Major Vibration Rear left passenger footwell accellerating

[sam029]

Hi all,

Just got me a 480 GT 2.0 as a project car that will probably need a bit of work, it's been off the road for 2 years

One major concern i have is understanding what could be causing this:


Major vibration / noise/ (clanging?) to behind driver's seat ( left side of CAR ) , pretty much in the footwell of rear passenger when accelerating in first and second, it's less in Third and i can't feel it in 4th and 5th. It's as if multiple hammers were hitting the subframe/chassis at the same time.

From the old MOT / control technique i can see a few things which may cause it:


Rear Stabiliser left side

Rust to Subframe ... ( it passed the MOT ./ control back in 2012-2013 with it
rust to wheel arches rear left side

Obvious things i tried so far:

* Checked lug nuts wwere tight on wheel, they are
*Checked for broken bracket / rubber mounts exhaust when shaking it, it doesnt touch the chassis.

Wheel bearing looks a bit rusty / seaping, may just be water.

ANY IDEAS? I'm worried it could be subframe mounts / damage ( could it cause this noise / problem? would really hate to have to replace/ may get shot of car if it's this, i'm going to get some Jack stands today, to get a proper look underneath, any ideas on what to look out for are really appreciated!

Thanks - Sam

[doingitsideways]

My best guess would be the exhaust knocking, it turns around that area.

[Ade]

Hi,
What you describe would seem to be most likely caused by the exhaust. I appreciate that you have waggled it around and had no contact but don't forget that under acceleration the engine (and therefore the exhaust) will move because of the torque reaction. Don't entirely discount the exhaust until you have inspected underneath. The exhaust does run very close to things in certain places. One place in particular that I noticed recently while removing my back axle was where the middle section loops over the panhard rod mounting (essentially a big bracket which bolts up to the underside on the chassis where your toolkit lives. The two bolts visible in the toolkit well are among the ones which secure this bracket) before meeting the back box.

As far another things to check, the rear end is quite simply designed to anything major enough to cause such a noise should be quite apparent. Once you have the car in the air just get a pry bar and work your way round the trailing arms, support arms, drop links etc to check for play in bushes and joints.

Also, just to clarify, what are we talking about when saying subframe? There isn't a rear subframe per se, just an axle mounted on arms. Or are you referring to the front subframe? If so then it's not going to be causing noise from the rear of the car.

If you have subframe/axle rust that needs welding and you can get the parts over to Coventry, I will do the welding for a nominal fee (just cover the consumables and a few beers afterwards). Don't let a bit of rust kill the car, I hate to see 480's go to waste because garages charge such extortionate rates for relatively simple rust repairs.

Hope this helps, if you have any further ideas that you want to run by me/other members then post back with an update. Good luck, hope its nothing too serious!

[sam029]

Hey guys cheers for the replies, it has to be the exhaust as you say, another clue is that the rear footwell is warm when it happens.
I'm a newbie to car mechanics, bought the 480 to self teach, and a Haynes manual is coming in the post. I've done basics on my golf 4 such as brake over hall, changing thermostats, alternator belt etc, and now I want to be able to do oil changes, and witty the right guide timing belt renewal.

That's top of you to offer welding if needed, I'd take you up on that, I used to be in England but now I'm now in Belgium..

Any tips I can do to tighten it all / avoid the Vibration again?
but check/ replace exhaust brackets, and possibly rubber hangers? they seem to be ok...

I'll put it in for an mot probably next week, so stay tuned, glad I've come Across this club!

[Ade]

Hi, I guess the easiest way of making that section of the exhaust sit differently would be to bend the hangers on the back box. The middle section is quite free to move about when there is no back box attached so making the back box sit differently will have a knock on effect further back down the line. Just try and see which direction it needs to go in and modify your back box hangers accordingly. It may be the case that the rubbers aren't quite right. Hard to say. I'm fortunate in that my turbo still has a genuine Volvo exhaust system and rubbers all the way through, an aftermarket one may sit wrong (they often do) and therefore require a bit of fettling to get it right. If you can achieve what you need with different rubbers then that's the first port of call, if not, bend brackets to suit.

Hope this helps.

[CaptainQwerty]

I would have said exhaust but you say you have checked the hangers and rubbers.

What about engine mounts? I had a similar vibration and it was actually because the rear engine mount had collapsed completely and the engine was leaning too far back on acceleration.

good luck.

[sam029]

Hi,

tomorrow i'll be properly looking at it, and removing rear back box / straight up to the middle muffler, I had these given with the car,along with brackets, so whilst there i can check if any hangars need bending / tweaking on the box ~( if i know what i'm doing :S )

I mounted a camera today to the underneath left side, to take it on a test drive to show you, so you can judge if movement is excessive of exhaust / also for the rear axle etc,

in the beginning of the Vid i have a wooden block wedged between shield / exhaust in middle to see if vibration notes were different, this falls off @ 2 mins 50 Seconds in in as you can see !

The camera isn't what it used to be, so wasn't too concerned if it fell off during my ride... ( it didn't )

Ok i just found out I can't post URL's , if interested in the vid / photos please send me your emails ill forward you the link


the engine mounts, that's a point- the owner did include a new one, but said it wasn't needed... I'll have a look tomorrow, i'm looking out for perished rubber im guessing? If collapsed what happens / it breaks/ the bushes are ruined?


Look forward to any comments regarding the Vid, I did notice thevibration was a bit less today when ragging it. ( not a boy racer, i just appreciate a good engine )

Cheers again !

[sam029]

Turns out it was the exhaust at fault, i believe it was knocking on the chassis frame where it bends/ curves around next to the fuel tank, I've now fitted what i had given with the car: the new mid section silencers, + clamps and new pipe all the way back to the rear back box ( I wish i changed this at same time i don't have the new back box yet ) , the new rear rubber hangers were installed, old were becoming saggy. No more vibration/ noise under acceleration in 1st + 2nd !! what a task when i could only use the lowest axle stand height Next time ramps ( if i can reverse on it )

Cheers for the help !

[CaptainQwerty]

Glad to hear you got it sorted.
Well done