buying a second-hand front diff how do i inspect

Dirty,

I haven't done any diff work for years and I've never set up a Toyota diff. But generally speaking check the following:

The diff should be stiff to turn. When you turn the pinion, there should be a fair resistance in the crown wheel. That's the effect of pre-load on the bearings.

Inspect each tooth on the crown wheel for any signs of the case hardening breaking down on the metal surface. This can be seen as pitting or flaking of the metal.

Look for polish marks on the surface of the crown wheel teeth. These are normal but they must be in the correct place on each tooth. This is an indiaction of correct meshing of the teeth between the pinion and the crown wheel. The correct position for this "polish mark" is the centre of the tooth. And the "polish" mark shouldn't extend to the extreme edges of the teeth. The mark should be in the centre.

If possible, wash the gears of any oil and use Engineers Marking Blue Paste on the crown wheel teeth. Rotate the pinion and you should see exactky where the teeth are meshing. This is best done with a screwdriver or tyre lever UNDER the crown wheel whilst applying downward pressure, as if you were trying to liff the crown wheel.

These are just general rules and not Toyota specific.

Bilbo

to add to above, Hear is a Drawing to show acceptable gear patterns, once agene it's not Toyota specific.

Ideally if you open it up you would want to check the backlash if you know how.





Cheers.

open it up and look for damage....best way, feel the backlash for minimal amounts, use common sense, but most importantly, check the ratio is thesame as what you have in there now.....there were a few dependant on model, motor etc....seen a few diffs on ebay for the front of IFS lux/surf/etc.....

Hi dirty, you can also get backlash from too much clearance between the `axle ` and ` spider ` gears in the crownwheel carrier.
These gears have thrust washers and they in time ( read distance travelled ) wear and let the gears move slightly out of mesh thus creating backlash. Worth checking, they will not cost a fortune , worth replacing if worn. Regards G.T.

thanks for all your help i think im on yhe right track ill let you know how it works out