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Technical 1952 Oldsmobile Wheel Cylinders - Confused!

Discussion in 'The Hokey Ass Message Board' started by cmarcus, Sep 4, 2019.

  1. cmarcus
    Joined: May 23, 2012
    Posts: 936


    Hey all,

    There is some massive confusion (for me...) around wheel cylinders for my car. Seems like there is different information around. And before anyone jumps on me, I rebuilt these once, and are leaking again after 2 years. Not sure how many times before me they were rebuilt, so I just want new ones to be safe for peace of mind.

    According to AC Delco's site, part #18E743 and 18E744 are for front drum brakes, and the 1952 Oldsmobile is listed as a fit (see attached). Unfortunately, it gives no information on for bore size. When you click "product information" it just blows up the picture real big.

    When I went to Rock Auto to overnight these (NAPA doesn't have in stock, and our car club has a big show on Friday/Saturday...) it says the bore size is 15/16", which is the rear. The fronts ( I believe) are supposed to be 1 3/32".

    Can anyone out there confirm? Will it greatly compromise braking safety to go down that size?

    Attached Files:

  2. engine138
    Joined: Oct 5, 2007
    Posts: 1,182

    from Commack NY

    KoolKat-57 likes this.
  3. cmarcus
    Joined: May 23, 2012
    Posts: 936


    Thanks man! Yes, I have them Fusick on my radar, just extremely pricey, and not sure they will overnight...just trying to make sure I have what I need, and the AC Delco part # thing is just confusing. Called an old-timer REAL shop locally here, and he pulled a catalog - couldn't even find an original part # for the fronts. Calling Fusick will be next...just that the part #s above from Rock Auto are 1/2 the price of Fusick, and guarantee overnight...
  4. 302GMC
    Joined: Dec 15, 2005
    Posts: 5,774

    from Idaho

    Pull your original cylinders. If they're unpitted, hone & replace the cups & boots. They'll be better quality than the new chinese crap on the market.
    Don't try using smaller diameter cylinders - lockup will occur.
    The Olds factory front cylinder part numbers are 5450471 (R) & 5450472 (L), & fit '50 - '56 Olds only.
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  5. onetrickpony
    Joined: Sep 21, 2010
    Posts: 387

    from Texas

    Do not use the rear cylinders on the front! You might get away with a 1/16" difference but even that is pushing it. If the actual size is 1 3/32, I would go 1 1/16 or 1 1/8 if the originals are no longer available.

    Be aware that any change in size will cause a difference in braking but we make changes in other areas that affect braking every day. Tire/wheel size, engine, vehicle weight, etc will all have an impact.
  6. cmarcus
    Joined: May 23, 2012
    Posts: 936


    Thanks all! I just decided to bite the bullet and go with what Fusick had, and overnighted it. Since they are the Olds specialists, and were super helpful. Got me dirt cheap overnight shipping.
    302GMC likes this.
  7. jimmy six
    Joined: Mar 21, 2006
    Posts: 4,771

    jimmy six

    Sounds crazy but wheel cylinders are wheel cylinders...GM, Ford, etc bought them.. and they all are pretty much the same. If yours are 15/16" I'll bet they are the same as my 1992 Ford F-150s that I installed where 1" ones were. Even the the direction of the fitting doesn't mean jack if your replacing the lines or building one from scratch. If you had one of yours as a sample and a good guy at a parts counter I'd bet a comparison could help you get whats needed.

    We have a brake/steering shop near me who wouldn't have even asked what they fit. Just looked at the diameter and went back and taken them off the self from memory. There are very few bolt patterns and the rods going into them are whats different.

    We are currently putting 1956 Ford emergency brake levers and arms on a 1962 Pontiac rear brakes and they are exactly the same only the attaching cable is different.
    Anyway glad to see you got what you needed....
  8. Ebbsspeed
    Joined: Nov 11, 2005
    Posts: 4,749


    A little hydraulic cylinder math: Smaller diameter wheel cylinders (15/16) will not lock up the wheel easier than the larger ones (1 3/32) will. A larger bore cylinder has more piston area, so at the same line pressure will exert a lot more force on the brake shoes. The larger cylinder will have an area of .9396 in² vs .6903 in², so will apply approximately 30% more force.
    Last edited: Sep 4, 2019
    57 Fargo likes this.
  9. junkyardjeff
    Joined: Jul 23, 2005
    Posts: 7,171


    I used 78 C10 wheel cylinders on my 53 Olds,I had to use adapters since the 53 had 1/4 lines where the cylinders were made for 3/16. I know I use a different year for the front too but can not remember what it was but might have been late 60s C10.

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