question anybody here replaced a Bedford MK pinion bearing ??

[Rob2497]

hi guys hope you dont mind me taxing the experts but i have a bad pinion bearing on an MK front axle and i wondered if i can slip the pinion out with the bearings, flange complete ? or whether the pinion has to come out through the diff casing and the bearings the opposite way ?

thanks in advance, i'm just wondering how much of a job i'm getting into regards laying up my truck ?

[Grasshopper]

Unfortunately you'll need to remove the whole differential/final drive assembly as the mesh between the pinion gear and the crown wheel teeth will need to be reset accurately. Changing the bearing will alter the mesh of the gears, and could cause accelerated damage/wear to the assembly. I've not done it on a Bedford, but setting these things up usually involves some way of measuring pinion bearing preload, engineers blue on the teeth and a whole bunch of trial/check/re-adjusting until the desired gear contact and bearing preload is achieved. Sometimes this will require shimming to achieve.

 

Hope this helps.

 

Vince

[Sean N]

Rob, you can remove the pinion assembly from the nose of the axle casing by removing the prop shaft and the ring of bolts on the cover the way you think, rebuild and check on the bench and then refit. However you should also take the rear cover off and check the crownwheel etc. to make sure the damaged bearing hasn't caused any knock-on damage. If there's no damage you won't need to remove the crownwheel and diff assembly.

 

On re-assembly you should check the mesh to make sure it's correct as Vince suggests, and adjust if necessary.

 

None of this is difficult provided you take it carefully and use some common sense - I've done them at the side of the road without problem. You will need engineer's blue, a dial gauge and mag base, a caliper or mike and a spring balance or some other way of checking the preload on the pinion bearings (1 - 3 lb-ish at 8").

 

Pinion preload is set independently of CWP lash so it's not too much of a faff to do.

 

You'll also need a decent quantity of new pinion housing gaskets as the pinion setting is done by varying the thickness of the gasket pack. Buy new bearings of a quality make, not cheap unbranded Chinese ones.