Tab:
The majority of brake modifications offered are to prevent brake
fade after multiple hard uses. This normally does not happen in regular
street driving unless one lives in canyon country and makes suicide runs up
and down the roads.
There has been a wonderful discussion of vented brakes on the E-Type
list with the supplier of vented rotor kits stating that most owners have
absolutely no need for his product.
It's all a question of mass and momentum. Heavier mass, or higher
velocity requires the generation of more heat to slow the vehicle. Most MGs
are light and do not make many hard stops from high speed. Panic braking
tends to be a one time event (unless you are in LA) and the brakes then have
time to cool. As stated, the MGB has more than enough brake to lock up all
wheels if you put enough foot pressure on the brake pedal. Under hard
braking the center of gravity moves forward lightening the rear end. This
allows the rear wheels to lock up, which is the limiting braking factor. To
prevent this different diameter wheel cylinders are used to reduce rear
wheel braking.
The four puck vented brakes from the UK are real expensive, and not
legal for most racing in the US. That is why Moss has never carried them.
I'm hoping that we can come up with a US supplied set up at a more
reasonable cost sometime, for the Ricky race set.
Drilled rotors look really cool and do improve cooling. So they do
qualify as useful HFPD accessories. (This is a standard of coolness that I
created in college, measured in quantity of sexual gratification per dollar,
HFPD items include LED meters on stereos, plastic wheel covers etc.) As
for wet weather improvements, the concept that water will magically
dissipate through the holes IMHO is hooey. The lack of braking in wet
weather is due to the rear drum brakes getting all icky, nothing to do with
sweeping water from the front discs. Test this by slamming on your brakes
in the wet. The front wheels will lock almost instantly.
The feel of your brakes is what makes the driving difference, not
the real braking ability. Increasing the braking ability for a certain
amount of pedal force gives the feeling of better brakes. The braking
ability is limited to the grip of the tire under braking conditions. Bigger
brakes give the impression that there is more braking ability, because for a
given pedal pressure the car stops quicker. If however you are able to lock
up all four wheels with stock brakes, then you are gaining nothing in
braking ability, except the lack of leg exercise. Improvements come from
the ability to modulate pressure so that maximum braking force before lockup
can be exerted. It is easier to modulate the brakes at lower pressures,
than with your leg mashed to the floor. That is where brake servos and
bigger brakes come in handy. You can apply full braking with more control.
Increased cooling ability becomes useful only under aggressive use, not
normally found in street driving.
Tab. My suggestion is that you make sure that your stock brakes are
in good condition, and adjusted correctly. Then take a good hard look at
your tires. I would put any investment into your tires first, as they are
the weakest link on the car. A high quality 185/70 tire mounted on the
stock Rostyle or 5 1/2 inch alloy will make a huge difference to all around
safety.
BTW don't worry too much about misquotes. Most advertising text is written
at the last minute by well meaning folks, who don't always get it quite
right.
Kelvin.
> Before I misquote our friends at Moss...
>
> I have seen something in their catalog, pretty sure, and I
> believe it was
> the cross-drilled rotors, basically with the holes to let the
> water out and
> stop faster in wet weather. I agree in theory it makes
> sense, but I'm
> looking for someone who actually has tried them.
>
> However my Moss catalog is in the MG at the moment, and the
> MG is at the
> shop getting some work done to it.
>
> The VB catalog is here, though. They offer 2 things. It may
> be my fault
> for not differentiating. First (pg 28 of Spring 2000 edition) has
> "Ventilated Brake Disc Rotor... For Safer & Shorter Stopping
> Power" (With
> the Ventilated Disc Brake Rotor Set you can improve your brakes heat
> dissipation to insure safer, straighter, and shorter stopping
> power. Ventilated with holes to help keep your brakes
> cooler, any water
> that forms is shifted into the holes, therefore the need for
> the brake pad
> to shift the water before it begins braking is eliminated. The more
> efficiently your MGB's brakes dissipate heat, the more
> efficient they will
> perform."
>
> Second, page 26, what I looked quickly and thought was the same, is
> not. "The Ultimate in Stopping Power for Your MGB" (and it
> lists years
> 62-80, so I'm not sure this is the same as what Kelvin was referring
> to). "(marketing stuff snipped) Complete Bolt-on brake kit Includes:
> Vented rotors with adapters, 4 piston calipers, Carbon fiber
> disc pads,
> Stainless front brake hoses, and Hardware. The four piston calipers
> increase clamping power of carbon fiber pads on vented
> rotors. This gives
> you many benefits: decreased stopping distance, better
> cooling, and reduced
> brake fade. These brakes perform better and last longer under harsh
> conditions. Track proven on MGB race cars. This is the kit
> MGB racers are
> using."
>
> The picture, now that I look at it, clearly shows the kit on pg 26 is
> vented (on edges) and not cross-drilled (like the
> "Ventilated" ones on page
> 28).
>
> I'm interested in opinions on either kit. Given what Kelvin
> said about my
> having power brakes, is the Vented Rotor kit still
> applicable? Which I
> presume it is, given it lists the years 62 to 80 (mine is a '78).
>
> Hope this clears it up a bit...
>
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