Re: 88 Spider Differential Question

[Simon Favre <simon@domain.elided>]

Paul Weimer wrote:

>I finished the brake master cylinder job this afternoon.  Mini-Vac'ed the
>brake lines, all seems well although I haven't taken it down yet to drive.
>While under the car I noticed that some fluid was being deposited on the
>undercarriage above the rear axle.  More so to the passenger side than the
>driver side.  Figuring the options to one of three:  brake fluid, gasoline
>or differential lube.  Had a friend work the brakes and start the car,
>nothing.  Therefore I am assuming it is differential lube.  Elected to drop
>the lube (probably needs changing anyhow).  Removed the bottom plate of the
>differential (where the drain plug is) and found the gasket to intact but
>harder than a rock.

You should probably run right out and buy the Alfa Romeo Owner's Bible. It's
almost never necessary to remove that bottom cover. The Bible might keep you
from making mistakes like that again. If the bottom cover was leaking, all
the oil would be on the bottom. If the oil is spraying on the passenger side,
odds are it's coming out of the differential pinion seal. That's the one
behind the driveshaft flange. Think about it. The driveshaft turns clockwise
as seen from the front. The passenger side (for LHD) of the flange is moving
upwards. Oil flung off the passenger side ends up on the undercarriage. Oil
flung off the driver's side ends up on the ground. Replacing the seal requires
removing the flange nut with a special tool. You can probably borrow one from 
your local club. Other than that, the job isn't hard. Make sure the driveshaft
and flange are marked so they go back together in the same position. The pinion
shaft and flange should also be marked. If you get driveshaft vibration after
replacing the seal, you probably put one of them back together in the wrong
position.

>Rather than ordering a new gasket I am considering making one from gasket
>material that I have on hand.  Is this gasket anything special or will
>gasket material (the kind you can buy by the roll) be OK?

You can make your own bottom cover gasket, but if you can buy one easily, why 
bother? Use a good non-hardening gasket compound on it. My preferences would
be Permatex Form-A-Gasket Copper Spray, Copper Form-A-Gasket in a brush-on 
can, or plain Permatex 3H Form-A-Gasket. Don't over-torque the cover nuts.

>Second question:  the shop manual says the differential should be filled
>with 2.75 lbs. of lube.  I've got a quart of 80/90W.  How do I convert
>liquid ounces to pounds?  Should I just weigh out 2.75 pounds of this stuff
>on our kitchen scale?  Thinking that must be a conversion for this but can't
>find anything in all the books and manuals I have at the house.

The way you fill an Alfa Spider differential is to pump oil in the fill hole
until it pours out in a steady stream. Don't be fooled by a quick gush of oil
caused by trapped air. When it's full, the excess will pour out for several
seconds. The car should be level when doing this. If the rear end is up, jack
the front as well. Good luck with it.

Simon

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