The "race pedal box"

[Lee]

I always found that the two extra linkages between the brake pedal and the master cylinder was a source for slack and feeling of "remoteness".

There fore, I have started fabricating a pedal box where the MC is bolted directly on it. Therefore I acquired a pedal box, emptied it and ground the upper section. Then, measuring the distance between the two pedal stems, it was clear it was not enough to clear the brake MC and the clutch MC. The brake pedal could not move to the right because of the throttle rod. Therefore the clutch pedal had to move to the left. All it took was to remove 15mm from the metal sleeve/pivot, and from the nylon sleev, leaving the inner steel sleeve intact. An aluminum bushing with 14,1mm ID and 15mm width will keep the pedals apart. Then I drilled a hole on the pedal stem, about 32mm away from the pivot, which gives a 6:1 pedal ratio (pedal is 195mm long). I used one of the clevis to make the linkage. Next step is to fabricate a monting plate for both MCs, from 1/4" steel, cut the back of the pedal box, and weld the plate.

The intent of such fabrication is to bring more feel in the brake pedal, make the car a bit lighter at te front for the S14, and clear the fiberglass DTM airbox. The car is a track car only driven on public road to go to the events.

Picture coming soon.

[instructorbill]

ooohh pictures please, what master cylinder, details!!!

No booster too I'm guessing.

[peteinjp]

Lee,

Excellent description. If your going to all the trouble why not incorporate a balance bar?

P.S. I put the cover on the s14 cam box- super slick! Thanks again!

Oh and I forgot to ask but if you still have a set of Motor Mount brackets I'd love to get them off you. I'll use them to fit the s14 on a spare subframe and check out what needs to happen to the oil pan.

Pete

[NickVyse]

I've finally sourced a decent shell to re-shell my Touring and I'll be using the RHD pedal box fabbed into the LHD bulkhead. As you probably know RHD pedals hang from under the dash - they have only one pivot point and operate direct to the MC, and you can then mount the remote servo where you like.

Having driven both types of pedal for sometime I think the RHD feels much better all round, even the arc of action just seems more 'right' if you'll pardon the pun.

Mine will be a road car not a track car so you may have different priorities - but it's food for thought.

Nick

[Lee]

Hi Pete

When I boxed your parts, I couldn't remember what was missing. Damn, now I know. The set of engine mounts. Please post a picture of the installed block-off plate. I just got te S14 and need to de-gunk it and make a thorough inspection before I can install the plate.

In regard of the MC spacing (clutch and brakes) I measured I needed 62mm center to center. The relocated clutch pedal allows me to get 64mm. Only 2mm will separate the two MCs.

BTW I am using a single MC to make things simple. The way the caliper pistons are sized, it will be okay.

Lee

[peteinjp]

Yeah i forgot about it too- until you posted about cutting up the oil pan....

I'll get a shot of the plate installed soon. It looks too cool.....

Not sure how I got the idea that you were going towards a double master setup. I'd love to see a pic when you have it all done.

[Todd21]

Lee,

Where is the picture for this mod? I'd like to get a look at it.

Thanks, Todd

[Lee]

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[Mike_B]

Very nice!

What is the pedal ratio?

[Lee]

Very nice!

What is the pedal ratio?

Pedal ratio is 6:1

I will use a 23.8mm MC with 1.63" front and 1.12" rear pistons and if it feels too hard, I will go to a 21mm MC. If too soft, then will go to a 25.4mm MC.

[Baikal.2002]

Which MC did you end up using? Do you have finished pics with both MCs installed?

[Lee]

Which MC did you end up using? Do you have finished pics with both MCs installed?

Here's a little follow-up since my 2002 now has a new cage, 3rd version oil pan that leaves a lot of room all around (more about that) and most importantly, the car is now back in my yard. Ready for reassembly (gutted doors, pedal box and CTM CF airbox, Recaro SPG etc).

In regard of the pedal box, the main difficulty comes from fitting an ATE master cylinder as it has horizontal mounting points, and they make the assembly quite wide. Requiring to space the the clutch and brake masters, as well as the pedals. Even though my pedal box is almost done, and designed for an ATE master, I will make some changes so that it can accept a Tilton or Wilwood MC.

First they are cheap as a complete kit with reservoirs. From $70 to $100 for a complete kit. Also, they come with vertical mounting points. Which makes they location on the front plate much easier. I think it doesn't even require to space the pedals out.

Between Tilton and Wilwood, I am getting a Tilton 75 serie MC as it is shorter than the regular size (about 3.2"). Don't forget that as the MC is located below the calipers, you don't want brake fluid to flow back into the MC. Therefore it is required to install a 2lb residual pressure valve.

I am starting with a small 3/4" MC and will see how it works.

[Harv]

Don't forget that as the MC is located below the calipers, you don't want brake fluid to flow back into the MC. Therefore it is required to install a 2lb residual pressure valve.

If the res is up high on the fire wall, won't that be enough? Single circuit brakes?

John

[Lee]

If the res is up high on the fire wall, won't that be enough? Single circuit brakes?

God point, John. I did not think of that. If the reservoirs were to be located remotely, higher up, then the residual pressure valves won't be needed. I guess that guys with the reservoirs directly on the masters will need them.

Single circuit. One piston for all four calipers. Hydraulic pressure will be the same everywhere anyay.

Lee

[Harv]

If the reservoirs were to be located remotely, higher up, then the residual pressure valves won't be needed.

Plus, it would be a bitch to fill up the brakes from down there.

John