Kelvin,
A thoughtful and well-reasoned answer.
It does seem that I should just make sure the regular ones are in tune and
buy a top set of tires. Then I can save my money for other higher HFPD
items (like an OD transmission? :)
Thank you (and all others who responded).
- Tab
At 10:56 AM 4/25/00 -0700, Dodd, Kelvin wrote:
>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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