Jump to content

Gear Shift Control

Anthony Parle

Recommended Posts

Okay so I must be missing something in the setup of the Gear Shift Control or maybe not,

In the software it has the ability to lock out a gear change if the conditions are not correct, so for example if the rev's are to high then it prevents the gear changing down.  The bit I don't get is why would that feature be in the software if it doesn't have the ability instigate the change.  In other words if the driver pushes the lever forward with a sequential gearbox the box will change and the ECU has no ability to stop it.

The bit I may have missed but can't find, is the ability to output a digital event if conditions for the change are correct.

Link to comment
Share on other sites

Hi Anthony,

The gear shift control on our ECUs is not currently set up to control the actual physical shift of the gears, it is there to control engine torque output to assist with shifting. It may be possible to make the ECU control the actual physical shift, but this would be through the GP Outputs, timers, and other functions that are not specifically designed for this. 


Link to comment
Share on other sites

Hi Tony,

The attached image of settings from PCLink show how it may work.

The digital inputs start the ECUs gear shift torque reduction and also the timers. The aux outputs then activate based upon the timers, causing the actual shift to occur. The values I've put a red dot next to would need to be adjusted to suit the actual time requirements of the system.



Paddle shift.PNG

Link to comment
Share on other sites

Hi Scott,

Please accept my apologies up front if I am teaching you how to suck egg or have the totally wrong end of the stick,

If we do it the way you suggested it will execute the gear change even if for example the rev's are to high to change down.  This is because the activation is brought about by input from either DI 1 or 2.

Right now I haven't got my head around it completely but it would be smarter to use the 3 conditions in a different way,

Say for up shift,

RPM > 1,500

Fuel Cut % >95%

Ignition Cut % > 95%

What you need to do is find 3 conditions that only occur during the gear change up.

The up just needs to be different to the down.

If would could Latch D1 & D2 then unlatch after Aux 1 or 2 had done there job that maybe even better as they will stay latched till the rest of the code in the Gear Shift Control starts its bit then away it goes.

Its also possible to set up say fuel cut to be within a tight range when you want the change to occur,

Fuel Cut % > 65 % and Fuel Cut % <= 67%

Maybe even have Aux 1 that allows up Shifts when the gear shift control is functioning and Aux 3 that does it direct input from D1 when its not.  Not reason other then being tidy that you can't have two GP Outputs for up and 2 GP Outputs for down.  Might need to use diodes to stop the outputs shorting.

As the saying goes "There is more then one way to skin a cat"

I think the gear change part of the PCLink is a lot better then I thought it would be.  Its a great problem to nut out should be fun.

Keep well and thanks for the help.


Edited by Anthony Parle
Link to comment
Share on other sites

Hi Tony,

You would be in no ways telling me how to suck eggs, I've never set up the gear shift control myself on a paddle shift system.

The conditions used for activating the Aux Outputs are many, and spending some time testing and thinking will produce many possible solutions. One thing to consider is if some other combination of the conditions could cause the Aux Output to switch on also, for example, when a hard rpm limit is active the conditions you listed for an up-shift could be met.

Let us know what you come up with, I'm sure it will be useful for others in the future who want to achieve the same thing.


Link to comment
Share on other sites

Simon without knowing the code behind, should be an output or maybe an axis option that can be span with gear cut status not be very easy to to span? Isn't it?  

With a gear cut status axis, pwm table can be spaned to define what combination of gearcut status and rpm shifts are physicaly outputed. 

Link to comment
Share on other sites

The best would be if we had a bit of maths on the up and down shift.

If we assume we have loaded the rotary voltages into the "Gear Detection" section of "Chassis and Body"

Then on the up shift it would be

Current gear plus 1 --- End shift

On the down shift

Current gear minus 1   ---- End shift

The existing part of the program already has the current gear in a register in the program and it will instantly know when its in the new gear.  In fact I would expect that the "Current Gear" had to be Stored to stop it being changed during the "gear Change action"



Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...