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Driveshaft issue in 2.5rs running a sti 6 speed
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Old 07-12-2019, 11:46 AM   #1
curiotmicuri
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Default Driveshaft issue in 2.5rs running a sti 6 speed

I have an issue with the driveshaft that we fitted to my gc. It has a 6 speed sti trans with a r180 that has the older style bolt pattern which required a ds from an automatic that has the smaller square pattern. When getting the car moving there is a thumping/vibration from the driveshaft and I was told it needs to be shortened. Anyone have experience with this?
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Old 07-16-2019, 12:44 AM   #2
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Quote:
Originally Posted by curiotmicuri View Post
I have an issue with the driveshaft that we fitted to my gc. It has a 6 speed sti trans with a r180 that has the older style bolt pattern which required a ds from an automatic that has the smaller square pattern. When getting the car moving there is a thumping/vibration from the driveshaft and I was told it needs to be shortened. Anyone have experience with this?

This is sorta incomplete.


Is the installed r180 diff the actual matched diff for the 6-speed? AFAIK, none of the 6-speed STi rear diffs had the smaller bolt pattern, at least none from the Version 8 (2004) onwards. And the only time that anyone ever used an automatic driveshaft is for an r160 rear diff.
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Old 07-17-2019, 12:22 PM   #3
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Quote:
Originally Posted by Wannabe WRX View Post
This is sorta incomplete.


Is the installed r180 diff the actual matched diff for the 6-speed? AFAIK, none of the 6-speed STi rear diffs had the smaller bolt pattern, at least none from the Version 8 (2004) onwards. And the only time that anyone ever used an automatic driveshaft is for an r160 rear diff.
There are older ones with the r160 pattern which is what I have.
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Old 07-23-2019, 04:02 PM   #4
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USDM STi R180's never came with the smaller bolt pattern, but the earlier JDM V7 R180 did.

To answer your question, I've never heard of a GD drive shaft having to be shortened. Perhaps it's out of balance or on its way out?
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Old 07-23-2019, 07:00 PM   #5
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Are you sure the driveshaft is from an automatic Impreza? I have essentially the exact combo in my car and there was no need to shorten the shaft


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Old 07-24-2019, 04:29 AM   #6
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I tried replying to this earlier but for some reason it never got through.


Whoever told you that the driveshaft needs to shortened has no idea what they are talking about UNLESS you don't have the driveshaft you think you do. One doesn't typically shorten a driveshaft. It's a lot of work and then the driveshaft will have to be re-balanced. If it's not done right, it's a major headache.


Very typical to use an automatic driveshaft in place of a 6MT driveshaft when you can't locate a 6MT driveshaft.


Let's presume for the moment you have the correct driveshaft. The thumping you are referring to could be from a couple of different reasons:
1. The driveshaft is not bolted in properly
2. The U-joints are bad.
3. The carrier bearing in the middle of the driveshaft is bad.


If either # 2 or #3 are true, then you need to replace the driveshaft. The U-joints and carrier bearing are not made to be replaceable.
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Old 07-24-2019, 07:45 AM   #7
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It's not hard to replace the u-joints. They can be had for fairly cheap. Way better than buying a new shaft.
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Old 07-24-2019, 01:53 PM   #8
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I think the carrier bearing is bad or the bushing around it something like that. I can feel play when I pull it side to side from underneath. It only thumps when getting moving once it starts rotating its fine. I have the option of getting a sti ds from a friend and buying the wider r180 flange that will fit on it. Is that a good plan?
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Old 07-24-2019, 02:00 PM   #9
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Old 07-24-2019, 03:15 PM   #10
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Yes older version 7 JDM R180s had a smaller pattern on the diff flange, all US R180s had the bigger flange. And if your getting noise/vibration theres a high chance you have dead bearings in the u-joints in the driveshaft which are not replaceable you'll need another shaft. Also, flanges are interchangable between R180/160 so you can swap them depending on the driveshaft you find.
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