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

[horizontally-opposed]

…if going with boxster fronts, you should have boxster rears to balance out the equation. If going with S or A up front you should have Ms or 914-6 rears... balance your setup

This isn't said often enough.

So many cars get an upgrade up front and make do with whatever they had in the rear, or something "close enough."

Pedal feel is intertwined with hydraulic displacment at the master cylinder vs. the displacment requirements of calipers. It has little to do with "bigger" brakes whatever that term may refer to (size of calipers, size of rotors, or both).

Pedal feel is also greatly affected by brake pad compressability which varies widely from compound to compound. Quite often bigger brake pads with high compressability result in even more fluid displacment which degrades pedal feel for those that prefer force modulation.

To compound matters, there is no ideal. Some people prefer travel modulation, others prefer force modulation. Some prefer the Goldilocks version in between.

Mixing the idea that bigger brakes results in better pedal feel will lead you astray.

^ Great post.

There is more to brake performance than stopping distances or the ability to lock the wheels up. Brake balance, modulation, pedal feel, and resistance to fade are other parameters—all of them are important to control and driver confidence—with perhaps fade resistance being the most important to me.

I've encountered fade on the track and on the road, for very different reasons: Circuits work brakes harder but tend to give them a chance to cool at speed where some mountain roads never give them a break, and don't offer much in the way of speeds sufficient to cool the rotors before the next pounding. Having to drive around the brakes (or even the mere smell, a clear signal of where things are headed if you don't adjust your style and/or speed) is distinctly unfun and shakes confidence in the car not just for that drive, but future drives.

This ad deals with the issue of fade really well:

http://www.vehiclecraft.com/Brakes/930_upgrade.htm

Why the 930 Upgrade? Why not the "Boxster" or 964 calipers?

The main part of a braking system that has to deal with the heat absorption and dissipation is the brake rotor - not the calipers. So their size and mass is the main factor in choosing and upgrade. Simply put the 930 upgrade offers the largest rotor size available that will fit inside stock wheels and narrow body of most 911's and 914's. The Boxster and 964 upgrades that are being sold are based on a stock size 911 carrera rotor (24 x 289mm). While the calipers are noticeably larger, and provide more stopping power than the original small steel calipers, they actually make the main problem worse!Putting more heat energy into the same small rotor dose not solve problems, it makes them worse.
This is where the 930 Upgrade really does the job. The rotor size is 12.0" x 1.25" front (300 x 32mm) and 12.18" x 1.10 rear (310 x 28mm). This is about double the heat-sink capabilities of the original rotors! Of course along with those rotors come the 4-piston 930 calipers also about doubling your stopping power. To put it in perspective, this rotor size/mass is about 85% of what a Big Red rotor upgrade is

While I agree that rotor size is too often skipped over, I can't see the OP needing anything larger than the rotor in his pic with a 2.0-liter Type IV. Suspect that rotor is probably just fine up to 200 hp in most use cases. If the OP is going to keep the stock rear brakes, I'd aim for the best front caliper to match them that will work with those 911 rotors. I've been running the "Alfa" aluminum two-piston Brembos made popular in recent years and like the setup, but have been eyeing 986 calipers all around.