pedal height specifications

[oly]

Does anyone know what these values are for a 1985 Carrera? There are plenty of brake pedal height posts but none give Porsche's intended height range. And I don't want to use the trial and error method of finding out that I have too little brake throw while driving.

My goal is to lower the pedals for street driving but stay within the specifications. I have a Panorama from 1997 that says the you can adjust the brake pedal by about 5/8 ths of an inch. But it does not say how to make sure that you don't have too little throw. I can't find any specs in my Bentley manual either.

Art

[jorian]

Subscribed - my brake pedal is too high to heel & toe.

[Por_sha911]

Its like salting your food-all a matter of taste. Just be careful not to set the brake pedal too low cause you'll loose some height during Auto-X from fade and you don't want to run out of brake room before you run out of braking zone.

[oly]

Por_sha911,

Thanks for the post. But I've read the subjective "don't set the brake too low" advice before and don't want to use it. I'm sure that advice works for somebody who has lots of experience driving the car hard. But I don't have that experience so I don't have confidence that I can identify what "too low" feels like. And I don't want to gain that confidence by leaving the road because the brake pedal was "too low". So I'm hoping to take the easy way out and just use objective Porsche specs.

Art

[oly]

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[oly]

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[javadog]

I've never seen a spec from Porsche that specifies how much you can adjust the pedal height. I'm not sure one exists. I think you are on your own here.

Try the 5/8ths inch adjustment and see how it feels. If your brake pads and fluid are in good shape you'll be fine. Keep in mind that the harder you brake, the easier it will be to heel/toe, as the brake pedal will be much closer to the floor. When poodling around town at low speeds, you won't depress the brake pedal as far and it will seem harder to heel/toe.

JR

[ZOA NOM]

Rather than lowering the brake pedal, I raised the accelerator by about 1/2". I've found it to be helpful for heel/toe on the street, but it causes problems at the track due to more aggressive braking. My advice is to leave it stock. Adjust your driving to the pedals.

[jorian]

I think I'll raise my accel pedal AND lower the brake pedal just a bit. Even at the track under threshold braking I can't get anywhere near my gas pedal. My SC's pedals are set up great. I can heel and toe on the street and track and have never run out of pedal travel at the track.

[oly]

Rats...

[oly]

Jim Pasha (the Excellence Tech Forum writer) has these comments for a 1985 Carrera:

"I checked with a few people at Porsche on this one. They do not recommend changing the pedal height via the adjustment rod as that is adjustable to ensure that the master cylinder gets full stroke. The did say that the pedal play is 10mm as is confirmed in the 911 service manual. In your car you have bell cranks which transmits the motion to the master cylinder which is in the front trunk. Changing the ratio changes the amount of pedal force transmitted to the master cylinder. From what I can see, this will reduce total braking effort."

"10 mm free play before the brake pedal starts to operate the master cylinder. That's what the adjustment is for.

On most of the race cars, I add spacers to the pedals to bring the face height up equal for the brake and gas. Teh gas is the pedal I usually play with first. On the brake, I make the face larger so that the gap is smaller You do have to be careful operating the pedals when you do this. What I usually do is get another gas pedal, figure the height and drill holes in the existing pedal to add spacers and the modified second pedal."

[jorian]

Good post oly. I haven't moved the brake pedal yet buy am experimenting with the gas pedal.

[ZOA NOM]

What I found easiest was to simply remove the accellerator connecting rod and lengthen it. I used an old linkage piece from my door lock assembly.

[oly]

Zoanas,

Could you get a smaller pair for you animation? Those basketballs are KILLING me.

: )

[oly]

I'm diverging from my original subject. But here are some more related bits of information from PCA Tech people:

Allan Caldwell 3-13-02, answer to someone elses question:
Yes, the brake pedal can be lowered by adjusting the linkage in the pedal cluster assembly that connects the brake pedal bellcrank to the master cylinder. On all the 911s from 1977 on with the master cylinder in the front trunk compartment, there is an actuation rod with an adjustable ball joint on each end that can be changed in length to lower the static brake pedal position. It is important to make sure that there is adequate clearance with the floorboard when the brakes are fully applied.

My question (12-24-02):
Same as my first post in this thread.

Chris Powell 12-24-02, response to my first e-mail:
The only spec given for the brake pedal adjustment is that there should be 10mm of play after the brakes have been bled and the engine stopped. Since Porsche considers the high pedal as being correct, they don't give any other numbers, even though they do give you an adjuster. I think Al's (Caldwell) description is accurate, but I would emphasize "fully applied", meaning threshold braking from high speed. I have lowered brake pedals before, and this is the method we use. You can lower it more than 5/8", and I think you would run into clearance problems with the floorboard before it actually would not work. It really does take a trial or two to get it where you want it. Experiment with the height before you bolt everything back together. You will find that it behaves differently while driving as opposed to sitting in the garage.

I proposed (12-24-02), in my second e-mail:
Do you have a recommendation for a first trial setting? I plan to use 1" of clearance from the floor boards when I have the pedal all the way forward (with brakes bled and engine stopped). Does that sound reasonable?

Chris Powell 12-24-02, response to my second e-mail:
I would start with 1-1/2" (when brakes bled and engine stopped), as the pedal will drop a bit once you get vacuum to the system.