Brake upgrade, Parking brake Options

[Krank]

I have been thinking about doing the beemer front disk brake upgrade. The only thing that bothers me is the loss of the parking /(cough, cough) emergency brake. I had an idea to look for a motorcycle front disk brake rotor mounted to the axleshaft with a cable operated brake assembly mounted to the tranny (I think there are three useable bolts on the RH side). Anyone play with this idea before?

[Eric_Shea]

If your F100 brakes lock up your wheels... their job is done. How could they suck? You would only need a larger contact patch to get better braking once your wheels lock (read: fatter tires).

If you don't know how to drive down a mountain without getting brake fade (in a car that should "never" experience brake fade other than "heavy" track duty) you really shouldn't be driving a 914 down a mountain. (IMG:style_emoticons/default/biggrin.gif)

Carrera calipers weigh 9+ frigg'n pounds EACH. I will guarantee you I would "Never" put those on one of my 914's. But wait, it gets better... 24mm Carrera vented rotors add an additional 4lbs. each. Welcome to nearly 20lbs. of additional UNSPRUNG weight to your 2000lb sports car. Guess what, the BMW caliper weighs almost the same! (IMG:style_emoticons/default/biggrin.gif)

Upgrade away gang... I'm enjoying the show. (IMG:style_emoticons/default/thumb3d.gif)

P.S. My thoughts on "Why"people think they need "upgrades": Most of us enjoy modern cars on a daily basis. The wife has an E500 wagon with excellent brakes. My Cayenne has the largest set of calipers ever thrown on a standard road going Porsche (I found a small pony living in my right front). All of these brake systems are well designed and power assisted. Put your big toe on the pedal and the big car stops... really fast

It takes a few minutes to get use to the Cayenne after driving her car... now, imagine getting out of the Cayenne and going to a brake system from 1970, be it their top of the line 1970 914-6/GT model or a lowly (and lovely) 1970 914-4 (which has better brakes than anything in it's class!) Or... plop yourself into a 1970 Ford F-100. THINGS ARE GONNA FEEL DIFFERENT GANG.

Does this mean our brakes suck? All things being equal... NO. Your 2000lb 914 can still stop much faster than the 2012 7000lb. Suburban behind you so... keep that in mind.

Could they be better? Depends. To me, better means "stopping the car faster" and again, I'll go back to -- "If you can lock up your wheels with your current brakes, the answer is NO." Get bigger tires... you'll stop faster. Get better pads that allow you to modulate your pedal almost as well as an anti-lock devise... you'll stop faster. Learn "how" to brake/modulate and... you'll stop faster

Given enough money, time and engineering know-how, I'm sure someone could install my Cayenne calipers on a 914. It still won't stop any faster if the tire is sliding along on the pavement.

[914Mike]

...

Carrera calipers weigh 9+ frigg'n pounds EACH. I will guarantee you I would "Never" put those on one of my 914's. But wait, it gets better... 24mm Carrera vented rotors add an additional 4lbs. each. Welcome to nearly 20lbs. of additional UNSPRUNG weight to your 2000lb sports car. Guess what, the BMW caliper weighs almost the same! (IMG:style_emoticons/default/biggrin.gif)

... Get bigger tires... you'll stop faster.

A larger contact patch alone won't add to the amount of friction available for stopping. (Lbs per square inch goes down as the contact patch size increases.)

There needs to be more weight on the contact patch to get _any_ more friction. So the Carrera calipers and rotors actually help in that regard...

...Get better pads that allow you to modulate your pedal almost as well as an anti-lock devise... you'll stop faster. Learn "how" to brake/modulate and... you'll stop faster...

(IMG:style_emoticons/default/agree.gif)

[Dave_Darling]

There needs to be more weight on the contact patch to get _any_ more friction.

True in theory, not so true in practice. In theory, wider tires do not help with any grip. In practice, they do. That's because tires do not work on pure classical friction, they also have mechanical grip where bits of the rubber actually interlock with the irregularities in the pavement.

In general, larger tires will provide some extra grip. Softer tires definitely will.

Oh, but don't ignore the effect that wheel, tire, hub, and rotor weight! The heavier all of those parts are, and the further out the weight is from the center of rotation, the more work has to be done to stop them from spinning! You can see in some of the magazine tests that going with huge brakes and the equally-huge wheels and tires needed to fit around them actually INCREASES stopping distances!

But the point about repeated use is certainly valid, especially for cars on the track. Most especially for those with more speed potential than stock 914s.

--DD