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Discussion Starter #1
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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Cluster Specialist
1999 Impreza RS - WRB
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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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Discussion Starter #3
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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2000 Impreza 2.5RS BRP
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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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'98 RS Swap & '13 GMC Sierra
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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


Sent from my iPhone using Tapatalk
 

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2002 WRX
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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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2001 SRP 2.5RS/RA/SOHC Monster
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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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Discussion Starter #8
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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99 Coupe
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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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Discussion Starter #11 (Edited)
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.
GD STI driveshaft and the flange I linked from ebay above. Thoughts? Do you know the usdm bolt pattern dimensions.
 

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2002 WRX
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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.
You don't seem to understand that u-joints in a Subaru driveshaft are not designed to be replaceable.

Can it be done? Yes, but why would you?
Is it easy? No
It's far cheaper, easier, faster to simply replace the driveshaft with another used one


curiotmicuri said:
Is that a good plan?
Definitely!
You also need to remember that there will be * some * play in the carrier bearing to allow it to move since you are bringing two halves of the driveshaft together and this joining has to be able to move up and down as well as side to side.


You also said that this thumping only happens when you initially start to pull away from a stop & the once moving everything is OK.


Are you sure the noise is coming from the driveshaft?
This may also be a possibly bad motor mount.
Hard to diagnose anything over the internet.


Best thing is to pull the driveshaft and check how much actual play you have in the center carrier bearing and the u-joints. Everything should move freely and smoothly
 

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Discussion Starter #13
You don't seem to understand that u-joints in a Subaru driveshaft are not designed to be replaceable.

Can it be done? Yes, but why would you?
Is it easy? No
It's far cheaper, easier, faster to simply replace the driveshaft with another used one




Definitely!
You also need to remember that there will be * some * play in the carrier bearing to allow it to move since you are bringing two halves of the driveshaft together and this joining has to be able to move up and down as well as side to side.


You also said that this thumping only happens when you initially start to pull away from a stop & the once moving everything is OK.


Are you sure the noise is coming from the driveshaft?
This may also be a possibly bad motor mount.
Hard to diagnose anything over the internet.


Best thing is to pull the driveshaft and check how much actual play you have in the center carrier bearing and the u-joints. Everything should move freely and smoothly
When i grab the ds (automatic gc driveshaft) and pull it side to side close to the carrier, it feels like a rubber bushing flexing quite a bit.
 

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2001 SRP 2.5RS/RA/SOHC Monster
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You don't seem to understand that u-joints in a Subaru driveshaft are not designed to be replaceable.

Can it be done? Yes, but why would you?
Is it easy? No
It's far cheaper, easier, faster to simply replace the driveshaft with another used one

So $25 and an hour of work is cheaper and easier than trying to source a quality used 15 year old shaft? Cheapest I can find a shaft with questionable joints on Car-Part.com is $75. They aren't getting any easier to find either.

Yes it's a staked joint. I guess it comes down to whether or not you have the mechanical aptitude to follow a guide on the internet for replacing a staked joint or not.

Do what works best for you, more power to you. However, replacing the joints IS an option and for me, it's the best one.
 

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When i grab the ds (automatic gc driveshaft) and pull it side to side close to the carrier, it feels like a rubber bushing flexing quite a bit.

You would have to define what you mean by " quite a bit " because everyone's interpretations are different but it's sounding more and more that, at a minimum, the carrier bearing is gone.
 
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