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01-11-2019, 04:13 PM | #1 |
Scooby Newbie
Member#: 496336
Join Date: Jan 2019
Location: Massachusetts
Vehicle:2019 WRX-STI WR Blue Pearl |
Clutch Delay Valve (CDV) - 2019 WRX-STI
Hey guys,
I bought a brand new 2019 STI over the holidays!! So far I love the car except the clutch. Its horrible!! Its jerky, it lets out at different engagement points, it very difficult to be smooth with. I have owned, driven and tracked many manual cars for 40 years, so I am experienced. Do these cars have a CDV valve in either the master or slave cylinder? I have seen posts about early STI's ('05 ish). If it does, does anybody have a detailed mod fix (replace the slave with part# or replace the master with part #). Or do you remove said components and remove the culprit and tie off the fittings? My old BMW 330i (ZHP) had a CDV with the exact same symptoms. Once removed the clutch was perfect. I suspect the same with my awesome new STI. HELP please!!! Many thanks. Henry '19 WRX-STI (lip)
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01-11-2019, 09:23 PM | #2 |
Scooby Newbie
Member#: 495452
Join Date: Dec 2018
Location: Harrisburg PA.
Vehicle:2019 STi Crystal White Pearl |
I too recently purchased a 2019 STi. Turning off the the hill assist made a huge difference for me. I think the clutch seats after a few hundred miles and became smoother.
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01-14-2019, 10:43 AM | #3 |
Scooby Newbie
Member#: 496336
Join Date: Jan 2019
Location: Massachusetts
Vehicle:2019 WRX-STI WR Blue Pearl |
@LeeOnline - Thanks for the tip.
Still trying to get a definitive answer if the car has a CDV valve. HELP!!!!! Thanks, Henry '19 STI |
01-14-2019, 11:18 AM | #4 | |
Scooby Newbie
Member#: 242905
Join Date: Apr 2010
Vehicle:2019 STI WRB |
Quote:
That said, I only have ~750 miles on it, so maybe it gets better? My BRZ had the same problem, and it drove me bonkers until the day I sold the car Hopefully someone on here with more knowledge can shed some light on how to remedy this! |
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01-14-2019, 11:22 AM | #5 |
Scooby Specialist
Member#: 220971
Join Date: Aug 2009
Chapter/Region:
South East
Location: NC
Vehicle:2004 Impreza |
There is no delay valve on STi, there is on WRX.
The hill holder operation uses the ABS module to keep the vehicle from rolling back on hill, till the clutch is partially engaged. Disabling the feature will give more consistent engagement point due to foot timing , however obviously then the feature doesn't work. |
01-14-2019, 11:24 AM | #6 |
Scooby Specialist
Member#: 468117
Join Date: May 2017
Chapter/Region:
SCIC
Location: Southern Cali
Vehicle:2017 WRX DMG |
also the way the engine is tune, most aftermarket tunes takes away that CDV feeling
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01-14-2019, 11:27 AM | #7 |
Scooby Newbie
Member#: 242905
Join Date: Apr 2010
Vehicle:2019 STI WRB |
That makes sense re: hill holder. So it's normal to have the clutch engage at different points on the pedal in these cars?
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01-14-2019, 11:29 AM | #8 |
Scooby Specialist
Member#: 220971
Join Date: Aug 2009
Chapter/Region:
South East
Location: NC
Vehicle:2004 Impreza |
Yes, because depending on incline and the power of brake applied, the VDC has to see Clutch switch #2 off, Brake switch off, increase of throttle, before releasing the brakes.
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01-14-2019, 11:30 AM | #9 |
Scooby Specialist
Member#: 220971
Join Date: Aug 2009
Chapter/Region:
South East
Location: NC
Vehicle:2004 Impreza |
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01-14-2019, 12:55 PM | #10 |
Scooby Newbie
Member#: 242905
Join Date: Apr 2010
Vehicle:2019 STI WRB |
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01-14-2019, 02:18 PM | #11 | |
Scooby Specialist
Member#: 459799
Join Date: Dec 2016
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Quote:
There definitely is restrictions on the factory line that are causing a lot of these issues. If you follow the hardline you will find these brass unions that are inline restrictions that act as a damper. I know the wrx also has a damper in the slave cylinder that can be modified. As for the STI, in the past, there were also restrictors inside the slave cylinder that needed to be removed to improve engagement and operation. I have done a Perrin braided clutch line (bypasses/removes hardline and connects directly to slave cylinder) for a 2015+ wrx (would also work for 2015+ STI) and it made a world of difference. After driving the car for a time after the line install it seemingly allowed the clutch to wear into a smoother operating clutch with a much more positive engagement. I highly recommend a Perrin or any other like designed SS braided clutch line and any other related modification to improve the clutch operation overall. |
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01-14-2019, 02:32 PM | #12 |
Scooby Newbie
Member#: 496336
Join Date: Jan 2019
Location: Massachusetts
Vehicle:2019 WRX-STI WR Blue Pearl |
@bp05obxt - Thanks for your reply and photo.
Can you direct me a little. Where did you take this picture? Underneith at the gearbox? Or up top? Thanks. Henry '19 WRX-STI (lip) |
01-14-2019, 07:44 PM | #13 |
Scooby Newbie
Member#: 430450
Join Date: Sep 2015
Location: Indianapolis
Vehicle:2019 STI Lapis Blue |
Group N trans mount with polyurethane corresponding bushing around said mount, engine mounts, pitch stop, rear diff bushings and a one peace carbon fiber drive shaft will 95% cure all issues in the sti drive line play. I'd look into super pro bushing kits. I to have a 19 sti by the way.
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01-15-2019, 07:25 AM | #14 |
Scooby Specialist
Member#: 459799
Join Date: Dec 2016
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You can see the brass unions if you follow the hydraulic hardline from the clutch master cylinder down along the firewall.
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01-15-2019, 10:19 AM | #15 |
Scooby Specialist
Member#: 491095
Join Date: Sep 2018
Chapter/Region:
SWIC
Location: New Mexico
Vehicle:2009 STi Blue Blue |
+1 on the one piece driveshaft helping...also did diff and pitch stop mounts myself...i did the Prothane kit for my car...would love to disable hill start assist...i actually learned how to drive on hills with manual trans way back when lol
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01-15-2019, 12:12 PM | #16 | |
Scooby Newbie
Member#: 430450
Join Date: Sep 2015
Location: Indianapolis
Vehicle:2019 STI Lapis Blue |
Quote:
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07-28-2021, 09:03 PM | #17 | |
Scooby Newbie
Member#: 233053
Join Date: Dec 2009
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Quote:
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