Clutch Slipping on stock A91 MT...

[Stvee]

One key thing to note, is that the BMW #21526785964 people are talking about is not the BMW number stamped on the MKV slave cylinder. The actual BMW part number on this is #21526795713, so that's what I'd recommend ordering instead.

That's correct it's not going to be the same part number. BMW 21526785964 is from the E90 generation cars and is the same thing, it just doesn't have a CDV in it like the version that comes on our car.

Either one will work, you just have to remove the CDV on the supra one. Good to know what the bmw part # is for the supra version though.

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[UYCR]

Well look what I got this morning...



..and here's the little bastard we all want to be rid of



One key thing to note, is that the BMW #21526785964 people are talking about is not the BMW number stamped on the MKV slave cylinder. The actual BMW part number on this is #21526795713, so that's what I'd recommend ordering instead.

How much did it end up costing you if you don't mind me asking?

 

[FuzzyRev]

How much did it end up costing you if you don't mind me asking?

A little over $90. I still have the Z-shaped metal line on order for it as well. That's going to cost me around $30 when it finally gets here, which is looking like July as of now.

 

[FuzzyRev]

That's correct it's not going to be the same part number. BMW 21526785964 is from the E90 generation cars and is the same thing, it just doesn't have a CDV in it like the version that comes on our car.

Either one will work, you just have to remove the CDV on the supra one. Good to know what the bmw part # is for the supra version though.

Yeah, I knew there was some kind of interchangeability to those two part numbers, and many of those applications will "require" a new hydraulic line to go with the 85964, which possibly contains the CDV relocated to there.

The main thing was not to argue about which one is right or wrong, just wanting to share the BMW part number so people finally know which one Toyota is installing in these cars.

 

[UYCR]

A little over $90. I still have the Z-shaped metal line on order for it as well. That's going to cost me around $30 when it finally gets here, which is looking like July as of now.

That's actually not bad. I thought the dealer would mark it up quite a bit more.

 

[Spart]

Someone on one of the facebook groups posted that they tested it out and the E90 slave cylinder works fine on the Supra. That slave cylinder doesn't have the CDV from the factory. This is just another option if you don't want to modify the stock slave cylinder by removing the valve.

BMW part# 21526785964 -- costs around $80

I installed one of these today and it's a night and day difference, particularly on heel-toe downshifts where you have to be quick with the clutch to catch the engine revs at the right spot. Before I felt like I had forgotten how to heel-toe. Now it's very natural.

I think someone somewhere said this would be a five minute job.... yeah no. Not unless you have like two helpers and you've done it zillion times.

My notes on the install:

• Both bolts are a little tricky to get to and mine had a bit of blue loctite on them from the factory. Universal joints or wobble/swivel sockets help.
• A video I watched said to pull out the tip of the new slave before installing - don't do this. It just makes installation more difficult. It's "locked" in the closed position and there's a spring that pushes it out to full extension, but as soon as you put pressure to it, it's going to pop out on it's own. It's also just going to put more air in the system that you'll have to then bleed out.
• It took quite a lot of bleeding to get all of the air out. Be careful about that because you'll think (especially if not using a power bleeder) that you've got it bled, but you'd be wrong. I probably flushed the equivalent of four BMW bottles of brake fluid through it before I was really confident that I had gotten it all. I didn't have four bottles, but I was using a clean drain bottle so I put the fluid I drained out back in the power bleeder. (Definitely DON'T do this normally, but this car was built a few months ago and has under 1000 miles on it, all of the fluid I bled looked exactly like the new BMW fluid and I used a clean container to drain into. Just buy way more brake fluid than you think you'll need, the BMW spec stuff is cheap.)
• Now that I think about it, you might avoid some unnecessary bleeding if you have your new slave ready and disconnect the line from the old one and immediately plug it into the new slave. If you remove the bottom bolt on the slave first, the bracket holding the line comes with it and you'll be able to let it dangle out of the way while you work on the top bolt, which is easier to get to with the line out of the way. Otherwise, gravity drains a lot of fluid out of the line and the master.
• I used a Motive Power Bleeder, part number 0109. 15 psi as recommended worked just fine for this.I bought mine from Summit a long time ago, but you can get it from FCP Euro at the same time as the slave here: https://www.fcpeuro.com/products/european-power-bleeder-black-label-motive-products-mot0109 Note that there's some assembly required with these and you'll want some teflon tape handy to seal the threads on the connectors.
• If you use a power bleeder, you'll overfill your fluid reservoir. Have a syringe handy to suck brake fluid out of the reservoir until it's down to the "Max" level. I used one I had lying around that the vet gave me for shooting antibiotics down my cat's throat. Looks like this and works great: https://www.amazon.com/dp/B07P25XH8Z/
• I also used a Longacre brake fluid bleed bottle, part 52-45202. This thing has a magnet on it (which saves you time futzing around with zip ties or baling wire) and I hung it from the angled surface where the firewall is transitioning into the floorboard. Worked great in that position. https://www.summitracing.com/parts/LNG-45202
• I used BMW low viscosity DOT4, part number 81220142156. I assume the low viscosity helps in the winter with clutch feel/speed. Again, buy like four bottles just in case, particularly if you don't expect to be able to reuse your flushed fluid like I did. From FCP Euro: https://www.fcpeuro.com/products/bmw-brake-fluid-81220142156
• I bought my clutch slave from FCP Euro as well: https://www.fcpeuro.com/products/bmw-clutch-slave-cylinder-21526785964

 

[Spart]

There's literally no proof that this is causing people to "burn up their clutch". I'm sure it helps fine with better pedal feel and power shifting, but it's ridiculous to claim this is a solution to a problem that isn't even fully understood yet.

Proof? No. But I can definitely tell you that getting rid of the CDV has pretty much eliminated instances where I find the clutch slipping when I'm not expecting it because the CDV basically moved the bite point.

Maybe it's a contributing factor, maybe it's not. I do feel better about my chances with this clutch now.

 

[Eddy90]

Proof? No. But I can definitely tell you that getting rid of the CDV has pretty much eliminated instances where I find the clutch slipping when I'm not expecting it because the CDV basically moved the bite point.

Maybe it's a contributing factor, maybe it's not. I do feel better about my chances with this clutch now.

Does changing the out the slave, change the behavior of the auto-downshift rev match (manual noobs like me need love too)
What i mean is, does the auto-downshift rev match still work like before, or does the system now get confused since it's expecting a different behavior from the clutch.

i hate the slippage / delay in fast upshifts from the CDV, but I do lean on the auto-downshift rev match quite a bit.

 

[Spart]

Does changing the out the slave, change the behavior of the auto-downshift rev match (manual noobs like me need love too)
What i mean is, does the auto-downshift rev match still work like before, or does the system now get confused since it's expecting a different behavior from the clutch.

i hate the slippage / delay in fast upshifts from the CDV, but I do lean on the auto-downshift rev match quite a bit.

No, no effect. The system doesn't know but three positions of the clutch pedal: all the way out, somewhere in between, and to the floor. The whole point of that system is that you can be absolutely sloppy with your clutch work and it doesn't matter because engine speed = road speed, so no slip.

But I have that junk turned off in favor of 100% organic, cruelty-free, non-GMO heel-toe downshifts, just like pappy used to make. If I wanted a computer to help me shift I'd buy a DCT.

 

[UYCR]

I installed one of these today and it's a night and day difference, particularly on heel-toe downshifts where you have to be quick with the clutch to catch the engine revs at the right spot. Before I felt like I had forgotten how to heel-toe. Now it's very natural.

I think someone somewhere said this would be a five minute job.... yeah no. Not unless you have like two helpers and you've done it zillion times.

Glad you mentioned the heel-toe. I was thinking the same when doing down shifts at higher rpms where the revs just drop too fast compared to the how slow the clutch can engage. For me it's like I either over rev to compensate or I didn't and the car jerks cuz of the mismatch in speeds.

 

[UYCR]

Does changing the out the slave, change the behavior of the auto-downshift rev match (manual noobs like me need love too)
What i mean is, does the auto-downshift rev match still work like before, or does the system now get confused since it's expecting a different behavior from the clutch.

i hate the slippage / delay in fast upshifts from the CDV, but I do lean on the auto-downshift rev match quite a bit.

Turn it off every once in a while to get some practice. I feel the supra is much better to rev match than my previous brz just cuz of how much better the pedal placement is and how quick the engine responds. having the computer do it for you is still nice when you're fooling around but really don't wanna mess anything up.

 

[Spart]

Glad you mentioned the heel-toe. I was thinking the same when doing down shifts at higher rpms where the revs just drop too fast compared to the how slow the clutch can engage. For me it's like I either over rev to compensate or I didn't and the car jerks cuz of the mismatch in speeds.

Exact same experience, CDV delete fixed it. Has really helped my enjoyment of the car.

 

[Quinn]

No problem! I specifically went to Speed Logic because of the extensive BMW knowledge and experience and now with A90 Supra experience.

I definitely felt a difference and would recommend the CDV delete being done at Speed Logic.

What did they charge?

 

[visbits]

Does changing the out the slave, change the behavior of the auto-downshift rev match (manual noobs like me need love too)
What i mean is, does the auto-downshift rev match still work like before, or does the system now get confused since it's expecting a different behavior from the clutch.

i hate the slippage / delay in fast upshifts from the CDV, but I do lean on the auto-downshift rev match quite a bit.

No, the rev match will be improved with this because instead of you letting the clutch out, activating the ECU switch that you've done so and it resuming throttle, it will now act like it should.

I imagine the CDV was added to help novice drivers... i think just running open downpipe would help most people learn how to drive.. quiet/low-nvh cars are incredibly difficult to shift without a lot of experience.

 

[Spart]

I imagine the CDV was added to help novice drivers...

The f***ing Good Idea Fairy strikes again.

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