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Brakes! PDF Print E-mail
Written by Peter   
Thursday, 24 January 2008
ImageAdding some stopping power.  Whew, what a project! 

Whew, what a project! It probably would not have been so challenging had I done this project by itself, but instead I combined it with my 5-lug conversion and opened up a can of worms. All previous equipment that worked with the 4-lug setup, that had been proven by many XR guys everywhere, no longer worked. So, I was out on my own!


So what all did I replce you might ask?

- Master Cylindar (from a 94 t-bird)
- Brake Booster (from an 88 XR)
- Front Calipers (Wilwood 6-piston)
- Rear Calipers (88 T-bird)
- Front Disks (Cosworth, redrilled to 5x114.3)
- Rear disks (Mustang GT for now, not vented though)
- Wilwood Prop Valve for rear
- Stainless lines on all 4 corners

Whew. A lot of time, and a litte bit of money too, and unfortunately I'm still not pleased with the result.  Shortly I will update this page with further additions, including:

-Dual MC Adjustable pedal box
-Godfrey two piece hat/rotor system
-Different pad selection


Until then, however, here are the pictures from the first phase of this project.  Scroll down to see the second phase, and I'll update with the third phase soon!


Phase two.  

Rear brakes were locking up before the fronts, and the Tbird rear calipers weren't built for the heat generated during road racing. So, I turned to David Godfrey @ Technical Toys to work up a solution. He developed a bracket to fit a Wilwood Dynalite 4 piston caliper to the rears. So, now my setup is like this:

Willwood 6 piston calipers
'91 Brembo 12" Toyota Supra Rotors from Tire Rack

Wilwood Prop Valve installed by shifter
Wilwood 4 piston calipers
11" Cosworth front rotor redrilled to 4x4.25 from BAT

Since I broke my windshield, I haven't tested the setup at full speed. But at 45mph I can finally lock the fronts of first. Yes!

This was not a straigh forward conversion. First, a front bracket had to be made to fit the larger Supra rotor. Again, Dave at Techical Toys came to teh rescue. Once I had the bracket, the installtion of the fronts was a snap.

The rears, however, were more difficult. I have a Scorpio rear hub assembly, and the bracket was designed for an XR (which is smaller). So, fortunately I have Dan at Valley Precision to do some mill and lathe work. In the end, I had to have the hub machined down to fit the Cosworth rotor, and I had to have the bracket hole enlarged to fit the Scorpio bearing carrier.

I replumbed the rears completely, bringing the brake line to the inside of the car and down the transmission tunnel, right before the shifter. This allows easy tuning while on track to get the brakes just where they need to be. Once it's set, I'll probably leave it, but this way I didn't have to get out of the car, try it out, get out of the car, try it out, etc.

Sadly, once it was all together, it still wasn't right. I could still lock the rears before the fronts, even with the prop valve on full restriction.

So, I got out the pressure gauges I got from Racer Wholesale and found a very interesting discovery - at full brakign force, (and with the prop valve open) I could get 750psi to the rear, yet only 400 psi to the front!

I check three reliable sources and all promised I had the MC hooked up correctly, but on a hunch I switched the front/rear side of the MC, and the problem was solved. Finally!

Thanks to Sean for the late night help before the track event!




Phase three:  

Right now, I'm in the planning stages.  but I do have a few pictures I'm going to post for reference.  Once I get it all together I'll update this with the parts I actually used...


Last Updated ( Tuesday, 29 January 2008 )
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