[CantComplain]

Originally Posted by mrdstr

a bubble in the clutch line won't lead to a delay on engagement. It will prevent full disengagement as you are using clutch pedal travel to compress the air bubble and not move the clutch towards disengagement and that can result in accelerated wear and glazing of the disk and flywheel, especially under the conditions you describe, which will in turn result in slippage. If you suspect that is the case, you should be able to test it by getting into a tall gear 4th or 5th), low speed out of boost, and standing on it. You should know if its slipping as it goes into boost.

I did the CDV removal as well. Used the motive. It does require you pump the pedal, and you will see air moving from the reservoir thru the bleeder hose. It takes a lot of pedal pumping and for a bit I was losing confidence. But eventually the pedal started to gain pressure and the bleed was successful.

Hey thanks for the reply mrdstr . I missed it when you posted. And I haven't exactly put a lot of miles on the car in the last couple months.

So you're saying stay in 4th, low RPM, then floor it and when boost kicks in (and assuming air in line) the additional boosted torque when turbo kicks in will cause a slip? So in other words, I'm not shifting anything during this?

I'm also experiencing what I thought could be differential slip when turning tightly at slow speed and my foot in the pedal a bit. Could that be a manifestation of the same problem, or something different? Basically it just feels a little "crunchy." Man I'd be stoked if both of these issues were a result of something simple....

[mr_lab_rat]

I'm planning to replace my brake fluid for the first time soon (probably will take out the CDV at the same time).
I was thinking about making an adapter that would screw on top of the reservoir and hold significant amount of new fluid. Wouldn't that help avoiding accidentally letting the fluid level drop too low?

[CantComplain]

Originally Posted by mr_lab_rat

I'm planning to replace my brake fluid for the first time soon (probably will take out the CDV at the same time).
I was thinking about making an adapter that would screw on top of the reservoir and hold significant amount of new fluid. Wouldn't that help avoiding accidentally letting the fluid level drop too low?

Yeah I think that’s basically what a Motive bleeder would do for you. It would also allow you to force the fluid through via pressure. For $50 it may be worth it to use something that’s already pretty well proven.

[Nezil]

Originally Posted by mr_lab_rat

I'm planning to replace my brake fluid for the first time soon (probably will take out the CDV at the same time).
I was thinking about making an adapter that would screw on top of the reservoir and hold significant amount of new fluid. Wouldn't that help avoiding accidentally letting the fluid level drop too low?

Originally Posted by CantComplain

Yeah I think that’s basically what a Motive bleeder would do for you. It would also allow you to force the fluid through via pressure. For $50 it may be worth it to use something that’s already pretty well proven.

+1 on this. It is certainly possible to do it without pressure, but the Motive is proven and known to work well by pressurising and filling at the same time.

The issue with filling is that you have to be really really careful. A single pump of the pedal may be enough to drain the clutch side, resulting in bubbles in the line.

I'm not in favour of reverse bleeding, despite those that have had success. There is a reason you need a lot of pressure to bleed backwards... there are 1 way valves in the clutch line that you're pushing against. Knowing this is helpful because it also means that you don't need two people to bleed even if you don't use a pressure system

[mr_lab_rat]

I didn't realize it was relatively inexpensive, I thought it was some complicated machine with electrical compressor that would cost hundreds. I'm gonna be putting some high temp fluid for track and that needs to be replaced more often so I will definitely benefit from it.

[fleetfoot]

I recently had the E90 slave cylinder installed on my M2. Engagement feels MUCH better, just like my old E92 clutch after CDV delete. However when I first hopped in the M2 after the install, I noticed the clutch pedal had a couple inches of very soft travel before I felt normal pedal resistance. I asked the shop to re-bleed the clutch, which they did and most of the softness went away. But there’s still about an inch of travel at the top that is totally soft. Do you think this is due to air bubbles still in the line? Or is an inch or two of soft travel normal for the M2? For comparison, my E92 that I bled myself has consistent pressure throughout the pedal travel.

[2020M2Competition]

Originally Posted by fleetfoot

I recently had the E90 slave cylinder installed on my M2. Engagement feels MUCH better, just like my old E92 clutch after CDV delete. However when I first hopped in the M2 after the install, I noticed the clutch pedal had a couple inches of very soft travel before I felt normal pedal resistance. I asked the shop to re-bleed the clutch, which they did and most of the softness went away. But there’s still about an inch of travel at the top that is totally soft. Do you think this is due to air bubbles still in the line? Or is an inch or two of soft travel normal for the M2? For comparison, my E92 that I bled myself has consistent pressure throughout the pedal travel.

As noted in this and in other threads the clutch can be difficult to bleed properly given the reservoir it shares with the brakes

I had a similar experience as you when I had the E90 clutch slave cylinder installed

https://f87.bimmerpost.com/forums/sh...3&postcount=41

I had the shop completely rebleed both the clutch and brakes which pretty much took care of the issue

Nevertheless, I still found the clutch pedal to be just a little bit softer than it was with the stock slave cylinder

As a result, I ended up installing an Ultimate Clutch Pedal

HTH

YMMV

[fleetfoot]

Originally Posted by 2020M2Competition

I had the shop completely rebleed both the clutch and brakes which pretty much took care of the issue

Thanks, that thread was very informative. I saw some folks mentioning they still had a bit of "dead" travel at the top. Do you still have that 1" of nothingness after your re-bleed?

[2020M2Competition]

Originally Posted by fleetfoot

Thanks, that thread was very informative. I saw some folks mentioning they still had a bit of "dead" travel at the top. Do you still have that 1" of nothingness after your re-bleed?

The re-bleed got rid of it

However, as I mentioned earlier, the clutch pedal was still just a bit too soft for me with the E90 slave cylinder so I got an Ultimate Clutch Pedal to firm it up

[CantComplain]

I originally reverse bled after removing the CDV. I posted in this thread about some odd behaviors. I went out and bought a $50 Motive bleeder and I think I corrected the issues I had from the reverse bleed. I'm not saying reverse bleeding doesn't work, but in my case I don't think I was able to do it effectively.

When I used the motive (process: remove clutch stop, dumped what I had left of a quart bottle of DOT4, pressurized it to ~15PSI and simply let it pass through a couple pints of fluid by opening the bleeder on the slave, waiting until bubbles dissipated, and closing it again), it sputtered a little air through at first, and then flat out farted out a lot more air before settling down again and eventually just passing new fluid through. So not sure what I did with the syringe when reverse bleeding (I used the same one linked earlier in the thread) but it either introduced or left air in the system after CDV removal.

Clutch was limp after the process I listed above until I gave it 20-30 presses, now it feels good again. I didn't touch the pedal while the Motive was connected, so not sure if that's a problem or not per another post--I was relying on pressure from the Motive to move the fluid.

Honestly it's been months since I did the reverse bleed, and I haven't put a ton of miles on it during COVID, so it's hard for me to compare now to before all of the work, but I feel like the clutch feels lighter. Engagement is better. I don't appear to have the super scary delay at WOT but need to drive it some more.

[F87source]

Originally Posted by CantComplain

I originally reverse bled after removing the CDV. I posted in this thread about some odd behaviors. I went out and bought a $50 Motive bleeder and I think I corrected the issues I had from the reverse bleed. I'm not saying reverse bleeding doesn't work, but in my case I don't think I was able to do it effectively.

When I used the motive (process: remove clutch stop, dumped what I had left of a quart bottle of DOT4, pressurized it to ~15PSI and simply let it pass through a couple pints of fluid by opening the bleeder on the slave, waiting until bubbles dissipated, and closing it again), it sputtered a little air through at first, and then flat out farted out a lot more air before settling down again and eventually just passing new fluid through. So not sure what I did with the syringe when reverse bleeding (I used the same one linked earlier in the thread) but it either introduced or left air in the system after CDV removal.

Clutch was limp after the process I listed above until I gave it 20-30 presses, now it feels good again. I didn't touch the pedal while the Motive was connected, so not sure if that's a problem or not per another post--I was relying on pressure from the Motive to move the fluid.

Honestly it's been months since I did the reverse bleed, and I haven't put a ton of miles on it during COVID, so it's hard for me to compare now to before all of the work, but I feel like the clutch feels lighter. Engagement is better. I don't appear to have the super scary delay at WOT but need to drive it some more.

Thanks for you input.

But a couple of pints? Holy crap that's alot of fluid, imagine flushing with castrol SRF that would be like throwing liquid gold down the toilet. I think if I were to do it I would flush it with oem dot 4 since it is dirt cheap and then once all of the bubbles are gone I will switch the whole loop to SRF, or maybe motul rbf.

[CantComplain]

Originally Posted by F87source

Thanks for you input.

But a couple of pints? Holy crap that's alot of fluid, imagine flushing with castrol SRF that would be like throwing liquid gold down the toilet.

The original bottle was a quart and it was maybe half full, so I guess less than "a couple pints." I didn't want to save any of it, and didn't really want to use an open container in the first place. But it was maybe $10 for the bottle to begin with, so maybe more like liquid lead. Works better than air though it turns out

edit: I think Nezil said above to run 3 oz. through. At roughly that amount I was still pushing serious bubbles in the line. But as we now know, I'm not good at estimating. But for other rooks, I'd go until you see new fluid and no air.

[echoshotz]

Those of you using the motive bleeder, are you pumping the clutch through the process while the motive is pressurized and the bleed screw is cracked? Or just pressurizing, cracking the screw, and letting the fluid and air go. I've got a motive on hand from previous cars and thankfully got a BMW reservoir attachment for it so I'm considering giving this a go

[F87source]

Originally Posted by echoshotz

Those of you using the motive bleeder, are you pumping the clutch through the process while the motive is pressurized and the bleed screw is cracked? Or just pressurizing, cracking the screw, and letting the fluid and air go. I've got a motive on hand from previous cars and thankfully got a BMW reservoir attachment for it so I'm considering giving this a go

I recommend pulling the slave end out of the transmission and hand pumping it like the video I linked, because bmw suggests doing that as well in ISTA. If you are deleting the clutch delay valve and need to remove the air bubbles. If you are just bleeding fluids for the purpose of flushing the clutch fluid then I don't currently have an answer for you, probably don't push the clutch if using a power bleeder.

[CantComplain]

Originally Posted by echoshotz

Those of you using the motive bleeder, are you pumping the clutch through the process while the motive is pressurized and the bleed screw is cracked? Or just pressurizing, cracking the screw, and letting the fluid and air go. I've got a motive on hand from previous cars and thankfully got a BMW reservoir attachment for it so I'm considering giving this a go

Just cracking the valve and letting it go. Did you do something to introduce air or are you just doing it for the helluvit? If you pulled out the CDV or did something else to introduce air, I’d say go for it. If you don’t think there’s anything wrong I don’t think you’d be helping anything and could only create new problems.

[echoshotz]

Sorry, didn't make it clear I wanted to pull the CDV out

[F87source]

Originally Posted by echoshotz

Sorry, didn't make it clear I wanted to pull the CDV out

Yeah bleed it by squeezing the slave cylinder in your hand while opening and closing the bleed nipple and tiling the cylinder around to get the air bubbles to rise out. This is the best way to do it, ista says to do it this way as well do bleeding a brand new slave cylinder. Squeeze it until it is firm, the best way to get a feel for this is to remove the slave cylinder from the transmission and feel how firm it is before removing it.

[vrooooom]

Oh great. I just got to reading all these. Same experience…. Kinda light at top. I didn’t remove the BMS stop but I didn’t thought about it. so now what? Nezil’s advice of filling the reservoir full, opening the bleed screw then pumping the clutch pedal 1-2 times isn’t going to work?

[F87source]

Originally Posted by vrooooom

Oh great. I just got to reading all these. Same experience…. Kinda light at top. I didn’t remove the BMS stop but I didn’t thought about it. so now what? Nezil’s advice of filling the reservoir full, opening the bleed screw then pumping the clutch pedal 1-2 times isn’t going to work?

It should still work but it'll take longer because with each pedal stroke you're effectively pumping less fluid.

[vrooooom]

Originally Posted by F87source

Yeah bleed it by squeezing the slave cylinder in your hand while opening and closing the bleed nipple and tiling the cylinder around to get the air bubbles to rise out. This is the best way to do it, ista says to do it this way as well do bleeding a brand new slave cylinder. Squeeze it until it is firm, the best way to get a feel for this is to remove the slave cylinder from the transmission and feel how firm it is before removing it.

F87. Would you mind explaining this method further? I don’t get squeezing the slave cylinder with my hand. Is that pumping the clutch pedal?

Also tiling. Is that supposed to be tilting?

Sorry man I’m really confused by the instructions. So the procedure requires we remove the slave out and doing all these bleeding BEFORE finally mounting it?

I also tried looking for the link you said you posted to demonstrate the process. Didn’t see any link you posted here. Is it on another group perhaps. Is that the link below?

[vrooooom]

Originally Posted by Nezil

Put a flashlight under the reservoir so that you can see the level of the clutch section.

Fill up to the very top, making sure that the clutch part does really fill.

Open the bleed nipple on the slave cylinder and leave it open, but with a tube and bottle connected so that you can see that something is flowing out.

Keeping an eye on the level in the clutch section by looking through the windshield as you pump.

Pump the clutch once, check the level in the clutch side, see if you need to top up and do so if necessary.

Pump the clutch again, continuing to check the level.

Once you’ve pumped about 3oz through and out of the slave, and provided the level didn’t drop too much, you’ll be done. Tighten the bleed screw and test.

I believe there are one way valves in the system so you don’t need to tighten the bleed screw between pumps. Just leave it open until you’re done.

Nezil. Question on your process…. So if I have a 2 guys helping out, one to just keep topping up the reservoir. And another to just monitor the slave and what’s coming out…. I can just remain in the car doing the hand pumping of the pedal (slowly bring the pedal back up). Just hand pump until around 100ml has gone out. Again no opening and closing of the bleed valve. Yes?

I thought the power bleeders keep the reservoir always full? Isn’t that what it’s designed to do? So if I put 355ml into that then I don’t need anyone watching the reservoir anymore with a flashlight. I can safely assume it’s always full.

Am I understanding you well?

[vrooooom]

Was going to drive the car out this morning and the clutch had no resistance. All air. Crap.

Going to buy a couple more bottles and

1) Remove the clutch slave out of the transmission

2) Fill reservoir. Attach the pressure bleeder and pressurize it.

3) Remove the BMS stop. Not sure if this matters but will just do it anyways. Not sure this will come off without a fight.

4) Do as the video shows. Depress plunger and hold…. Open bleed screw & close. Repeat a few times.

Sounds about right?