<VV> Weak brake action

[Tony Underwood]

At 09:00 AM 12/5/2009, kenpepke at juno.com wrote:

>While you have done everything properly, within your power, there 
>are a couple of factors behind this situation.  Back in the day your 
>Corvair rolled along on 6.50-13 bias ply tires.  The rolling action 
>was halted with soft organic based brake shoe linings.  EM stopping 
>performance was comparable with other economy cars at the time.
>
>Today you are almost undoubtedly rolling on radial ply tires that 
>have a wider foot print and a much greater traction ability.  And it 
>is unlikely the brake shoes you installed are lined with a soft 
>organic material.  Usually the rolling radius of modern radial tires 
>is a bit greater than the original tires and that combined with the 
>greater traction effort of the tires provides the effect of a 
>greater lever advantage over the brakes which, by virtue of modern 
>brake shoe lining, are also requiring more pedal effort.  It should 
>still be possible to lock up the tires for that screeching halt ... 
>but it _might_ take both feet!


My ancient stock-brake system '60 sedan with brake linings from the 
FLAPS will readily lock the brakes with one foot without a lot of 
trouble and has done so recently with a load of people (well, myself 
and 4 teenage girls anyway) to avoid a dog with a deathwish.   It 
screamed like a banshee (Goodyear shreeker tires) and left long 
blackmarks equally spaced, car stopped straight as an arrow.

The linings are relatively soft, seeing as how I have to adjust them 
every month or two or the pedal starts to creep down, likely the 
reason the car stops ok without a lot of pedal pressure.   No 
self-adjusting brakes on the '60.   Master cylinder is stock, rebuilt 
a year anna half ago, I think, with parts from a kit for a '65 'Vair 
MC which worked.

I've replaced most of the brake lines and the rear brake hoses, got 
two fresh hoses to go on the front, jus' b'cuz, next time I have it 
up on stands... checked the steel line under the tank a couple years 
ago when I had the tank out to work on a leak and the line there was 
solid and clean, left it alone.   I regularly give it a hard-harder 
stomp just to make sure.   This summer I had things loose again to 
work on the sender to the gas gauge would read right, everything I 
could see still looked fine although the front hoses (which are about 
ten years old now) had some small cracks on the outside, which is why 
I got two more to go back on it.


It stops just fine for most purposes, will start to fade the brakes 
quickly after a couple of long hard stops.    Now:    Who's gonna 
drive on the streets in such a manner as to end up indulging two long 
hard stops?   Corvair drum brakes work just fine for normal driving 
if the car is driven like a car and not like a racer.    You wanna go 
racing, put on some Brembos.   You wanna cruise the Parkway or the 
local burger joints or a trip down highway for the fun of it, the 
factory brakes will work out just fine, even better if you use modern 
materials like better shoes and stay on top of volatile stuff like 
the rubber hoses and keep an eye out for leaks.





>You have all new stuff now so you may not want to do it all over but 
>at least you could add a power booster.  This would also give the 
>perfect opportunity to convert to a dual master cylinder.  Remember, 
>on an EM the loss of a rear axle bearing means total loss of 
>braking, including the parking brake and the clutch!  You have to 
>hope for a high curb to rub the tires against :-(


The response is that an early wheel bearing is gonna give you fair 
warning that it's ready to fail.   Regular maintenance and an eye for 
potential troubles will keep things in shape so you won't need to 
worry about them.


>Personally, I would not drive an EM on a regular basis without 
>re-engineering the braking system and I would even limit the driving 
>of a LM.  OK, I know there are a lot of guys out there that are not 
>as fussy and cautious as me when it comes to stopping ability ... I 
>am sure we will be hearing from them.


...here I am.   ;)   I *am* kinda fussy and that's why my ugly-ass 
'60 has good brakes.   And, I'm keeping a very close eye on those 
rear wheel bearings that have been repacked regularly, last time with 
premium hi-temp synthetic grease.   They make a slight noise which 
I've been listening to closely... hasn't changed in years.  If it 
DOES change, they're gonna get replaced...

I've also converted more than one single bowl MC to a dual bowl MC... 
of course the '67 and the '69s don't need it.   The '60 and Lakewoods 
are kinda stuck as-is with the single bowl unless I get very frisky 
with a welder, so they get their share of attention and if the MC 
needs work, it gets it.

Last time, I rebuilt the '60 MC in the kitchen sink.   ;)   Easy cleanup.





I intend to drive these cars.   I'm always listening, watching, 
noticing.   If something brings itself to my attention, it gets 
attention.   ...been driving that '60 sedan for 25 years and I don't 
intend to stop now.   Sure, nothing wrong with being very careful but 
not wanting to drive the car, because you're afraid of something bad 
happening if you do, may well be stretching things, especially if you 
do simple preventative maintenance to make sure things work like 
they're supposed to work.

Do this, and the car will do what it was intended to do.   No problems.



tony..              ...annoying