Lotus Elan

diff spider-gear play

PostPost by: richboyd » Sat Oct 30, 2004 4:58 pm

For reasons I don't fully understand, I have decided to take my
differential apart. No real problems (no noises, no metal particles, etc.).
My psychiatrist says ...

Ignoring the crown and pinion for the moment, I have some questions about
the spider gear arrangement: two that rotate on a cross shaft and two with
internal splines for the stub axles. I've noticed a small amount of
backlash in this four-gear arrangement; not sloppy, but a little play. I
haven't yet taken this assembly apart and haven't yet pressed the crown
wheel off its carrier (a step needed to get at the spider gears). I'm
debating whether I really want to (or need to - or should) take this
portion of the diff apart.

Should there be some play (backlash) between the four spider gears? How much?
Or should this assembly be set-up to eliminate (almost?) all backlash?
Do the cross-shaft gears ever generate excessive wear on their shaft?
Do the conical thrust washers behind them wear out?
Can adjustments (lash elimination) be made with shims behind the conical
washers?

Are the internal-spline gears a loose fit in the crown-wheel carrier?
Do these gears ever generate excessive wear with the carrier?
Are the thrust washers behind these gears special material, or just steel?
Can adjustments (lash elimination) be made with shims behind the thrust
washers?

These spider gears don't rotate unless the car is cornering. Even then,
they probably don't spin like crazy. But they do deliver the torque of the
engine. So, how much of an issue is wear in this assembly (given no
catastrophic events, like no lubrication)? Should I take it apart just to
get a visual inspection? When I reassemble, should I try to eliminate lash?

Any hints for pressing the crown wheel off the carrier?

All information or comments are appreciated - included "Are you crazy?" and
"Don't go there!"

Rich Boyd
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richboyd
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Posts: 272
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Location: Seattle

PostPost by: "Roger Sieling" » Sun Oct 31, 2004 1:02 pm

Rich,

You are perceptive about the amount of wear to expect. Little or none. There should be some backlash, w/o measuring a decent diff, I would expect as much as .010-.020" w/o alarm. Don't add shims to any of the spider gears. Ifyou go to the next step and pull it apart, you might want to replace the thrust washers, which might tighten it up a bit, but probably no need.

The one thing I have seen fail in open diffs is the cross shaft and more often the roll pin retaining it. I don't remember if the Elan diff uses a roll pin or a solid one. It's been a long time since I've been in there.

Roger

>> ***@***.*** 10/30/04 12:26 PM >>>

For reasons I don't fully understand, I have decided to take my
differential apart. No real problems (no noises, no metal particles, etc.).My psychiatrist says ...

Ignoring the crown and pinion for the moment, I have some questions about the spider gear arrangement: two that rotate on a cross shaft and two with internal splines for the stub axles. I've noticed a small amount of
backlash in this four-gear arrangement; not sloppy, but a little play. I
haven't yet taken this assembly apart and haven't yet pressed the crown
wheel off its carrier (a step needed to get at the spider gears). I'm
debating whether I really want to (or need to - or should) take this
portion of the diff apart.

Should there be some play (backlash) between the four spider gears? How much?
Or should this assembly be set-up to eliminate (almost?) all backlash?
Do the cross-shaft gears ever generate excessive wear on their shaft?
Do the conical thrust washers behind them wear out?
Can adjustments (lash elimination) be made with shims behind the conical
washers?

Are the internal-spline gears a loose fit in the crown-wheel carrier?
Do these gears ever generate excessive wear with the carrier?
Are the thrust washers behind these gears special material, or just steel?
Can adjustments (lash elimination) be made with shims behind the thrust
washers?

These spider gears don't rotate unless the car is cornering. Even then,
they probably don't spin like crazy. But they do deliver the torque of the engine. So, how much of an issue is wear in this assembly (given no
catastrophic events, like no lubrication)? Should I take it apart just to get a visual inspection? When I reassemble, should I try to eliminate lash?

Any hints for pressing the crown wheel off the carrier?

All information or comments are appreciated - included "Are you crazy?" and"Don't go there!"

Rich Boyd








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