Hydraulic Brakes on a ‘35’ Buick.

[Frank DuVal]

First all wheel failure of dual master cylinder to mention is the internal bypassing failure. Very common. Usually first noted as stepping on brakes very softly, like approaching a fuel pump, you are going slowly and just easing on the pedal when..... the pedal is on the floor. Luckily, if you repress the pedal it usually works at normal height  (the internal seals work with pressure on them) leading you to believe it didn't happen, ...until the next time it does. Continue to drive this way and soon you will be pumping the pedal to get any brake action at all. Steady application goes right to the floor.  That is when they showed up at the shop for repair, dual system, no brakes. This failure mode also occurs with single piston masters too.

 

Second failure is rear wheel system leaks fluid out, or a piece of dirt cloggs the inlet port for the rear wheel system in the bottom of the master(that's what happened to me, slowly dropped pedal), and you don't notice, since the fronts do most of the work anyway. Sure the pedal is lower, but, still working. Then the front line (steel or rubber flex) goes. Typically this is when you are pressing harder to avoid something, in my case it was a sudden red light. Stomp, to the floor!

 

So I steered the 70 Buick wagon through the red light, turning left through the cross traffic, using horn and lights...?  pulled into a 7-11 to calm down, using the parking brake to stop. Once composed, I drove home using the parking brake and giving looottss of room. It is a three speed manual, so leaving it in first gave pretty good speed control at low speeds. A Turbo 400 would have had different results.

 

So the lesson here is proper brake maintenance and keep aware of small issues. Back then no one heard of flushing DOT 3 every few years

 

In the Corvair world we do stress doing a hard-HARDER test every year or sooner. That is (and we don't have power brakes, those that do should probably start the engine)  step on the brake pedal, step harder, grab the steering wheel and pull yourself up to apply the most pressure possible. The system SHOULD hold. If you break something, glad it happened in the driveway! Do not fret that you broke something. I remember my dad (product of the depression) saying "don't step so hard on the brakes, you might pop a line or wheel cylinder". After the wagon incident, I WANT to break the system in the driveway!

[Jim Nelson]

Thanks Frank.   Verrrry good lesson.   I guess its flush time.    What is the failure part in DOT 3 ?   DOT 4 ?    This flushing ?requirement? appeared in the car manuals but I don’t know  ANYONE who talked about it and WHY.   I have my own tale on tube tires vs tubeless.   Driving at night going home on a trip.    My car can run 65 / 70 all day long.    On the Inter State, in the left lane, passing cars.   Now the best point, I had just crested a hill and going into a decending sweeping left turn.   BANG the left front tire exploded.  I usually (all the time) drive with both hands on the  wheel.   So the steering wheel went into convultions.   I managed to keep the car in the left lane, let up on the gas and managed to move left into the break down lane. As I was stoppin I found myself  between the steel gaurd rail about 3’ away and about 18” away fron the painted left siide of of the left lane.   I turned on my emergency lights and calmed down for a few moments.   Obviously traffic on an Inter State could not see me untill it was to last for them to move into the center lane.   Got it ?    So I got out of the car and went back up the road (with my cell) to keep from becoming “road kill”.   Finally got Road Ranger to help me and a county mounty to stay at the top of the hill with his red / blue lightsvon.   People pay more attention to those lights.   My whole side wall had separated from the main tire body of the tire.   The tires were from a major classic tire mfg.   you know, it advertises looking like original tires.   Well, they all came off and got replaced with modern radial ply tires.    It had been over 50 some year and many cars since I a problem with radials so lesson learned for me.   BTW, my new tires look wonderful.   I kept one of the tires as a spare.  I need to look up the mgf construction date -   just cuz.   Isn’t life fun ?

[Beemon]

7 hours ago, billorn said:

Plus if your worried about brake fade thats something that happens on hydralic brakes not mechanical because the fluid gets hot and boils.

 

Brake fade is when inert gases are generated between the pad and the rotor/ drum from high heat that creates a squish zone. Has nothing to do with boiling fluid. 

[old-tank]

29 minutes ago, Beemon said:

7 hours ago, billorn said:

Plus if your worried about brake fade thats something that happens on hydralic brakes not mechanical because the fluid gets hot and boils.

 

Brake fade is when inert gases are generated between the pad and the rotor/ drum from high heat that creates a squish zone. Has nothing to do with boiling fluid. 

Fluid will boil and cause partial or total loss of brakes:  driving in the mountains with a front disc car and auto trans following some timid fool that was causing me to brake more often even with downshift.  The brakes started pulling to one side (fluid had boiled in the opposite side caliper and the resultant vapor would not compress).  The fluid was about 10 years old and contaminated with water over those years lowering the boiling  point.  Less likely to happen on drum brake cars.

I now flush all of mine every 2 years: suck out the master cylinder, 4 pumps to each wheel cylinder (2 ounces).

[Ben Bruce aka First Born]

I was taught, way back when, that brake fade came about when drums expanded due to extreme braking.,

 

  Ben

[Bloo]

There are 4 kinds of brake fade:

 

1) Expanding drums:

 

The drum gets bigger due to heat, the shoes have to move farther, and maybe they don't even reach. The pedal might get all the way to the floor. If the brakes are hydraulic, maybe you can take a second stab. Sheet metal drums are the worst offenders. I have also heard that large drums (like the 12" ones on my Pontiac, and on the 36 Buick) are worse offenders than 11 inch due to the larger circumference. For whatever reason, 12" all but disappeared on later cars, and they instead had wider shoes to gain the swept area back. Maybe it was just due to smaller wheel size, I don't know.  Drums also get bell-mouthed when really hot, since one side is supported and one side isn't. Presumably the shoes remain more or less square, and don't make as good of contact as they do cold.

 

2) Gas fade:

 

The brake lining literally burns, and the escaping gases prevent the lining from touching the drum. Brake linings are designed to prevent this as much as possible, but if the linings have ever been contaminated with anything that burns at a lower temperature (oil, brake fluid, etc), gas fade will happen at a MUCH lower temperature. Washing them off with solvent does not work. If you don't believe me, try playing an acetylene torch over the lining, and watch the contaminant come boiling out of the pores.

 

You can stand on the pedal as hard as you want when this happens, but there won't be a lot of stopping going on.

 

3) Brake fluid boiling:

 

Brake fluid has a high boiling point, but it attracts and absorbs water out of the air, and in addition to becoming corrosive, the boiling point drops dramatically. Regular brake fluid changes prevent this. When it happens the pedal will just go to the floor.

 

4) Some combination of the first three.

 

Gas fade (2) is by far the most common kind of fade in properly maintained drum brakes. It happens to discs as well, but they don't hold the heat in as much, and have an advantage.

 

The limiting factor on these old cars (with 4 wheel brakes) is and always has been the size of the contact patch of the tires, followed closely by the suspension, and how well it deals with weight transfer. Any 4 wheel drum system that cant do one panic stop without brake fade is extremely suspect. Something is wrong. Coming down a Washington mountain pass while using the brakes to regulate your speed is a whole different matter....

 

 

 

 

[Jim Nelson]

Yup.   So true..   Except if you use the mechanicalbrakes they are not even.   At my repair shop Dose a lot of antiques the ?modern - 60’s cars, they set and adjust mechanical in their back alley..   its gravel so a mls-adjusted brake shows up right now.   They spend several hours trying to keep them in ballance.   On our black top street, it leaves nice long tire marks.   As they show me, any slightly worn bracket will make ballancing of mechanical very hard..   Pad, rotor ?  how about just shoes and drums.   And when all is said, and done,  tire construction and condition and road temps  all complete the pix.

[Jim Nelson]

Bloo,  your analysis on brakes and their problems / possible solutions is well put.   The test of your brakes surviving one panic stop is great.  Of course, providing a nice cooling  time before you head back home would be nice.   Remember, its only physics : mechanical to heat.   Cannot change that.   Just the method and process.   As I mentioned,  “lays your money down and takes your chances” still holds true.    

[Beemon]

10 hours ago, Bloo said:

Coming down a Washington mountain pass while using the brakes to regulate your speed is a whole different matter....

 

Snoqualmie at 80 going West?

[Bloo]

2 minutes ago, Beemon said:

 

Snoqualmie at 80 going West?

 

HAH! I was thinking of Stevens, but any of them will do......

[Ben Bruce aka First Born]

2 hours ago, Beemon said:

 

Snoqualmie at 80 going West?

 

 Well, duh!!.  One solution is DON"T LET HER GET THAT FAST!.  But, I was young once. Coupla days back.

 

  Ben

[60FlatTop]

I was around 35 when the company I worked for transferred me from an operator and mechanic to a management position. It was a company that gave annual performance reviews. And, within  a short time of the transfer, reviews were held. My old friends in the power plant asked me how my review in the management position went. "Everything was fine, but they told me my ability to overreact was low." Somehow, these brake modification discussions make that memory resurface.

Bernie

[Jim Nelson]

Does anyone have any info on Trippe driving lights ? ?

[Guest]

8 minutes ago, Jim Nelson said:

Does anyone have any info on Trippe driving lights ? ?

Seems off topic.

Go back to "forums" and search "trippe"

FOUND 567 RESULTS

 

[Jim Nelson]

Thanks Tinindian.   That worked.  Earlier searces came up zero.   To many words - - 

[Jim Nelson]

McDurment ?   I lost your comment about clutches.   I found a company who rebuilds the three finger pressure plates.   It looks like brand new.   It is going in my '38' engine.   The company is Ft. Worth Clutch and Driveline in Ft Worth Indiana.   It ran about $230 to rebuild.   They might have some that do not have to have a return.   I don't know about it but ...   You said you had a  conversations with Bob's Automobilia and they said they did not have anybody to rebuild the three finger PP.    Now we do ! ! !    Its in my trunk ready for replacement.   The Disc  was rebuilt locally and its also like new.    

[Ben Bruce aka First Born]

Perhaps you mean FT Wayne

 

  Ben

[Jim Nelson]

Ya,  I was talking to an Apple employee from Ft Worth when I figured out the clutch rebuilder was in Ft Wayne.   That thought was rattling around in my brain when I posted the location.    BTW, mine looks like a brand new PP.    Thanks for the correction..     BTW  I finally figured out how I’m changing to hydraulic brakes on my ‘35’.   

[Jim Nelson]

How do you get the bulb out of my Trippe driving light ?    I have taken it partially apart but I don’t want to force it. ?