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The mkiv Supra Owners Club

Where to install a brake pressure sensor?


Wez

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By the M/cylinder, one in the front circuit, one in the back. I'd need to sit down and think just how the ABS would affect readings. Can you log it?

 

I was hoping I could do it with a single sensor as they are £150 each, they will be wired into a datalogger so yes logging will be possible.

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This is the sensor I am looking at, what would be the best way to install them?

 

image

 

Description

Manufactured by Bosch, this brake pressure sensor is specifically designed for measuring the high pressures in automotive braking systems. It is extremely robust and resistant to brake fluids, mineral oils, water and air.

 

Technical Data

Pressure range (bar) 250

(Mpa) (25)

Offset accuracy (Uv) 2.0%

Sensitivity accuracy at 5V In range 0...35 bar FSƒU of measured ≤0.7%

In range 35...250 bar (value) ≤5.0% (of measured value)

Power supply voltage Uv (V) 5 ±0.25

Power supply current Iv (mA) ≤20

Output current ID (uA...mA) -100...3

Output voltage (V) 0.5 - 4.5

Temperature range (°C) -40...+120

Overpressure max. Pmax (bar) 350

Burst pressure Pburst (bar) >500

Tightening torque Ma (Nm) 20 ±2

Pressure port thread M10 x 1mm pitch

Overal length (mm) 55

 

Note: All data are typical values

 

Design and function

Pressure measurement results from the bending of a steel diaphragm on which are located polysilicon strain-guage elements. These are connected in the form of a Wheatstone bridge. This permits high signal utilisation and good temperature compensation. Part of the evaluation IC is applied for a diagnostic function which can detect the following potential defects:

- Fracture of a bonding wire to the measuring cell.

- Fracture anywhere on any of the signal lines.

- Fracture of the bridge supply and ground.

 

Following switch-on the sensor runs a self-test diagnostic function checking for correct calibration and functionality. During normal operation a diagnostic function checks for errors. If an error is detected, the signal output is switched to the voltage range >96% Uv.

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Wez, if Chris' instructions mean more to you than they do to me, please take 'how to' style photos when you follow them, ta. :innocent:

 

Stupid question: why not rig up a crude brake pedal position sensor? I know it's not going to be as accurate (e.g. is brake pedal position proportional to brake pressure?) but what does that exctra acuracy give you, Wez?

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To get accurate front and rear brake pressures, wouldn't the sensors have to be fitted after the proportioning valve?

 

Good point, does the MKIV have one? Or does it rely on multi channel ABS for "proprtioning"? I know the UK spec has a more sophisticated ABS than the J-Spec. Ripping the ABS off altogether would simplify things. Fitting the Bosch Motorsport configurable ABS would be awesome, but probably bankrupting.

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Wes,

 

I think what you're more interested in rather than the amount of pressure being applied to the discs, is how much force you're hitting the brake pedal with? If so then putting the sensors post ABS might be a bit misleading as I'm not sure how the ABS regulates the pressure?

Imagine if you brake into a corner and the ABS kicks in, you're going to end up seeing fluctuating pressures which would have little to no correlation to pedal force.

 

Chris,

 

If Wes was to place a sensor between the master cylinder and the ABS pump, would that give a direct indication of pedal pressure?

 

At this stage in his racing career I would imagine he's looking to get driving consistency?

Of cource the ultimate set-up would be to monitor pedal pressure (or even position) as well as pressure at each caliper (although on each circuit should give very similar results).

 

What do you guys recon?

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  • 5 months later...

Digging up this thread as I am in process of ordering everything to fit the sensors, I decided that near the MC is the best place but without pulling the lines out does anyone know if the M10 x 1mm threads are inverted, concave or flat?

 

I am planning to use a single -3 output bango fitting to the sensors with a -3 M10 x 1mm bango bolt out to a female -3 M10 x 1mm adapter but need to know the seat type.

 

:thumbs:

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I am 90% sure the M/C has inverted flare seats in it. They certainly are not flat! Just flare the pipe end to suit if using hard lines. The fitting will be the same on hard lines.

 

Where is the best place to get the hardline parts, I have been looking at getting the bits needed from speedflow.

 

 

This is an inverted seat

http://www.speedflowshop.co.uk/ekmps/shops/speedflow/images/231_cut_away_08.07.gif

 

 

This is a concave seat

http://www.speedflowshop.co.uk/ekmps/shops/speedflow/images/female_concave_metric.gif

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Hadnt thought about the hardline option, I could cut the stock line back and fit a -3 fitting using a flaring tool, then run a new -3 line from the MC and sensor into a -3 T-Piece.

 

How does that sound?

 

Would this flaring tool be any good, they retail at approx £26

 

http://www.screwfix.com/sfd/i/cat/35/p1159535_x.jpg

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