UGH... DFL this weekend. Lot's of brake questions!

[bstuke]

So I removed the PV from the front over the winter, bled the brakes, and headed off to Dixie Nationals.

I had zero back brakes, and the fronts lock up way too quickly. I'll post video so you can see..

Jeff at Whitbys is designing a new bracket that will locate Wilwood dual masters outside(YEAH!) and the balance bar inside the footbox. Marty already has this on his Challenge car and it looks promising. John George has done some testing as well and likes what he has seen.

Of course AutoX is a little different. We don't use the brakes much, but when we do, we need balance!

What I decided to do in the meantime is see what I can figure out in the next few weeks that will help me understand what I need from a brake perspective.

I am running PBR fronts 13.65 with Hawk HP+ and GT backs 11.65 with Hawk HP+.

So I bought two Longacre brake mount gauges. They plug in to where the bleed valve goes. That way I can test my pressures and get an idea of where to start.

So where to start?

What are your thoughts about pads?

What are your thoughts about what pressures I should see? 500PSI? 750PSI?

And what do you think about a ratio front to back? 50/50? 60/40? 61.2/38.8?

Thanks in advance for comments, uncontrollable laughter, jokes, or questions about how bad I got my *** whipped by Jason, compared to Nashville last year.. Feel free to pile on.
__________________
FFR 4615 - MkII: 302 FRPP Crate Motor
B Cam - FAST EZ-EFI - T5 - 3 Link

"My car is a celebrity and I'm just along for the ride." dv/dt
"We don't just build cars, we build friendships and memories" Chip Foose

[CHOTIS BILL]

When I was running my DSR with Wilwood breaks the best pad I found was the Wilwood "A" pad.
It had great initial bite even when cold and was easy to modulate. They were gentle on the
disk but did ware rather quickly. This was on a DSR that only weighed 850 pounds and had
several thousand pounds of down force so YMMV. I am thinking about trying them out on my
coupe when I change pads.

I had the same gauges and I found that you need to press on the brake peddle at least 3 time
to get a reading that repeats. I would run around 600 psi in front and 300 to 350 psi in rear
to start and adjust from there. I never checked the pressure while driving but I don't think
it ever went over 800 psi. My weight distribution while sitting still was about 47/53 front
to rear so I would think your adjustment would be different but 600/300 psi would be a good
starting point. Another way I setup the initial brake balance to use a block of wood and
depress the brake peddle and check how much torque it took to turn the wheels. I made a
plate that would bolt to the wheel hubs with out the wheels on and it had a ½" square
hole in the middle so I could attach a bending beam type torque wrench. I would set the
break so that it took about 100 pound feet of torque to turn the front wheels and that
set the brake bias so it took about 60-65 pound feet of torque to turn the rear wheels.
This was always pretty close to correct.

[johngeorge]

bstuke, what size masters for the front and rear? what is your pedal ratio? what pedalbox do you have?

I data-log brake front and rear pressures and will tell you after VIR Mar 23-25 as that will be the first time with the 13" PBR fronts/GT rear..

87-93 front calipers with 13/16 front master, and GT rear with 5/8 master I was around 600psi front, 1200psi rear (Carbotech XP10 front, Carbotech XP12 rear.)

[bstuke]

Bill,

Thanks for the info, That is exactly what I was looking for, a starting point. Did you run Solo B Mod as well? My buddy Perry has a LeGrand and runs B Mod. He is in the middle of installing a diff instead of the solid axle.

John,

Thank you for that as well, happy to hear the info you gather at VIR. If you were down here last weekend sorry I missed you.

I am running PBR fronts like you, and I suspect the same 11.65 backs with a GT caliper.

I think you went to 7/8" on the front? According to your other post and a conversation I had with Marty. And 5/8 on the back.

I am waiting to get the brackets Jeff made for Marty. Having all that in the footbox just makes it such a paint to service.

Good to hear on the softer pad on the back. I am going to leave Hawk HP on the front since I already use them, and go with Hawk HP+ on the back.

Oops. I current have a FOX pedal box, unbent pedal, and a Whitbys vacuum booster and Cobra MC.

[johngeorge]

You are correct, I switched from 13/16 to 7/8 for the front MC when I went to the PBR brakes. Still keeping Whitby's vacuum booster or switching to manual brakes?

[Jim Schenck]

Also John is running the 10.5 inch rear rotors which would throw the bias off a little more to the front as well. It might be that the rotor size difference and the pad compound difference would offset each other so you could run the same master cylinder combo as John but with the same pad compound front and rear, no way to know for sure until you experiment a bit but should get you pretty close.

[mhoward1]

I'll also post my results with the Whitby setup on the VIR weekend.

[bstuke]

Ok,

1000-1100PSI on the front, PBR caliper, motor running
700-800PSI on the front, PBR caliper, motor NOT running
1200-1300PSI on the back, GT caliper, motor running
900-1000PSI on the back, GT caliper, motor NOT running

John, Booster will go away, pedal mod may be needed. I will cross that bridge later when I get it closer. With those pressures, maybe it should go away now?

Jim, You rock dude! Thanks for chiming in, I appreciate your support.

Marty, as always thanks for the feedback, I look forward to yours and John's feedback on the new brakes, and anyone else that wants to comment.

[bstuke]

Back Brakes

http://youtu.be/z8AIVnp8u1o

[bstuke]

Front Brakes

http://youtu.be/8WmbZcqsiaI