knocking noise at full lock???

eden

eden

bush bash'n ranga
Joined
Jul 10, 2008
Messages
1,259
Location
Bondi, Sydney-Australia
after a longish drive a get a weird knocking noise at full lock. the longer i drive the worse it gets and the louder it sounds. at first i thought it had to be the CV's so i replaced them but it's still there. the noise is definatly coming from the gearbox (EJ25). has anyone experienced this or might have some idea, any info would be good. thanx in advance
 
Eden, is it a sound that you experience when changing gears up and down / taking off from first and second?

And you say the sound comes from the gearbox when the wheels are at full lock?

Have you checked the forward body lift spacers?
 
ok, spoke to a few subie tech guys today, and they both said straight away without hesitation that the viscous something or other has gone gone and when it gets hot (after a longish drive) the something is binding causing it to do what it's doing. they said this normally happens when you put 2 different size tyres on which i never have, but who knows what the previous owners did? so got a quote (the cheapest) to replace the whole gear box with a fully recon one for just under 2k with 12 months warrenty. what choice do i have but to go for it. i want to get her offroad and dirtier than ever.:woohoo: will ask them in detail how it happens and will post it up.
 
A question for you Eden if I may.

Do you have, what feels like slack in the drive train? By this I mean, say, when you are coasting along in traffic in 2nd and put your foot down to get going, there is a lurch as everything kicks in, and similarly when you then back off the accelerator.
 
eden said:
ok, spoke to a few subie tech guys today, and they both said straight away without hesitation that the viscous something or other has gone gone and when it gets hot (after a longish drive) the something is binding causing it to do what it's doing. they said this normally happens when you put 2 different size tyres on which i never have, but who knows what the previous owners did? so got a quote (the cheapest) to replace the whole gear box with a fully recon one for just under 2k with 12 months warrenty. what choice do i have but to go for it. i want to get her offroad and dirtier than ever.:woohoo: will ask them in detail how it happens and will post it up.
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Normally, binding of the centre differential viscous coupling should only occur when there is considerable difference in speed between the front and rear propellor shafts, which causes the fluid to heat up and expand and push the coupling's plates together (and hopefully helps you out of your sand or mud bog or whatever). I can hear this happen on my car in really loose or boggy surfaces. There is a delay of maybe a second while the fluid heats up and then a continuous whining/buzzing noise if wheel slip continues. The difference in speed between the front and rear propellor shafts that occurs when turning at full lock (on a high-traction surface) shouldn't be sufficient to induce binding. That is, unless the fluid has already been 'pre-heated' by some condition such as differences in tyre size or pressure. Maybe if your viscous coupling has been damaged somehow it is more inclined to bind than normal - you may have inadvertently ended-up with a great offroad car on your hands Eden:). People pay good money for the STi 20kg.m centre diffs!

I just stumbled on this article https://autospeed.com/cms/A_108266/article.html which has some interesting info about options for swapping out Subaru centre diffs, (although they incorrectly use the unit kg/m instead of kg.m for torque -don't mind me, just an Engineer into semantics :)).

Anyway let us know how it goes, whatever you decide to do.
 
spinners said:
A question for you Eden if I may.

Do you have, what feels like slack in the drive train? By this I mean, say, when you are coasting along in traffic in 2nd and put your foot down to get going, there is a lurch as everything kicks in, and similarly when you then back off the accelerator.
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Carlo - I thought this slack or backlash was a 'factory feature' in Subarus :) (at least manual ones). A recent Wheels magazine road test noted this even on the 2009 Forester!
 
You are probably right Simon. I guess I am just a little over it.

I do notice however, that, especially when the car is cold, when taking off and going through the gears (up to 3rd) I get a creaking sound which is driving me nuts.

I have to drop into Tom Kerr service centre and get Steve to have a look.
 
spinners said:
A question for you Eden if I may.

Do you have, what feels like slack in the drive train? By this I mean, say, when you are coasting along in traffic in 2nd and put your foot down to get going, there is a lurch as everything kicks in, and similarly when you then back off the accelerator.
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YES! but it has always done this and i think it's unrelated. if i need to take off quickly i just use the clutch again and it solves that problem
 
simxs said:
You and me both!

It is one of the few things about the car that sometimes irritates me enough to consider a non-Subaru as a next purchase (since it seems they haven't fixed this on the later models).
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Or get an auto :p

Mind you, my wife has an MY06 X auto and, after 2 years she is averaging 8.7km/L :( I seem to be running at 9.9km/L (after 3 years of data) :D
 
Over Christmas (actually while I was on my way to Adelaide) I started getting this binding while making sharp turns so my centre viscous coupling is misbehaving as well. It's fine when cold, but after driving a few km their is considerable resistance and clunking while turning. Apparently the centre diff can be replaced separately from the gearbox and this can be done without removing the gearbox from the car (see https://www.subaruforester.org/vbulletin/f89/center-diffs-how-replace-them-46979/). The problem will be either finding a used centre diff that doesn't have the same problem or forking out for a new one :-(
 
Maybe try alldrivesubaroo even if it's just the parts as they recondition all that stuff.
 
I have a spare centre diff that requires at the very least re-greasing of the bearing (#28 in the drawing) or replacement. There is some rust on the outside from where it had been sitting but none on the inside that I could see. You can clean it up and try it and if it works we can chat then say $50?
 
Kevin said:
Maybe try alldrivesubaroo even if it's just the parts as they recondition all that stuff.
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Thanks for the tip Kevin. I remember now that you recommended them previously after some work done on yours.

Rally said:
I have a spare centre diff that requires at the very least re-greasing of the bearing (#28 in the drawing) or replacement. There is some rust on the outside from where it had been sitting but none on the inside that I could see. You can clean it up and try it and if it works we can chat then say $50?
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Hi Tony - is this one just removed from your Impreza? Sounds good. However is it Phase 1 or Phase 2 style? If the article is correct I need Phase 2.

eden said:
Simxs, how many k's has she done?
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Hi Eden - it started at about 168000. I've now done about another 4000 due to a return trip to Adelaide. Fortunately this 4000 was a lot less problematic for it than 4000 of urban driving would have been - not many corners on the Hay plain!
 
No, the centre diff from the WRX is still in the gearbox. I know bugger all about the diff's internal condition. I believe it is the later model diff. (Phase 2)
 
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