Brake pedal feel: How do you like it?

[1 Wild R/T]

Well… how hard is it to purge the DOT 5 stuff and go back to DOT 3?
I only bought the DOT 5 to preserve paint.

Since you've already gone to DOT5 I'd leave it... But I would be religious about bleeding the brakes every years... Just a little out of each bleeder... Since moisture seeks the lowest points it will be at the wheels, just flush it out...

 

[Kern Dog]

That makes sense. Tighter maintenance intervals are fine by me.

 

[1STMP]

Well… how hard is it to purge the DOT 5 stuff and go back to DOT 3?
I only bought the DOT 5 to preserve paint.

The system should be thoroughly
flushed. Mixing dot 3 or 4 with dot 5
creates a gel.
Been reading up on this a bit. Some
say the dot 5 is absorbed into the
rubber parts of the brake system since
it's a silicon base, and, that changing
back to dot 3 or 4 will gel some with
the dot 5 fluid absorbed into those
parts. But I would think that would
depend on the type of rubber those
parts are made from.

 

[Kern Dog]

I've read that a few places too.
Screw that....I'll just keep the DOT 5 and change it out every 2 years or so. It isn't humid here and we may be moving to Arizona where there is even LESS humidity.

 

[EmitRDetsaw]

Don't simply flush DOT 5 out with DOT 4. All rubber rubber brake system components need to be replaced and the metal parts inspected for corrosion and then replaced/cleaned as necessary.

BTW, I like my brake action to be progressive, yet aggressive. Still haven't found the perfect balance yet.

 

[68 Sport Satellite]

Not so much moving or flexing.
But line pressure. Most of the
flexing occurs at the caliper,
and associated parts/hardware.
The appropriate pressure at the
caliper is key. Utilizing lines
engineered for a 4 drum system
move to much volume of fluid
for a 4 disc system.

Interesting and makes sense on the brake line ID. On my car it came stock with 4 wheel power drum and I converted it to front disc / rear drum, but the lines were left as-is.

 

[Kern Dog]

Same here. 3/16" lines everywhere.
Who ever bothers to change the size of their hard lines?

 

[1STMP]

Same here. 3/16" lines everywhere.
Who ever bothers to change the size of their hard lines?

Not many would.
Many factors come into play when
designing a braking system. Factory
set-ups are designed around GVW,
pad/shoe surface area, wheel cylinder/
piston volumes, pedal arm ratios, total
system fluid volume, master cylinder
piston diameter, caliper/shoe
bracket integrity. And must meet
a percentile of the driving public.
Your 150 lb wife can stop the car
at the same proficiency as your 300
lb linebacker son.
The system on my build took a month
or two of calculations before buying
any of the system components.
Pieced together with a hodge podge
of parts. My guess at final GVW was
3200 lbs. with the system designed
around that number. After everything
was assembled (interior, front and rear
bumpers, etc,) it came in at 3100 lb.
Each major part was weighed before
being added to the sprung/unsprung
weight. This info is needed for the
suspension calculations as well.
And the braking works very well.
Panic stop straight and level, all four
leave their mark from 50 to 0.
Vendors that sell aftermarket
conversions rely on an average of
performance as the system they
provide cannot fine tune for every
scenario of the system for your car.
Though, most are adequate.
Hope you can understand where I'm
coming from with this wall of text.
Anytime one deviates from proven
factory systems, there will be certain
issues that need ironing out. And
they're going to be different for
every car.

 

[Kern Dog]

Your 300 lb ex wife can stop the car
at the same proficiency as your 160 lb nephew.

I had to correct this to be accurate.

 

[1STMP]

I had to correct this to be accurate.

Now that, is funny! I stand corrected...

 

[Kern Dog]

She was so fat, I had to get to the restaurant early just to get an estimate.

 

[1STMP]

Interesting and makes sense on the brake line ID. On my car it came stock with 4 wheel power drum and I converted it to front disc / rear drum, but the lines were left as-is.

Is your braking system functioning at
or above what your four drum system
delivered?

 

[68 Sport Satellite]

Is your braking system functioning at
or above what your four drum system
delivered?

don't know. I converted it immediately after buying it in 2010 because it has other issues and was pulling to the left, so I didn't get to do a good comparison.

 

[Scott Engelhardt]

She was so fat, I had to get to the restaurant early just to get an estimate.

 

[Scott Engelhardt]

I like a semi-firm pedal. My F250 has a great pedal. It reacts fast in a panic stop, but it is smooth during normal stops.

 

[Kern Dog]

I've been reading online about master cylinder bore sizes and how they deliver different types of "feel".
The bigger the bore, the shorter the pedal travel and the higher the effort needed by the driver to stop the car.
Some people like a pedal with a longer pedal stroke because it allows them to incrementally sneak up to the limit instead of accidently reaching it.
Other people like the shorter pedal stroke because to them, it inspires more confidence since the pedal reacts further up off the floor.

 

[68 Sport Satellite]

I've been reading online about master cylinder bore sizes and how they deliver different types of "feel".
The bigger the bore, the shorter the pedal travel and the higher the effort needed by the driver to stop the car.
Some people like a pedal with a longer pedal stroke because it allows them to incrementally sneak up to the limit instead of accidently reaching it.
Other people like the shorter pedal stroke because to them, it inspires more confidence since the pedal reacts further up off the floor.

and with smaller bores the pedal is closer to the floor at rest than with a larger bore. With my car, I have power front disc / rear drum and with the 15/16" bore MC, the at rest height was not bad, but during a hard stop the pedal was almost at the floor. This was not confidence inspiring at all. When I switched to the 1-1/8" bore MC, at rest pedal height is higher and the end of pedal travel is now off the floor at a comfortable distance. I guess if I were to fine tune it, maybe something in between like a 1-1/32" could be perfect. It's all a balancing act when going with aftermarket mods.

 

[Kern Dog]

The pedal height at rest has been the same for me with several setups. I had manual, 73-76 A body power and hydroboost and all of them had a similar pedal height. All had different sized master cylinders including 15/16". 1 1/32", 1 1/16" and 1 1/8".
This B body booster has put the pedal much lower and I'm not happy about it. I'm tempted to modify something.
I could lower the clutch pedal but I'd have to make sure I still have enough travel for proper operation.
Another option is to modify this pushrod:

Without having an adjustable pushrod, I'd have to do some mock-up work to get the length right. I have spare pushrods that I could cut and weld together....I could start with adding a small amount like 1/4"-3/8" and see how close it is. I think if I get it sort of close to the clutch pedal height, I could adjust the clutch linkage to get them to match.
I know what the down side is.
A higher pedal than the factory intended means that at the end of the master cylinder travel, the pedal may not touch the floor.
So what...? Once the system is bled out, it should never reach the floor anyway, right?

 

[1 Wild R/T]

Take a look at the pushrods you have... There are different lengths...

It wouldn't be difficult to make one of your spares adjustable... Send it to me & I'll make it happen..

 

[Kern Dog]

That is a generous offer. I do wonder though....
I could cut the stock ends off then weld a male thread on the end of one and a female on the other, huh?