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Bad Vibrations
Shilvers - 8/6/08 at 07:25 PM

Evening all.

I've managed to develop a noticable vibration at 50mph. It's not present until 50 & disappears if you go quicker. It's speed related as well as it's still there when you dip the clutch and just roll at that speed. Nothings seems loose and the car behaves exactly as before except for the vibration. My first thoughts are obviously the wheel balance (it's coming from the rear as far as I can tell because the vibration doesn't affect the steering.) So, apart from getting the rear wheels re-balanced, is there anything else I should be looking for that could cause the problem? Anyone had anything similar?

Thanks folks

big_wasa - 8/6/08 at 07:32 PM

wheel nuts

Shilvers - 8/6/08 at 07:39 PM

quote:
Originally posted by big_wasa
wheel nuts


Checked and they were okay, but will check again

britishtrident - 8/6/08 at 07:43 PM

The speed range affected tends to indicate a wheel balance issue.

(1) Check the propshaft flange bolts are tight and that any balance weights haven't been thrown off the shaft.
(2) Check all tyres and riims for running out of true
(3) Get front wheels balanced ---- just because you don't feel it through the steering dosen't mean it isn't from the front wheels.


If that dosen't work get all four wheels rebalanced by another tyre shop.

omega 24 v6 - 8/6/08 at 07:43 PM

prop thrown a balance weight??

Triton - 8/6/08 at 07:56 PM

Driveshafts maybe? And agree check the fronts as could be misleading

joetait - 8/6/08 at 08:28 PM

Is the wheel located on the hub centrally?
Some people fit wheels which dont have the correct spigot ring and just rely on the nuts to try and centralise the wheel to the hub which doesnt work well.

Shilvers - 8/6/08 at 08:35 PM

Cheers guys

The rears are off and I'll check them tomorrow. One of the weights isn't looking in very good nick so I'll hope for the simple fix, will check the fronts as well just to be sure.

Watch this space.....

britishtrident - 9/6/08 at 07:00 AM

quote:
Originally posted by joetait
Is the wheel located on the hub centrally?
Some people fit wheels which dont have the correct spigot ring and just rely on the nuts to try and centralise the wheel to the hub which doesnt work well.



Wheels have been centralised using the nuts for about 90 odd years.

britishtrident - 9/6/08 at 07:19 AM

quote:
Originally posted by Shilvers
Cheers guys

The rears are off and I'll check them tomorrow. One of the weights isn't looking in very good nick so I'll hope for the simple fix, will check the fronts as well just to be sure.

Watch this space.....


Too explain a bit about wheel balance, wheels have to be kept in two types of balance static and dynamic.

How badly a car is affected by wheel balance depends a lot on factors like king pin inclination, wheel offset and scrub radius, caster and stiffness of the wishbone mountings.

If a wheel is in Dynamic balance but not static balance in many cases if the car has a smal scrub radius and king pin inclnation it might not be felt through the steering but will be felt transmitted through the suspension to the structure


Taking 1970s Fords as an example Capris were very sensitive to static wheel balance which could be felt through the steering wheel because of the large scrub radius and the use of the anti-roll bar to form part of the lower wishbone.

The 1970s Cortinas had much less scrub radius and king pin inclination than the Capri as result were less sensitive to static wheel balance problems being transmitted through the steering.


A very common cause of difficult to balance wheels can be a chunk rubber debris left rolling around inside the tyre after a puncture repair.



[Edited on 9/6/08 by britishtrident]

Hellfire - 9/6/08 at 10:49 AM

quote:
Originally posted by britishtrident

Taking 1970s Fords as an example Capris were very sensitive to static wheel balance which could be felt through the steering wheel because of the large scrub radius and the use of the anti-roll bar to form part of the lower wishbone.

A very common cause of difficult to balance wheels can be a chunk rubber debris left rolling around inside the tyre after a puncture repair.



[Edited on 9/6/08 by britishtrident]


As the owner of three 1.6, 2.0S and 2.8i - I used to get them balanced on the car. Not sure it exists anymore...

Still makes me want another 2.8i as I loved that car...

Steve

britishtrident - 9/6/08 at 12:50 PM

quote:
Originally posted by Hellfire
quote:
Originally posted by britishtrident

Taking 1970s Fords as an example Capris were very sensitive to static wheel balance which could be felt through the steering wheel because of the large scrub radius and the use of the anti-roll bar to form part of the lower wishbone.

A very common cause of difficult to balance wheels can be a chunk rubber debris left rolling around inside the tyre after a puncture repair.



[Edited on 9/6/08 by britishtrident]


As the owner of three 1.6, 2.0S and 2.8i - I used to get them balanced on the car. Not sure it exists anymore...

Still makes me want another 2.8i as I loved that car...

Steve


Used to do a lot of them we had an old fashioned hand spun wheel balancer that gave excellent results but even with that Capri front end vibrations could be hard to cure.

Quite often changing the anti-roll bar bushes would alleviate it --- the vibration could sometimes be triggered by even a tiny ammount of run out in the brake discs, Girling brought out a special abrasive brake pad to take the high spots off the disc that usually cured the difficult cases.

[Edited on 9/6/08 by britishtrident]

Shilvers - 10/6/08 at 06:29 AM

Well, got the rears balanced, went for a drive and ended up having to wait for the AA for an hour and a half!

I heard what sounded like some metal deciding to escape from under the car and slowed right down, by this time the vibration was unbearable! Anyways, it sheared 3 of the bolts connecting the prop to the engine and when I got back was only connected by one, which I cut out as I was all bent out of shape. So there you have it, lesson learnt.

From what I can see everything seems to be turning true so I'll hopefully be able to just bolt it all up again, I'm just hoping I don't miss too much of the sun!