vibration in body at 50-90 km/h - better when warm? not wheels/brakes/engine

another strange problem.

since the first drive in my zed ive noticed that it has a strong high speed vibration felt through the whole body of the car - you feel it mostly in your upper back.

it happens above 50 ish km/h and goes away mostly at around 100 km/h - its still there a little but its not as bad.

Funny thing as after a good 15 mins of driving its not even 30% as bad as when its stone cold.

It happens when the car is coasting and accelerating and it dosnt change - I can throw it in neurtal with no change to the vibration so I dont think its engine related

Happens no differently when braking so I dont think its rotors

had the wheels balanced today and got told they are fine so I dont think its wheels

There is a bit of wheel bearing noise coming from somewhere...

Im not sure if its tailshaft, tailshaft center bearing, drive shaft or wheel bearings causing this strong vibration but I want it gone... In my experience with R31's the tail shaft center bearing will be worse under heavy acceleration, my issue is not noticeably worse under any condition except "warm"

thoughts?

 

How good are your tyres any flat spots that you know of?

 

Probably the u-joints in the prop shaft. Sorta balance themselves after a while.

I've had that problem on 2 cars. Changing the center bearing made no difference. One piece solved it

 

Are you thinking the uni's warm up and get less notchy ?

I have experienced changes in the centre bearing as maybe the rubber support gets warmed from the exhaust from a removed heat deflector which is commonly missing.

Maybe the rubber gets soft and when the car parks, it sags and cools gets harder off centre, so when you start cold it is worse, and as it softens with exhaust heat in becomes better.

 

I drive my Zed on average every 6 months for a 100 km round trip so it sits in the shed a fair bit :rofl:. What I find is the first 5 - 10 ks of driving I get a bad vibration. It took me a while to figure out that it was the tyres forming a different shape while sitting. Maybe it is certain brands but I personally think it is normal for a tyre that sits so long to do this. No big deal and goes back to normal after a few ks. If I was to drive the car a few times a week it does not happen. Perhaps that's the noise you are getting ?.
Cheers
Dave

 

Probably not wide enough and a pain to park on. http://www.supercheapauto.com.au/on...yre-Protector.aspx?pid=343759#Recommendations

 

Not that I know of. the previous owner did a good job of keeping them smooth :br:

One of the tyres does have some bad wear on the outer edge

Where do 'in the know' zed owners living in Tasmania go to get one-piece shafts? custom fabbed job by hardy spicer?

That is interesting... as this car has sat for a few years on these tyres... Ive put around 300 kms on it since its sat and no change.

Will keep you posted.

--

Wanted to advise that it dosn't really go away once its warm, yes its less severe but it is still there... Noticbly so at 110 however its nothing comapred to how it is at 50-90 km/h.

 

I got these when I got the carcoons for my cars, only drive them 3 times a year at most and the rear tyres on mine are 335 wide, so I doubt you'll have a problem with width. Have had a deformed tyre in the last year of using them.

https://www.carcoon.com.au/products/bump-n-stop/

 

If they've properly deformed and flat spotted, they won't change, the tyre is shagged. (unless you light em up)

From what you've said it's more likely than not driveshaft related. Uni's or CB, I'm sure even backwater tasmania has a shop that can fabricate you one, or get one made in Melbourne and shipped down.

 

Have or haven't had a deformed tyre ?

 

I had that issue with my first zed.

Put in a new centre bearing - fixed low speed clunking but still had a vibration.
Put in a new 1 piece drive shaft - slightly improved vibration, but still bad when cold
Put in new engine mounts - no change
Put in new subframe and diff mounts - small improvement

Bought another zed - fixed

 

oh...

 

Weird thing was the next owner didn't have any vibration issues. Can't remember if I gave him the gearbox and driveshaft with it. Definitely had no engine...

 

Hmm I'd check the rims as well might not be round do the easy stuff first
And get a balance they will soon tell you if anything wrong and only about 50 bucks and if not we'll you got a balance just the same
:br:

 

The wheel balance and rotation has been done. First thing I did.

Ill probably be looking for a one-piece tail shaft... Should give me at least 14hp at the rear view mirror.

Pending shipping costs from ConceptZ that is... the shaft itself is quite reasonably priced and probably not far off the cost of getting my current one refreshed and balanced. (at a guess at least)

 

Haven't had.

 

Lol thought so, thanks !

 

Flat spots on tyres

A tyre bloke on another forum posted that tyre flat spots can be removed by lowering the tyre pressure & then driving @ lower speeds (70-80kms?) for a short distance.

Obviously the lower the tyre profile, the less you can safely lower tyre pressure & would require a longer drive.

It heats the tyres up & removes flat spots; but maybe not suitable for everyone.

 

Could it be the output shaft in the gearbox having too much end play? Hence wobbling around?
If changing to one piece tailshaft (with new universal joints) and the body vibration does not change much after that, other than tyre out of round, could this be the issue? g/box or auto Tranny output shaft?