JSG

I have three things I want to do, in order of importance:
1) Reduce steering lock-to-lock turns from 3.0 to 2.46 (or around that figure)
2) Reduce brake pedal travel by around 50%
3) Reduce accelerator pedal travel by around 50%

Will this be hard to do you think? I have no experience of ever mod'ing a car. I assume mods like this won't affect insurance.

My problem is that we've got a great car, great engine, great chassis with a sedan user interface. I can't get used to how far I have to move all of the controls to get a reaction. I'm very happy with the reactions when I get them but it feels I'm making too much effort. Your arms and legs are punching and flailing on a twisty mountain road where I just want to flick the steering and gently push (not stamp on the pedals). I haven't measured but there has to be over 30cm or more of travel. Full throttle is a long way down and so is decent braking power.

If anyone ever hears of people who can do/offering these types of mods then please PM me!

Sputnik

Yeah, I normally end up going with power steering on sports car models because they normally offer less turns to lock. The NB Miata is one example. But if Mazda doesn't already make a steering rack with the ratio that you are looking for, it will be very expensive to get a good custom setup made for you. Especially since it isn't a standard design. The best/easiest way I can think of is to modify the pedal so that the "pivot point" is relocated. This will be awkward to do, but it can be done. Changing out the master cylinder might be a different way, but it would involve alot more to get a balanced system, and would void alot more warrantied items. The only way I can think of effectively doing this with the "fly-by-wire" setup is relocating pivot points and attachment points on the pedal itself. Again, awkward and difficult, but doable.

---jps

MaRX8

Since the system is "Fly-By-Wire" I would think you could adjust the setting inside the CPU of the car. You would have to have a tech do this of course. Since the system is Fly-By-Wire, it would be like adjusting the settings or calibrating a Joystick on a computer system. You could probably have this done for the Gas and Brake system. But the steering system would be different as far as I know.

This is just theory. But I think it would be possible.

JSG

Thanks for the comments. If it's going to be hard / expensive / void warranties I'm probably not going to do it. But I was hoping there might be a computerised way of doing it as even the steering is electronic.

I think my best bet is to wait until Mazda makes a MazdaSpeed 8 or something similar which has settings similar to this, then buy the parts and move them over.

Sputnik

How would you be able to affect the brake pedal travel by a CPU setting?

---jps

MaRX8

You wouldn't actually effect the brake travel, you would effect the pressure applied based on the amount of travel.

Standard set up would be

100% travel is 100% pressure applied.

Recalibrated would be

50% travel 100% pressure applied.

There would still be travel in the brake pedal, so this would manually have to be adjusted also. As far as feel would go.

Efini 8

I know that you can tighten the throttle cable, but the rx8 might be different. this allows faster response in throttle

wakeech

...it's an electronic throttle, there is no cable.

Sputnik

The steering is merely electrically boosted, so changing it would be similar to a normal steering rack (as opposed to the unit BMW is installing in the one car). Depending on how things are setup, you might be able to adjust boost levels, but not the steering ratio.
And how are you supposed to be able to do that by modifying the CPU?

---jps

MaRX8

The CPU would have to connect with a cable interface that would connect to another computer. I'm sure there would be a way to adjust the settings with this computer setup. I don't think you'd be able to do these adjustments on your own. (Fly-By-Wire) means your driving by electrical wire. Or basically a computer is controlling everything. Your Gas and Brake pedals are like game controllers, connected to the CPU. You provide the input through the pedals, the CPU issues out your commands to the other parts of the car. So calibrating these is a possible situation.

B-Nez

Yes, it is throttle-by-wire, but is NOT brake-by-wire. The brake pedal is connected to a master cylinder via a brake booster like any other car. The CPU does not control braking force - only the ABS and application of brakes with DSC.

MrWigggles

A smaller aftermarket steering wheel would be the easiest way to make the steering more responsive. Not exactly the same but similar.

Changing the pivot point on the pedals like Sputnik mentions probably won't be that difficult and is pretty straightfoward. It is merely a mechanical change; sort of like a short shift kit. If you want to make the pedal travel 50% less, make the lever 50% shorter to the pivot point (mind you the pedal pressure is going to be twice as hard.)

I wouldn't want anyone modifying the code for throttle by wire. That is one area that you don't want a computer bug!

-Mr. Wigggles

Sputnik

That's where I was heading. And even if you can change the throttle input in the CPU, that won't change the pedal travel, which is what we are trying to do in the first place.

---jps

RomanoM

JSG, follow the link to see what's involved in brake pedal travel and feel.

Then you can best decide if and what you would like to do.

The RX-8 DOES NOT HAVE brake by wire.


Pedal feel in general:
http://mysite.verizon.net/romano.michael/#_Pedal_Feel_2

Master cylinder and caliper sizing on pedal travel:
http://mysite.verizon.net/romano.mic...aster_cylinder

Farsyde

wouldn't something like gas pedal settings be hardcoded into the ECU?? Maybe just move the seat forward alittle more will help you out.

Section 8

i can't help you with the steering or throttle question, but as for the brake pedal, here's a suggestion: Replace your rubber brake lines with stainless steel lines, you'll get a much stiffer feel, and better brake response, however you'll want to check the new SS cables about once a year, and possibly replace them, the only drawback to the rubber, it will require more maintainence.