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Old 02-14-2014, 02:15 PM   #1
knuckles27
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Default need new clutch? slipping?

I have an 09 WRX wagon (71K miles) with mods:
COBB DP
SPT CBE
AEM CAI
Kartboy Short Shifter (not sure you need to know this one)
EFI Tuned, 272 AWHP, 311 AWTQ

When I am WOT throttle my RPMs will drop by 500ish and then start climbing again. I have 2 logs..... 3rd gear pulls that I will upload which show this. This RPM drop also happens when I am in boost, at or near WOT. This has been going on for at least 6 months.
EDIT = actually looks like I was not at WOT throttle on the 2 logs below but a long gradual 3rd gr. pull. Sorry for the confusion. I tend not to floor it. The rest of this statement is accurate as far as during acceleration and boost 15+ the RPMs tend to drop for split a second and then catch and start to climb.

I also have an issue of getting a grind when I am up shifting from 2nd to 3rd. It happens about 50% of the time if not more but If I "quick shift" then it almost never happens. It has never happened in another gear nor downshifting from 4th to 3rd. Syncro issue????

Do I need a new clutch? If so my tuner suggested going OEM replacement with resurfacing the flywheel. I wonder if I might be better of with Exedy Stage 1 vs OEM??????

This is my daily driver. I really dont beat on it but like to do a couple pulls a day.
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Last edited by knuckles27; 02-17-2014 at 02:20 PM. Reason: WOT comment not accurate
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Old 02-14-2014, 02:31 PM   #2
knuckles27
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Default data log

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Old 02-14-2014, 02:32 PM   #3
knuckles27
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Old 02-17-2014, 07:39 AM   #4
knuckles27
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bbump
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Old 02-17-2014, 10:57 AM   #5
BLkdubRX
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Quote:
Originally Posted by knuckles27 View Post

When I am WOT throttle my RPMs will drop by 500ish and then start climbing again.


If your tuner says go with the stock clutch, then go with the stock clutch. unless you plan on making more wtq
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Old 02-17-2014, 11:19 AM   #6
Back Road Runner
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RPMs don't drop with a slipping clutch. They rise.

Exedy Stage 1 is a viable option once you're running 21psi or so. There's enough torque where the grip is relatively light. You will mostly notice this when launching or during gear shifts and heavy throttle. There will be a little more slip than you want, and the clutch will feel as if it barely holds the output. At the actual limit, you will find that the clutch will slip and grab under full throttle. This is to say that going down the highway you can floor it, and you will get a jump in rpm, feel the clutch slip a little, and then regrab. Worse, it will simply just slip continuously until you get off the gas and lower the torque output.

What you describe seems to be more an issue of tune or mechanical error if there's a problem with the car just cutting power. Also, those logs are...uh...sort of junky. What are you using to take them and what were you trying to measure? All you really need is rpm and manifold pressure or target boost + boost error. Virtual dyno like throttle position %, but you can add that line yourself after the fact and just toss in 100 down the column. Less things measured means you get more data at higher precision. You typically select the fewest possible things to measure if you have no need for the other information relative to what you're doing. The problem I see with your data logs is they show nothing related to any type of steady acceleration pull, just a short bit of random driving.

If we're talking clutch slip here, you'd be doing a full throttle pull. You'd put it in 4th or 5th and floor it. You'd hold it and let the turbo boost up and the car accelerate. Then you'd wait, wait to see if something happens. You'd have a log of 100% throttle position from say 2000rpm to redline or however fast you want to go. A slip of the clutch will look like an rpm rise and then drop. If you plotted torque and hp on a virtual dyno, it would look like a torque spike. This typically happens at peak torque output at peak boost and engine efficiency, typically between 3000-4000 rpm where the car is making the most torque.
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Old 02-17-2014, 01:46 PM   #7
knuckles27
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Black Road Runner- Thanks for looking into this. Maybe i uploaded the the wrong log. I will go out at lunch and to a 3rd gear pull at WOT from around 2000RPM to 6300. I am doing a 3rd gear pull cause I have a WRX (5sp).
........
ok, just went out and did a 3rd gear pull at WOT. obviously my previous posted logs were not WOT. Did this twice and instead of it slipping the RPMs shot straight up and felt as though the the car was not in gear had to shift to 4th quickly. Hit 17.6 PSI. Tuned for around low 18s. Below are RPMs and Throttle

RPM (RPM) Throttle Pos. (%)
2247 18.43
2301 21.57
2394 100
2445 100
2640 100
3365 100
4459 78.82
6092 100
6739 10.59
6036 10.59
4851 39.22
4903 41.57
5794 39.61
4744 14.12
2170 9.41
2414 8.24
2252 7.45
1826 12.16
3267 28.63
3061 30.59
3174 30.98
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Old 02-17-2014, 02:16 PM   #8
knuckles27
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BLkdubRX- I hear ya. Stock is fine with me. Def need to research more. Just looking for other perspectives. I do not plan to add more TQ then the 311 I have. I just want to daily drive this thing and have some fun for another 50k miles or so. Thanks.
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Old 02-17-2014, 02:22 PM   #9
JonnyV2889
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Knuckles, that post is useless without any other info, it doesn't even have a time stamp.
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Old 02-17-2014, 02:35 PM   #10
knuckles27
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Johnny- here links to the .csv files. Thanks.
lunch data log 1: https://drive.google.com/file/d/0B4x...it?usp=sharing

lunch data log 2: https://drive.google.com/file/d/0B4x...it?usp=sharing

EDIT: Both logs are 3rd gear WOT pulls. By the time shifting into 4th I was off the gas and doing around 60MPH

Last edited by knuckles27; 02-17-2014 at 02:49 PM.
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Old 02-17-2014, 03:13 PM   #11
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Strange, you normally have 30-40 data points per second. It's normally pretty easy to get a couple hundred data points during a single pull. You get whopping 10 data points, although I don't know why. Are you using Romraider? If so. uncheck a lot of the parameters. There's only so much throughput of data, so more parameters means less data points. The speed of your laptop can also influence this. You really should have 20 times more data points in your log file.

From what I can see, you peak at 17psi which should not be a problem for the stock clutch. With so few data points, it's impossible to tell what the car's doing. The precision simply isn't there. You should have a point of data about every 50 milliseconds. You get only around 3 data points a second which is quite course. With only a few parameters selected, you should be getting 30-40 points per second.

Now if your clutch is slipping, you should not be doing more pulls. You should drive the car lightly, buy a new clutch, and get it installed. You don't want to wear it out too much to the point where you can barely get the car to move or hold speed down the highway.
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Old 02-17-2014, 03:29 PM   #12
knuckles27
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BackRoad- thanks. I am using my Cobb Access Port V2 and the default settings. The 2 data logs were just a 3rd gear pull. I will look into adjusting the parameters for future logging. Maybe the Cobb defaults has it wonly taking data points 3/sec? I will not do any more pulls as you recommended. I trust my tuner, EFI Logics in Bethel CT. I'm waiting for my tax return in the mail and will make an appointment then to get the new clutch. Did you have any advise on why I get a grind when shifting into 3rd. more info in my first post. Thanks.
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Old 02-17-2014, 06:13 PM   #13
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Quote:
Originally Posted by knuckles27 View Post
BackRoad- thanks. I am using my Cobb Access Port V2 and the default settings. The 2 data logs were just a 3rd gear pull. I will look into adjusting the parameters for future logging. Maybe the Cobb defaults has it wonly taking data points 3/sec? I will not do any more pulls as you recommended. I trust my tuner, EFI Logics in Bethel CT. I'm waiting for my tax return in the mail and will make an appointment then to get the new clutch. Did you have any advise on why I get a grind when shifting into 3rd. more info in my first post. Thanks.
If Dom @ Maxwell power saw the torque your engine is putting out, he would most definitely say a new OEM wrx clutch from the dealership with a resurfaced stock flywheel, no exedy here.

The grind could be coming from worn out fluid. Has the gear oil in the tranny even been changed? If not, then go with either subaru Extra-S or redline 75w90 NS gear oil, no full synthetic stuff.

I also had an issue with a grind going into 3rd on my na 5 spd trans but I know it was gear oil issues. I have now done enough research to know some of the gear oils that actually work and a few combo's that are good too.
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Old 02-17-2014, 06:26 PM   #14
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Syncro function is sensitive to the gear oil used. I personally really liked Amsoil Severe Gear. Synco function works really well with it. If the grinding is specific to one gear, it may very well be a worn synco. It should be similar in all gears if it's the oil.

I'm not familiar with how the Cobb stuff works.
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Old 02-18-2014, 07:38 AM   #15
knuckles27
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I had the 60k service don in March 2013. I believe the fluid was changed then. Sounds more and more like the OEM clutch is the way to go. I am pretty sure that is what I will go with. I will ask EFI about the sncro being worn vs a gear oil issue.
Thanks to all for there posts. I will update this thread in a few weeks when the car goes into the shop.
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