brakes as you're using them less and trail braking more.

olemiss540

09-14-2016, 04:00 PM

Thanks Doc! Will do your approach.

Is there an approximate amount of fluid to drain from each corner? How does one know when to stop bleeding / all the old fluid is out of the system. I assume the fluids will be same color so hard to tell....

My braking technique consists of mashing hard on the brake as late as my cajones will allow as I approach a corner, heel-toeing, and squeezing back on the gas. I'm probably scrubbing more speed than I need to and putting unnecessary heat in brakes given how slow my lap times are. I realize it's kind of off topic, but I'm open to braking advise here.

No need to put fluid into the Motiv, just top off the reservoir after flushing each corner and repump the bottle.

I use Motul RBF600 and flush once a year with a quick bleed after every 2 events or so. If you see serious discoloration, you are overheating the fluid and need to bleed more often. On my e36, the fluid looks fresh but I do a quick bleed anyways. On my brothers e46, the fluid can get dark after one weekend if it is hot enough.

You can probably get away with just flushing once a year, but then you have nothing to blame slow lap times on, so might as well bleed them once in a while since it is soo easy to do with a pressure bleeder.

scooper

09-14-2016, 04:02 PM

There's two ways to use the Motiv. I choose not to put fluid into the Motiv bleeder instead just use it as an air pump. This method requires me to fill the reservoir much more often. You need to keep fluid above the level of the opening to the clutch cylinder. I usually open the nipple for around 10 seconds then close it then check on the reservoir. More of a hassle this way but a lot less messy. Since fluid is corrosive I don't want unnecessary wear on the pump as simple as it is.

Also I use the baster to transfer fluid from the can to the reservoir. It can be messy so make sure you surround the reservoir with old towels or else your paint could be damaged. Maybe the other guys who put fluid into the Motive bleeder can add their suggestions. Just keep pumping old fluid out until new fluid can be seen. Follow the 2-person instructions for bleeding the clutch line if all the lines have been replaced. Otherwise, opening and closing all 5 nipples should suffice.

The amount of old fluid to suck out is not too much (between max and min fill lines roughly) so it's not totally necessary but couldn't hurt I guess.

TXBDan

09-16-2016, 02:50 PM

Why do you keep filling the brake reservoir when you can just throw the whole liter in the Motive and let it autofill? When you break the seal when finished at the pump, it auto fills the reservoir perfectly.

I've always used Type200 Gold and never had any issues, but I also bleed after every event. I never love my pedal, though. Maybe i'll heed Scotch's advice and try the fancy stuff. Since I flush/bleed so often I have about 14 liter cans of old fluid in my garage right now. I'd love to only do that once a year...

wintershade

09-16-2016, 06:48 PM

Since I flush/bleed so often I have about 14 liter cans of old fluid in my garage right now. I'd love to only do that once a year...

I read you can dispose of brake fluid by putting it in a box of kitty liter and it will safely evaporate after a few days outside. Just keep it way from open flame.

scooper

09-17-2016, 09:37 AM

Because I feel it's messier...

Why do you keep filling the brake reservoir when you can just throw the whole liter in the Motive and let it autofill? When you break the seal when finished at the pump, it auto fills the reservoir perfectly.

I've always used Type200 Gold and never had any issues, but I also bleed after every event. I never love my pedal, though. Maybe i'll heed Scotch's advice and try the fancy stuff. Since I flush/bleed so often I have about 14 liter cans of old fluid in my garage right now. I'd love to only do that once a year...