Nashville road tour

[mmarshall]

Last day to early register.

I will be there with my Daytona Coupe, who else is going?

[P_Matt]

Bob Stuke and John McIver will be there. I was all set to do it until I sold my car. I'll be heading out your way to pick up my new car. Good luck. Have fun.

[bstuke]

Yep. PM'ing you my wireless number. I am staying in Murfreesboro. Happy to have you hang with the ATL group if you are alone...

[mmarshall]

Here is a course map for Nashville:
http://solomatters.files.wordpress.com/2011/10/nash.jpg

And a video preview of where we will run:

TN SCCA Auto-X (Nashville Track) - 7-25-10 (2).mp4 - YouTube

TN SCCA Auto-X (Nashville Track) - 7-25-10 (2).mp4 - YouTube

[bstuke]

Too funny you post that particular video Mike. James is a co-worker...

[NBWW]

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[P_Matt]

It is 29 - 30 October.

[jirehn]

I guess this will really have a fun.

[NBWW]

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[bstuke]

Schedule

http://www.scca.com:8080/assets/2011NashvilleSupps.pdf

[mmarshall]

Originally Posted by bstuke

Schedule

http://www.scca.com:8080/assets/2011NashvilleSupps.pdf

You read my mind as I was just looking at it today.

[mmarshall]

I had a blast at Nashville. It was pretty cool running on a Nascar track and I learned alot at my 1st national level event. Thanks Bob S. and John M for all the help! I promise to be faster next time and give you guys more competition. You can hear on the video that I spent alot of time on the rev limiter and did not have enough top speed for the faster sections. Looks like I may have to swap to a 3.27 gear to rectify that situation.

Here is a video of one of my runs: stlmarshall's Channel - YouTube

[bstuke]

I had a blast as well. Great meeting you two. Are we on for Blytheville next year?

My two best runs:

[mmarshall]

Planning on Blythville! Any idea of dates yet?

BTW was that a shift to 3rd in the 1st video on the back straight?

[bstuke]

I'll post the dates as soon as I know but it won't be till next year.

Yes I did shift into third on Saturday.

[NBWW]

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[bstuke]

I figured out that there are a lot of things you can do to get a balanced brake system. Prop valve on the front, different pad combinations and such.

The only real solution to me, is a dual master cylinder of some sort. That way you can utilize the correct bore master cylinder for your front and back brakes to get a good balance, and then fine tune with bias adjuster.

That could be the CNC dual master, which is bolt in.


It could also be the Tilton remote mount pedal assembly, which requires fabrication.


The benefit to these solutions is that they are external to the footbox, so easy to access and easy to work on. The Spec cars like this.

The CNC unit is a little harder to work on in that the MC is CNC's own design with a reservoir built in. The Tilton needs a bracket fabbed to work, but uses a more universal MC, which can be tilton, Wilwood, etc.

The third dual MC solution is the Wilwood that FFR provides, and FFR and Forte make a bracket for.


There is nothing wrong with this solution either. The only challenge is that it is mounted in the foot box, and difficult to get at and work on. If I were to go this route on a new build, I would split the top cover, and make the inside portion removable. I would also run all of my electronics on the passenger side to keep that out of the way of the footbox. The other benefit is that you can also go hydraulic on the clutch, and have a nice tidy installation.

I am leaning towards the Tilton, which will suit my autocross/track requirements,and Mard D is going to fab some brackets. I think the spec guys will go this way as well. John McIver has the CNC on his XP car, and he is happy with his.

So I think it comes down to what works best for you.

[Wade Chamberlain]

I have the dual CNC on my car, along w/ a cockpit mounted bias control. I like it alot. If you're not happy w/ the integral reservoirs, I believe you can get remote reservoir M/C's as well.

[NBWW]

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[mmarshall]

Bob how come that brown towel in the CNC pic looks so familiar?

Please don't underestimate the need to increase the effectiveness of the rear brakes before trying to balance them. When I had the CNC setup I went fully rear once and found it had no braking at all. That is because the single piston cobra rears are just too small to work properly. I now wish I had tackled the rear brake problem 1st before switching to hydroboost. If I had I may still be using the CNC setup today. Get the brakes close to balanced 1st, then tackle the fine tuning.

[bstuke]

Originally Posted by mmarshall

Bob how come that brown towel in the CNC pic looks so familiar?

Nope, just a pic from the internet..

Originally Posted by mmarshall

Please don't underestimate the need to increase the effectiveness of the rear brakes before trying to balance them. When I had the CNC setup I went fully rear once and found it had no braking at all. That is because the single piston cobra rears are just too small to work properly. I now wish I had tackled the rear brake problem 1st before switching to hydroboost. If I had I may still be using the CNC setup today. Get the brakes close to balanced 1st, then tackle the fine tuning.

Totally agree. Looking for someone to fab those PBR brackets for me, since my fab skill are less than Lego or Lincoln log.. Know anyone?

It looks like Baer has a kit that uses a PBR, but it is single piston. It would be nice to have the same pad type and part number on the front and back.

[Wade Chamberlain]

Originally Posted by mmarshall

That is because the single piston cobra rears are just too small to work properly.

That's a pretty broad brush statement....LOL... . I run cobra brakes on my car w/ the dual CNC's. I've had Carbotech XP8, AX6, and stock cobra pads on at different times. In all cases, I've been able to perfectly balance the brakes to the point where 2 or 3 clicks on the bias control will change which end locks up first if I step over the line when threshold braking. The fastest 3 FFR autocrossers in the DC region all run cobra brakes w/ dual masters and all are very well balanced.

If you couldn't balance yours, there was something else wrong.

[mmarshall]

Originally Posted by Wade Chamberlain

That's a pretty broad brush statement:

Wade I have had brushes with broads before! My opinion was formed from extensive testing on my single piston cobra rears. You know what they say about opinions.

I started with the standard Jeep MC and Cobra brake kit. To improve braking I changed to the CNC MC. With it dialed fully to the rear I could still not lock the rears. I then installed a hydroboost and a proportioning valve in the front circuit. With the front reduced 57% I could barely lock the rears with max effort braking. I then tested the brakes with a tool that measures actual clamping pressure at the caliper. When the front GT calipers were at 1000psi the rears were at 250psi. This explains the imbalance with the PV. Even with the fronts reduced by 50% they were still providing double the clamping pressure of the rears.

This is when I decided to make a major change. I made some brackets to mount 94 Cobra 2 piston PBR's on the rear. I am still running these, and have found the system to be very balanced in testing and at the track.

So if the single piston rears are ok for a balanced system then answer 2 questions that I have been chasing around in my head.

1. When I reduced the front circuit by 57% why did the bias not go too far to the rear?

2. When I doubled the caliper surface area with the PBR's why is the bias now perfectly balanced? How can a 38mm single piston caliper give the exact same bias as a caliper with two 38mm pistons? This goes against the laws of physics.

Here is the thread about my brake mods:
New brakes for the back

[Wade Chamberlain]

like I said, there was something else wrong. If I cranked bias all the way to the rear on my car, it would lock the rear INSTANTLY if I so much as breathed on the pedal...even with 315 A6's.