My GTD pedal box upgrade.

I'm starting to put things together now with a view to getting the car back on the road by Feb/March time.
My upgraded brakes are here and ready to be fitted and I have enclosed some pictures of my GTD pedal box with the upgraded twin master cylinder/balance bar fitted.
This is a standard unit from Rally Design and has twin Willwood master cylinders as standard.
It fits to the GTD pedal box like it was made for it, requiring NO modification apart from four bolt holes to fix it to the GTD "upright" that the original master cylinder was fixed to.
I have a query about the amount of movement I need to acctuate the brakes and clutch though.
As many of you may know, the standard GTD pedal box was "adjustable" (after a fashion) and on my car was fixed at the position most rearwards (the previous owner was a lot shorter) I could drive the car, but noticed there was plenty of room BEHIND the pedals. I am therefore able to move the pedal box "upright" (A on the enclosed picture) further back (left) in regards to flat plate (B in the pic) about an inch and a half to give myself some more room. HOWEVER this means that the back of the pedal (Y) is very close to the front of the plate (B) at X (confused?...you will be...) does this mean that I won't get enough movement?

Another picture

and another

a fourth

last one

PART NUMBERS?!!!!!!!!! What is the wilwoood part number you used for the duel master with ballance bar. It looks like you used your old peddle. Did you use different bore sizes? What calipers did you use? What piston sizes? I gotta have it!! As you can tell I have been all over this the last couple of months.

I have just started sorting my wilwood rotor and caliper upgrade but have had problems with front to rear ballance. I think I will be able to work it out with a porportioning valve in the rear line but am still into it and with Christmas it will need to wait a couple of weeks.

I would love to hear more as you sort it out. Great job!!

Oh I almost forgot your question. Couldnt you notch the base plate to allow for clearance of ther peddles or is the base plate in alinement with the chassis cross bar. If so I think the wilwood catalog on line has dimentional drawing and mounting guidance. MERRY CHRISTMAS !!!!!!!

Howard,

It's a part made by Rally Design using Wilwood master cylinders. one of .625 and one of .75 (although they will ship with whatever size you want I believe)
You can find the part here...http://www.rallydesign.co.uk/catalog/product_info.php?products_id=4045
If the link doesn't work for you, the part number is RD 3636. As I said, it fits the standard pedal box like it was made for it.
I am using the standard sized master cylinders as a starting point but may need to change one of them when I get the car back on the road.
I will be using HiSpec calipers on the front and Scorpio calipers (with HiSpec big disc conversion vented and cross drilled rotors) on the rear.
It's all a "suck it and see" situation at the moment, I won't be roadworthy for a couple of months yet so will let you know as soon as I can how it works out.
Yes, the front of the base plate lines up with the chassis rail, so the other option would be to notch the chassis rail and extend the whole footwell area.
Simon

ps, if you are interested in getting a pedal box from Rally Design, I would be more than happy to be a "gift buddy" if that will save you some taxes (don't we all pay enough?)

Simon,

Well done for that Rally Design dual master cylinder/GTD pedal box link up. May i just ask you to be cautious though regarding the shortness of the pedals and the much lower leverage that the standard GTD "servoless" pedals will give you. You may well still have to "stand" on the brakes for optimum stopping !!!

Regards,

Graham @ GTA

Hi Graham,

Thanks for the advice.
I am retaining the servos that were originally with the car, and all the locating points are the same so my leverage on the balance bar SHOULD be the same as it was with the original master cylinder. I thought that as this load is now spread between two master cylinders the pressure needed would even be less? (I stand to be corrected on that though)
Simon

Would this set up get clearance under a deep throat nostril section? Just a thought. Those master cylinders stick out quite a way.

Next time I fit it, I'll take some pictures and some measurements if anyone's interested. At the moment the front clip's off so it'd be difficult to judge. There's plenty of room with my twin nostril setup (which I'm going to deepen)
Simon

FYI, the master cylinders are 9 inches from the upright plate to the end, and the highest part (where the green bung is in the last picture) is 3.5 inches high, when measured from the flat plate that bolts to the chassis. Hope this is of use to anyone who's interested.
Simon

Hi Simon,

To answer your first question about travel, the geometry of the pedal arms are ideal when the mid point in the stroke results in the clevis pin on the pedal arm to master cylinder being perpendicular to the pedal pivot pin. That way you have minimised the tendancy for pedal effort to change as you depress the pedal. Also angularity of the pushrods are minimised.

This is the only way to go. If you have to adjust the pedal distance for comfort, do it by modifying the pedal arm past the clevis pin or move the whole assembly. Do not use master cylinder push rod length to adjust pedals for driver seating. Been there, done that, bought the T-shirt!

Cheers

Hi Simon, I just read my response again and realized that "the geometry of the pedal arms are ideal when the mid point in the stroke" should have included "stroke of the master cylinder" It may have obivious or not. Hope this makes it clear. As an example the picture below shows our revised CAV pedal tray with clutch slave repositioned in proper geometry.

Cheers