Any of you data logging caliper or axle to axle brake pressure?

Any values you would like to share? MC diameter and what not as well.

Curious if this is a valid data point and worth the time and money in sensors for identifying problems with components.

Thanks!

sander

 

I am not, but know many teams do.

It is very valid, and combined with other sensors can tell you a lot.

IE brake pressure sensor and wheel speed sensors can be used to see where thresh hold braking is. How much rear bias can be put in before you start having rear lock up issues.

It can also be a good tool for driver coaching.

A brake pressure sensor by itself with no other sensors probably wont tell you much though.

 

http://www.race-technology.com/brake_pressure_2_68.html

The DL1 has a Brake Pressure sensor. I log the brake pedal switch, which works well enough for my use.

 

Thats interesting, Id be willing to bet money that is the same Bosch pressure sensor used on almost ALL of the later BMW DSC Hydraulic modules.

http://www.realoem.com/bmw/showparts...32&hg=34&fg=20

#3.

I am using a dash logging unit (PCS), with RS-232 comms with AEM, I have a number of extra 0-5v inputs left, I'd like to start logging brake and suspension travel stuff. I have just enough inputs for 4 corners of travel sensors and 1 brake pressure sensor.

Is a 3500 psi sensor (Assuming I would use the DL1 sensor linked above) needed? Something with tighter resolution? 2000 psi?

good points listed here, thank you guys for your input.

 

Seriously, I couldn't imagine looking at data without the brake readout. It helps so much, even if its just to spot random driving mistakes like fluctuation while downshifting and other similar problems.

 

I use the Race Technology DL-1 as well and have logged the brake switch in the past but a braking problem at the end of last season motivated me to measure the brake pressure as well. I don’t have any values yet as the car is still on jack stands but as a data point Motec sells a brake pressure sensor made by Honeywell.

http://motec.com/sensors/pressure/#fluid

If you click on the link for the 2000 psi sensor you will find the link to the data sheet for the MLH series of sensor. Motec is a great source and they already have the right connector but if you are willing to put your own connector on then they can be purchased from a number of different sources. One online link is:

http://search.digikey.com/scripts/Dk...9&keywords=MLH

From there you can choose pressure range, thread type, electrical connector style etc.

A direct link to the 3000 psi version is here:

http://search.digikey.com/scripts/Dk...me=480-2537-ND

I went with the assumption that Motec sells a 2000 psi version and so it’s likely the brake pressures will be under that limit. Further reading seems to confirm that pressures are about 800 – 1400 but that is just a guess for now until I get out on track.

Another company that provides pressure sensors and in fact many of the AiM products sensors are made by them is Measurement specialties.

Having just looked as some data that had the measurement it is very revealing. What happens to the brake pressure during the heal and toe downshift, trail braking can all be seen. The brake switch was a good start for me but the pressure so provide that much more. IMHO

Dave
#76 IP2 / ITS GSR

 

I will be logging Brake pressures on my new car using a DL1, But car is not done yet.

 

Dear Sander,
I hate you and your little gold box.
Sincerely,
Spencer.


brake pressure would be huge to monitor. using that info to your advantage will go along way.

 

Here is a link for the technical data on the Bosch pressure sensors that you would require for calibration:

http://apps.bosch.com.au/motorsport/...ghpressure.pdf

The 14 MPa one is good for 2000 psi while the 25 MPa one is good for 3625 psi

 

Wow, thank you for that. Bosch always seemed very through with their documentation, but that is excellent. Thank you.

IP2GSR, Thanks for the links regarding the available sensors. I was aware of the Motec sensors although I was trying to look for a more affordable sensor if at all possible. The Bosch sensors are great just because I work at a BMW and Mercedes shop, and now with those bosch x xxx xxx xxx numbers provided by descartesfool, i would be able to look those up against any of the available BMW sensors and get the connectors and pins next day if the numbers cross over properly.

I'll check tomorrow and see if I can dig up dealer part numbers if the sensors are the same.

 

This book has a very nice chapter on data logging brake pressures and other things to do with brakes. I would highly recommend it:

http://www.amazon.com/Competition-Da...6341030&sr=8-1

 

Success!

0 265 005 303 Bosch PN. 250 Bar Sensor. The calibration chart is provided by descartesfool.

IS

34 51 1 165 467 DSC Pressure Sensor Available at any BMW Dealer.

Working on finding the plug and pins now.

Sweet!

 

Also found the connector and pins I believe. Have them coming on tuesday. I will report then.

That sensor at cost is only around $110.00 I believe.

 

That is a GREAT book any who owns, or wants to own a data logger should buy it.

 

what do you guys think of measuring brake pedal position vs pressure? and is measuring both redundant/overkill?

itd be easier for me to measure pedal position with a simple LVDT, rotary pot, or adapt a TPS even.

i know AIM sells turn-key brake pressure sensors. but you know, gotta pay...

 

IMHO pedal position is not useful unless you want to diagnose problems with your braking system like kickback, fade, pedal sinking, etc

 

At cost that is a great price but for others that don't have access BMW parts at cost the Motec Honeywell sensor is $81. Connector and harness also avalible from Digi-key if you don't fancy the flying lead options.


edit..... I just realised that I posted the wrong part in my first post since it was a 4-20ma loop type output... That is NOT what you want. Sorry.

The correct type is the 0.5-4.5 output as shown in the bosch data sheet.
The correct link is
http://search.digikey.com/scripts/Dk...me=480-2537-ND

the digi-key part is 480-2537-ND for the 3000 psi part


Dave

 

all that sounds horribly useless to diagnose...

 

One would think that they would be mostly linear, no?

 

Awesome, I had that in my head as much more expensive. And, its standard thread which is excellent for this side of the world that still uses the fractional system.

 

but when its not....? isnt that why you log things? you dont care about how it helps you realtime, but to look back at the data. if every lap you try to run the same lap, but brake pedal position changes vs speed over time, then wouldnt the difference mean something? help diagnose an issue?

i dunno. its why im asking.

otherwise, what does brake pressure alone tell you? vs pedal position?

 

I guess I would ask are we trying to find car problems or driver problems?

- If it is just to get a understanding of what the driver did then I think brake pressure or pedal position will get you "pretty" much the same information. Did the driver react to the car and use more or less brake or did the car react to the driver's application of the brake. The data can show these things and no matter how you get the data it is valid.

- If we are looking for problems in the car then measuring brake pressure can be more relevent since now we can measure front to rear bias (2 sensors). Pad knock back with small periodic spikes in brake pressure proportional to speed. etc. If you have wheel senors then we can compare brake pressure to when a wheel locks and compare that to max deceleration rates.

If we measure both the pedal position and brake position now we could see if there are some non-linear characteristics in the master and brake booster but to be honest I don't think this is common or very relevant in trying to go fast.

I don't THINK you would see brake fluid fade since this is really a measure of the displacement on the piston vs pressure applied. The air in the fluid compresses more than the fluid for the same applied pressure.
I also don't THINK you would get a measure of brake pad fade since this is not being measured. The pad has a reduction in the friction for the same applied pressure.

IMHO.... your results may vary

Dave
ITS GSR

 

yeah, i think i care more for driver improvement at this point.

my goal is to set up the data aq we have to log driver inputs and feedback. have faster drivers the car and compare. at this point, between my teammate and i, its a matter of confidence. the knowledge of being able to match or at least know the limits of the car in advance, would help get us to the limit faster, safer.

thats why TPS and brake pedal position is slated for the 2 available channels i have.

 

I would do the brake pressure sensor. The brake pressure sensor is 149 from AIM vs. 105. not much of a difference and the data will be much better. Too many things affect the pedal position in my opinion.

 

i already have an old linear transducer i've been saving for this purpose anyway. it runs off 5v, perfect for the mychron, i hope.

i dont see what you mean by too many things affect pedal position. it will always spring back to its original position. plotting position vs speed, what more is pressure going to tell you?

the TPS also runs off 5v too. so if i wanted, i could turn a stock TPS sensor in a rotary sensor anyway. theyre pretty cheap off the junkyard....