Road rumble in rear nearside only

[MikeDB]

My Impreza rear nearside fell down a council pothole and ever since replacing the shock absorber with a new one, and rebuilding it twice to make sure I haven't done something wrong, there.has been a not loud but annoying rumble from the rear nearside.   It's at the wheel revolution speed and using brakes, going into neutral and so on do not affect it at all.  It sometimes seems louder over bad road surfaces though that may be my imagination.

 

I put the car up on four stands today and checked the wheel bearings which all seem ok with no 'grit' points or anything.  Diff play is about 1/8 of a turn on both rear wheels - no idea if that's the norm or not.

 

Then ran the engine up with all wheels in the air and the noise I am after does not occur.   Thus it seems it may be actual noise from the road coming through the suspension somehow.

 

Any suggestions as to where to look for the fault ?

[Gambit]

I would say bearing problem myself maybe a dry one but if you have done that and checked the Hub. Would look at the pistons in the break calipers, and tyre pressure. Other then that I'm not sure you have checked everything else :)  

[Jay762]

that or check the top mount - but that would be more of a clunk than a grind...

[Miggs]

i was thinking top mount too, it sounds more like a moving part than a pressure part, if it's a dry part it might be worth spraying some lube on individual bits that you suspect, spray one part then test drive then another then test drive, once it's gone quiet it's the last thing you sprayed, maybe it's the type of shocker used, if you have had gas filled ones and gone to an oil filled one it might make a different noise when running, this is based on not knowing the exact noise or severity of said noise, i could be way off mark

[MikeDB]

Eventually traced the problem to a hole in the inner wing opposite the strut which must have been damaged when the strut broke.  Does anyone know how structural the inner wing underneath the outer wing is ?  i.e. do I need to replace it with a complete new inner wing or can I patch it with some weld.  This is not the main part around the strut with the strengthening joints what take most of the shock absorber load - obviously if damaged they would need exact replacement.  As far as I can see the inner wing under the outer wing is not a key load bearing part but I may be wrong.

 

Thanks

[Gambit]

I'm not sure mate any chance you can take a picture ? 

I would say a weld should be fine as it's not a major part :)

[Adam]

Not an area I know much about, but I would say it needs to be addressed as the damaged area will start to rust.

[Gambit]

Same with me I was hoping a picture might show more if it's possible to get one of the area. 

[MikeDB]

Changed my profile pic to it for speed.  This is upside down and taken looking backwards.  The spring is on the left and on the right you can see the hole in the inner wing and the fortunately undamaged outer wing panel right behind it.

[Gambit]

I'd say from looking at that as long as all the rust can be taken out and you can get a bit of plate welded on there almost like a body panel maybe some filler for extra sound proofing it is doable. Is a strange place to see rust on an Impreza. But think that is repairable and make sure bit of underseal is put around there after repair I think should see it for the rest of the car's life. 

[MikeDB]

I think it was either damaged by the actual strut collapse or at some earlier time.  It's more a rip than just a standard rust hole.  I was thinking of welding a small plate over it then pushing some filler behind it if I can get in there.  And then some underseal to hide the whole lot from the MOT guy :-)

 

I've also just noticed someone sells fibreglass inner wings - are these in any way recommended ?  It would seem to imply the inner wing has no structural value which I find unlikely on a modern car.

[Gambit]

I would go with the 1st option myself ;)  MOT guy 

It look's far enough away from anything and behind it you can see it look's rust free. I'm not sure with the inner wing's but as long as you did the above and then replaced it with a fiberglass wing would do the same job. But I would see it as a waste of money if you can do it yourself :) 

[Jay762]

patch it - if it is a decent piece of metal and an intact weld job it doesnt need to be hidden from the MOT person. As said before it needs sorting to stop the rust

[Daley2450]

At looking at the pictures and reading the posts, I will agree with the last Post, as long as the welds are good then that will be fine, it looks ripped, so I would guess that it was the shock breaking and moving that did it, I think that inner wings are structural, so don't change them for fibre glass.