Suspension 5: Sprint Speciale Differential housing clean up

Having this blog to look back on is pretty neat – I get to revisit my younger self, see what I thought about stuff, and reflect on what’s changed.  Most people can probably relate to how it feels when they discover an old essay they wrote for school, or a set of pictures from some big event in their life – a very human mix of nostalgia, slightly embarrassed introspection and my-god-where-has-the-time-gone reflection on changing priorities.  Anyway, I was doing some house keeping and found this post.  I think it is as useful now as it was then.


Me in a younger mans clothes – a few days before I wrote this post.  How’s the Sprint Veloce doing Corey?

From July 30, 2008:  Cleaning up the differential housing was one of those jobs I resisted doing for a while.  Every time I looked at it the 2 hours of scraping, solvent bathing and degreaser scrubbing I would have to do flashed before my eyes and I found something else to do.  Last week I rearranged a lot of my stuff to fit the Berlina in my space and found myself once again faced with this greasy lump in a tray sitting on my bench top waiting for me to clean it.  It was time to face the subject of so much procrastination.

The housing was covered in a thick coating of dirt that had bonded with oil and built up over the years.  To save time and solvent I used a small scraper to remove the big stuff.  By the time I was done I had removed probably three pounds of the caked oily dirt.


Greasy oily goo scraped off easily, but there was so much of it that it took about an hour to get it ready for a solvent bath.

 While scraping I discovered a grease pencil marking on one of the fins near the collar that mounts the pinion gear to the drive shaft.  Maybe this mark is how they knew what the ratio for the read end is.  I cleaned off the same spot on my spare Veloce rear end and found a similar mark.  When I open it up to clean it out I’ll see what the ratio for that rear end is and see if the marks mean anything.   Unfortunately I couldn’t think of a way to clean the rear end completely without removing the markings.


Grease pencil marking on the SS differential I am cleaning.  If you look closely you can see there are two markings.


This is the same spot on the Sprint Veloce rear end.  Only one mark on this one.


Ahhh.  So clean.  Once the scraping was done I used a little stale gasoline then scrubbed it with Purple Power degreaser.  I wore gloves and eye protection and worked in a well ventilated space.  You can’t leave the degreaser on the aluminum long or it will etch it and if it gets on your hands for any length of time your skin will dry and flake off over the next few days.  Yuck.  If it does this to you skin, one can only imagine what your body does with the chemicals it absorbs if you don’t wear gloves.

clean differential big side

I did my best to keep any grit out of the pinion bearings and didn’t clean out the inside parts until the outside was spotless.  I rinsed the degreaser away with water then used air followed by a heat gun to chase all the water out of the bearings.  I sprayed the bearings with WD (water displacer) 40 when everything was clean. 

clean differential small side

The other side.  Very clean.  Note “520” marking.

differential numbers too

Someone went through the trouble to stamp this number here.  Perhaps a casting batch number?

differential detail numbers

Another stamping, this one on the side opposite the “520” stamp.  I wonder if the 9 is for how many teeth the Pinion has or possible a spacer shim size?

Next on the agenda for this part is a new pinion seal, cleaning up the rest of the gears, repairing, cleaning up and painting the axle tubes, painting the pinion gear to drive shaft collar and lots more.  Stay tuned.






2 thoughts on “Suspension 5: Sprint Speciale Differential housing clean up

  1. I can certainly identify with avoiding this job. My Nuova Super still had every bid of dirt and oil it had collected since it left the factory in 1976 when I took on the job last year. The fins were almost lost in the mess.

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