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Thread: 1938 Pontiac Master Cylinder Sleeve

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  1. #1
    Join Date
    May 2009
    Location
    Mass
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    374

    Default 1938 Pontiac Master Cylinder Sleeve

    I haven't bothered to post projects for a while - really since the "picturebucket" meltdown. I figured i would post this one since I could not find a good post with pictures when I needed it.

    I picked up a car to restore and the master cylinder was pitted too far to clean up - so i figured i would give it a try to sleeve it, and if i destroyed it i could buy a replacement.

    First step was to figure out how to hold it. Since one end was threaded I made a stub shaft ad mounted it in the four jaw. I liked this better than trying to hold the outside of the casting and getting it square. This also let me make a practice cut on a rougher master cylinder that I had as well.



    First step was to bore and then i cleaned it up with a 1-1/8 reamer that I had. It came out at 1.126" which was fine since i was machining some tube to fit.





    I was able to buy some 304 stainless DOM drops that were 1.3" od and 0.95" ID. for $12 delivered. My first plans to open them with a 1" reamer went poorly as i took too much of a cut and it ended up with grooves in it. Next I ended up borrowing a positive rake insert boring bar and went at it with light cuts and slow feeds. I got a lot of shop cleaning done while the cut was happening! I also experimented on speeds and feeds to be able to land on the final dims. And proceeded to oversize the bore - so i needed to make a third one. BUT the third one was a charm. ID is 1.001". Another key was to support in a steady-rest.



    The outer bore could be cut much faster and it set for between half and a full thou interference.



    I cut to length, deburred, and put it outside in the winter air. I made an aluminum bushing to press on and heated the cylinder with a propane torch. The green smear is loctite bearing retainer. It went in very evenly with not much pressure.





    Final steps were to drill the holes from the resivoir. The 0.030" hole had me paniced that i would snap the bit. I used a high quality bit in a pin vice in a sensitive drill press and was relieved when it came though. Final step was to hit the bore with a ball hone to debur the holes, and futher smooth the bore. It came out better than expected and the spool fits in with a nice slip fit.




  2. #2
    Join Date
    Mar 2003
    Posts
    4,331

    Default

    Nice work!Now show us more of the actual Pontiac!

    Doc.
    Doc's Machine. (Probably not what you expect.)

  3. #3
    Join Date
    Oct 2005
    Location
    British Columbia
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    6,467

    Default

    Quote Originally Posted by Doc Nickel View Post
    Nice work!Now show us more of the actual Pontiac!

    Doc.
    Yes indeed, very nice work!
    Also thanks for the write up and the photographic documentation, I realize this takes extra time and is sometimes an extra distraction when you are focused on the actual project.

    Final steps were to drill the holes from the resivoir. The 0.030" hole had me paniced that i would snap the bit.
    I always start sweating at this point too.
    It seems the more time you have invested into a part the more likely that things will/can go wrong. Glad to see you got that out of the way during the early stages of the project.
    Home, down in the valley behind the Red Angus
    Bad Decisions Make Good Stories

  4. #4
    Join Date
    Nov 2007
    Location
    Woodinville, WA
    Posts
    9,272

    Default

    Finally a thread with some machining . Nice work!

  5. #5
    Join Date
    Jan 2014
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    Long Island, N.Y.
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    2,585

    Default

    Quote Originally Posted by gda View Post
    ... Since one end was threaded I made a stub shaft ad mounted it in the four jaw. ...
    Maybe it's the angle the picture was taken at, but that looks like a 6 jaw chuck to me.

  6. #6
    Join Date
    Nov 2008
    Location
    SF East Bay.
    Posts
    6,315

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    Quote Originally Posted by RichR View Post
    Maybe it's the angle the picture was taken at, but that looks like a 6 jaw chuck to me.
    It's obviously a 4 jaw. It just looks like a 6 jaw because of the two part jaws visible in that picture. In the one below he's swapped to solid jaws and that made it a 4 jaw chuck.

    At the end of the project, there is a profound difference between spare parts and extra parts.

  7. #7
    Join Date
    Oct 2002
    Location
    Saskatoon, Saskatchewan
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    Years ago I did the same for a friend's old International truck with the dual clutch and brake master cylinder. I cheated and stripped down a couple of old shock absorbers and found one where the thin wall seamless tubing had the exact same bore as the the master cylinder had - 1 1/8" - and the bore had a perfect finish already!

  8. #8
    Join Date
    Jan 2004
    Location
    Missouri
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    30,396

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    Quote Originally Posted by RichR View Post
    Maybe it's the angle the picture was taken at, but that looks like a 6 jaw chuck to me.
    Well, you can count at least 4 visible jaws and likely 5, and that is over less than the whole circle. There are two obviously opposite, with two other jaws between them. I'd have to agree.
    1601

    Keep eye on ball.
    Hashim Khan

  9. #9
    Join Date
    Jun 2008
    Location
    Toronto Ontario Canada
    Posts
    768

    Default MY customer was a little concerned.

    Some 20 years ago I resleeved the master cylinder and the slave cylinders for a large 1930s Chrysler.
    The slave cylinders were single ended and so I bored them in the mill.
    I made the sleeves a sliding fit, as recommended for the green loctite I used.
    My customer expressed concern that if the loctite failed then the sleeves in the slave cylinders might move outwards if pressure got under the blind end of the bores
    . I do not believe that likely, but wonder whether it is a poor idea to sleeve single ended slave cylinders without mechanically locking the sleeves from movement.
    The Chrysler has been reassembled, but is still just a " Yard driver" , and, as such, the repairs have not been thoroughly tested.
    Can anyone who has experience of this sort of work please comment.
    Regards David Powell.

  10. #10
    Join Date
    Jun 2009
    Location
    san jose, ca. usa
    Posts
    870

    Default

    most excellent work, thanks for sharing. now, post more often.

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