In stripping the gearbox due to a stripped level plug thread, found that the thrust washer at the base of the drive is missing.
Can anyone provide the dimensions of the washer, particularly the thickness, in order that one can be made?
Any help would be really appreciated.
I seem to recall reading that they are hardened to prevent wear, I would try and get a genuine one from Gutsibits etc, it would probably only cost pennies.
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There are two washers (one at each end) and they are supposed to be hardened. The thickness must be 1mm for both. When taking the drive out it is VERY easy to drop the bottom washer into the crankcase! Both of them were missing when I rebuilt my box and the drive was badly damaged, perhaps as a consequence. I could only source one, so I used that on the lower end and substituted a stainless steel washer at the top. Seems to work ok and the flapping on the speedo needle is much less! Best to check the case and discarded oil to see if the lost washer is hiding somewhere.
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I don’t think there is a bottom washer. There is one above the gear because this is where the thrust is. Parts book shows complete “Pinion Z” assembly. This doesn’t have two washers. (12 76 33 00".
If you can wait a couple of days I have my Cali engine on the bench and I can check what that has.
Guzziology suggests otherwise.
“On each side of the worm gear is a small hardened washer that is not available as a separate part. Worse yet, removing and reinstalling the worm gear shaft without due care can dislodge the lower washer, leaving it to possibly ruin the two speedometer drive gears”
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Have a look at page 5 of this (very useful and comprehensive) article: Gearbox rebuilding - with pictures - Technical : The complex stuff - exciting but heavy reading, take your time. - guzzitech.dk archive - courtesy of Jens Lyck
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I could be wrong. Its been a couple of years since I rebuilt the Spada gearbox
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Checked my Cali and there are two hardened washers.
They are identical 6 x 12 x 1mm
Just to confuse matters… the 850T manual and the Haynes manual both show only one washer at the bottom! I can’t find anything in my notes to say if I used one or two, but I know the used drive I bought only had the one.
Thanks for the great response to my question. All very helpful. I am confident that a hardened steel washer is required at the bottom of the speedo drive to protect the ally gearbox case. I have been offered a spare washer that has been made as a replacement for the original which is a great stroke of luck. Now all I have to do is rebuild the box!!
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