Jump to content

Model 20 Differential


PMac
 Share

Recommended Posts

One for the Model 20 team.... in filling the diff with oil, which of the two bungs represents the correct fill height? My diff pumpkin has two square bungs at the rear, one being slightly higher than the other. I am guessing it is the lower one but want to be sure.

Thanks,

Peter

 

Link to comment
Share on other sites

I can't speak directly to Hupp, but 1910s Pierce-Arrows' diffs have two bungs, one above the other, on the side of the  diff rather than the rear cover (there isn't a rear cover in the cast housing).  The owner's manual says to remove both, and fill through the upper one until the gear oil runs out the lower one, then replace both plugs. I speculate that due to the heavy viscosity of the 600-W steam cylinder oil, they feared that the oil could build up without flowing back through the filling hole. 

 

Note that on the Pierces, there is a separate single plug for the pinion gear. 

 

For what it may be worth...but I'm sure some Model 20 owners will reply.

  • Like 1
Link to comment
Share on other sites

Until it flowed out the bottom hole is how I filled mine.  I'm sure everyone has an opinion, I use a semi-fluid oil/grease to minimize oil loss.  Braking is a little weak on the Model 20, and when the shoes get oily, then braking power is downright imaginary....

  • Like 1
Link to comment
Share on other sites

No, I used some semi-fluid grease, bought it from Restoration Supply in California.  It's the consistency of pudding, it flows but slowly.  It won't stop leaks but it makes them less severe.  It lubricates well, but it's not really a semi-solid like a lot of grease, it does flow.

 

If I remember correctly the stuff from them comes in some sort of squeeze bottle, either that or I put it in a squeeze bottle.  Put a bottle full in, wait and see if it comes back out the plug in an hour or so, if not, put some more in.

 

Our early cars are kind of like the engines on DC-3 airplanes, when they quit leaking you know you're out of oil.  Reminds me of the story of the maintenance logs on DC-3's, pilot enters "engine missing" and mechanic writes "found it!".....

Link to comment
Share on other sites

I bought a gallon of Restoration Supply's 1500 Meropa (1500 is the ISO viscosity, not SAE, "Meropa" is a Chevron trademark) for about $45 + shipping and am pleased with its leak reduction and lubrication qualities for my 1918 differential.  It was clearly repackaged from a drum.  Gave some, probably too much, to friends who wanted to try it in their early cars, so I tried to obtain a 5-gallon pail from a local wholesale jobber through a friend employed by a large industrial operation, but apparently this product is only available from Chevron in 55-gallon drums.  Does anyone know if it might be available in 5-gallon quantities from other sources?

Edited by Grimy
added further clarifying info (see edit history)
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

×
×
  • Create New...