I found a 911 front suspension, now what? newbee question Options

[Thierry]

Hi,

I recently bought a nice '76 2.0 that I would like to give some extra goodies. One of the projects I'm looking at is doing a 4-5 lug conversion. I read most of the articles describing the process of doing so and I think the route with a 911 front suspension is the way to go.

So I found these parts of a (supposedly) 3.2 911 online but then the questions start popping up. The missing parts are break callipers and master cylinder. As I understand 3.2 breaks also use a break booster. Is that also needed or would a 19mm master cylinder also work fine? What breaks should I search for? What will work and is doable for a newbee 914 fan?

Anyway, thanks in advance for helping my with my shopping list.

Thierry

[mepstein]

Horsepower means nothing when it comes to braking. Only mass and velocity.

[Superhawk996]

Horsepower means nothing when it comes to braking. Only mass and velocity.

(IMG:style_emoticons/default/agree.gif) but will add the other important factor is tire friction (mu). And a slight correction -- what matters is acceleration (deceleration). Acceleration is the change in velocity per unit of time.

You don't need big brakes if your going 60 mph but have miles and miles to stop. If you want to stop in 130 feet, that will take some bigger brakes.

To elaborate on Mark's math:

Force = mass x acceleration

So where does the Force side of the equation come from? The tires!

Force = Tire mu x weight on the tire is the equation that defines tire force.

So the entire system is governed by:

Tire mu x weight on the tire = mass x acceleration.


Mass is set by the vehicle itself and acceleration (deceleration) is determined by the driver.

Therefore, Braking distances are determined by braking forces over a period of time, but, are ultimately dictated by what the tire can deliver. . We won't go down the path of the math to determine braking distance.

Giant brakes on hard rubber and/or skinny 4.5" tires of the 60's and 70's will still have terrible stopping distance.

Braking endurance is determined by the size of the components which provide thermal mass to keep fade at bay as previously pointed out.

Yeah, there is a lot more to brake sizing (balance, effectiveness, pedal feel, etc.) but I find most folks don't really appreciate that stopping distance is set by the rubber.

So when you say you need bigger brakes, the question is to really ask why? If you can lock up the brakes, what you really need is better tires. When you have so much tire that you can no longer lock up the brakes, now it's time to mess with the brakes.