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Discussion Starter #1
I was examining the suspension on my 1972 Montreal the other day and noticed significant gear lash in the differential (the wheels could be turned backwards approximately 10-15 degrees in a forward gear). Can anyone tell me how far gone the differential is with that lash or whether it is normal? There are several issues with the suspension that I plan to address with the Alfaholics Fast Road Kit. Should replace the differential during the Kit install or wait until the problem gets worse?

Any advice appreciated. Thanks in advance.

Brewster
 

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But Mad North-Northwest
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I think that's pretty normal with a diff, no? There's typically a reasonable amount of play in the spider gears, and that's not a problem. With the wheels on the ground you can typically turn the driveshaft 1/4" or so too.

Play in the ring & pinion is a problem, but play in the wheels is not how you test for it. If the diff isn't whining or clunking I'd call it good.
 

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Push hard and live
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A limited slip dif has a sort of "take up" between the input shaft and ring gear. Different than a non-LS-dif, which more or less transfers rotation straight from the input shaft to ring gear, with a little lash between the pinion and ring, there's quite a bit of slop between the input shaft and axles. This is just due to the mechanism that senses the difference in input torque and output torque to bring in the friction disks.
 

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But Mad North-Northwest
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I don’t think that’s correct as you’re stating it, Don. The LSD clutch assembly has nothing to do with ring and pinion play. The pinion in a clutch-type LSD diff still meshes directly to the ring and there should be no play between them.
 

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But Mad North-Northwest
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I'll add also the Alfa LSD is set up without preload, so it effectively acts as an open diff unless there's power being input through the driveshaft and the two wheels are spinning at different rates. The play you feel is in the spider gears, and there's really no difference between the LSD and non-LSD diffs in this regard. My '63 and '91 have the same play, and only the latter is LSD.
 

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Push hard and live
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I know that on my Montreal, I could grab the pinion and rotate it back and forth without moving either axle. I'm not saying there is play between the axles and ring gear, just between the axles and the input pinion.
 

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Richard Jemison
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R&P Lash

It takes a sensitive hand to feel the actual "Lash" play on the Alfa LSD diff.

You should be able to sense a small resistance in load when moving the pinion about 1/16" or so, measured at the outer diameter of the U-joint flange.
The rest of the free movement is the travel of the spider gears moving their shafts up the ramps to put pressure on the clutch disk.
 
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