Gunson Trackrite - Can anyone make one of these actually work?

[Mjit]

So my 2000 has always had a slight steering pull to the left and as I needed to replace the track rod ends I thought I'd give my Gunson Trackrite another go...

1. Car on basically flat, reasonably smooth, solid surface concrete car park.  Drive back and forth in a straight line a few times to settle everything, then with steering wheel centred pop zeroed Trackrite in front of/in line with the d/s wheel, then drive slowly over not touching the steering wheel.
2. Jump out and shows a little bit of excess tow in.
3. Tweak d/s track rod length and re-test and showing more or less zero.
4. Check p/s wheel and also showing zero.
5. Got for a test drive and...steering wheel now offset to the left and steering still pulls to the left!

Just retested with the Trackrite and still getting zero on both front wheels.

Driving over I can see the steering wheel rotate to the left as I go over the Trackrite, if I wobble the Trackrite with my hand it slides easilly and smoothly from side to side, and pushing the car over I can be sure the Trackrite's in line with the wheel and I drive over it in a straight line.

What exactly am I doing wrong - or are they just another Gunson tool that should stay on the shelf, like the Clickadjust?

[NonMember]

I would have thought the most likely is that the pull to the left has nothing to do with tracking, which is now spot on.

To keep the steering wheel centred, you should have adjusted both track rod ends by the same amount. A toe gauge can only measure the total alignment of the pair, it cannot tell you which is wrong (since there's no really meaningful definition of that). Similarly, a bit of extra toe-in won't cause steering bias, just tyre wear (even, both tyres).

If it's pulling to the left it could be: brake binding, stiff bearing, camber or castor wrong, flat tyre, mis-matched tyres, twisted subframe/chassis/body, broken spring (though you'd normally see the lean before it matters), brake reaction rod broken/loose/punched through main rail, or just heavy road camber.

[Mjit]

40 minutes ago, NonMember said:

I would have thought the most likely is that the pull to the left has nothing to do with tracking, which is now spot on.

To keep the steering wheel centred, you should have adjusted both track rod ends by the same amount. A toe gauge can only measure the total alignment of the pair, it cannot tell you which is wrong (since there's no really meaningful definition of that). Similarly, a bit of extra toe-in won't cause steering bias, just tyre wear (even, both tyres).

Actually with a Trackrite you're actually measuring the scrub angle of a single wheel at a time, not as a pair so I don't think you ARE meant to adjust both sides?  They certainly don't mention that in their own "How to use a Trackrite" video on YouTube! (But then all the YouTube videos seem to start with cars with correctly set tracking and just go "There you go, the Trackrite shows the tracking's correct!")

I'm actually wondering if the issue is that I've been getting the car 'settled' by driving back and forth while holding the steering wheel in the 'straight ahead' position and just releasing it for the drive over test.  Perhaps to 'settle' everything that should be back and forth hands off, so letting everything go to the 'pulling slightly to the left' position, and THEN set up the Trackrite/drive over it hands free - both lined up with the tyre (so 'pointed slightly left' for a d/s wheel with too much toe in to drive down its centre line) and with the body (so the same toed in d/s wheel will start on the centre line but roll off slightly to the left of it).

Assuming it's dry again tomorrow lunch time that is

[johny]

yes I suppose the normal way tracking is put out is by clipping a kerb or other object with one wheel so the Trackrite can be used to find the error on one wheel and then by choosing which track rod end to adjust the steering wheel should end up centred...

[NonMember]

1 hour ago, Mjit said:

Actually with a Trackrite you're actually measuring the scrub angle of a single wheel at a time

No, you're not. You're removing the scrub effect so that the other wheel isn't scrubbing at all. If you've got a lot of toe-in then the whole car moves toward the trakrite and pushes it further. The thing about adjusting both track rods is nothing to do with how you measure tracking and everything to do with how the wheels work. If you only adjust one then you are moving the steering centre point, no ifs, no buts.

[Pete Lewis]

side slip gauges have been made by many different companies over the years i had a weaver one weighed a lot of Kg but does exactly the same as the current trakrite which i also use as well as the two sticks and a tape measure .

they do measure the combined alignment so you should half the results if you have some idea you need to know what each wheel is doing 

if its set to zero slip and both track rods are of approximately   equal lengths then any drift is as said  other problems influencing the handwheel 

do not dispel rear wheel errors especially on the 2000/2500/|TR /Stag rear wishbone bushes  when a bit tired they make very good rear wheel steering 

and do check the flexible /UJ of the steering column the rubber one can bias the handwheel  ( if it has a rubber one )  

are you sure there is not shift in the brake reaction bushes on the front , these are often fitted wrong way round and without realizing you get a lot of movement you dont want   its dome to the washers and flats to the body bracket    -( ¦¦ )====   

Pete