# Configuring Clutch Slip (Or math channels in general) in Race Studio

I need to monitor clutch slip on my rentals and I’m a little (read: rusty) on race studio. Wondering if someone can talk me through it including adding math channels in general. I have an axle speed sensor and RPM of course.

Screenshot below is about as far as I can get: "Error: an identifier, a constant or a symbol is unknown ", I’ve tried correcting the fields and whatnot but still kinda at a loss here.

Couple of questions.

1. Are you using Chain Drive or Belt Drive?

2. If using Belt Drive, does it have a Torque Converter?

The theory is, you create an equation with (Axle RPM times the Gear Ratio divided by the Engine RPM). This will yield a number between 0 and 1 unless the axle is somehow spinning faster than the engine which could tell you when the clutch disengages and the kart is coasting. When the clutch is engaged, the value should be 1. If it drops slightly, then you know the clutch is slipping. A non-slipping clutch should result in a straight line with a value of 1 or very close to it.

A torque converter changes things as the gear ratio is variable. You would have to account for a range in your calculations and it would be difficult to know if the clutch is slipping or just transitioning gear ratios. However, small troughs and spikes could indicate slipping.

It’s belt with a dry shoe clutch. It’s more configuring it in race studio as a math channel to present the graph you described that I’m looking for.

Check this out. It may help.

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Jim,
Try substituting “RPM” for “Engine” and “GPS_Speed” for "Speed#1).
Assuming here that when viewing the Measures tab, your engine speed is listed as RPM and you have GPS_Speed as you speed channel.

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The current version of Race Studio 3, v 3.38.03, comes with version 2.56.84 of Race Studio Analisis. This version of RSA comes with the math channel AiM_Slip_Factor built in and can be enabled in the Measures tab. This channel decodes as slip(RPM, GPS_Speed.

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I’m on a mychron 3 gold so GPS for me, but it would need axle speed anyway. I’ll have another stab tomorrow.

The manual is where I am stuck

May I suggest starting a new Math Channel. Click on Insert at the top left. Type in a name for the channel just to the right. Check the box for Use as Reference Speed. Full Scale is 1.10, Zero Scale is 0.00. With the new channel name highlighted in the left channels column, select Add. It should move into the small box below if not already there.

In the larger box at bottom left, you start to build your formula. The “=” symbol is understood, so you just start inputting your base channels by double clicking on their source name from the middle column, lower right. Should look something like this:

Axle_RPM*GearRatioConstant/Eng_RPM

Select the TEST Channel to verify.

This function becomes undefined when Engine RPM is 0, but realistically the data you want is when the engine is running i.e. above 0. You can type your gear ratio in a (x/X) or build a constant in the upper right box. If all the karts run the same ratio, I would just use the Parentheses to save time.

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What about starting an FAQ Math Channels thread. Where you can get the math channel and it’s explanation. Maybe even a versioned KartPulse Match channel export (and profile).

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It looks like you’re using the variable “Speed #1”, but this isn’t listed in the list of Identifiers. That would be why it gives you the error. Are you intending to use “Speed1” as the speed variable?

I tried different identifiers for the variable and seemed to have the same issue.

Got it to work in the end, I’m sure I did it the long way by having to break it down…
Needed to figure out…

Expected Axle RPM (Engine RPM\Gear Ratio)

Recorded Axle RPM (MPH from speed sensor to Miles per min divided by tire circumference)

RPM Delta of Expected vs Recorded

Represent that RPM Delta as a %

There’s a lot of slipping happening when it should not be it seems. Represented by the blue peaks below. Of course any such peaks that occur while stationary or under engine engagement RPM (1800) speed don’t count. But there’s some BIG deltas showing.

Accelerating between 27 and 38 MPH, seven slip events where the delta is above 16%
Kinda confirmed what I was thinking in that the engine is overpowering the clutch somewhat and the clutch is struggling to cope.

Congrats. I’m fascinated with seeing other people’s solutions to problems. I’d never would have come up with your method.

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Don’t get too excited, it could be wrong It’s serving it’s purpose for now though.