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not so good vibrations


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Ok, I am beginning to think I am going mad!

I have a vibration which is coming through the 90 300 tdi at about 50mph, and seems to get worse when the vehicle is warmed up - and when accelerating - decelerating it seems to go away.

I have replaced the a frame ball joint, all the bushes, checked the front hubs - and rear ones. And replaced the ujs on the props (those that were gone). yes still a vibration.

Where else should i be looking?

thanks

Jerry

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chock the wheels

get underneath with the handbrake off and try the prop ujs/transfer box output flange.

jack a wheel at a time and spin them by hand to see if you have a bent rim

check all the bushes panhard/radius arms etc

then see what may need attention.

suspect wheel/tyre damage

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whats vibrating the whole truck? is it just noise or can you feel it? does it shake the steering wheel?

it feels like classical propshaft vibrations - and is worse on acceleration.

and yes i can feel it thru the steering - it feels like its transmission related - the whole truck shudders/vibrates.

I have just gone to check the props again, and they seem ok, but i'm going to whip each one off and drive it to see if anything changes.

When moving the props up and down for movement, i noticed the gearbox mounts seem quite soft - ie when moving the props i can see the mounting rubbers mvoing and teh tx box/gearbox moving slightly - whereas the gearbox on my 200tdi (this one is a 98 300tdi with r380) the same movement is not visible - but they are different mounting setups....could it be this - has anyone got the chance to check if their setup moves slightly if you move the prop on a 300/380 set up?

cheers

jerry

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thanks guys - i will try and get the props off today - if that doesnt isolate it - then i will order a couple of mounting rubbers (would this cause the type of vibration im describing?)

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Bear in mind that the problem may not be the front prop, but possibly front axle. The removing prop test only reduces the possibilities.

Les.

hmmm...the saga continues

So replaced rear prop with a known entity from my 200tdi - and the vibration is still there. I guess that means its either the axle or transfer box? (since there was nothing with no prop connected).

Anybody got any ideas how to eliminate which one it is?

apart from bolting on new ones to see if it goes away! :angry:

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Ok, so i have taken the front prop off and the vibration is still there, I have changed wheels and tyres to known well balanced and again still there. So at the moment the only time i can isolate is when i dont have a rear prop on. Whats the thoughts - transfer box or axle ?

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Remove the rear drive members and see if it goes away. The diff will still turn, but under no load. If the noise is still there with no prop or drive members, then it's outside of the axles - wheel bearings. If the noise goes away, then diff problem or possible transfer box. I would expect the noise to have changed if it was the transfer box in lock with only forward drive on it, so you might have noticed if that was the case.

Les.

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Remove the rear drive members and see if it goes away. The diff will still turn, but under no load. If the noise is still there with no prop or drive members, then it's outside of the axles - wheel bearings. If the noise goes away, then diff problem or possible transfer box. I would expect the noise to have changed if it was the transfer box in lock with only forward drive on it, so you might have noticed if that was the case.

Les.

Les, good idea - but they are the one piece flange and shaft on mine - :angry:

so without a prop or shafts the diff wont be working will it?

\will just taking the bolts out work ? - suspect i am going to have shafts flying out at 50mph though :o

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leave the rear prop on & pull the shafts, then go for a drive in diff lock so the front axle is doing the driving, the rear diff will be able to rotate & may produce the vibs.

ok - will do tomorrow

appreciate all the help guys !

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ok - no shafts in rear axle and both props on - the vibrations have stopped.

Cheers jerry

Are the shafts straight?

What about one shaft at a time? (still with the diff lock in)

Seems to me that it goes away when the rear half of the transmission is unloaded, either by removing the rear prop or rear shafts. So, it could still be the transfer box or the rear diff making noise when loaded.

If it's temperature related, maybe try draining and replacing the t'box and diff oils, one at a time and see if there's any change.?

Given the work you've done so far, there's not much left to change!

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I had a very similar problem very recently - severe shaking from the chassis up at 45-50 mph. Spent a fortune on wheel balancing and replacing stuff - in the end it was the preload not set correctly on one swivel.

so thanks to Les, got the back diff out today, and it apparently looks ok. I am going to check the bearing in the back of transfer box tomorrow - might as well stuff the x-eng handbrake on as well whilst i'm there!

If its not that then i will go off and look at the swivels

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