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Zopilote

Bedford MJ Front Diff

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Hi All

 

My 84 Bedford MJ is making noise while 4 wheel drive is engaged, and the truck is moving, off of pavement. It could be described as a 'whirring'... Its not too loud and is consistent through speed changes etc. Also, the hub is weeping oil on one side, on the outside.

 

I haven't yet worked on one of these trucks and I'm going to start to tackle this, so I'm looking for any guidance people here may have.

 

My first move is going to be pulling the diff cover and having a look... Right?

 

Thank you

 

Colin

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Hi All

 

My 84 Bedford MJ is making noise while 4 wheel drive is engaged, and the truck is moving, off of pavement. It could be described as a 'whirring'... Its not too loud and is consistent through speed changes etc. Also, the hub is weeping oil on one side, on the outside.

 

I haven't yet worked on one of these trucks and I'm going to start to tackle this, so I'm looking for any guidance people here may have.

 

My first move is going to be pulling the diff cover and having a look... Right?

 

Thank you

 

Colin

 

Hi Colin,

The weep on the outside of the hub could be from a round plate in the centre retained by a hex head screw. This retains the outer drive shaft in position and there is a sealing ring behind the round plate. Other than that it could be the gasket on the drive flange, also used as a step ring for climbing in cab.

 

As for noise, be aware that there are three oil levels on the front axle, diff and left and right swivel housings. Check these first.

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First check if there's excessive lash in the diff by the free play (rotation) in the prop. Also check whether there's any detectable play in the pinion shaft bearing by trying to move the prop / pinion shaft radially - the bearing is preloaded so there shouldn't be any radial play.

 

Might be worth just jacking it up and spinning the wheels by hand to check for wheel bearing problems, but really you'd expect that in two or four wheel drive.

 

Also, if you're not sure where the noise is coming from check the transfer box for bearing problems, again by pushing and pulling on the props to see if there's any play.

 

Check all oil levels as Richard says.

 

Popping the cover off to check the diff is a five minute job. It's a cork gasket which might tear if it's been on there a while, so having another gasket ready might be an idea. Look at the crown wheel for excessive wear and correct meshing marks.

 

Don't be afraid of it, they're a simple axle to repair if there is a problem.

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Wow.

This forum is a game-changer for me!

Thanks you guys.

I'll get back on here when I have looked things over better.

 

One question: 80-90w goes in the diffs and gearboxes?

Edited by Zopilote

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Originally 90 EP but 80W-90 EP will be fine. My preference is for GL-4 if available, it'll be OK with GL-5 though. Must be an EP oil as it's a hypoid diff.

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I think I would first check the wheel bearings for play on the side where the oil leak is.

 

And - while you have the wheel off the ground - how about (with fwd disengaged) getting someone to spin the wheel round while you listen for the source of the noise?

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I would start with tyre pressures and Tyre diamiter miss match, easiest first Good luck

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