Brake test

M

mmarshall

Member #053
Location
Florissant
First Name
Mike
Last Name
Marshall
To tide me over until we can get together and do the brake test I started collecting data just for fun and for comparison. It is a little cold today around 63 degrees for the data collection, but the results were better than expected.

I have a Samsung android and have found the sensors to be fairly close. I found a program called Garmin Mechanic. It has a skid pad function that records current and max G's lateral and braking / acceleration.

I tried a few faster corners and could average 1 - 1.10 G's before I got scared. I then tried some slaloms and recorded max of 1.27, 1.35, and 1.31 G's lateral. I have seen 1.29 before.

Under braking I found the front brakes locked at 1.10 to 1.20 G's depending on the pavement. I found some smoother blacktop and did a low speed braking and locked the rear near the very end of the stop and recorded 1.28 G's.

Now I am not sure how accurrate it is but if you zero it with the phone vertical and lay the phone on it's back it reads 1.02 g's. So at the 1 G mark it is off by 2/100 of a G.

November 2010 Road and Track did a track test of a bunch of cars. They recorded the ZR1 at 1.17 G's braking and lateral. The stock M3 only did .92 G's braking and .96 G's lateral.

I am looking forward to more testing.
 
Good tip

Mike
Forgot about the app's on the phones. iPhone has a similar app.

While the actual numbers may be suspect, the relative numbers will be very useful. You'll be able to tell if you're making it better or worse.

When do you plan to do this brake testing? I'd like to be involved, along with my car.

Paul
 
Paul I am not sure about the date. We need to find a good location for multiple cars to be involved.

I have had the phone in 3 other cars.

1. 2005 tundra - pulled .69G's before it started to slide.
2. 2002 Odyssey - .75 G's
3. FFR roadster - 275F/315R, 4 link, bilstein shocks - it pulled a max of 1.1 G's in a parking lot with very good grip.

Based on those 3 other vehicles I think it is not too far off. Our daily drivers were close to what magazines have tested them at. The roadster may be a little high which would make mine a little high. I was suprised that I was .2 G's higher than a stock FFR roaster. I just need to spend a few minutes side by side with a G-tech to note any errors.
 
Dynolicious

Mike
I have an iPhone with the Dynolicious app. does much the same thing, relies on the accelerometers in the phone for the read-outs. We can add those readings to the mix and see how they compare.

Your recommendations on a site? What size is needed or desired? I assume the more remote it is, the happier the neighbors will be and less likely a visit from the Gendarmes

Paul
 
I've.....got....an....idea.... will try and go check it out today.
 
If you find a place, DON'T do it next week, it's Bad Luck to test the last week of May! :eek:

(actually, I'm out-of-town and would miss all of the excitement! :rolleyes:)

I wanna see this, I'm very curious. This is intriguing.
 
Include me in that too. You've peaked my curiousity. Never a good thing (at least according to my wife.)
 
I leave town tomorrow so no testing this week.

I did a few more tests today due to the bossman not making me work today. I have a hydraulic valve for a parking brake plumed into the rear system. To set it I stomp on the brakes and then turn the valve which traps full line pressure in the rear system. So today I tried some braking tests with my Proportioning valve turned off (no reduction to the front system) and then turned off the rear brakes completely using my parking brake valve.

Here are the results:

Full brakes (yesterdays test) - 1.28 G's
Proportioning valve off - 1.05 G's
Rear brakes off - .75 G's

So it appears that there is about a .23 G difference between a normal mustang system with no proportioning valve and my proportioning valve system using threshold braking. There also appears to be a .30 G difference between the normal mustang system and using the fronts only.

Even with the proportioning valve off I was able to get some spikes into the 1.2 G range by pushing on the pedal so hard that all 4 locked up. So if you panic brake in a normal system and can lock all 4 tires then any cobra will stop as fast as mine. The problem is we are trying to threshold brake on the track and street so we maintain control of the car. Everytime I have locked the brakes on the track the car stopped turning and went straight off course. At 120mph at Putnam that is not so good.
 
mmarshall said:
I have locked the brakes on the track the car stopped turning and went straight off course. At 120mph at Putnam that is not so good.
Click to expand...

I think this is the key point. You don't want to lock up at anytime on the track - you'll always just slide. But with the proper set-up you'll be able to control your braking.
 
I've only ever locked up once on Putnam, and yep, drove straight off. But have never locked up in to turn 1. I've always been able to control the braking in to 1, and I'm sure I am losing some time/speed by braking earlier than some, but my braking zone is getting deeper. I haven't had my car want to swap ends yet, but first time for everything. Thinking of going back to Putnam July 30/31st (see thread in road course area).

I didn't get to go out to area 51 ;) yesterday, have a lot going on right now that ranks above a brake test.
 
Will get back to you, this past week has....well been interesting. I've got to get my son moved out of his apartment by Friday, and taking Linda to Ribfest Saturday. So, Sunday may be the first time I get out to look. There's a place out off of Hwy 94 near the airport (Smart field?) that has a long straight of road with very little traffic on it.
 
Was at Omer's today and he said he had this tool to check caliper pressures. He had never used it though. He pulled it out and let me borrow it. I told him I may have it a couple weeks. Will be interesting to see if the pressures are equal on my front calipers. Let me know if you are interested in using it too.
 
??

Tim
What is the name/brand of the tester. I assume it is some type of hydraulic or electronic pressure gage that installs between the pads? or is it a gauge that goes in the line?

Paul
 
Gives a much more accurate reading of the force actually applied at the rotor.
The other gauge will give the line pressure but does not factor in any possible problem that could lie within the caliper.The other thing I like about this gauge is the fact you do not have to tap into the brake line, or bleeder, and run the risk of bringing air into the system.

Nice tool...

Skip
 
Omer said we could borrow it as a club for as long as he didn't need it :D I will try this thing out soon, after Hallett that is.
 
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