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Old 06-17-2018, 01:33 PM   #1
bji
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Default Why does my 5MT Impreza shift more smoothly/easily when the vehicle is loaded?

I'm curious what the reason for this phenomenon would be:

I have a 2016 Impreza Sport Premium 5 MT Hatchback. Since I bought the car new in April 2016, I have always had a hard time with smooth shifting from 1st to 2nd gear. Inevitably there is a little bit of 'chatter', almost like a grab-release-grab feel by the clutch, when shifting from first to second.

I can attenuate this a little bit by slipping the clutch slightly during this shift. I don't like to do it because of clutch wear concerns but if I do not, I end up having to wait too long for the shift so that the engine revs can fall enough to avoid the worst of this chatter, which is also annoying.

I have noticed that when the car is heavily loaded, it is easier to avoid this chatter. I have taken a few road trips with the car loaded with people and gear and in this situation, it feels like it is just easier to get smooth shifts from 1st to second. Less chatter. I can release the clutch more quickly without having to slip it at all and the whole shift just feels better.

By the way, 2nd to 3rd shifts are almost always quite smooth, and 3rd to 4th and 4th to 5th are always butter smooth.

What is the mechanism of operation that would be causing this 1st to 2nd shift chatter that is reduced by having the vehicle loaded?

My biggest concern is, do I have some kind of flaw in my clutch or its installation that could be causing this, or does every 5MT suffer from the same issue?

I would love to try another 5MT Impreza out to see if it feels the same or if there is some unique problem with mine, but not only do I not know anyone who has another Impreza, let alone a manual transmission one, I have never even *seen* another one despite the numerous times I've looked through the window of another Impreza in a parking lot to check out of curiousity if it's manual. And certainly my dealer has never had a manual on the lot, I had to order mine from Japan and wait 6 weeks for it.
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Old 06-17-2018, 07:00 PM   #2
AcquaCow
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2001 B50 RSTi
2011 DGM WRX hatch

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Weight is the most effective damper.
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Old 06-18-2018, 12:52 PM   #3
bji
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Default

Quote:
Originally Posted by AcquaCow View Post
Weight is the most effective damper.
So you're saying my clutch/drivetrain needs a better damper?

How do I go about making that happen without loading my car with 500+ lbs?

Do all Imprezas need better dampers? Or just mine?

Design flaw? Or something particular to my car?
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Old 06-18-2018, 12:59 PM   #4
AcquaCow
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Quote:
Originally Posted by bji View Post
So you're saying my clutch/drivetrain needs a better damper?

How do I go about making that happen without loading my car with 500+ lbs?

Do all Imprezas need better dampers? Or just mine?

Design flaw? Or something particular to my car?
Your driving style is the cheapest to adjust... After that, there are heavier flywheels...
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Old 06-18-2018, 04:23 PM   #5
amiexploited
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garage queen 15 WRX 6mt

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I'm a little confused by your "chatter" description. But I would try a heavy shift knob, motul gear oil, and a 5 speed Group N transmission mount. How many miles do you have?
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Old 06-18-2018, 11:33 PM   #6
bji
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Quote:
Originally Posted by amiexploited View Post
I'm a little confused by your "chatter" description. But I would try a heavy shift knob, motul gear oil, and a 5 speed Group N transmission mount. How many miles do you have?
The car has 30,000 miles. It's hard to describe the 'chatter'. It's like the clutch grab is not clean. It doesn't just grab, it kind of grabs-ungrabs-grabs, resulting in a little judder. Or at least that's what it feels like.

Maybe I'll ask a mechanic to take it for a ride and tell me if there is really something there or if it's just my shifting style (or lack thereof) ...
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Old 06-19-2018, 12:14 AM   #7
drewdogg
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I think it could be a combination of things. As AcquaCow said the weight of the car loads the drivetrain more which could be causing the clutch to slip a bit more on its own and your driving style is the same as the car unloaded.

Another thought I have, which I've seen a lot in drivers of non-sporty vehicles, is you are prob shifting a good bit below 3k. Try accelerate in first gear faster and staying in first gear a little higher in the rpm's than usual.
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Old 06-19-2018, 11:47 AM   #8
amiexploited
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garage queen 15 WRX 6mt

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Quote:
Originally Posted by bji View Post
The car has 30,000 miles. It's hard to describe the 'chatter'. It's like the clutch grab is not clean. It doesn't just grab, it kind of grabs-ungrabs-grabs, resulting in a little judder. Or at least that's what it feels like.

Maybe I'll ask a mechanic to take it for a ride and tell me if there is really something there or if it's just my shifting style (or lack thereof) ...
If it feels clutch related maybe you should get that checked out. On my old bugeye I got "chatter" from a dead stop to first as I was letting go of the clutch. It turned out I had a input shaft seal leak and it contaminated the clutch. Had the shop replace all the seals and bearings, new clutch and flywheel and it was as good a new (easier said than done).

If you feel it is shifting related, I would change your gear oil. 30k is around that time.
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