Wheel Cylinder Bleeder Screw on my 39 Desoto

[desoto1939]

I noticed a wet spot on the back of my rear rim the other day.

 

Today pulled the right rear drum, pulled the cups back to see if there was any leakage at the cups and both were dray no brake fluid.  Noticed that I thought maybe some grease or differential fluid might have seeped out from the axle.  removed the outer oil seal. Cleaned up the axle and the inner seal area. I think put on the metal seal that is a pressure fit around the axle shaft and applied some Lubriplate as per the instruction to help hold the metal  seal in place. Put the external seal back on the backing plates and bolted it to the backing plate. Turned the axle to make sure there was not cutting into the shaft.

 

Cleaned up the shoes and used the Miller MT19 brake gage to adjust the brake lining and also the Miller Trubrake tool to cut down any highspot on the lining. This insured that the lining was symmetrical to the drum. Used the toe and heal setting and everything was in spec.

 

Put the drum back on and used a brass drift to put the key back into the drum.

 

Looked at the back of the backing plate and looed at the bleeder screw and saw a little wet spot of brake fluid.

Cleaned it off with a rag so it was dry. Pumped the brake pedal came back to look at the bleeder screw and saw a wet spot on the area around the bleeder screw. These are new bleeder screws.

 

Went to my 1936-42 Desoto master parts book and also 39 desoto specific parts manual found the part number   691471.  very unique style of bleeder screw the hole that the fluid comes out is threaded and a cap nut screws into the hole.  

 

Now here is the good part.  from 1936-38 they use a different part number 77671, But for 1939 they used part number 691471 and then from 1940-42 they used a different part number 854039.

 

Do not know what the difference  is but why only one year use a different bleeder screw?  i can find on ebay the 36-38 bleeder screws and the 40 and up but not the 39 style.

 

Learn something everyday when you try to work on a problem.  Might be that the newer length is not bottoming out or the shape of the cone at the end is not seeting correctly. Trying to get the proper bleeder screw.  The bleeder screw has the 3/8 nut to screw it into the backof the wheel cylinder.

 

I found an original rear wheel cylinder that has the correct bleeder screw so hoping to find these at a swap meet.

 

Rich Hartung

desoto1939@aol.com

 

 

 

 

[Dodgeb4ya]

Common issue these days....new bleeders leaking...poor machining of wheel cyl bleeder seat and bleeder seat taper.

Seen it many times in the last 10 years.

[wagoneer]

I couldn't find the bleeder screw by itself for my 48, but I was pleasantly surprised new bleeder screws  came with new wheel cylinders. 

  I think you might just have to go with the new 39 wheel cylinder for certainty. 

  @desoto1939 I'm coming to your house for the brake job; you have all the good miller tools from the book!

 

[Petermarc]

If I didn't live so far........