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MG MGA - Uprated power requires improved brakes?

One thing I have never understood, is the constant reference to having to improve the brakes when putting more engine power under the bonnet. If the engine weighs the same, why do the brakes have to be improved. You are still stopping the same weight from the same speed at the same repetitive rate etc.

I understand that there are improvements that can be made. And I also understand that the possible more spirited use may tax the older brake system. But most of us still run our cars within (wink-wink) the speed limit on everyday streets. Yet the topic always seems to come up that with faster acceleration there must be improved deceleration (I know, there is no such physics term). The connection just doesn't make sense to me.

Why is this so?

Chuck
Chuck Schaefer

Chuck! C'mon, think about it... what are the chances that you'll be going the same speed? Is the only reason for more hp better 0-55 times? I don't think so.

Concerned

Chuck

Speed of the vehicle squared is proportional to the temperature rise in the brakes. If the speed at which the brakes are used increases by 40% the temperature rise in the brakes would increase by nearly 100% {1.4 x 1.4).

The assumption is that you intend to use the additional bhp, which as you pointed out is not always the case.

Paul
Paul

If you need to slow down quicker when the radar detector goes off, you need better brakes.
Tom

It's not about speed, it's about safety in an environment where all the other cars on the road have disc brakes. I put front disc brakes on my MGA because I think the modern cars in front of me had better stopping power. A perfect example happened on the way to my office earlier this week. A pickup truck in front of me did a panic stop at + or - 35 mph (it was a two lane city street) to avoid hitting a dog. I was a couple car lengths behind, but I do believe the front discs kept me out of his tail gate. I know there are some good people on this board who believe well-maintained drum brakes are just as safe, but I'm not one of them. Another reason I like the front discs is that it takes a lot less leg muscle on the brake pedal than it used to take to get the MGA slowed down and stopped.
Frank Nocera

Even the original discs on the later cars are no match for today's modern brake systems. large discs, anti-lock technology and 4 wheel power brakes all conign our systems to the ever increasing pile of junk known as yesterdays cutting edge technology. If you're going to spend money on performance--it just makes sense to spend it on ALL aspects of performance. Sometimes it's more important to get from 60 to 0, than it is to go the other way. Those of us with original equipment should keep it in mind, and drive (like Frank) accordingly.
R. L Carleen

All very good points.
If you are to modify and improve the MGA, then the safety items should come first. No argument there. Seatbelts come to mind first. Brakes maybe a close second. I have added a 3rd brakelight only because I have been rear ended more times than I can count on 1 ,and possibly 2, hands.

I don't use the A for anything but recreational driving. I don't use it as daily transportation. When the rare occassion occurs where I do have to drive it thru rush hour traffic, I am very, VERY mindful of the distance to the car in front of me and all other driver induced hazards. I have never been more defensive in my driving habits than when driving my A(except maybe when I had my motorcycle).

But none of the answers really address the often stated advice of "More powerful engines require better brakes". Maybe it would be better stated, "Today's driving conditions require better brakes".


Chuck
Chuck Schaefer

I've enver understood that outlook either. By all means, make your brakes work better. But if your new 160 horsepower MGA can't stop properly from 80 MPH, or control the car's speed in a fast run through a tight canyon, then it couldn't do it safely when the car had the stock engine either.

The only reason you would NEED to upgrade a set of brakes that work fine on your car which will "only" go 100 MPH, is if you plan to use the new power to drive 125 MPH.
Steve Simmons

Chuck

Tyre grip stops the car, so tyres are first improvement or at least keeping them in good condition.

The brakes need to apply sufficient brake torque to keep tyres at approx 10% slip the point before lock during the period of braking or multiple braking. The brake system needs to provide the driver with the information to maintain maximum braking, sophisticated ABS systems can do this for driver.

The brake system then has to dissipate the heat from high speed stops or multiple stops to suit your requirements.

With increased Bhp an assumption is made that your driving may be more spirited than the OE system was designed for on OE spec engine. This assumption may be incorrect or the driver can allow for imperfections in the system. Equally a driver of a OE spec engine may drive in a more spirited manner or "todays conditions" that warrant an increase in braking performance.

MG made the decisions for the owner at time of build, with modifications the owner now has to make these decisions in the current driver climate.

Paul


Paul

This thread was discussed between 27/10/2005 and 29/10/2005

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This thread is from the archive. The Live MG MGA BBS is active now.