Topic

I followed Mr Bell's guidance today and nulled out the slight left handed bias on my car which had become apparent once the car was properly set up. If the tyre pressures are wrong, or the ride height or the tracking, you are wasting your time so this was the last job to do. Rob uses a 6 Volt battery across the sensor but it does no harm using a 12 volt one and it allows for finer calibration so that is what I usedwith a decent four digit Fluke DMM. Knowing that Gortour's car was pulling further to the left than Chairman Mao, I made up a small wiring harness to make the job easy and it was. I dialled mine in to about 2.5 millivolts and found the steering weight to be much more similar left to right, so once I had returned from the coven's care home where Madam was visiting her mother, I called Gortour over to adjust his steering which was about 300 mV out. I got it to about 4mV of offset following the deluge during which the car locked him out, A little guile got us back in without difficulty, to his relief and while the fuse box was dislodged, I took the opportunity to add an accessory wire to the spare terminal behind the box which connects to fuse 3. The test run went well, the car responds far better to the helm. Two down today and all we both need to do is fit the UK plates on the back of our MGs and be in Newhaven on Thursday!

Mine being an early car, it has two separate sensor pots and six wires from the sensor. That means that it will be possible to fit a trimming pot between the two to make the adjustment even finer. At present, though, I shall see if it wanders on the autoroute and take my cue from that.

In practice, one takes the red and the white wires from the sensor and places a 100 Ohm potentiometer between them by removing them from the plug and connecting the red wire to one end and the white one to the other. The wiper goes to the connection vacated by the red wire. Starting with the pot centred, (I would use a 10 turn wirewound type,) it will be possible to introduce a bias into the steering and, conversely, trim one out. This only works with the six wire torque sensor and it needs to be done at your own risk, of course. Road testing needs to be done with care. Make adjustments of half a turn, until a difference is felt and then, using your judgement, trim the steering weight to be equal left and right. This is easier than trying to move the sensor on the column to get the last couple of per cent. Effectively, you can get very close at the column and then home in on the sweet spot with the trimmer.

This is a stroke of genius. I’m away at present but have the trim in job to do when I’m home. I too have a bespoke loom made when I trimmed it first time years ago & it’s with the fluke in the workshop waiting for my return & I’m fairly sure I’ve a Bournes ten turn 200r pot, I’ll give it a try.

Thank you. Each pot is about 2200 Ohms so a 200 Ohm swing will give a big variation. I think I would shunt each end to the wiper with 220 Ohms to avoid it being too fierce. Good luck with the experiment.

I’ll experiment with what I have in my bit boxes & if it’s a useful exercise I’ll refine the system, a Chinese ten turn pot of the right value is only a fiver & a long wait, that’s with a turns counting dial.
I’m away for a couple of weeks & there are bits for other projects piling up in the workshop so don’t expect rapid results reporting.