OH LORDY! SHE WON'T STOP!

[Steve Passmore]

I agree with Rod.  All these symptoms lead to the booster and grinding compound is made of iron fillings and grease isn't it? no way would I put that on my linings.

[Dave Burke]

I should clarify:

I rebuilt the booster and made sure that the leather was well-greased with the grease provided.  The brake pedal is not "hard" per se, but has good, solid resistance.  The pedal returns to its original position.  I didn't listen for a "hiss" but I'll try it out.  I put in new brake hoses.  When the car stalled on me the other night, I could still brake without the booster.  I have worked on both disc and drum brakes before (I had a '78 Camaro once) and again let me describe the feeling of stopping the car: it is like there is grease on the linings and the shoes, but I cleaned them.  I push the brake pedal down and the car decelerates and comes to a stop, but I expected more stopping power from them.  I drove it a bit to try and bed-in the shoes. 

This shouldn't be rocket surgery, and if I can't lick it myself, I'll take it to the brake guys here in Opelika, AL who said they could probably handle things if it fell outside my abilities. 

One more thing - the advice about not using petroleum-based lapping compound: thanks!  Mr. Brain overlooked that! 

Cheers!

Dave 

[Jon S]

When the engine stalled and you had no vacuum assist, was the braking more difficult than with the engine running?  did the pedal feel different?  If not, how many pumps until it felt different?  Just trying to fine tune the problem.

[bcroe]

After my experiences with brakes over many, many miles, I won't have a car without dual
brake circuits and discs in front.  Do be sure the brake hoses are recent; older ones can do
strange things. 

In the early 60s I saw shoes being "arced" and drums turned to remove some minor
irregularity.  Worked perfectly for the customer.  Since there weren't any high spots
left to wear down, they wouldn't soon need adjusting. 

Hmmm, the irregularity didn't matter to the old shoes.  I concluded all that fitting & sizing
was taking away half the service life of the components.  My new home process started by
being very careful not to wear the brake steel into the drums/discs.  Putting on the shoes
out of the box created some high contact spots.  The car stopped all right, but crooked.  I
then drove it around the block about 5 times, jamming the brakes all the way.  Adjust them,
much better.  After a couple days they were perfect.  Bruce Roe

[dplotkin]

David:
If you have not previously screwed around with the pushrod, don't. That adjustment is very sensitive and should never be used to correct a pedal height problem unless the problem was caused by a previous adjustment to that rod. If you mal-adjust it you can end up with brakes that drag, get hot, expand, drag worse, get hotter until the car locks up. I went through this very nightmare with a 62 Bonneville and a 63 Ford. Neither would stop well at all until I replaced their boosters.

If you can rule out improperly installed shoes & hardware, your problem is likely a defective booster, power brake cars have pedal levers whose leverage is designed to work with power brakes. Manual brakes are set up so that considerably more leverage is provided by pedal application, which usually requires the higher pedal found on manual brake cars.

I think you have no power brake action. I think you are trying to stop a 4,500 pound Cadillac without power assist and without the leverage manual brakes provide the drivers foot. It sounds like it is stopping exactly the way it would had you clamped off the vacuum supply to the booster. So verify you have vacuum to the booster and that the booster is holding vacuum.

Dan

[59-in-pieces]

Folks,
I twigged to one statement about the 'hanging up" issue.

I don't recall if the wheel cylinders were replaced or not.  A trick I use, if I do not replace the wheel cylinders, I run some wet dry emery paper threw the bore of the wheel cylinders, flushing with brake fluid.  And if the car had been sitting for a long while, you will see red/brown rusty brake fluid coming out.
That way, if there are burs/rust areas in the bores, they wont tear up the pistons/plungers or drag or bind and stop the full extension of the pins that move the shoes apart - so the pistons & pins will move smoothly fully apart and move the shoes tight against the drums.

I agree with the arc statements as being history.  If you looked at a newly arced shoe you see the arcing grind marks are heaviest/deepest at the ends.  Even without power assist, if you stand on the brakes you should be able to lock'm up.

Just my opinion and I'm poor so without the 2 cents.
Have fun,
Steve B.

[dplotkin]

  Even without power assist, if you stand on the brakes you should be able to lock'm up

I don't think so. It would be very hard to lock up a car as heavy as a Cadillac with no power assist. I've been there.
If the hydraulics & the shoes check out it only makes sense.

Dan

[Dave Burke]

UPDATE: Well, last night I pulled the front drums and the shoes are indeed in the right place, with the smaller-faced pads in front, plus the drums were reluctant to come off, so I guess that they might be bedding in.  The wear looks like it is in the correct place.

Standing on the brakes, I could not lock them, and I agree, the power assist makes it a LOT easier.  There is a noticeable difference!  I did not adjust the brake pedal pushrod because it feels like it has more than adequate travel and returns to where it should.  It could be a simple issue of continuing to run in the brake shoes.  I'll re-bleed the system to make sure there are is no air whatsoever, but it could just be needing more time.

I put radial tires on her, which are harder and higher pressure - I wonder if this affects things?

Best,

Dave

[Jon S]

David -

The radial tires should make no difference whatsoever.

[35-709]

FWIW, I am in agreement with those that are leaning toward a problem with your power booster.

[Dave Burke]

But - but - but I followed all of the instructions to the letter....   I wonder if it just needs to work itself in because it is having an effect on braking, just not as much as I expect...  That being said - anyone know of a trustworthy rebuilder in the Southeastern U.S. a la AL, GA, MS, TN, FL?

Darn it - I CAN fix things!

Dave

[Jon S]

I'm still convinced you are not getting full travel of the Power assist - check the pedal to firewall distance - it should be 4 7/8".  Anything longer or shorter will cause problems.

[Steve Passmore]

I'm not familiar with your model but a lot of booster problems can be laid at the door of Vacuum. Have you check that it IS getting vacuum?  When that stops for any reason, split or blocked pipe, the booster go's right out.

[Jeff Rosansky CLC #28373]

Can you just pull the vac line to the booster and then drive it?  If there isn't much difference.....or if there is, then that will tell you if the booster is doing its thing.
Jeff

[Dave Burke]

EUREKA!!!

Now I haven't driven her yet and tried the brakes but I feel pretty optimistic here...

Give Mr. S. Passmore a potential cigar here: VACUUM LEAK.

The car ran poorly and as I was trying to set the timing I couldn't get her to idle steadily at any speed.  Hmmm, now what could cause that?  I also pulled the front drums and saw that the shoes were on correctly.  YOINK - I pulled the carb, tore it back down, rebuilt it, and shellaced all of the gaskets.  Then I pulled up the insulator spacer at the base of the carb - it was cracked so I slathered it with shellac, replaced the fiber gaskets, let it cure for a bit and turned the key...

Normally I had to prime the engine with a few kicks to the accelerator.  Not this time!  VAROOOOOM - idle started on the top step of the cam and she slowly descended to a workable idle of around 690RPM in Park - now to lower that in drive to around 500 (I know, the manual says 420 but I don't know if I can achieve that same lope).  So I deduce that I have been suffering from a substantial vacuum leak which then extends to - you guessed it - the booster system that runs off the intake manifold vacuum.  I may have killed two birds with one stone here -

FINGERS CROSSED!

Thanks for all of the help, you guys!

Dave

-oh yeah, I also ordered a new spacer from OPGI and a new sock strainer for the gas tank - how come the manual doesn't bother to show it?  The 1957 Shop Manual is lacking in many ways...

[Walter Youshock]

AHHHH!!!!  You didn't mention the way the car was running.  Makes perfect sense.  The '57's are very touchy.  Another area to check is your windshield washer and wiper.  When setting timing and adjusting the carb, I disconnect and eliminate the wipers/washers from the equation.

Which carb do you have-Rochester or Carter?