59 Olds Power Brakes

[Stacie]

Hi All, 

anyone know what might be going on with my ‘59 Olds Power Brakes?  The brake pedal sags too much to contact the brake light sensor.  If I lift up on the left side of the pedal, it makes contact and the brake lights go off.  Should there be a return spring that may be missing. Or is there maybe low fluid in the cylinder. I wanted to check the fluid, but even with pliers, I can’t get the dip stick out. 

[61polara]

You should be able to adjust the brake light switch so it will contact the brake pedal arm.  Low fluid will not cause this, but you should check the level at least every few months.  You need to find the master cylinder.  I don't know what you are trying to check but there is no dip stick on the master cylinder to pull out.  It has a screw-on cap on top.

[The 55er]

All 1959 Oldsmobiles with power brakes (both the Bendix and Moraine types) had dipsticks. Check that the return spring is there and adjust if necessary. It might be in a tight space but you will need to work that dipstick loose and remove it to check the fluid level sooner or later. 

[m-mman]

I had a 59 Lincoln with chronically low brake pedal. (similar treadle-vac master cylinder design) 

Over the years someone had added a heavy return spring under the dash. 

 

I rebuilt the master/booster twice and no improvement, then when I had it out getting professionally rebuilt, I noticed that the pedal LINKAGE was STIFF(!) It would hardly move with nothing connected to it. I pulled the linkage completely apart, cleaned all the pivot points (two on a Lincoln) put a little grease on both of the pins and the pedal swung freely. 

 

New master/booster installed and no more problems. 

 

Edited April 4, 2022 by m-mman (see edit history)

[Stacie]

Thank you. 
Is the standard brake pedal supposed to be the same as the power brake pedal?  Mine is different. The brake light contact is above the pivot point. So it’s supposed to be contacting when the brake is not in use. And the pin will fall out if I adjust it far enough to contact the sensor.  I have the service manual and it only shows that standard brake assembly that’s posted above. 

[Stacie]

I went back out to take a better pic and realized there’s a secondary adjustment for the sensor. Neither could reach on their own, but with both adjustments, they are now making contact. 

[Stacie]